C u rre n t c o n c e p ts o n th e tra n s m is s io n o f b a c te ria a n d
p a ra s ite s b y b lo o d c o m p o n e n ts
Hospital Sirio-Libanes
Blood Bank, Siio Paulo, Brazil
Several bacterial and parasite transfusion-transm itted diseases have been described in the m edical literature. This review deals w ith the m ain bacterial (Syphilis, Lym e disease, G ram positive and G ram negative agents), parasite (C hagas disease, m alaria, leishm aniasis, toxoplasm osis and babesiosis) and rickettsial diseases that are carried by blood products. Preventional aspects (e.g. storage, screening tests, use of leukocyte-depleted com ponents), diagnosis, geographical distribution and the incidence of these transfusional hazards are also discussed.
U N ITER M S: Blood Transfusion. Infectious D isease. Bacteria. Protozoars. Viruses.
IN TR O D U C TIO N
I
nt h i s e r a , w h e n v i r u s e s a r e t h e m a i n a g e n t s o f T r a n s f u s i o n - T r a n s m i t t e d I n f e c t i o n s ( T x I ) , o n e h a s a l w a y s t o k e e p i n m i n d t h a t o t h e r n o n - v i r a l o r g a n i s m s c a n a ~ s o p l a y a r o l e i n m a n y T x I , s u c h a s b a c t e r i a a n d p a r a s i t e s .Transm ission of bacteria/parasites by blood products: som e com m on features
T h e r e a r e s e v e r a l a p p r o a c h e s t o p r e v e n t T x I : t h e f i r s t o n e i s r e l a t e d t o a n a p p r o p r i a t e s e l e c t i o n o f b l o o d d o n o r s b a s e d o n a c a r e f u l h i s t o r y a n d i n t e r v i e w , r e j e c t i n g t h o s e
A ddress for correspondence: S ilvana W endel N eto
H ospital S irio-Libanes - B lood B ank R ua D ona A dm a Jafet, 9 1 - 2Qandar S ao P aulo/S P - B rasil - C E P 01308-050
w i t h a c u t e d i s e a s e s ( e .g . f e v e r , p r e s e n c e o f i n f e c t i o n a t t h e s i t e o f v e n i p u n c t u r e , r e c e n t d e n t a l m a n i p u l a t i o n , e t c .) o r b e l o n g i n g t o h i g h r i s k g r o u p s ( s e x u a l b e h a v i o r , p a i d d o n o r s , e t c .) ( l ,2 ,3 ,4 ,5 ) . I n a d d i t i o n , a d e t a i l e d p h y s i c a l e x a m i n a t i o n m a y a l s o d i s c l o s e d o n o r s w h o m i g h t b e c a r r y i n g a n i n f e c t i o u s d i s e a s e . U n f o r t u n a t e l y , s u c h m e a s u r e s ( t h o u g h e f f e c t i v e t o s o m e d e g r e e ) m a y n o t e n s u r e a n a d e q u a t e l e v e l o f s a f e t y , s i n c e t h e m a j o r i t y o f c h r o n i c i n f e c t e d d o n o r s a r e a s y m p t o m a t i c , r a i s i n g n o d o u b t s a b o u t t h e i r h e a l t h ; t h i s h a s l e d t o t h e u s e o f a d d i t i o n a l s e r o l o g i c a l s c r e e n i n g ( w h e n e v e r p o s s i b l e ) . O n e h a s a l s o t o c o n s i d e r t h a t t h e r i s k o f a s p e c i f i c T x I m a y c h a n g e w h e n d i f f e r e n t g e o g r a p h i c r e g i o n s a r e c o n c e r n e d ; o n e p r e v e n t i v e p o l i c y m a y b e n o t e f f e c t i v e w h e n a d o p t e d i n a n o t h e r r e g i o n o r c o u n t r y . I n s u m m a r y , T x I c a n b e p r e v e n t e d b y a n c o m b i n a t i o n o f d i f f e r e n t p r o c e d u r e s :
A d e q u a t e s e l e c t i o n o f b l o o d d o n o r s .
S e r o l o g i c a l s c r e e n i n g p r o c e d u r e s a i m i n g a t d e t e c t i n g t h e m a i n a g e n t s f r o m a s p e c i f i c r e g i o n o r e t h n i c g r o u p s .
P r o p e r s t o r a g e a n d h a n d l i n g o f b l o o d c o m p o n e n t s . U s e o f i n a c t i v a t i o n m e t h o d s ( e .g . p h y s i c a l , c h e m i c a l o r c o m b i n e d ) , w h e n e v e r p o s s i b l e .
S50 Paulo M edical Journal/R PM 1 1 3 ( 6 ) : 1 0 3 6 - 1 0 5 2 , 1 9 9 5 W EN D EL, S. - C urrent concepts on the transm ission of bacteria
D e s p ite th e c o n tin u o u s in c r e a s e in s a f e ty p r o c e d u r e s in B lo o d T r a n s f u s io n M e d ic in e , T x I w ill s till b e p r e s e n t. I ts m a in c o r n e r s to n e s a r e :
T h e d o n o r b e a r s a v ia b le o r g a n is m in h is /h e r b lo o d s tr e a m a t th e tim e o f d o n a tio n .
• T h e a g e n t r e m a in s a c tiv e d u r in g th e s to r a g e p e r io d o f th e b lo o d c o m p o n e n t.
T h e r e c ip ie n t is n o t in f e c te d b y th is s a m e a g e n t c o n ta in e d in th e in f e c te d u n it.
T h e a g e n t is a b le to in d u c e in f e c tio n o n c e tr a n s f u s e d in to a s u s c e p tib le r e c ip ie n t, o r its p r e s e n c e c a n b e d e te c te d e ith e r b y d ir e c t is o la tio n p r o c e d u r e s o r b y s e r o lo g ic a l m a r k e r s .
• T h e r e c ip ie n t is a liv e a t th e o n s e t o f th e in f e c tio n . • O th e r r o u te s o f tr a n s m is s io n h a v e b e e n d is c a r d e d .
BACTERIAL
CONTAMINATION
B a c te r ia l c o n ta m in a tio n ( o th e r th a n s p ir o c h e te s ) is s till a m a jo r h a z a r d in b lo o d tr a n s f u s io n . T h e f r e q u e n c y o f c o n ta m in a tio n v a r ie s a c c o r d in g to th e p r o d u c t s tu d ie d : w h o le b lo o d o r p a c k e d r e d c e lls ( 0 .3 1 % ) , r a n d o m d o n o r p la te le t c o n c e n tr a te s ( 0 to 1 0 % ) , s in g le d o n o r a p h e r e s is p la te le ts ( 0 - 4 .9 % ) a n d f r o z e n d e g ly c e r o liz e d c e lls ( 0 -0 .2 % ) ( 6 ,7 ) . W ith th e in c r e a s in g u s e o f p la te le t c o n c e n tr a te s , w h ic h a r e k e p t a t r o o m te m p e r a tu r e , th is c o m p o n e n t is r e s p o n s ib le f o r o v e r 5 0 % o f T x s e p s is r e p o r te d in th e U S A ( 6 ,8 ) . A s th e p r e - f r e e z e a n d th e p o s t-th a w p e r io d f o r F r e s h F r o z e n P la s m a is q u ite s h o r t, th e c h a n c e s o f b a c te r ia l p r o lif e r a tio n a r e le s s th a n in o th e r c e llu la r c o m p o n e n ts .
T h e r e a l in c id e n c e is n o t k n o w n , a s m a n y c a s e s m a y h a v e g o n e u n d e te c te d . S in c e m a n y c o n ta m in a te d u n its h a v e le s s th a n 1 0 m ic r o o r g a n is m s /m l, it is f u n d a m e n ta l to r e ly o n v e r y s e n s itiv e m e th o d s f o r c u ltu r in g . T h e r e a r e s e v e r a l f a c to r s th a t p la y a r o le in th e in c id e n c e a n d d e te c tio n o f T x s e p s is , s u c h a s th e s to r a g e te m p e r a tu r e ( b e lo w O °C ,
4 ° C o r 2 2 ° C ) , th e v o lu m e o f b lo o d c u ltu r e d , th e te m p e r a tu r e a n d th e c u ltu r e m e d ia u s e d f o r th e d e te c tio n , a n d th e s e n s itiv ity o f th e m e th o d . N e v e r th e le s s , th e in c id e n c e o f c o n ta m in a te d p r o d u c ts r a n g e s f r o m 1 : 1 3 ,1 0 0 to I :3 3 0 f o r r e d b lo o d c e lls , f r o m 1 :2 0 ,0 0 0 to 1 :3 ,6 0 0 f o r s in g le d o n o r a p h e r e s is p la te le ts , a n d f r o m 1 : 10 ,0 0 0 to 1 :2 5 0 f o r p o o le d r a n d o m p la te le t c o n c e n tr a te s ( 6 ,7 ,8 ,9 ,1 0 ) .
D e s p ite th e u tiliz a tio n o f s tr in g e n t a s e p tic p r o c e d u r e s a n d th e u s e o f c lo s e d s y s te m s f o r c o lle c tio n , m a n ip u la tio n a n d s to r a g e o f b lo o d p r o d u c ts , th e e v e r - in c r e a s in g u s e o f
p la te le t c o n c e n tr a te s ( k e p t a t r o o m te m p e r a tu r e , w h ic h f a c ilita te s b a c te r ia l p r o lif e r a tio n ) a n d th e p r o lo n g e d s to r a g e o f r e d c e lls u p to 4 2 d a y s ( id e a l f o r th e s lo w g r o w th o f p s y c h r o p h ilic o r g a n is m s ) , h a v e c o n tr ib u te d to th e r is in g in c id e n c e o f T x s e p s is . M o r e o v e r , p la te le t c o n c e n tr a te s a r e u s u a lly tr a n s f u s e d to p a n c y to p e n ic im m u n o -c o m p r o m is e d r e c ip ie n ts u n a b le to h a n d le a ia tr o g e n ic in f e c tio n , w h e r e u p to 2 5 % o f d e a th s h a v e b e e n a s s o c ia te d to th e u s e o f c o n ta m in a te d p r o d u c ts . O n th e o th e r h a n d , m a n y c a s e s m a y h a v e n o t h a v e b e e n d e te c te d , a s m o s t c o n ta m in a tio n is u s u a lly m in o r in r e c ip ie n ts w h o a r e r e c e iv in g a n tib io tic s f o r o th e r r e a s o n s ( s e e b e lo w ) .
U n f o r tu n a te ly , d e s p ite v a r io u s e f f o r ts , n o s o u r c e o f c o n ta m in a tio n c a n b e a s c e r ta in e d in m o s t c a s e s . I n th o s e w h e r e a c a u s e c o u ld b e r e c o g n iz e d , tw o w a y s o f c o n ta m in a tio n a r e d e s c r ib e d ( 1 ) :
• E x o g e n o u s - D u e to th e in a d e q u a te u s e o f a s e p tic p r o c e d u r e s . T h e r e a r e s e v e r a l s a p r o p h y tic o r g a n is m s in th e d o n o r s ' s k in ( s ta p h y lo c o c c i, s tr e p to c o c c i, p s e u d o m o n a s , d ip h te r o id s , b a c ilii, e tc .) th a t m a y e n te r in to th e p r im a r y b lo o d b a g c o n ta in e r w h e n th e d o n o r 's a r m is n o t p r o p e r ly c le a n s e d ( 1 1 ) . A f te r a n tis e p s is , th e p h le b o to m is t m u s t n o t to u c h th e v e n ip u n c tu r e s ite a g a in . R e p e a te d c o lle c tio n o n s c a r r e d o r d im p le d s ite s m a y a ls o r e s u lt in c o n ta m in a tio n , e v e n a f te r a n tis e p s is , s in c e b a c te r ia h a v e b e e n f o u n d in th e d e e p e r la y e r o f d e r m is ( 7 ) , a n d a s k in p lu g m a y b e f o r m e d d u r in g v e n ip u n c tu r e , th is th e c o lle c tio n b a g .
T h e u s e o f n o n - s te r ile e x te r n a l d e v ic e s ( v a c u u m tu b e s f o r p ilo t s a m p le s ) , a n d s o lu tio n s ( e .g . s a lin e ) , o r th e in a d e q u a te m a n ip u la tio n d u r in g p r o c e s s in g ( e q u ip m e n t in c o n ta c t w ith b lo o d u n its c a u s in g in c o n s p ic u o u s p u n c tu r e s in th e b a g ) , o r e v e n th a w in g in c o n ta m in a te d w a te r b a th s a r e a ls o a s c r ib e d to in d u c in g e x o g e n o u s c o n ta m in a tio n ( 7 ,1 1 ) .
F in a lly , th e p r e s e n c e o f m in o r c r a c k s a n d le a k a g e in b lo o d b a g s o r th e in a d e q u a te s te r i I i z a tio n ° d u r i n g m a n u f a c tu r e - a s h a p p e n e d in B r a z il in th e la s t d e c a d e ( 1 2 ) a n d r e c e n tly in S c a n d in a v ia ( 1 3 ) - m a y b e r e s p o n s ib le f o r e x te r n a l c o n ta m in a tio n .
E n d o g e n o u s - th e p r e s e n c e o f a p e r s is te n t o r tr a n s ie n t a s y m p to m a tic lo w g r a d e p a r a s ite m ia in d o n o r s a t th e tim e o f d o n a tio n h a s a ls o b e e n a p p o in te d a s r e s p o n s ib le f o r b a c te r ia l c o n ta m in a tio n . T h is c a s e m a y b e th e a f te r d e n ta l m a n ip u la tio n ( u s u a lly a s s o c ia te d w ith s ta p h y lo c o c c i) , o r a g a s tr o in te s tin a l illn e s s ( Y e r s in ia a n d S a lm o n e lla s p e c ie s ) . W h a te v e r th e m e c h a n is m s o f b a c te r ia l p e n e tr a tio n in b lo o d b a g s a r e , a s e r ie s o f f a c to r s m a y p r e v e n t o r e n h a n c e th e ir g r o w th . T h e f ir s t lin e o f d e f e n s e lie s in th e
W E N D E L , S . - C u r r e n t c o n c e p ts o n th e tr a n s m is s io n o f b a c te r ia a n d p a r a s ite s b y b lo o d c o m p o n e n ts
bactericidal
properties
of plasm a (opsonins,
com plem ent
and antibodies)
and w hite blood cells. O ther factors, such
as source
of nutrients
in the storage
m edium
and the
com petence
of the inoculated
bacteria
to develop
in a
particular
tem perature,
are also relevant
issues affecting
bacterial
grow th.
S tudies w here deliberately
infected units w ere used
have show n that after a lag resting
phase, a log grow th
stage
ensues,
reaching
m ore
than
105 to 106 colony
form ing
units
(C F U /m l)
w ithin
3-4 days
in platelet
concentrates
stored
at room
tem perature,
or after 20-25
days in red cells refrigerated
at 40°C .
S everal
m icroorganism s
have been
im plicated
in
blood
product
contam ination.
P sychrophilic
G ram
-negative
bacteria,
capable
of grow ing
at 40 C (e.g.
S alm onella,
E scherichia,
P seudom onas,
Y ersinia species)
are the
m ain
responsible
agents
for red cell product
contam ination
(7, 8,11,14)
w hereas
both G ram -positive
and G ram -negative
organism s
(m ainly those derived from
the
skin
flora)
have
been
associated
w ith
platelet
contam ination
(6,7,14).
A m icroorganism
isolation in blood com ponents does
not necessarily
m ean
a clinical
consequence
for the
reci pients.
M any
bacteri
a are
considered
as
non-pathogenic
(e.g.
diphteroids),
or
show
a too
low
concentration
at the tim e of the infection
«
10 C F U /m l)
to induce signs or sym ptom s.
M oreover,
m any recipients
are concom itantly
receiving effective antibiotics and clear
this iatrogenic
contam ination.
C linically
recognized
T x
sepsis
is recognized
by the onset of high fever, rigors,
chilling,
nausea,
vom iting,
w heezing,
dyspnea
and
tachycardia.
S eptic
shock
w ith hypotension,
peripheral
vasodilatation,
hem oglobinuria,
acute renal failure
and
dissem inated
intra-vascular
coagulation
are related to the
direct
infusion
of endotoxin
rather than the am ount
of
transfused
bacteria.
In the m ost dram atic
cases, a high
rate of fatality
is observed
(up to 25-30% ),
occurring
m ainly
w ithin
24-48
hours after the episode,
even w ith
the use of adequate
therapeutic
m easures.
P revention ofT x sepsis m ust be perform ed, at several
levels:
C ollection
facilities
- donors
m ust be asked about
dental m anipulation
or gastrointestinal
illness in the
previous
m onth, though
this last m easure
is of low
sensitivity
and specificity. A thorough skin antisepsis
and stringent
aseptic venipuncture
procedures
m ust
be perform ed, avoiding the collection in scarred areas
or in repeatedly used punctures, w here antisepsis m ay
not
be achieved.
P rocessing
units - B lood units collected
in a closed
system
should
not be violated
and turned
into an
open
system .
If a unit has to be split into several
aliquots, this m ust be done w ith the help of a sterile
connecting
device.
O nce the seal is broken,
blood
units m ust be used w ithin
24 hours and discarded
after this period.
T haw ing of frozen products
m ust be perform ed
in a
clean w ater bath, using a plastic w rapping to prevent direct
contact of the units w ith w ater.
M inor defects in centrifuges,
benches,
baskets
and
any other external devices in contact w ith blood units m ay
cause sm all undetected
punctures
and m ust be carefully
controlled
(II).A ll
external
solutions
used
for
m anipulation
m ust also be sterile.
V isual inspection
- A ll units
m ust undergo
visual
inspection before being released for transfusion,
w ith
special attention
to the presence
of clots (14)
(the
am ount of citrate decreases
due to its use in bacterial
m etabolism
as a
carbon
source),
hem olysis
(15)
(especially
w hen it is present only in the blood bag
and not in the attached
segm ent),
or a "pearlescent
sw irl" in platelet units (16).
Inactivating
agents - A ntibiotics
have been proposed
as com ponents
of storage
preservati
ve m edium ;
how ever,
this
m easure
is
no
longer
used.
P hotochem ical
inactivation
using
8-M
ethb-xypsoralen (8 M O P ) and long w avelength
ultraviolet
light (U V A ) has been proved
to inacti vate at least
105 C F U /m l
of several
bacteria,
and is perhaps
a
prom ising
alternative
for the future (17).
S torage
period
decrease
- S ince
m assi ve bacterial
grow th is usually observed after 3-4 days for platelets
and 3 w eeks for red blood cells, it w as thought that
a reduction
in the storage ti m e,
e.g. 4 and 25 days
respectively
for these com ponents,
m ight dim inish
the likelihood
of T x sepsis.
H ow ever,
this m easure
has proved neither effective nor cost-effective
(8, 18).
H olding
units before
processing
-
E vidence
have
show n that the natural bactericidal
effect present in
w hole
blood
should
be greatly
beneficial
w hen
collected
w hole
blood
units
are stored
at room
tem perature
for 6-24 hours before being processed
into com ponents
(19,20).
P re-storage
w hite
blood
cells
reduction
- W hite
blood
cells
(W B C )
playa
m ajor
role
in the
bactericidal
effect
over
w hole
blood
units.
N otw ithstanding,
som e
bacteria
phagocytized
by
W B e
m ay still survive
in the cytoplasm
and be
released,
once W B C disintegration
occurs
after 24
hours in refrigerated
units, allow ing for new bacterial
grow th (20,21).
T herefore,
som e authors suggested
the rem oval of W B e
by using leukodepletion
filters
after a "holding
period".
W hether
W B e
should be
S a o P a u lo M e d ic a l J o u rn a l/R P M 1 1 3 (6 ): 1 0 3 6 -1 0 5 2 , 1 9 9 5 W E N D E L , S . - C u rre n t c o n c e p ts o n th e tra n s m is s io n o f b a c te ria
re m o v e d im m e d ia te ly b e fo re , o r a fte r p ro c e s s in g in to c o m p o n e n ts is a n is s u e u n d e r in v e s tig a tio n (1 6 ,2 1 ). It is a ls o n o t q u ite u n d e rs to o d w h e th e r b a c te ria l re m o v a l o c c u rs b y re d u c in g W B C , o r b y a d ire c t b a c te ria filtra tio n e ffe c t, o r b o th (1 8 ).
B a c te ria l s u rv e illa n c e - S in c e b a c te ria l c o n ta m in a tio n w ill s till b e p re s e n t (d e s p ite a ll p re v e n tiv e m e a s u re s ), s c re e n in g o f c o n ta m in a te d u n its w ill d e c re a s e th e p o s s ib ility o f tra n s fu s in g a m a s s iv e ly b a c te ria l in fe c te d c o m p o n e n t. S e v e ra l a p p ro a c h e s h a v e b e e n te s te d a n d th e y in c lu d e :
M ic ro s c o p ic e x a m in a tio n : th e G ra m m e th o d o r a c y to s p in s m e a r, w ith a c rid in e o ra n g e s ta in in g , h a s b e e n p ro p o s e d to b e c o m e p a rt o f th e b a c te ria l s c re e n in g fo r ra n d o m d o n o r p la te le ts (p o o le d ) o r s in g le d o n o r p la te le t u n its o ld e r th a n 2 -3 d a y s (9 ,1 0 ). Its s e n s itiv ity is o f 1 0fi
b a c te ria / m l. H o w e v e r, fa ls e p o s itiv e a n d fa ls e n e g a tiv e re s u lts a re e n c o u n te re d . T h e m e th o d is la b o rio u s , e x p e n s iv e a n d its e ffic ie n c y is s till d e b a ta b le (9 ), th o u g h a p ro s p e c tiv e s tu d y s h o w e d e v id e n c e th a t it m ig h t b e s u ita b le fo r ro u tin e s c re e n in g (1 0 ).
B a c te ria l c u ltu re s : d iffe re n t re s u lts h a v e b e e n re p o rte d s in c e th e re is n o s ta n d a rd iz a tio n a s to th e v o lu m e to b e in o c u la te d , th e c u ltu re m e d iu m , te m p e ra tu re , a tm o s p h e re , tim e o f in c u b a tio n a n d m ic ro o rg a n is m q u a n tific a tio n . F u rth e r m o re , s o m e s p e c ie s re q u ire a lo n g c u ltiv a tio n p e rio d , m a k in g th e m e th o d u s e le s s w h e n d e a lin g w ith u n its th a t h a v e a s h o rt s to ra g e p e rio d (e .g . p la te le ts ). R e c e n tly , th e u s e o f a u to m a te d p re -tra n s fu s e d c u ltu re s w ith a re d u c e d in c u b a tio n p e rio d h a s b e e n in tro d u c e d in m a n y b lo o d b a n k s (2 2 ). It is v e ry im p o rta n t to d is c a rd e x te rn a l c o n ta m in a tio n b y c o n firm in g th e in itia l re s u lts , w h a te v e r th e m e th o d is . T h e s e p re v e n ti v e m e a s u re s h a v e b e e n a d o p te d a s p a rt o f th e n a tio n a l s u rv e illa n c e in s o m e c o u n trie s (7 ). B lo o d g a s a n a ly s is - w ith b a c te ria l g ro w th , p C 02 in c re a s e s a n d P 0 2 d e c re a s e s , b o th re la te d to th e s iz e o f c o n ta m in a tio n a n d to th e g a s e x c h a n g e p ro p e rtie s o f th e p la s tic u s e d in th e c o lle c tio n s y s te m . A s tu d y u s in g a P 0 2 c u t-o ff o f 1 2 0 to rr s h o w e d h ig h s e n s itiv ity a n d s p e c ific ity , e s p e c ia lly fo r 5 -d a y p la te le t u n its , in d ic a tin g th a t its u s e m a y e x te n d th e s to ra g e p e rio d (2 3 ). In a d d itio n , it is p o s s ib le th a t a d h e s iv e g a s la b e ls u s e d a s a c o lo r in d ic a to r m a y b e d e v e lo p e d in th e n e a r fu tu re to ro u tin e ly m o n ito r g a s c o n c e n tra tio n in b lo o d u n its (2 4 ).
D N A a n d R N A p ro b e s - A m e th o d u s in g a c h e m ilu m in e s c e n t a c rid in iu m -e s te r la b e le d u n iv e rs a l b a c te ria l rib o s o m a l R N A (rR N A ) p ro b e , w h ic h h y b rid iz e s w ith b a c te ria l n u c le ic a c id s a n d is re v e a le d b y a lu m in o m e te r, h a s re c e n tly b e e n p u b lis h e d (2 3 ). T h is m e th o d is e a s y , fa s t a n d m a y b e u s e d fo r m a s s s c re e n in g ; its c o s t is a n tic ip a te d to b e s im ila r to E L IS A te s ts . S e n s itiv ity o f a s lo w a s I to 2 x 1 03
C F U / m l in s o m e a n d Ix 1 04
C F U /m l in a ll d e lib e ra te ly in fe c te d u n its h a s b e e n c la im e d , re g a rd le s s o f in o c u lu m s iz e o r th e c o lle c tio n s y s te m e m p lo y e d (2 4 , 2 5 , 2 6 , 2 7 , 2 8 ).
P C R - T h is is s till a v e ry e x p e n s iv e m e th o d w h ic h , a lth o u g h v e ry e ffic ie n t, h a s n o t b e e n d e v e lo p e d fo r ro u tin e b a c te rio lo g ic s c re e n in g in b lo o d b a n k s y e t, a s it is s ti I I u n d e r in v e s tig a tio n .
SYPHILIS
S y p h ilis is tra n s m itte d b y
Treponema
pallidum,
a c y lin d ric a l c o rk s c re w s h a p e d s p iro c h e te th a t is e a s ily d e s tro y e d b y s e v e ra l fa c to rs s u c h a s : h e a tin g , lo w te m p e ra tu re s , p H c h a n g e s , c o n ta c t w ith w a te r a n d s o a p ; it a ls o re q u ire s a n a n a e ro b ic a tm o s p h e re fo r a n o p tim a l g ro w th (2 9 ).S in c e its firs t lin k a g e to b lo o d tra n s fu s io n (1 9 1 5 ), m o re th a n 2 0 0 c a s e s h a v e b e e n p u b lis h e d (m a n y m o re m a y h a v e b e e n u n d e te c te d o r u n n o tic e d , m a in ly in d e v e lo p in g c o u n trie s ). H o w e v e r, le s s th a n 1 0 c a s e s a re k n o w n to h a v e o c c u rre d in th e la s t 3 0 y e a rs (3 0 ,3 1 ,3 2 ).
T h e p re v a le n c e a m o n g b lo o d d o n o rs , a s e v id e n c e d b y p o s itiv e s e ro lo g ic a l te s ts fo r s y p h ilis (S T S ), ra n g e s fro m a s lo w a s 0 .0 0 4 % in in d u s tria liz e d c o u n trie s to a s h ig h a s 1 3 % in s o m e A fric a n c o u n trie s (3 2 ).
T h e ro u tin e u s e o f S T S in b lo o d d o n o rs , th e s to ra g e o f b lo o d c o m p o n e n ts a t 4U
C o r th e s o -c a lle d fre s h c o m p o n e n ts (e .g . p la te le ts ) a t ro o m te m p e ra tu re u n d e r a e ro b ic c o n d itio n s , u s u a lly w ith th e c o n c o m ita n t a p p lic a tio n o f a n tib io tic s to re c ip ie n ts o f th e s e la tte r c o m p o n e n ts , h a v e a ll c o n trib u te d to th e d ra m a tic d e c lin e o f T x s y p h ilis in th e la s t th re e d e c a d e s .
Treponema
pallidum
is h ig h ly s e n s iti v e to c o ld te m p e ra tu re s a n d s to ra g e o f u n its a t 4 ° C u p to 1 2 0 h o u rs c o m p le te ly d e s tro y s th is s p iro c h e te . T h e re is a d ire c t re la tio n s h ip b e tw e e n th e a m o u n t o f o rg a n is m s p re s e n t in th e b lo o d a n d th e tim e n e c e s s a ry to k ill th e m (3 3 ,3 4 ,3 5 ). F u rth e rm o re , a s tu d yW E N D E L , S . - C u r r e n t c o n c e p ts o n th e tr a n s m is s io n o f b a c te r ia a n d p a r a s ite s b y b lo o d c o m p o n e n ts
u s in g 9 8 u n its fro m S T S p o s itiv e d o n o rs in 9 0 re c ip ie n ts , w h ic h w e re q u a ra n tin e d fo r a m in im u m o f 7 d a y s a t 4 ° C , d e m o n s tra te d th e la c k o f d is e a s e tra n s m is s io n o r s e ro c o n v e rs io n in a ll te s te d re c ip ie n ts (3 6 ); in th is s a m e s tu d y th e p re s e n c e o f p a s s iv e ly tra n s fu s e d re a g in s w a s n o t d e te c te d w h e n th e o rig in a l tite r w a s < 1 :8 , a n d in th o s e re c ip ie n ts fro m u n its w ith a tite r ra n g in g fro m 1 :8 to 1 :6 4 , th e p a s s iv e ly tra n s fe rre d a n tib o d ie s w e re n o lo n g e r d e te c te d a fte r 1 0 d a y s .
T h e ris k o f a c q u irin g s y p h ilis s e e m s to b e ra th e r lo w . A lth o u g h
T. pallidum
re m a in s v ia b le fo r s e v e ra l w e e k s in p la s m a c o m p o n e n ts w h e n s to re d a t te m p e ra tu re s lo w e r th a n -2 0nC , n o c a s e s h a v e b e e n re c e n tly d e s c rib e d w ithth e u s e o f fro z e n c o m p o n e n ts o r p la s m a d e riv a tiv e s , b u t o n ly w ith p la te le ts o r w h o le b lo o d fo r e x c h a n g e tra n s fu s io n (3 0 ,3 1 ).
T ra n s m is s io n o f T x s y p h ilis h a s b e e n s e e n fro m s e ro n e g a tiv e in fe c te d d o n o rs in th e in c u b a tio n p e rio d , b e fo re th e o n s e t o f p o s itiv e s e ro lo g ic a l te s ts , o r le s s lik e ly , fro m th o s e w ith a c tiv e p rim a ry s y p h ilis ; a n d h a s n o t b e e n re p o rte d fro m d o n o rs -p re s e n tin g th e s e c o n d a ry o r te rtia ry p h a s e , s in c e th e y u s u a lly a re s y m p to m a tic a n d re fra in fro m d o n a tio n . T h e in c u b a tio n p e rio d ra n g e s fro m 4 to 1 4 w e e k s (a v e ra g e 6 -8 w e e k s ) a n d is in v e rs e ly p ro p o rtio n a l to th e n u m b e r o f tra n s fu s e d v ia b le o rg a n is m s . T h e re is n o p rim a ry s ta g e , w ith n o lo c a l in fla m m a to ry le s io n s a s o b s e rv e d in s e x u a l tra n s m is s io n (c h a n c re ); th e d is e a s e p ro c e e d s d ire c tly to th e s e c o n d a ry s ta g e , w ith g e n e ra l ra s h , fe v e r a n d ly m p h a d e n o p a th y , th e re a fte r fo llo w in g its n a tu ra l c o u rs e , if n o t tre a te d (3 7 ).
P re v e n tio n is c a rrie d o u t b y S T S , w ith d e te c tio n o f n o n -s p e c ific (n o n -tre p o n e m a l, a n tic a rd io lip in o r re a g in s ) o r s p e c ific (tre p o n e m a l) a n tib o d ie s (3 8 ,3 9 ). T h e fo rm e r c o m p ris e s : C o m p le m e n t F ix a tio n T e s t (W a s s e rm a n ), V D R L (V e n e re a l D is e a s e R e s e a rc h L a b o ra to rie s ) o r R P R (R a p id P la s m a R e a g in s ) a n d th e la tte r: F T A -A b s (F lu o re s c e n t T re p o n e m a l A n tib o d ie s a b s o rb e d w ith R e ite r's tre p o n e m a ), T P H A
(Treponema
pallidum
h e m a g g lu tin a tio n a s s a y ) o r E L IS A te s ts . O th e r te s ts a re a v a ila b le b u t n o t u s e d a s ro u tin e p ro c e d u re s in s e ro lo g ic a l s c re e n in g . T h e ris k o f in fe c tio n fro m s e ro n e g a tiv e d o n o rs is in v e rs e ly p ro p o rtio n a l to th e in te rv a l b e tw e e n in fe c tio n a n d b lo o d d o n a tio n (w in d o w p e rio d ), w h e n te s ts a re s till n o n -re a c ti v e , re g a rd le s s o f th e m e th o d u s e d . O n a v e ra g e , tre p o n e m ic te s ts b e c o m e re a c tiv e 2 w e e k s a fte r in fe c tio n , w ith a la g p h a s e ra n g in g fro m a fe w d a y s to 2 -3 w e e k s fo r th e a p p e a ra n c e o f re a g in s . S e n s itiv ity in c a s e s w ith le s s th a n 3 0 d a y s , fro m 3 0 to 4 0 d a y s a n d o v e r 4 0 d a y s o f in fe c tio n , is re s p e c tiv e ly 6 3 % , 8 7 % a n d 1 0 0 % fo r F fA -A b s , 7 2 % , 8 0 % a n d 1 0 0 % fo r T P H A a n d 4 0 % , 6 8 % a n d 9 6 % fo r V D R L (3 8 ). A fte r tre a tm e n t, V D R L tite rs u s u a lly
d e c lin e , e v e n b e c o m in g n o n -re a c tiv e , w h e re a s tre p o n e m ic te s ts w ill re m a in p o s itiv e fo re v e r (s e ro lo g ic a l s c a r).
A m a jo r p ro b le m w h e n u s in g n o n -tre p o n e m ic te s ts is th e p o s s ib ility o f b io lo g ic a lly fa ls e p o s itiv e re s u lts (B F P ), d u e to c ro s s -re a c tio n w ith o th e r d is e a s e s s u c h a s in fe c tio u s m o n o n u c le o s is , m a la ria o r c o lla g e n o s is . D a ta o n B F P in d e v e lo p in g c o u n trie s ra n g e fro m 7 % to 5 0 % o f p o s itiv e S T S d o n o rs , re a c h in g 8 0 % in in d u s tria liz e d re g io n s . A lth o u g h it m a y p o s e p ro b le m s to b lo o d b a n k s , le a d in g to th e u s e o f c o n firm a to ry te s ts (m a in ly F fA -A b s ), th e o v e ra ll n u m b e r o f B F P is re la tiv e ly s m a ll w h e n c o m p a re d to th e a b s o lu te n u m b e r o f re je c tio n s b y S T S o r to s u rro g a te m a rk e rs c u rre n tly in u s e in b lo o d b a n k s (e .g . A n ti-H B c o r A L T ). In a d d itio n , a p o s s ib le a s s o c ia tio n b e tw e e n s y p h ilis a n d o th e r d is e a s e s , m a in ly A ID S a n d h e p a titis , is o b s e rv e d , b e in g a p o s s ib le s u rro g a te m a rk e r (4 0 ).
W ith th e c o n tin u in g d e c lin e o fT x s y p h ilis in th e la s t d e c a d e s , e v e n w ith th e in c re a s in g u s e o f fre s h c o m p o n e n ts , s o m e c e n te rs h a v e s u p p o rte d th e d is c o n tin u a tio n o f S T S a m o n g b lo o d d o n o rs (3 2 ). T h e a rg u m e n ts a g a in s t th is s u g g e s tio n a re : th e lo w c o s t o f te s ts e v e n fo r d e v e lo p i n g c o u n trie s , th e id e n tific a tio n o f d o n o rs tru ly in fe c te d w h o a re s u b s e q u e n tly re fe rre d to a n d a ls o in v e s tig a te d fo r o th e r s e x u a l c o n ta c ts , o r th o s e fro m h ig h ris k g ro u p s fo r o th e r s e x u a lly tra n s m itte d d is e a s e s (A ID S a n d h e p a titis ), w h ic h m a y h a v e a n a d d itio n a l im p a c t o n th e p u b lic h e a lth s y s te m , e s p e c ia lly in p o o r a re a s w ith o u t a d e v e lo p e d s y s te m fo r b lo o d d o n o r s c re e n in g ; th e in c re a s e o f s y p h ilis p re v a le n c e a n d in c id e n c e in p o p u la tio n s fro m m a n y c o u n trie s w o rld w id e ; a n d fin a lly , b e c a u s e it is s till a le g a l re q u ire m e n t in s e v e ra l c o u n trie s (2 9 ,3 4 ). T h u s , d e s p ite th e lo w ris k o f s y p h ilis in b lo o d b a n k s , th e m a in te n a n c e o f S T S s h o u ld s till b e re g a rd e d a s a p re v e n tiv e m e a s u re w ith a m a jo r im p a c t o n th e h e a lth s y s te m .
B lo o d u n its w ith p o s itiv e S T S b u t n e g a tiv e c o n firm a to ry te s ts a re u s u a lly d is c a rd e d , th o u g h th e U n ite d S ta te s F o o d a n d D ru g A d m in is tra tio n A g e n c y (F D A ) a c c e p ts its u s e if p ro p e rly la b e le d (4 1 ). In a d d itio n , d o n o rs w ith d ia g n o s is a n d tre a tm e n t fo r s y p h ilis o r g o n o rrh e a in th e la s t 1 2 m o n th s m u s t a ls o b e d e fe rre d , s in c e th e y a ls o c a rry th e p o te n tia l ris k o f H IV in fe c tio n .
T h e re is a w o rld w id e c o n tro v e rs y a b o u t a c c e p tin g re c e n tly tre a te d d o n o rs w ith p e rs is te n c e o f c o n firm a to ry te s ts . B lo o d u n its w ith p o s itiv e S T S fo r a u to lo g o u s p u rp o s e s s h o u ld b e u s e d re g a rd le s s o f th e c o n firm a to ry re s u lts , if p ro p e rly la b e le d ; in s u c h c a s e s n o c ro s s in g -o v e r s h -o u ld b e a c c e p te d . F re s h u n its th a t a re to b e u s e d in re m o te a re a s w h e re te s ts c a n n o t b e a p p lie d m u s t b e fo llo w e d b y a p ro p h y la c tic in je c tio n o f p e n ic illin G to th e re c ip ie n t.
:~
S a o P a u lo M e d ic a l J o u rn a llR P M 1 1 3 (6 ): 1 0 3 6 -1 0 5 2 ,1 9 9 5 W E N D E L , S . - C u rre n t c o n c e p ts o n th e tra n s m is s io n o f b a c te ria
O T H E R
T R E P O N E M A T O S I S
O ther tropical, non-syphilitic treponem atosis such as
yaw s
(T. pertenue)
and pinta(T. carateum),
althoughusually asym ptom atic and exhibiting a spirochetem ic
phase, have not been related to blood transfusion in tropical
countries (1,39).
L Y M E D I S E A S E
T his recently described spirochete disease presents
a w orldw ide distribution, but the m ajority of cases have
been seen in the U S A (42, 43). It is caused by
Borrelia
burgdoiferi,
transm itted by the biting of several tickspecies, m ainly of the genus Ixodes.
B lood cultures are found to be positive in 2 to 6% of
patients, indicating a possibility of transfusional
transm ission, but all cases happened in the presence of
sym ptom s (skin lesions, cardiac or neurologic disturbances
and arthritis and m usculoskeletal pains), w hich w ould
defer these donors should they w ant to donate blood.
D eliberately inoculated blood units show a survival
of
B. burgdoiferi
up to 6 days in platelet concentrates,and 45 to 60 days in packed red cells and frozen plasm a,
though the inoculum seem ed to be higher than that
naturally found in the bloodstream of infected patients.
In addition, 5 to 10% of patients are asym ptom atic,
increasing the likelihood of accepting infected donors.
H ow ever, despite the theoretical risk of transfusional
transm ission, no cases of L ym e disease by this route have
been reported so far. T o further elucidate the low risk of
transm ission, a report from D enm ark studied an infected
w om an w ho had donated blood 4 tim es during the
rem ission phase ofthe disease and none of the 4 recipients
of w hole blood, plasm a and packed red cells becam e
infected or seroconverted w ithin 6 m onths of follow -up
(44). T herefore, it is recom m ended that no routine
screening procedures should be adopted at the m om ent,
but all blood bank staff should becom e m ore acquainted
w ith this new disease. D onors w ho have received
appropriate therapy and rem ained asym ptom atic should
also be accepted (45).
R I C K E T T S I A L
I N F E C T I O N S
T he m ain hum an infections by
Rickettsia
includeepidem ic typhus
(Rickettsia prowazekii),
Q . fever(Coxiella
burnetii),
R ocky M ountain spotted fever(R. ricketsii)
andM editerranean spotted fever
(R. conarii),
w hich aretransm itted through insect or tick bites, ingestion or
inhalation of infected m aterial, or, rarely, by blood
transfusion, since rickettsem ia precedes the onset of
sym ptom s (headache, rash and neurologic disturbances)
(1,4, 39) .
T he prevalence of antibodies against som e R ickettsia
am ongst blood donors is m uch higher could be expected
from the prevalence of the disease am ong the general
population, or am ong recipients of blood products (46),
since only tw o cases have been reported in the literature
(47, 48) and, in both of them , the donors becam e
sym ptom atic shortly after donation (1 to 2 w eeks).
S ince the risk is extrem ely low , no routine screening
procedures are recom m ended.
C H A G A S ' D I S E A S E ( A M E R I C A N
T R Y P A N O S O M I A S I S )
C hagas' D isease (C D ) is a chronic m ultisystem ic
disease caused by the flagellate
Trypanosoma
cruzi (49),
w hose natural vector is a reduviid bug (kissing bug).
D istributed from U tah (U S A ) to P atagonia (A rgentine),
this disease affects 24 m illion people in L atin A m erica
(50).
A fter a blood m eal, the bug defecates, leaving m any
infective trypom astigotes in the feces, w hich enter the
bloodstream by local scratching or direct contact w ith the
m ucosae. A fter an acute phase (usuall in children but 20%
of cases m ay be asym ptom atic), the disease subsides into
an indeterm inate phase (asym ptom atic) w hich can last a
lifetim e, or durlops into a chronic phase after several
decades affecting m ainly the cardiac and gastrointestinal
system s (49, 51).
B esides transm ission by insects, it can also be
conveyed by transfusion of contam inated blood, organ
donation, transplacentally, by breast feeding or accidentally
during laboratory m anipulation.
A fter the first T x C hagas' D isease in 1952 (52),
several cases have been described in all L atin A m erican
countries; how ever, less than 300 cases have been
reported, clearly denoting an underreporting in these
countries (49, 53, 54). U ntil recently, C hagas' D isease
w as lim ited to poor rural areas or to m ajor cities w here
im m igration is an im portant occurrence in L atin A m erica.
W ith political turm oil and econom ical crisis, intense
im m igration m ovem ents tow ards developed countries
W E N D E L , S . - C u r r e n t c o n c e p t s o n t h e t r a n s m is s io n o f b a c t e r ia a n d p a r a s it e s b y b lo o d c o m p o n e n t s
(N o rth A m e ric a , E u ro p e , A u s tra lia a n d J a p a n ) h a v e ta k e n
p la c e . C u rre n tly , a n e s tim a te d 3 m illio n L a tin A m e ric a n
im m ig ra n ts a re n o w liv in g in th e U S A , a n d 1 0 0 ,0 0 0 to
1 5 0 ,0 0 0 o f th e m m a y b e in fe c te d (5 5 , 6 5 ).
S in c e a c u te c a s e s a re m a in ly s e e n in c h ild h o o d , o n e
c o u ld e x p e c t in fe c te d im m ig ra n ts to b e in th e in d e te rm in a te
p h a s e w ith o u t a n y s u g g e s tiv e s y m p to m s . F u rth e rm o re , a s
p h y s ic ia n s fro m d e v e lo p e d c o u n trie s a re u n a w a re o f th e
c lin ic a l s y m p to m s , it to b e e x p e c te d th a t s o m e in fe c te d
d o n o rs h a v e b e e n d o n a tin g th e ir b lo o d in n o n -e n d e m ic
a re a s (5 6 ). T h is is c o rro b o ra te d b y th e fa c t th a t th re e c a s e s
h a v e b e e n fo u n d in th e U S A (4 , 5 7 , 5 8 ), o n e in C a n a d a
(5 9 ) a n d a n o th e r o n e in S p a in (6 0 ).
T h e p re v a le n c e o f in fe c te d d o n o rs v a rie s in L a tin
A m e ric a c o u n trie s , ra n g in g fro m a s lo w a s 0 .0 1 %
(4 9 ,5 1 ,5 3 ,5 4 ), to a s h ig h a s 6 0 % (in c e rta in B o liv ia n c itie s )
(6 1 ). In th e U S A , o n e re p o rt fro m S o u th C a lifo rn ia , w h e re
4 0 % o f d o n o rs w e re o f L a tin A m e ric a n o rig in , fo u n d a
p re v a le n c e o f 0 .1 % to 1 .1 % (6 2 ), a n d a m u ltic e n te r s tu d y
w ith m o re th a n 7 ,0 0 0 d o n o rs re v e a le d a n in fe c tio n ra te o f
0 .1 6 6 % a m o n g H is p a n ic d o n o rs (6 3 ).
T h e ris k o f b e c o m in g in fe c te d fro m a w h o le b lo o d
u n it ra n g e s fro m 1 2 to 2 5 % .
T.cruzi
is v ia b le in re frig e ra te dw h o le b lo o d fo r o v e r 1 8 d a y s , a n d re s is ts fre e z in g
c o n d itio n s fo r a t le a s t 2 4 h o u rs . T h u s , a ll b lo o d
c o m p o n e n ts a re c o n s id e re d in fe c tio u s , e x c e p t b lo o d
d e riv a tiv e s (e .g . a lb u m in , im m u n o g lo b u lin s a n d
c o a g u la tio n fa c to rs c o n c e n tra te s ).
R e g a rd in g T x C D , a b o u t 2 0 % o f s u c h c a s e s a re
a s y m p to m a tic a n d fe v e r (th e m a in s y m p to m d u rin g th e
a c u te p h a s e ) c a n b e e a s ily a ttrib u te d to o th e r c a u s e s . O n ly
in a fe w p a tie n ts , u s u a lly in im m u n o s u p p re s s e d o n e s , a re
o v e rt s y m p to m s fu lly p re s e n t. T h u s , it is a ls o e x p e c te d
th a t m a n y c a s e s m a y b e o c c u rin g in d e v e lo p e d c o u n trie s
w ith o u t c o rre c t d ia g n o s is .
P re v e n tio n o f T x C D c a n b e a c h e iv e d n e b y th re e
m a in a p p ro a c h e s (5 3 , 6 4 ):
. D o n o r h is to ry a n d in te rv ie w - P a id d o n o rs s h o u ld
n o t b e a llo w e d . A B ra z ilia n s tu d y c a rrie d o u t in th e
1 9 8 0 's e s tim a te d th a t th e m e re c h a n g e fro m p a id to
v o lu n te e r d o n o rs le d to a 7 0 % d e c re a s e in th e ra te o f
in fe c te d b lo o d d o n o rs . In n o n -e n d e m ic a re a s , th o s e
w h o h a v e b e e n liv in g in in fe s te d d w e llin g s o r h a v e
b e e n b itte n b y th e b u g m u s t a ls o b e d e fe rre d . S p e c ific
p re -d o n a tio n q u e s tio n n a ire s h a v e b e e n in tro d u c e d in
C a lifo rn ia in o rd e r to a c h ie v e a c e rta in s a fe ty le v e l
(6 5 A ).
S e ro lo g ic a l s c re e n in g - S e v e ra l m e th o d s a re a v a ila b le
fo r a n tib o d y d e te c tio n . C o m p le m e n t fix a tio n h a s
b e e n g ra d u a lly re p la c e d b y IH A , IIF o r E L IS A , o f
w h ic h m a n y a re a v a ila b le in L a tin A m e ric a a n d a ls o
re c e n tly in th e U S A . W ith th e w id e a n tig e n ic p ro file
o f d iffe re n t
T.cruzi
s tra in s a n d th e h o s t's v a ria b leim m u n e re s p o n s e , n o n e o f th e s e m e th o d s c a n b e
re g a rd e d a s 1 0 0 % s a fe . T h is h a d le d W H O to p ro p o s e
th a t a t le a s t tw o d is tin c t m e th o d s s h o u ld b e u s e d fo r
b lo o d d o n o r s c re e n in g . F a ls e p o s itiv e re s u lts a re d u e '
to c ro s s -re a c tio n s w ith o th e r a g e n ts a s
Leishmania
sp, T. rang eli
a n d fu n g i. U n fo rtu n a te ly , th e re is n o ta g o o d c o n firm a to ry m e th o d , a n d w ith s o m e d o n o rs
it is h ig h ly d iffic u lt to a c h ie v e a fin a l d ia g n o s is
b a s e d s o le ly o n s e ro lo g ic a l te s ts . S e ro lo g ic a l m a rk e rs
c u rre n tly in u s e in b lo o d b a n k s , e v e n in n o n -e n d e m ic
o r in d u s tria liz e d c o u n trie s , c a n n o t b e u s e d a s
s u rro g a te te s ts , n o a s s o c ia tio n h a s b e e n fo u n d w ith
C h a g a s d is e a s e (6 6 ).
C h e m o p ro p h y la x is - S in c e s o m e a re a s p re s e n t a h ig h
p re v a le n c e o f in fe c te d d o n o rs , o n e c a n n o t re ly o n
s e ro lo g ic a l s c re e n in g o n ly . F u rth e rm o re , in re m o te
a re a s w h e re s ta n d a rd p ro c e d u re s a re n o t a v a ila b le ,
c h e m o p ro p h y la x is m a y b e th e s o le m e th o d o f
p re v e n tin g T x C D .
T h o u g h m o re th a n 1 ,0 0 0 c h e m ic a l c o m p o u n d s h a v e
b e e n te s te d s o fa r, o n ly c ry s ta l v io le t (g e n tia n v io le t) a
p h e n y l m e th a n e d y e is e ffe c tiv e , in a s ta n d a rd c o n c e n tra tio n
o f 1 :4 0 0 0 o r 1 2 5 m g /5 0 0 m l w h o le b lo o d (2 0 0 u g /m l 0 .6
m m o l/L ) a fte r 2 4 h o u rs o f tre a tm e n t (4 9 , 6 7 ). T h e
a s s o c ia tio n o f a s c o rb a te (1 0 m M ) a n d lig h t e x p o s u re (1 3 0
w1M
2) re d u c e d to 0 .4 m m o llL th e try p a n o c y d a l e ffe c t a fte ro n ly 2 0 m in u te s o f tre a tm e n t (6 8 , 6 9 ). U n fo rtu n a te ly , th is
d ru g h a s s id e e ffe c ts o n p la te le ts , a n d it is to x ic w h e n m o re
th a n 2 ,5 0 0 m l o f w h o le b lo o d o r c o m p o n e n ts a re
tra n s fu s e d in to a n a d u lt re c ip ie n t. N e v e rth e le s s , it is h ig h ly
e ffe c tiv e w h e n th is lim ita tio n is fo llo w e d .
O th e r a g e n ts a re c u rre n tly u n d e r in v e s tig a tio n , s u c h
a s p h e n o lic a n tio x id a n ts (7 0 ), g a m m a irra d ia tio n (7I)a n d
filtra tio n b y le u k o c y te filte rs , b u t th e y a re s till c o n s id e re d
e x p e ri m e n ta l.
A F R IC A N
T R Y P A N O S O M IA S IS
A fric a n try p a n o s o m ia s is o c c u rs o n ly o n th e A fric a n
c o n tin e n t a n d is c a u s e d b y tw o s p e c ie s o f try p a n o s o m e s ,
T. gambiensis
a n dT. rhodesiensis,
b o th tra n s m itte d b y th eb ite o fts e -ts e flie s
(Glossina palpalis).
T ra n s fu s io n a l ris ks e e m s to b e lo w , a n d th e re a re fe w re p o rts o n th e ro le o f
tra n s fu s io n a l-tra n s m itte d A fric a n try p a n o s o m ia s is .
In fe c tio n o c c u rs m a in ly b y
T. gambiensis,
w h ic h c a u s e s ac h ro n ic fo rm o f illn e s s w ith a s y m p to m a tic p e rio d s ; o n
S a o P a u lo M e d ic a l J o u rn a l/R P M 1 1 3 (6 ): 1 0 3 6 -1 0 5 2 ,1 9 9 5 W E N D E L , S . - C u rre n t c o n c e p ts o n th e tra n s m is s io n o f b a c te ria
th e o th e r h a n d ,
T. rhodesiensis
c a u se s a m o re se v e re a n d
sy m p to m a tic
d ise a se
w h ic h w ill d e fe r d o n a tio n
(1 ,9 ).
L E I S H M A N I A S I S
V isc e ra l
le ish m a n ia sis
(K a la -a z a r)
is c a u se d
b y
Leishmania
donovani
th ro u g h th e b ite o f sa n d flie s, le a d in g
to a c h ro n ic in fe c tio n w ith fe v e r, a n e m ia , ly m p h a d e n o p a th y
a n d h e p a to sp le n o m e g a ly ,
a n d a ffe c ts
a p p ro x im a te ly
1 2
m illio n
p e o p le
in tro p ic a l
a n d su b -tro p ic a l
a re a s.
T h e
p a ra site
is fo u n d
in th e re tic u lo e n d o th e lia l
c e lls a n d in
le u k o c y te s,
w h ic h c a n b e tra n sm itte d
to re c ip ie n ts
fro m
a sy m p to m a tic
d o n o rs.
T h e re
a re
fiv e
c a se s
re p o rte d
in th e
lite ra tu re ,
a ffe c tin g m a in ly n e w b o rn s a n d im m u n o su p p re sse d
p a tie n ts
(7 2 ,7 3 ,7 4 ).
T h o u g h
v e ry ra re , d o n o rs w ith a h isto ry o f
v isc e ra l
le ish m a n ia sis
m u st n o t b e a c c e p te d
(4 5 ).
S in c e K a la -a z a r
w a s d ia g n o se d
in A m e ric a n
so ld ie rs
se rv in g in in te rn a tio n a l
m ilita ry u n its, a n d a v isc e ro tro p ic
fo rm o f
L. tropica
w a s fo u n d a m o n g th e m ilita ry p e rso n n e l
w h o se rv e d d u rin g th e G u lf W a r, a te m p o ra ry
d e fe rra l w a s
a p p lie d in th e U S A u n til Ja n u a ry
1 9 9 3 o n th o se re tu rn in g
fro m th e P e rsia n
G u lf a re a , fo llo w e d
b y th e in tro d u c tio n
o f a re stric tio n
o n d o n o rs
w h o
c la im e d
to h a v e
h a d
le ish m a n ia sis;
h o w e v e r,
a n e x te n siv e in v e stig a tio n
c a rrie d
o u t b y th e U S D e p a rtm e n t
o f D e fe n se
fa ile d to c o n firm
a n y th re a t to th e A m e ric a n
su p p ly
b y th is v isc e ro tro p ic
fo rm o f
L. tropica
a n d th e se n e w g u id e lin e s
w e re re c e n tly
c a n c e le d
(7 5 ).
T O X O P L A S M O S I S
T o x o p la sm o sis
is a z o o n o sis
c a u se d b y
Toxoplasma
gondii,
w h e re fe lin e s
a re th e d e fin itiv e
h o sts, a n d b ird s
a n d
o th e r
m a m m a ls
(in c lu d in g
h u m a n s)
a re
th e
in te rm e d ia ry
h o sts.
T h e
th re e
fo rm s
o f to x o p la sm o sis
(tro p h o z o ite s,
c y sts
a n d o o c y sts)
a re fo u n d
in fe lin e s,
w h e re a s o n ly tro p h o z o ite s
a n d c y sts a re fo u n d in th e la tte r.
It is e stim a te d
th a t a b o u t 5 0 0 m illio n
p e o p le
w o rld w id e
a re in fe c te d
b y
T. gondii
w ith a n a n n u a l in c id e n c e
o f n e w
c a se s ra n g in g
fro m
I% to 5 % .
In fe c tio n
in h u m a n s
m a y
o c c u r
b y o n e
o f th e
fo llo w in g
w a y s (3 9 ):
In g e stio n
o f c y sts fro m ra w o r u n d e rc o o k e d
in fe c te d
liv e sto c k
(e .g . p o rk , la m b o r b e e f).
A c c id e n ta l
in g e stio n
o f o o c y sts
a fte r c o n ta c t
,w ith
in fe c te d
fe c e s fro m h o u se h o ld
c a ts, u su a lly
p re se n t
in g a rb a g e o r in th e so i
I .C o n g e n ita lly ,
fro m in fe c te d
m o th e rs
to th e ir b a b ie s.
D ire c t
c o n ta m in a tio n
o f
o p e n
w o u n d s,
o rg a n
tra n sp la n ta tio n ,
b lo o d tra n sfu sio n
o r a rth ro p o d
b ite s.
T h e re is v a rie d e v id e n c e to su p p o rt th e p o ssib ility
o f
to x o p la sm o sis
a c q u ire d
b y
tra n sfu sio n
o f
b lo o d
c o m p o n e n ts.
F o u rte e n
m o n th s to fo u r y e a rs a fte r th e o n se t
o f in fe c tio n ,
th e
o rg a n ism
m a y
b e
re c o v e re d
fro m
a sy m p to m a tic
d o n o rs
o r fro m
in fe c te d
p e rso n s
(7 6 , 7 7 ,
7 8 ,7 9 ,8 0 ),
a n d is a b le to su rv iv e a t 4 °C fo r u p to 5 0 d a y s
in c itra te d b lo o d (8
I ) ;fu rth e rm o re ,
a stu d y in th a la sse m ia
m a jo r p a tie n ts w h o h a d h a d m u ltip le tra n sfu sio n s
sh o w e d
a 6 -tim e h ig h e r p re v a le n c e
o f to x o p la sm a
a n tib o d ie s
th a n
th e a g e -m a tc h e d
c o n tro ls, d e sp ite th e a b se n c e o f sy m p to m s
in in fe c te d re c ip ie n ts.
S in c e T .
gondii
is a m a n d a to ry
in tra
-c e llu la r
o rg a n ism ,
th e p o ssib ility
o f tra n sm issio n
b y
a c e llu la r p ro d u c ts
is re m o te .
T h e m a jo rity o f in fe c te d re c ip ie n ts a re a sy m p to m a tic ;
o c c a sio n a lly
ly m p h a d e n o p a th y ,
m a la ise , fe v e r, h e a d a c h e ,
c u ta n e o u s ra sh e s a n d so re th ro a t m a y b e fo u n d , re se m b lin g
a m o n o n u c le o sis-lik e
sy n d ro m e
a n d u su a lly
u n re la te d
to
to x o p la sm o sis
b y th e a ssista n t p h y sic ia n . S e v e re c a se s h a v e
o n ly
b e e n
fo u n d
in im m u n o su p p re sse d
re c ip ie n ts
w h o
u su a lly re c e iv e d la rg e a m o u n ts o f le u k o c y te s
fro m c h ro n ic
m y e lo g e n o u s
le u k e m ia
d o n o rs
(7 8 ,7 9 ),
th o u g h
in o n e
c a se a p la te le t re c ip ie n t w a s d e sc rib e d
(8 2 ). S o m e p a tie n ts
m a y
d e v e lo p
se v e re
sy m p to m s
su c h
a s m e n in g o e n c e
-p h a litis, m io c a rd itis, h e -p a titis, re tin o c h o ro id itis
o r p o ste rio r
u v e itis,
c a u sin g
p e rm a n e n t
in ju ry o r
d e a th .
T h e p re v a le n c e
o f in fe c te d
d o n o rs
v a rie s
w id e ly
ra n g in g
fro m 8 % to
6 0 % , a c c o rd in g
to th e g e o g ra p h ic a l
re g io n .
A p p ro x im a te ly
1 8 % o f th o se
w ith
T. gondii
a n tib o d ie s h a v e d e te c ta b le Ig M , in d ic a tin g
re c e n t in fe c tio n
a n d 3 0 -4 0 %
a re h ig h ly tite re d se ra (3 9 ). T h e re is a g e n e ra l
tre n d to w a rd s
a n in c re a sin g
p re v a le n c e
w ith a g e (o ld e r
g ro u p s>
y o u n g e r g ro u p s) o r se x (fe m a le >
m a le in y o u n g e r
d o n o rs) (8 3 ).
D ia g n o sis
- A lth o u g h
d ire c t id e n tific a tio n
m e th o d s
o f p a ra site s
h a v e b e e n d e sc rib e d ,
th e y a re u n su ita b le
fo r
ro u tin e u se in a b lo o d b a n k , w h e re a s se ro lo g ic a l
te sts
(T.
gondii
a n tib o d ie s)
a re m o re a p p ro p ria te .
T h e re a re se v e ra l
m e th o d s
o f
d e te c tin g
T. gondii
a n tib o d ie s
(e .g .
D y e
e x c lu sio n
te st o r S a b in -F e ld m a n
re a c tio n ,
C o m p le m e n t
F ix a tio n ,
IH A , IIF , a g g lu tin a tio n
te sts o r E L IS A ).
S in c e
th e re
is a h ig h p re v a le n c e
o f a n tib o d ie s
in th e g e n e ra l
p o p u la tio n ,
a se ro c o n v e rsio n ,
a risin g tite r o r th e p re se n c e
W E N D E L , S . - C u r r e n t c o n c e p t s o n t h e t r a n s m is s io n o f b a c t e r ia a n d p a r a s it e s b y b lo o d c o m p o n e n t s
o f Ig M a n tib o d ie s m u s t b e c le a rly d e m o n s tra te d to s h o w
a n a c u te in fe c tio n .
P re v e n tio n - D u e to th e re la tiv e ly lo w ris k fo r
re c ip ie n ts , e x c e p t fo r th o s e im m u n o s u p p re s s e d w h o
re c e iv e d la rg e a m o u n ts o f le u k o c y te s , a n d p e rh a p s n e g a tiv e
p re g n a n t w o m e n (th o u g h n o c o n g e n ita l c a s e s h a v e b e e n
d e s c rib e d w h e re b lo o d c o m p o n e n ts w e re th e o n ly p o s s ib le
c a u s e ), it s e e m s in n e c e s s a ry to e s ta b lis h ro u tin e s c re e n in g
p ro c e d u re s fo r a ll b lo o d d o n a tio n s . W h e n th e re is a c h a n c e
o f tra n s fu s in g b lo o d c o m p o n e n ts to th o s e h ig h -ris k g ro u p
re c ip ie n ts , e s p e c ia lly le u k o c y te s , it s e e m s ra th e r p ru d e n t
to e s ta b lis h a p a n e l o f A n ti-T o x o p la s m a n e g a tiv e b lo o d
. d o n o rs (8 3 ). D e s p ite th e p o s s ib ility o f re in tro d u c in g
g ra n u lo c y te tra n s fu s io n s w ith G -C S F o r G M -C S F
s tim u la tio n to d o n o rs in b o n e m a rro w tra n s p la n ts , th e
a b o v e m e a s u re s a n d p re v e n tiv e c h e m o p ro p h y la x is w ith
s u lp h a m e to x a s o l/trim e tro p rim c o u ld b e ra th e r e ffe c tiv e .
T h e ro le o f le u k o c y te -d e p le te d b lo o d m a y a ls o b e
c o n s id e re d e ffe c tiv e , a s w e ll a s b lo o d in a c tiv a tin g a g e n ts (e .g . c ry s ta l v io le t) (8 4 ).
MALARIA
T h e firs t c a s e o f tra n s fu s io n a l m a la ria (T x M ) w a s
re p o rte d in 1 9 1I ,a n d m o re th a n 3 ,0 0 0 c a s e s h a v e b e e n
d e s c rib e d s in c e w o rld w id e (8 5 ).
. H u m a n m a la ria is c a u s e d b y fo u r d iffe re n t s p e c ie s ,
Plasmodiumjalciparum,
P. vivax, P. ovale
a n dP. malariae,
a ll o f th e m re q u irin g tw o d iffe re n t h o s ts to c o m p le te th e ir
e v o lu tiv e c y c le : a m o s q u ito (A n o p h e le s ), w h e re th e s e x u a l
s ta g e ta k e s p la c e , a n d h u m a n s , w h e re th e a s e x u a l s ta g e o c c u rs .
W h e n in fe c te d fe m a le A n o p h e le s m o s q u ito e s b ite
h u m a n s , th e y re le a s e a s e x u a l s p o ro z o ite s th a t c irc u la te fo r
a s h o rt tim e in th e b lo o d s tre a m , u n til th e y in v a d e
h e p a to c y te s (e x o -e ry th ro c y tic s ta g e ) a n d u n d e rg o a n
e v o lu ti v e s te p th a t e n d s w ith th e ru p tu re o f m a tu re
s c h iz o n ts a n d re le a s e o f m e ro z o ite s in th e b lo o d s tre a m ,
w h ic h w ill in v a d e re d b lo o d c e lls (e ry th ro c y tic s ta g e ).
A n o th e r e v o lu tiv e s te p o c c u rs in re d c e lls , w h e re o th e r
m e ro z o ite s a re re le a s e d in to th e b lo o d s tre a m a n d in v a d e
o th e r re d c e lls , re p e a tin g th is a s e x u a l p h a s e . T h is p ro c e s s
is ra th e r re g u la r, la s tin g fro m 4 8 h o u rs fo r
P.jalciparum,
P. vivax
a n dP. ovale
(T e rtia n fe v e r) to 7 2 h o u rs fo rP.
malariae
(Q u a rta n fe v e r).S o m e e ry th ro c y tic p a ra s ite s u n d e rg o a n o th e r
e v o lu tiv e s te p a n d b e c o m e s e x u a l g a m e to c y te s ; w h e n
re le a s e d , in s te a d o f in v a d in g re d c e lls th e y a re in g e s te d
b y a m o s q u ito a n d b e g in a s e x u a l re p ro d u c tio n in th e
A n o p h e le s 's s to m a c h , fo rm in g a n o o c y s t, w h ic h
s u b s e q u e n tly ru p tu re s , re le a s in g s p o ro z o ite s th a t m ig ra te
to w a rd s th e s a liv a ry g la n d to c o m p le te th e ir e v o lu tiv e c y c le
(3 9 , 8 5 , 8 6 ).
In th e p a s t 4 0 y e a rs , m a la ria h a s b e e n e ra d ic a te d in
m o s t E u ro p e a n c o u n trie s , th e U n ite d S ta te s , J a p a n a n d
A u s tra lia ; h o w e v e r, it s till a ffe c ts m a n y c o u n trie s
w o rld w id e , w h e re m o re th a n 1 0 0 m illio n in d iv id u a ls a re
in fe c te d e v e ry y e a r, w ith m o re th a n I m illio n d e a th s (8 7 ).
T x M is m o re a c o n s e q u e n c e o f th e s a n ita ry c o n d itio n s o f
a c o u n try , w h e n it o c c u rs in re g io n s w h e re c o m p le te
e ra d ic a tio n h a s n o t b e e n a c h ie v e d , o r is d u e to im p o rte d
c a s e s , b y im m ig ra n ts fro m e n d e m ic a re a s o r tra v e le rs
re tu rn in g to n o n -e n d e m ic re g io n s .
T h e in c id e n c e o f T x M ra n g e s fro m a s lo w a s 0 .2 5
c a s e s /m illio n u n its tra n s fu s e d (U S A , U K ), to m o re th a n
5 0 c a s e s /m illio n in s o m e e n d e m ic a re a s (8 7 ,8 8 ). E v e n in
n o n -e n d e m ic c o u n trie s , w h e re e ra d ic a tio n is c o m p le te , it
v a rie s a c c o rd in g to th e m ig ra to ry flo w th a t to o k p la c e in
th e la s t th re e d e c a d e s ; th is is p a rtic u la r tru e in F ra n c e ,
w h e re m o re th a n 1 0 0 c a s e s w e re d e te c te d d u rin g th e 1 9 8 0 's
( 8 9 ) .
In fe c te d b lo o d d o n o rs m a y h a rb o r p a ra s ite s fo r m a n y
y e a rs , e s p e c ia lly w h e n ' th e y a re fro m e n d e m ic re g io n s
w h e re im m u n ity re n d e rs a s o m e w h a t a b s e n c e o f s y m p to m s . D iffe re n t p e rio d s o f in fe c tio n a re s e e n fo r e a c h s p e c ie s ; it
is w id e ly k n o w n th a t
P.jalciparum
c a n b e c le a re d w ith ino n e y e a r, a lth o u g h lo n g e r p e rio d s (8 -1 3 y e a rs ) h a v e b e e n
d e s c rib e d .
P. vivax
a n dP. ovale
u s u a lly d o n o t p e rs is t fo rm o re th a t 3 -4 y e a rs , b u t in fe c tio n s a fte r 6 -8 y e a rs o r e v e n
lo n g e r h a v e a ls o b e e n d e s c rib e d . H o w e v e r, lo n g e r p e rio d s
o f lo n g e v ity ra n g in g fro m 1 0 to 5 0 y e a rs w e re s e e n fo r
P.
malariae,
a s re p o rte d in th e fo rm e r U S S R a n d in th e U S A(8 7 ,8 8 ,9 0 ). A lth o u g h e x c e p tio n s e x is t,
P. jalciparum,
P.
ovale
a n dP. vivax,
it s e e m s u n lik e ly th a t a d o n o r w illre m a in in fe c tiv e a fte r fiv e y e a rs o f in fe c tio n , w h ic h is th e
b a s ic e le m e n t fo r q u e s tio n in g b lo o d d o n o rs (s e e b e lo w ).
T x M is tra n s m itte d th ro u g h a s e x u a l fo rm s th a t a re
lim ite d to re d b lo o d c e lls , u s u a lly fro m a s y m p to m a tic
d o n o rs w h o c a rry a lo w p a ra s y te m ic le v e l, a n d ra re ly in
th e p e rio d b e tw e e n th e s u b c lin ic a l p a ra s ite m ia a n d th e
o n s e t o f s y m p to m s (u s u a lly a s s o c ia te d to p re v io u s
c h e m o p ro p h y la x is ). T ra n s m is s io n fro m s y m p to m a tic
d o n o rs is v e ry u n lik e ly , a n d w h e n p re s e n t it u s u a lly o c c u rs
in e n d e m ic re g io n s .
T h e m in im u m a m o u n t o f p a ra s ite s th a t le a d s to
in fe c tio n is n o t k n o w n ; fo r
P. vivax,
a to ta l o f 1 0 p a ra s ite s /m l w a s s u c c e s s fu l in in d u c in g e x p e rim e n ta l tra n s m i~ s io n
( 8 7 ) .
S a o P a u lo M e d ic a l J o u rn a l/R P M 1 1 3 (6 ): 1 0 3 6 -1 0 5 2 , 1 9 9 5 W E N D E L , S . - C u rre n t c o n c e p ts o n th e tra n s m is s io n o f b a c te ria
T h o u g h tran sm issio n o ccu rs m ain ly th ro u g h th e u se
o f red cells p ro d u cts (w h o le b lo o d o r p ack ed red cells),
all co m p o n en ts w ith co n tam in atin g cells are in fectio u s
(fresh p lasm a, p latelets an d g ran u lo cy te co n cen trates).
T h ey rem ain in fectiv e ev en in g ly cero lized p o st- th aw u n its
p reserv ed at -7 0 °C . N o in fectio n h as b een asso ciated w ith
freeze-d ried p lasm a o r in d u strialized d eriv ativ es (alb u m in ,
im m u n o g lo b u lin , etc.).
T h o u g h v iab ility at 4 -6 °C sto rag e is less th an fiv e
d ay s fo r
P. malariae
an d u p to 1 0 d ay s fo rP.jalciparum,
h o ld in g u n its fo r 7 -1 0 d ay s in o rd er to ach iev e a relativ e
p ro tectio n is n o t ju stified .
A su rv ey co v erin g th e 1 9 5 0 -7 2 p erio d sh o w ed th at
P. I1wlariae
w as resp o n sib le fo r 4 8 % o f cases,P. vivax
fo r 1 9 % ,
P.jaleiparum
fo r 5 % ,P. ovale
fo r v ery few casesan d in 3 0 % th e sp ecies co u ld n o t b e d eterm in ed . H o w ev er,
d u rin g th e 1 9 7 3 -8 0 p erio d , th e d istrib u tio n w as 3 8 % fo r
P. lnalariae,
4 2 % fo rP. vivax
an dP. ovale,
an d 2 0 % fo rP.
jaleiparum
(87).
T h e in cu b atio n p erio d d ep en d s o n sev eral facto rs:
th e n u m b er o f v iab le tran sfu sed p arasites; th e sp ecies an d
th e strain , th e h o st im m u n ity , an d th e p rev io u s u se o f
m alarial ch em o p ro p h y lax is. O n th e av erag e, T x M h as a
lo n g er in cu b atio n p erio d th an th at o b serv ed in n atu ral
tran sm issio n , w ith a 1 6 -d ay m ean p erio d (8 -2 9 d ay s) fo r
P.jalciparum,
a 1 9 .6 -d ay m ean p erio d (8 -3 0 d ay s) fo r th eP. vivax
an d th eP. ovale,
an d a 5 7 .2 -d ay m ean p erio d (6-1 0 6 d ay s) fo r th e
P. malariae
(85).
In th e b eg in n in g , th e sy m p to m s are u su ally n o n
-sp ecific, m ain ly fev er th at o n ly tu rn s in to its p ecu liar
p erio d icity w ith in 2 w eek s. S in ce m o st p h y sician s in n o n
-en d em ic areas are u n aw are o f th is p o ssib ility , a p erio d is
o b serv ed b etw een th e o n set o f th e sy m p to m s an d th e
d iag n o sis, ran g in g fro m 1 2 to 4 3 d ay s, b u t p erio d s o f 1 6 0
d aY $ o r ev en o n e y ear h av e b een rep o rted . E v en in en d em ic
co u n tries, a lo n g d elay can b e o b serv ed (9 1 ). S y m p to m s
are m o re sev ere in sp len ecto m ized , o rg an tran sp lan ts o r
im m u n o d efficien t recip ien ts.
T h e rate o f leth al cases is h ig h ly related to d elay in
d iag n o sis (esp ecially in n o n -im m u n e recip ien ts) an d p lay s
an im p o rtan t ro le w h en in fectio n is d u e to
P. jalciparum
(w ith cereb ral, ren al an d p u lm o n ary lesio n s). W h at w as
p articu larly strik in g in th e U S A after th e V ietn am w ar,
w h en a 2 4 tim es h ig h er m o rtality w as seen in p atien ts
d iag n o sed in civ ilian h o sp itals, co m p ared to th at fro m
m ilitary h o sp itals (3 9 ). F atalities are still h ig h , w ith so m e
rep o rts o f u p to 2 0 % o f cases, h ig h er th an th e im p o rted
cases
«
1 % ), m ay b e b ecau se T x M in d ev elo p ed co u n triesaffects n o n -im m u n e recip ien ts. T h u s, w e m u st alw ay s b ear
in m in d th is p o ssib ility w h en fev er en su es after a
tran sfu sio n al ep iso d e. S in ce n o ex o -ery th ro cy tic stag e is
o b serv ed in T x M , n o relap se is fo u n d (irresp ectiv e o f th e
cau sativ e sp ecies) after ap p ro p riate treatm en t. D iag n o sis
is su p p o rted b y clin ical fin d in g s an d b y th e p resen ce o f
circu latin g p arasites. T h ick sm ears are to b e d o n e ev ery 8
h o u rs d u rin g 2 -3 d ay s b y an ex p erien ced tech n ician ,
fo llo w ed b y sero lo g ical tests (w h ich are u su ally p o sitiv e
w h en sy m p to m s are p resen t). A d eq u ate id en tificatio n o f
th e sp ecies an d im m ed iate treatm en t are im p o rtan t; w h en
id en tificatio n is n o t p o ssib le, it is ad v isab le to treat th e
p atien t as h av in g a
P.jalciparum
in fectio n .A d ram atic d ecrease in T x M sh o u ld b e ex p ected after
m alaria erad icatio n in th e U S A . H o w ev er, d u e to
su ccessiv e w ars, A m erican tro o p s, w h en retu rn in g fro m
K o rea, V ietn am (an d lately fro m S o m alia), b ro u g h t b ack
a rem ark ab le n u m b er o f in fected p erso n n el, alth o u g h
p rev en tiv e m easu res w ere ad eq u ately tak en , resp o n sib le
fo r T x M in U S A . O n th e o th er h an d , m ig rato ry m o v em en ts,
p articu larly fro m A frica an d In d ia in to E u ro p e, an d fro m
S o u th eastern A sia an d S o u th A m erica in to N o rth A m erica
(9 2 ), are also resp o n sib le fo r T x M . T h erefo re, sp ecific
m easu res sh o u ld b e tak en in o rd er to p rev en t it.
T h e first o n e is an accu rate h isto ry in clu d in g p lace
o f b irth , p rev io u s resid en ce p laces d u rin g lifetim e,
im m ig ratio n , an d a co m p lete acco u n t o f p rio r trav elin g
d u rin g th e p ast th ree y ears. T h e u se o f sp ecific
q u estio n n aires aim s at ex clu d in g th ree ty p es o f in fected
d o n o rs:
• n o n -im m u n e trav elers w h o acq u ired m alaria ab ro ad ,
p rev en tin g relap ses after sp ecific treatm en t
(P. vivax
an d
P. ovale),
o r asy m p to m atic p arasitem ia fo llo w in gin ad eq u ate ch em o p ro p h y lax is.
m ilitary p erso n n el retu rn in g fro m en d em ic areas.
fo reig n v isito rs o r im m ig ran ts fro m en d em ic reg io n s
,w h o are u su ally im m u n e an d asy m p to m atic.
T h o u g h leg islatio n in d ifferen t co u n tries v aries (4 5 ,
9 3 ), b lo o d d o n o rs sh o u ld n o t b e accep ted u n til six m o n th s
after ch em o p ro p h y lax is h as b een fin ish ed , in th e ab sen ce
o f sy m p to m s. T h o se w ith alleg ed in fectio n in th e p ast, o r
w h o h ad tak en ch em o p ro p h y lax is in th e p resen ce o f
sy m p to m s, sh o u ld n o t accep ted d u rin g a 3 -y ear p erio d .
T h is m easu re is h ig h ly effectiv e fo r
P.jaleiparum,
P. vivax
an d
P. ovale,
b u t n o t fo rP. malariae,
fo r w h ich lo n g erp erio d s o f in fectiv ity h av e b een reco rd ed . T h e
q u estio n n aires are v alid o n ly fo r p ro d u cts w h ere v iab le
red cells are p resen t, b u t m ay b e d isreg ard ed fo r d o n atio n s
in ten d ed ex clu siv ely as so u rces fo r p lasm a fractio n atio n .
S in ce th e w o rld m alarial zo n e is to o v ast, an alp h ab etical
list o f co u n tries rep o rtin g m alaria tran sm issio n an d a
g eo g rap h ical m alarial m ap (p ro v id ed b y W H O ) sh o u ld b e
p resen t in ev ery co llectio n faci Iity . U n fo rtu n ately ,
W E N D E L , S . - C u r r e n t c o n c e p ts o n th e tr a n s m is s io n o f b a c te r ia a n d p a r a s ite s b y b lo o d c o m p o n e n ts
