Dalva M arli Valerio W anderley, Fernando M .A. Correa
E p id e m io lo g y o f C h a g a s' h e a rt d ise a se
Sociedade de Cardiologia do Estado de sao Paulo
-sao Paulo, Brazil
C h a g a s ' d is e a s e is a m a jo r p u b lic h e a lth p ro b le m in L a tin A m e ric a . A b o u t 1 6 m illio n p e rs o n s a re a ffe c te d a n d 9 0 m illio n o th e rs a re e x p o s e d to th e ris k o f b e in g in fe c te d b y th e p a ra s ite . T h e k n o w le d g e o f e p id e m io lo g ic a l a s p e c ts o f th e d is e a s e a llo w e d to d e lin e a te th e s tra te g ie s fo r th e c o n tro l o f th e d is e a s e re la te d w ith th e v e c to ria l tra n s m is s io n . H o w e v e r, th e s e s tra te g ie s h a v e h a d n o p rio rity in a ll e n d e m ic c o u n trie s . R u ra l-u rb a n m ig ra tio n in m o s t e n d e m ic a re a s c a rrie d in fe c te d in d iv id u a ls to u rb a n c e n te rs in c re a s in g th e
p ro b le m o f C h a g a s ' d is e a s e b y b lo o d tra n s fu s io n .
In B ra z il th e c o n tro l p ro g ra m h a s re a c h e d g o o d re s u lts in th e la s t y e a rs a n d in s e v e ra l s ta te s th e v e c to ria l tra n s m is s io n w a s c o n tro lle d .
M o re re c e n tly , h e m o th e ra p ic p ra c tic e s a re p e rfo rm e d u s in g s c re e n in g p ro c e d u re s b u t th is p ra c tic e m u s t b e im p ro v e d in o rd e r to e lim in a te th e p o s s ib ility o f C h a g a s ' d is e a s e tra n s m is s io n b y a n o th e r w a y s (c o n g e n ita l, a c c id e n ta l, o ra l, e tc .).
A n a d e q u a te h e a lth c a re to th e in fe c te d p e rs o n s m u s t b e im p ro v e d in o rd e r to d im in is h th e s o c ia l c o s ts o f th e s e v e re c a rd io p a th y w h ic h h a s b e e n re s p o n s ib le fo r th e a q u lts p re m a tu re d e a th s .
U N IT E R M S : C h a g a s ' d is e a s e . S o u th A m e ric a n T ry p a n o s o m ia s is . E p id e m io lo g y a n d c o n tro l.
IN T R O D U C T IO N
C
h a g a s 'tr y p a n o s o m ia s is ,d is e a s e , a ls ois a p a r a s itick n o w n a s S o u thd is e a s e A m e r ic a nc a u s e d b ya f la g e lla te p r o to z o a ,
Trypanosoma
(Schizotrypanum)
cruzi.
I t is e n d e m ic in L a tin A m e r ic a o c c u r in g in 1 8 c o u n tr ie s . I n th e A m e r ic a n c o n tin e n t, h u m a n in f e c tio n p r e v a le n c e is e s tim a te d in 1 6 m illio n c a s e s a lth o u g h o th e r 9 0 m illio n , th a t is , 2 5 % o f th e p o p u la tio n ,Address for correspondence:
Dalva M arli Valerio W anderleySuperintendencia de Controle de Endem ias (SUCEN)
Secretaria de Estado da Saude de Sao Paulo
Rua Paula Souza, 166
Sao Paulo - SP - Brasil- CEP 01027-000
a r e a t r is k o f a c q u ir in g th e d is e a s e ( 3 4 ) . I n 1 9 0 9 C a r lo s C h a g a s , w o r k in g in th e B r a z ilia n h in te r la n d ( 3 ) , b r o u g h t to lig h t th e e x is te n c e o f th e d is e a s e , its c a u s a tiv e a g e n t a n d la id th e f o u n d a tio n s o f its c o n tr o l m e a s u r e s w h ic h o n ly a f te r d e c a d e s w e r e p u t in to a c tio n .
C h a g a s 'd is e a s e h a s c la s s ic a lly b e e n c o n s id e r e d a s a tip ic a l L a tin A m e r ic a r u r a l a r e a d is e a s e . H o w e v e r , a s a r e s u lt o f la s t d e c a d e s u r b a n is tic a n d in d u s tr ia lis tic p o litic a l-e c o n o m ic a l m o d e ls , r u r a l- u r b a n m ig r a tio n f r o m m a n y e n d e m ic a r e a s h a s c a r r ie d to th e o u ts k ir ts o f th e g r e a t c itie s e n o r m o u s c o n tin g e n ts o f c h a g a s ic p a tie n ts p r e s s e d b y th e la c k o f w o r k in th e r u r a l z o n e s . T h e r e a r e e s tim a tiv e s th a t m ig r a tio n c a r r ie d a b o u t 3 0 0 th o u s a n d in f e c te d p e o p le to liv e in S a o P a u lo a n d 2 0 0 th o u s a n d to R io d e J a n e ir o ( 8 ) . C h a g a s 'd is e a s e s o c ia l im p a c t is v e r y h ig h . A b o u t 7 5 2 th o u s a n d y e a r s o f p r o d u c tiv e lif e a r e lo s t a n n u a lly d u e to p r e m a tu r e d e a th s in S o u th A m e r ic a c o u n tr ie s . T h is c o r r e s p o n d s to 1 2 0 8 .5 U S $ m illio n /y e a r ( 2 3 ) . I n B r a z il, if it is c o n s id e r e d th a t 1 0 % o f th e in f e c te d p e o p le d e v e lo p
s e v e re c a rd ia c o r d ig e s tiv e in ju rie s , th e tre a tm e n t c o s t o f
s u c h c a s e s w o u ld a m o u n t to 2 5 0 U S $ m illio n (8 ). O n th e
o th e r h a n d , th e a b s e n te is m o f 7 5 ,0 0 0 B ra z ilia n c h a g a s ic
w o rk e rs w ith s e rio u s c a rd ia c d a m a g e c o u ld re p re s e n t
m in im u m lo s s e s o f U S $ 5 ,2 5 0 ,0 0 0 p e r y e a r (7 ). In th e
S ta te o f S a o P a u lo , w h e re a p ro x im a te ly 1 ,5 0 0 d e a th s /y e a r
c a u s e d b y c a rd ia c in ju rie s in v o lv in g p ro d u c tiv e -a g e d
in d iv id u a ls h a v e b e e n o b s e rv e d , th e re is a n a v e ra g e lo s s
o f 2 3 ,7 5 7 w o rk in g d a y s p e r y e a r (1 3 ).
THE PARASITE,
SYLVATIC AND DOMESTIC
CYCLE, RESERVOIRS
Trypanosoma
(Schyzotrypanum)
cruzi
b e lo n g to th e s u b p h y lu m M a s tig o p h o ra o f th e p h y lu mS a rc o m a s tig o p h o ra w h ic h c o m p ris e s fla g e lla te s w ith a
s p e c ia liz e d D N A -c o n ta in in g o rg a n e lle , th e k in e to p la s t.
T.
cruzi
is in c lu d e d a m o n g th e s te rc o ra ria n g ro u p o f try p a n o s o m e s w h ic h d e v e lo p in th e p o s te rio r s ta tio n (lo w e rg u t a n d re c tu m ) o f th e v e c to r a n d tra n s m is s io n is
c o n ta m in a ti v e . In th e v e c to r, th e p a ra s ite is fo u n d in th e
d ig e s tiv e tra c t, w h ile in th e v e rte b ra te h o s ts it p re s e n ts
tw o d iffe re n t p h a s e s , h e m a tic a n d c e llu la r (3 4 ).
T h e s y lv a tic c y c le o f C h a g a s ' d is e a s e re s u lts fro m
th e in te ra c tio n b e tw e e n v e c to rs , p a ra s ite s a n d w ild
re s e rv o irs in d iffe re n t n a tu ra l e c o to p e s . T h e d o m e s tic c y c le
re s u lts fro m h u m a n -v e c to r c o n ta c t, in v o lv in g th e
c o lo n iz a tio n o f a rtific ia l e c o to p e s b y th e in v e rte b ra te v e c to r
(tria to m in e s ) a n d a s e rie s o f s o c ia l a n d e c o lo g ic a l
m o d ific a tio n s in th e e n v iro n m e n t. T h e p a ra s itis m , in th is c a s e , c a n c a u s e im p o rta n t d a m a g e to th e v e rte b ra te h o s t
-m a n - w ith h ig h d e g re e s o f m o rb id ity a n d m o rta lity a m o n g in fe c te d p e o p le (9 ,1 8 ).
T h e re s e rv o irs o f
T. cruzi
p la y im p o rta n t p a p e r inb o th s y lv a tic a n d d o m e s tic c y c le s o f C h a g a s ' d is e a s e a n d
in th e in te ra c tio n b e tw e e n th e m . O u ts ta n d in g s y lv a tic
re s e rv o irs a re : m a rs u p ia ls (o p o s s u m s ), e d e n ta ta (a rm a d illo s ), ro d e n ts (s y lv a tic ra ts a n d g u in e a -p ig s ), b a ts
a n d o th e r o rd e rs re p re s e n ta tiv e s s u c h a s p rim a te s
(m o n k e y s ) a n d la g o m o rp h a (ra b b its a n d h a re s ).
T h e in te ra c tio n b e tw e e n
T. cruzi,
v e c to rs a n dre s e rv o irs m a y , th e o re tic a lly , in flu e n c e th e c o u rs e o f th e d is e a s e in h u m a n s . A s a c o n s e q u e n c e o f th e p a ra s ite
p a s s a g e th ro u g h d iffe re n t o rg a n is m s , th e try p a n o s o m e
e n d u re s s e le c tiv e a n d a d a p ta tiv e p ro c e s s e s th a t m a y re s u lt,
fo r h u m a n b e in g s , in s tra in s w ith h ig h e r o r lo w e r m o rb id ity p o te n tia l (1 8 ,3 4 ).
H u m a n s a re th e m a in d o m e s tic re s e rv o irs
ofT.
cruzi,
fo llo w e d b y c a ts , d o g s a n d d o m e s tic ro d e n ts . A lth o u g hn o t b e in g
T. cruzi
h o s ts , o th e r a n im a ls s u c h a s b ird s a ls op la y th e ir p a rt in th e e c o lo g y o f C h a g a s ' d is e a s e a s fe e d in g
s o u rc e fo r a g re a t n u m b e r o f tria to m in e s p e c ie s .
B e s id e s b ird s , p o ik ilo th e rm ic v e rte b ra te s s u c h a s
s n a k e s , liz a rd s a n d fro g s c a n a ls o s e rv e a s fe e d in g s o u rc e
fo r tria to m in e s , a fa c t e v id e n c e d n o t o n ly in s y lv a tic b u t
in d o m e s tic e n v iro n m e n t a s w e ll (1 ,9 ,1 8 ).
TRANSMISSION
MECHANISMS
Vectorial transmission
T h e m o s t im p o rta n t m e c h a n is m o f tra n s m is s io n o f
T. cruzi
to h u m a n s a n d o th e r a n im a ls is th ro u g h o u t th e fe c e s o f in fe c te d tria to m in e s (1 ). T h e v e c to rs o f C h a g a s 'd is e a s e a re in s e c ts o f th e o rd e r H e m ip te ra , fa m ily
R e d u v iid a e a n d s u b fa m ily T ria to m in a e . O f th e 1 1 8 s p e c ie s
o f tria to m in e s , o n ly a re la tiv e ly s m a ll n u m b e r a re
e p id e m io lo g ic a lly s ig n ific a n t a s v e c to r o f
T. cruzi
a s ac o n s e q u e n c e o f th e ir c a p a c ity to d o m ic iliz e :
Triatoma
infestans,
T. braziliensis,
T. dimidiata,
T. sordida,
Panstrongylus
megistus
a n dRhodnius
prolixus.
T h e g e o g ra p h ic d is trib u tio n o f th e m a in v e c to rs o f C h a g a s '- " ' ,
(::::::::::::1 T . d im id ia ta
_ R . p ro lix u s
m
T . in fe s ta n s~ T .s o rd id a
~ P .megistus
e m
T . b ra s i6 e n s isFigure
1 . G e o g ra p h ic d is trib u tio n o f th e m a inT. cruzi
tria to m in e v e c to rs .d is e a s e is d e p ic te d in F ig u r e 1 . F r o m M e x ic o to V e n e z u e la a n d C o lo m b ia ,
R. prolixus
a n dT. dimidiata
a r e th e m a in v e c to r s w h ile s o u th o f th e E q u a to r lin e ,T. infestans
is u n d o u b te d ly th e o u ts ta n d in g s o u r c e o f th e d is e a s e f o r h u m a n s . T h e A m a z o n r e g io n a p p e a r s a s a b a r r ie r b e tw e e n s o u th e r n a n d n o r th e r n e n d e m ic r e g io n s d e s p ite th e e x is te n c e o f w ild v e c to r s a n d r e s e r v o ir s tr o u g h o u t th e f o r e s t ( 8 ,9 ,1 1 ,2 5 ) . S u c h s p e c ie s a r e c h a r a c te r is tic o f th e s o c a lle d o p e n s p a c e s o f S o u th a n d C e n tr a l A m e r ic a , b e in g th e m n a tu r a l o r th e r e s u lt o f a n th r o p ic a c tio n ( 7 ) . T h e r a te o fT. cruzi
tr a n s m is s io n w ill b e d e p e n d e n t o n s e v e r a l f a c to r s , in c lu d in g v e c to r s d e n s ity , f o o d s o u r c e p r e f e r e n c e , lo n g e v ity , s u s c e p tib ility to d if f e r e n t p a r a s ite s tr a in s , c a p a c ity to d e f e c a te im m e d ia te ly a f te r th e b lo o d m e a l, a n d a b ility to y ie ld a n d e lim in a te la r g e q u a n titie s o f p a r a s ite s ( 1 ,3 4 ) .Transfusional transmission
T h e p o s s ib ility o f tr a n s f u s io n tr a n s m itte d C h a g a s ' d is e a s e w a s f ir s t r a is e d in A r g e n tin a , in 1 9 3 6 ( 1 5 ) . I n 1 9 4 4 it w a s f o r m a lly m e n tio n e d a s a p u b lic h e a lth p r o b le m in L a tin A m e r ic a ( 6 ) . T h e f ir s t in f e c te d d o n o r s w e r e r e c o r d e d in 1 9 4 9 , a n d in 1 9 5 2 th e f ir s t c a s e s o f th e tr a n s f u s io n a l d is e a s e in S a o P a u lo , B r a z il ( 1 2 ) w e r e r e p o r te d . A n u p d a te d la r g e r e v ie w ( 2 2 ) r e f e r s to th e v a r io u s s u r v e y s c o n d u c te d in b lo o d b a n k s a ll o v e r th e A m e r ic a n c o n tin e n t in th e la s t d e c a d e s h o w in g p r e v a le n c e r a te s v a r y in g b e tw e e n 0 % a n d 6 3 % , w ith a n a p p r o x im a te m e a n o f 3 % . B o liv ia is th e c o u n tr y w ith h ig h e r p r e v a le n c e o f in f e c te d d o n o r s .
T h e s e d a ta b e c o m e v e r y im p o r ta n t w h e n s tu d ie s th a t s h o w p e r c e n ta g e s o f 6 0 % a m o n g c r o n ic c h a g a s ic p a tie n ts th a t p r e s e n t b lo o d - c ir c u la tin g
T. cruzi
a r e c o n s id e r e d a n d th a t th e r is k o f a c q u ir in g a c h a g a s ic in f e c tio n v ia a n in f e c te d d o n o r g o e s f r o m 1 2 .5 % to 2 5 .0 % f o r o n ly o n e tr a n s f u s io n ( 3 3 ) . I f it is c o n s id e r e d th a t y e a r ly m o r e th a n 4 m illio n b lo o d tr a n s f u s io n s a r e p e r f o r m e d in B r a z il, it is p r o b a b le th a t m a n y th o u s a n d in f e c tio n s m a y b e tr a n s m itte d in s u c h a w a y ( 3 4 ) . S u c h e s tim a te m u s t b e lo o k e d a t w ith c a r e s in c e it is b a s e d o n n o t- a t- a ll e x a m in e d b lo o d s a m p le s w h ic h p r e s e n tly a r e le s s s e e n in B r a z il.O n ly 2 8 4 c a s e s w e r e f o u n d in a r e v is io n o f th e lite r a tu r e o n tr a n s f u s io n a l C h a g a s ' d is e a s e c a s e s r e p o r te d in th e la s t 4 0 y e a r s a n d th e y s e c u r e ly r e p r e s e n t a m in o r ity a m o n g r e a lly o c c u r r in g c a s e s ( 3 3 ) . F a c to r s a s s o c ia te d to th e p a r a s ite a n d to th e r e c e p to r , th e n u m b e r o f tr a n s f u s io n s r e c e iv e d b y th e p a tie n t a n d th e p r e v a le n c e o f th e in f e c tio n in th e z o n e u n d e r s tu d y k e e p r e la tio n w ith th e r is k o f b lo o d tr a n s f u s io n tr a n s m is s io n o f
Trypanosoma
cruzi.
A n o th e r r is k f a c to r is th e v ia b ility o f th e p a r a s ite , th a t is , its c a p a c ity f o r c a u s in g in f e c tio n e v e n w h e n s to r e d u p to 3 w e e k s u n d e r lo w te m p e r a tu r e s .Congenital transmission
T h e f ir s t o b s e r v a tio n o n th e p o s s ib ility o f c o n g e n ita l C h a g a s ' d is e a s e tr a n s m is s io n w a s m a d e in 1 9 1 1 ( 1 0 ) . I n
1 9 4 9 th e f ir s t h u m a n c a s e w a s d e s c r ib e d a n d th e p a r a s ite o b s e r v e d in a th ic k b lo o d f ilm o f a 2 - d a y - o ld n e w b o r n w h o s e m o th e r d id n o t p r e s e n t p o s itiv e x e n o d ia g n o s is . F r o m th e n o n s e v e r a l r e p o r ts w e r e p r e s e n te d ( 1 0 ,3 4 ) . A lite r a tu r e r e v is io n p e r f o r m e d in 1 9 8 7 d e te c te d 2 0 0 c lin ic a lly c o m p r o v e d c a s e s . P r e m a tu r ity w a s o f te n in c lu d e d a m o n g c lin ic a l a s p e c ts ( 1 6 ) . S tu d ie s o n th e f r e q u e n c y o f C h a g a s 'd is e a s e a m o n g p r e g n a n t w o m e n in B r a z il s h o w e d a v a r ia tio n f r o m 4 % to 1 6 .4 % w h ile th e illn e s s in c id e n c e a m o n g n e w b o r n v a r ie d f r o m 1 6 % to 1 0 .5 % ( 1 0 ) . C o n g e n ita l tr a n s m is s io n in B r a z il m a y n o t b e u n d e r e s tim a te d if , w ith th e a c c e p te d r is k o f I % it is c o n s id e r e d th a t 7 5 0 th o u s a n d c h a g a s ic w o m e n in f e r tile a g e m a y o r ig in a te 7 .5 0 0 c o n g e n ita lly tr a n s m itte d c a s e s ( 8 ,1 0 ) e a c h y e a r .
I n A r g e n tin a s tu d ie s in d ic a te d p r e v a le n c e f r o m 6 % to 2 0 % a m o n g p r e g n a n t w o m e n a c c o r d in g to th e a r e a 's e n d e m ic ity . I n S a n ta C r u z , B o liv ia , it w a s 5 1 % . I n S a n tia g o d o C h ile a n d 3 o th e r C h ile a n lo c a litie s s itu a te d in e n d e m ic a r e a s , th e s e r o p o s itiv ity in p r e g n a n t w o m e n v a r ie d f r o m 0 .8 % to 7 .4 % . I n A r tig a s , U r u g u a y , it w a s 8 .9 % .
T h e m a jo r ity o f th e in f e c te d w o m e n w h ic h g a v e b il1 h to c h ild r e n p r e s e n tin g c o n g e n ita l c h a g a s ic in f e c tio n d o n o t s h o w c lin ic a l s y m p to n s o f C h a g a s ' d is e a s e c h r o n ic f o r m . T h e in f e c tio n d o e s n o t s e e m to in te r f e r e n e ith e r w ith th e f e c u n d ity n o r w ith th e p r e g n a n c y e v o lv e m e n t. D if f e r e n c e s b e tw e e n g r o u p s o f in f e c te d a n d n o n - in f e c te d m o th e r s c o n c e r n in g a b o r tio n , n e w b o r n lo w w e ig h t, p r e m a tu r e b ir th , in tr a - u te r in e d is o r d e r s a n d f e ta l d e v e lo p m e n t h a v e n o t b e e n o b s e r v e d .
C a s e s o f c o n g e n ita l C h a g a s ' d is e a s e h a v e b e e n r e p o r te d in A r g e n tin a , B o liv ia , B r a z il, C h ile , U r u g u a y a n d V e n e z u e la . I n A r g e n tin a , th e p r e v a le n c e o f th e c o n g e n ita l in f e c tio n o s c ila te s f r o m 0 .7 5 % to 3 .5 0 % . I n B a h ia , B r a z il, th e p r e v a le n c e w a s 1 0 .5 % ; in C h ile , 1 8 .8 % ; in U r u g u a y
1 .5 7 % a n d in S a n ta C r u z , B o liv ia , it r a n g e d f r o m 5 % to 8 % ( 3 4 ) .
Oral transmission
T h e r e a r e 3 r e p o r ts o f o r a l tr a n s m is s io n o f C h a g a s ' d is e a s e to h u m a n b e in g s : a n e p id e m ic o u tb r e a k in T e u to n ia , R io G r a n d e d o S u I , w ith 1 7 p e r s o n s s im u lta n e o u s ly in f e c te d , p r o b a b ly d u e to th e in g e s tio n o f c o n ta m in a te d m e a l w ith u r in e f r o m in f e c te d m a r s u p ia ls ( 2 6 ) ; a n o th e r in P a r a , B r a z il, w h e r e 4 p e r s o n s s e e m to h a v e b e e n in f e c te d th r o u g h th e in g e s tio n o f f o o d c o n ta m in a te d w ith tr ia to m in e e x c r e ta ( 2 4 ) ; a n d , m o r e r e c e n tly , a n o u tb r e a k in P a r a f b a S ta te , w h e n 2 8 in d iv id u a ls a c q u ir e d a c u te C h a g a s ' d is e a s e
follow ing the ingestion of sugar-cane juice probably
contam inated w ith triatom ine feces (14).
Transmission by breast-feeding
T his kind of
T.
cruzi
transm ission w as first suspectedin 1936 (16). T rypom astigote isolation from infected
m others' colostrum is a rare occurrence. T hus,
transm ission by breast-feeding seem s very unlikely and
there is no reason to restrict breast-feeding by infected
m others.
Accidental transmission
A lthough occurring very seldom , laboratorial
contam ination represents a serious risk of acquiring
C hagas' disease. It can occur very often as a consequence
of puncture w ith contam inated needles, contact of the
conjuntiva w ith contam inated m aterial and w hile
pippetting
T. cruzi
cultures. T here are about 50 casesreported all around the w orld in different developed and
underdeveloped countries (34).
Transmission by organ transplantation
T.
cruzi
m ay be transm itted by organ transplantationfrom infected donors. R eceptors suffer illness episodes
and the parasites m ay be isolated from peripheral blood
(4). A few fatal cases have been reported in w hich the
parasites have been isolated from different organs. A s
organ receptors are subm itted to im m unesuppressive
therapy their susceptibility to infections tends to increase.
In the sam e w ay, chronic chagasic recipients m ay present
a w orsening of the infection as a consequence of the
im m unosuppressive treatm ents. T he m ost frequent
situation recorded involves kidney transplants (w ith m ore
than 10 cases described) but cases of transm ission in heart
and pancreas transplants have been reported as w ell (10).
H U M A N C H A G A S ' D IS E A S E
Geographic Distribution
T he geographic distribution of
T. cruzi
hum aninfection goes from the south of the U nited S tates of
A m erica - w here sporadic cases have been reported - to
the south of A rgentina (F igure 2).
E ndem ic countries m ay be divided into 4 groups
according w ith the transm ission m agnitude, the quantity
and the quality of the epidem iological inform ation
available and the existence or not of C ontrol P rogram m es
(35) (T able 1).
In B razil, the endem ic area com prises m ore than
3,500,000 km2, that is, 44.5% of the national territory, being
the larger in the A m ericas. It involves 2,450 m unicipalities
from the follow ing S tates: A lagoas, B ahia, C eara, E spfrito
S anto, G oias, M aranhao, M ato G rosso do S uI, M inas
G erais, P arafba, P arana, P ernam buco, P iauf, R io de
Janeiro, R io G rande do S uI, R io G rande do N orte, S ao
P aulo, S ergipe and D istrito F ederal (8). R ecently,
autochthonous cases w ere reported from the S tates of P ara,
A m azonas, A m apa and A cre (5).
In practical term s, the hum an disease presents great
difficulties for specific therapy in its chronic phase and
the inexistence of a largely safe and sound vaccine has led
the sanitary authorities to priorize control actions against
vectorial transm ission (7,21) and prevention of
transfusional transm ission. T he previous selection of
infected donors and chem oprophylaxis have produced
positive results w herever they have been used (19,22,32).
T he C hagas' D isease V ectorial C ontrol N ational
P rogram m e initiated in 1950, reached its larger coverage
by 1983. In 1986, w hen it w as fully consolidated, the
im pact w as highly positive w ith drastic reduction of the
triatom ine-trypanosom ic rates over all the endem ic area
~
F ig u r e 2 . G e o g r a p h ic d is tr ib u tio n o f T
cruz;
h u m a n in fe c tio n in th e A m e r ic a s .Table 1
Prevalence of T. cruzihuman infection in Latin America, 1980-1985.
E ndem ic C ountries P opulation at risk P opulation infected
nQ-x(1000) % (') nQ'x(1000) % (")
Group I
A rgentina 6900 33 2640 38
B razil 41054 32 6340 26
C hile 1800 1 1460 81
E cuador 3823 41 30 1
H onduras 1824 42 300 16
P araguay 1475 45 397 27
P eru 6676 34 643 10
U ruguay 975 33 37 4
V enezuela 11392 68 1200 11
Group II
B olivia 1800 30 500 28
C olom bia 3000 10 900 30
C osta R ica 1112 45 130 12
M exico
Group III
E I S alvador 146 43 322 15
G uatem ala 4022 52 730 18
N icaragua
P anam a 898 42 220 24
Total 86897 25 15849 18
(*) A s% of total population /(*) A s % of population at risk S ource: W H O , 1990(24).
(7 ). S u c h su c c e ss w a s a tta in e d w ith re sid u a l in se c tic id e s
th ro u g h a n in te n siv e h o u se -sp ra y in g w o rk . In th e b e g in n in g
B H C , a re p re se n ta tiv e o f th e o rg a n o c h lo rin e , w a s th e
in se c tic id e o f c h o ic e a s stu d ie s sh o w e d its h ig h e ffic a c y
a g a in st
T. infestans,
its re la tiv e ly lo w c o sts a n d itsm o d e ra te d to x ic e ffe c ts. F ro m th e b e g iim in g o f th e 8 0 's
p y re trh o id s w ith g re a te r re sid u a l e ffe c ts a n d le ss to x ic to
h u m a n s w e re p ro p o se d a s su b stitu te s o f th e B H C (2 7 )
w h ic h w a s so o n a b a n d o n e d . B y 1 9 9 1 , th e m a in d o m e stic
v e c to r
T. infestans
h a d b e e n e lim in a te d fro m 3 2 .3 % o f th eB ra z ilia n m u n ic ip a litie s. N o tw ith sta n d in g , d e sp ite
T.
infestans
re sid u e , re su lts o b ta in e d in th e se a rc h e d a re a sh o w d w e llin g in fe sta tio n ra te s lo w e r th a n 2 % w h ic h isa n in d ic a tiv e th a t v e c to ria l tra n sm issio n p o ssib ilitie s a re
n o w a d a y s e x tre m e ly re d u c e d in th e c o u n try (6 ).
It se e m s in te re stin g to n o te th a t th e v e c to ria l c o n tro l
p ro g ra m m e s e m p lo y in g su c h a m o d e l - sp ra y in g o f h o u se s
w ith re sid u a l in se c tic id e s - a tta in e d in te rru p tio n o f C h a g a s'
d ise a se tra n sm issio n w h e n
T. infestans
h o u se in fe sta tio nra te s u n d e r 5 % w e re re a c h e d (2 ).
In th e S ta te o f S a o P a u lo , C h a g a s' d ise a se v e c to r
c o n tro l, sta rte d in 1 9 5 0 , a tta in e d fu ll su c c e ss tw o d e c a d e s
la te r (2 ,2 1 ,2 8 ). N o w a d a y s it is k e p t e p id e m io lo g ic a l
su rv e illa n c e o n se c o n d a ry sp e c ie s -
T. sordida
a n dP.
megistus.
T h e re su lts o b ta in e d in th e la st 1 0 y e a rs in d ic a te stro n g p re se n c e o f th o se v e c to rs in th e p e ri d o m ic ile (7 0 % ),lo w p e rc e n ta g e o f
T. cruzi
n a tu ra l in fe c tio n (2 .4 % ) a n dd isc re te p ro x im ity to w a rd s h u m a n s a s o n ly 5 % o f th e
c a p tu re d sp e c im e n s h a v e fe d o n su c h h o sts. T h e p re v a le n c e
o f c h a g a sic in fe c tio n in th e in h a b ita n ts o f h o u se s in fe c te d
w ith tria to m in e s w a s 3 .2 % , a n d th e c o n c e n tra tio n o f
p o sitiv e s in in d iv id u a ls o ld e r th a n 2 0 y e a rs o f a g e . S u c h
in fo rm a tio n c o n firm th e a b se n c e o f n a tu ra l tra n sm issio n
b y C h a g a s' d ise a se tria to m in e v e c to rs. In th is su rv e illa n c e ,
p o p u la tio n is h a v in g im p o rta n t ro le in th e n o tific a tio n o f
in tra d o m ic ile fo c u s. E a c h n o tific a tio n is a n sw e re d b y th e
co n tro l o rg an ism w ith a carefu ll search o f th e d o m icile
u n it w h ich h as as o b jetiv es ev alu ate fo cu s ex ten t an d , w h en
n ecessary , u se in secticid es. Q u ick an sw er to each
n o tificatio n feed s b ack th e p ro cess an d en su res co n tro l
o v er th e area (2 9 ,3 0 ,3 1 ).
A lth o u g h v ecto rial tran sm issio n is u n d er co n tro l in
S ao P au lo S tate an d larg e areas in B razil, th ere is n o
in frastru ctu re to assist th e in fected in d iv id u al d etected b y
th e p ro g ram m e. T h is asp ect h as a larg e im p o rtan ce an d
h as w o rried th o se resp o n sib le fo r th e o fficial co n tro l
in stitu tio n s (7 ,2 8 ,2 9 ).
Natural history
T.
cruzi
h u m an in fectio n m ay o ccu r u n d er d ifferen t w ay s acco rd in g to circu n stan ces an d situ atio n s. H ost-p arasite in teractio n is q u ite d y n am ic an d d ep en d s ?n
m u ltip le facto rs related w ith th e try p an o so m e (straIn ,
v iru len ce, in o cu lu m ), th e h u m an h o st (ag e, sex ) an d th e
en v iro n m en t. A s a ru le, th e ex isten ce o f tw o d ifferen t
d istin ct p h ases o f th e d isease is accep ted : th e acu te an d
th e ch ro n ic, each o n e o f th em p resen tin g d ifferen t
ch aracteristics.
Morbidity
A s it is k n o w n , an in d iv id u al in fected w ith
T. cruzi
w ill n o t n ecessarily p resen t an y ap aren t clin ical fo rm o f
th e d isease. T h is also h ap p en s sp ecifically d u rin g th e acu te
p h ase in w h ich th e g reat m ajo rity o f th e cases w ill g o
u n seen . T h e h y p o th esis o f acu te d isease, d esp ite th e
freq u en tly d iscrete p ictu re, m u st im p o se itself in th e
en d em ic reg io n s an d in p o s-tran sfu sio n al situ atio n s.
T h e larg e m ajo rity o f th e in d iv id u als w ill b e
assim p to m atic d u rin g th e d isease first 1 0 o r 2 0 y ears. In
g en eral, th e in d eterm in ate o r su b clin ical fo rm o f C h ag as'
d isease p ersists in at least 3 0 % o f th e ch ag asic p atien ts
fo r th eir en tire life. T h is in d eterm in ated fo rm is g en erally
d efin ed b y th e p resen ce o f p o sitiv e sero lo g y fo r
T. cruzi
inan asy m p to m atic p atien ts an d n o electro card io g rap h ic an d
rad io lo g ical ab n o rm alities. A g reat im p o rtan ce o f th is fo rm
o f th e d isease is th at p atien ts k eep an d m u st k eep a to tally
n o rm al life as th ey are ap ts fo r alm o st all task s an d jo b s.
T h e o n ly w o rk restrictio n fo r in d eterm in ated fo rm p atien ts,
acco rd in g to th e sp ecialists, refer to p ro fessio n s th at can
o ffer risk to th e life o f o th ers, as d riv ers in g en eral, m ach in e
o p erato rs, aircraft p ilo ts an d so o n . A m o n g th e clin ical
fo rm s o f th e ch ro n ic p h ase card io p ath y , eso p h ag o p h ath y
an d co lo p ath y are th e m o st im p o rtan t. .
C h ro n ic ch ag asic card io p ath y is th e m o st im p o rtan t
o f th e clin ical fo rm s o f th e d isease n o t o n ly fo r its
p rev alen ce b u t m ain ly d u e to th e serio u sn ess o f th e d am ag e
it m ay p ro d u ce. T h is lesio n is m o re freq u en t in m en an d
strik es p ro g ressiv ely fro m th e th ird d ecad e o f life 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 (2 ) M a r/A p r 1 9 9 5
T h e d ig estiv e fo rm s, sp ecially eso p h ag o p ath y an d
co lo p ath y are relativ ely co m m o n s. E so p h ag o p ath y p resen ts
h ig h er p rev alen ce in m ales in a p ercen tag e o f 6 % to 8 %
fo r th e reg io n s o f B ah ia an d M in as G erais. C o lo p ath y is a
late m an ifestatio n o f ch ro n ic C h ag as' d isease ap p earin g
p red o m in an tly after th e fo u rth o r fifth d ecad es o f life. O th er
p o rtio n s o f th e d ig estiv e tu b e m ay also b e affected b u t
less freq u en tly (9 ,1 8 ).
Mortality
M o rtality in C h ag as' d isease is v ery sig n ificativ e in
sev eral en d em ic co u n tries su ch as B razil, A rg en tin a,
B o liv ia, V en ezu ela an d N o rth o f C h ile, d ep en d in g b asically
o n th e in cid en ce o f sev ere card io p ath y (3 4 ).
In B razil, acco rd in g to o fficial statistics, at least 6 ,0 0 0
d eath s/y ear d u e to C h ag as' d isease h av e b een reco rd ed
(1 7 ), fig u res th at d em o n strate th e im p o rtan ce o f th e d isease
fro m th e m ed ical an d so cial stan d p o in ts.
E x am in in g th e m o rtality co efficien ts cau sed b y
C h ag as' d isease in fo u r o f th e en d em ic B razilian states,
calcu lated fo r each 1 0 0 th o u san d in h ab itan ts in th e y ears
fro m 1 9 7 7 an d 1 9 8 7 , a sig n ifican t red u ctio n m ay b e
o b serv ed . T h u s, fo r M in as G erais, S ao P au lo , P aran a an d
B ah ia th e v alu es felt fro m 1 7 .7 , 6 .9 , 5 .1 an d 4 .2 , in 1 9 7 7 ,
to resp ectiv ely , 1 3 .0 , 4 .7 , 4 .1 an d 3 .9 , in 1 9 8 7 .
F ro m 1 9 7 7 to 1 9 8 6 , in S ao P au lo S tate, a m ean
n u m b er o f 1 ,5 3 7 an n u al d eath s in w h ich C h ag as' d isease
w as id en tified as th e b asic cau se w ere o b serv ed . T h e
p articip atio n o f th e A m erican try p an o so m iasis in th e
p ro p o rtio n al m o rtality ran g ed to 0 .9 % ; sp ecific v alu es fo r
each y ear v ary in g fro m 1 ,4 5 5 to 1 ,6 1 5 (1 3 ). A su rv ey b ased
o n th e d eath certificates in S ao P au lo S tate, in 1 9 8 7 ,
v erified th at o u t o f 1 ,6 4 6 statem en ts in w h ich C h ag as'
d isease w as m en tio n ed , it w as co n sid ered th e m ain cau se
o f th e d eath in 1 ,5 1 6 an d it p articip ated in 1 3 0 as a
co n trib u to ry cau se. It w as o b serv ed th at m en d ied m o re
freq u en tly o f C h ag as' d isease th an w o m en an d th at th e
p ro p o rtio n o f th e d eceased raised w ith ag e. T h e reg io n o f
th e G reat S ao P au lo co n cen trates a larg er n u m b er o f d eath s
attrib u ted to C h ag as' d isease.
C ard iac failu re w as o b serv ed in 9 1% o f th e d eath s.
In th is stu d y it w as p o ssib le to co n firm th e im p o rtan ce o f
C h ag as' d isease in th e S tate an d to p o in t o u t in fo rm atio n
th at co n trib u ted to th e p lan n in g o f atten d an ce to th e
ch ag asic p atien t.
F IN A L C O N S ID E R A T IO N S
A v ailab le ep id em io lo g ical d ata in d icate th at C h ag as'
d isease is an im p o rtan t m ed ical an d so cial p ro b lem in larg e
ex ten sio n s o f L atin A m erica. T h is p ictu re is w o rsen ed d u e
to th e in ex isten ce o f v ecto rial co n tro l p ro g ram m es an d
b lo o d co n tro l p o licies in m an y co u n tries, sin ce th e p rio rity
to tran sfu sio n al C h ag as' d isease h as n o t b een estab lish ed
in m an y en d em ic reg io n s. O n ly w h en A ID S b ecam e a
m ajo r p ro b lem co u n tries su ch as A rg en tin a, B razil,
U ru g u ay an d V en ezu ela d ecid e to settle co n tro l p o licies
(2 2 ). In B razil, a su rv ey carried o u t in 8 5 0 m u n icip alities,
fro m 1 9 8 8 to 1 9 9 0 , in d icated th at C h ag as' d isease p rev io u s
screen in g w as p erfo rm ed in 6 6 .9 % o f th e h em o th erap ic
serv ices (1 9 ). F ro m th ese, 5 5 .3 % p erfo rm ed o n ly o n e
sero lo g ical test fo r th e d o n o r screen in g , d esp ite th e o fficial
reco m m en d atio n fo r th e u se o f at least tw o screen in g
tech n iq u es (3 4 ).
Im p lem en tatio n an d m ain ten an ce o f reg u lar v ecto r
co n tro l p ro g ram m es, w h o se co st-b en efit relatio n sp eek s
h ig h ly in fav o u r o f th e in v estm en t (2 3 ) an d th e am elio ratio n
o f th e h em o th erap ic secto r, m u st lead to th e triato m in e
v ecto r d o m iciliary tran sm issio n an d to th e tran sfu sio n al
tran sm issio n co n tro l in th e fu tu re. T h e co n g en ital d isease
an d o th er ev en m o re rare fo rm s o f
T.
cruzi
tran sm issio n toh u m an s o u g h t to b e ex cep tio n al.
In fected in d iv id u als, w ith o r w ith o u t clin ical
m an ifestatio n s, m u st receiv e m ed ical an d p rev id en ciary
atten tio n , restin g to th e S tate to co p e w ith su ch d em an d s,
acco rd in g to th e p recep ts estab lish ed in th e last B razilian
co n stitu tio n al law .
REFERENCES.
1. B A R R E T O , M .P . - E p id em io lo g ia. In : B ren er Z , A n d rad e Z . ed s.
Trypanosoma cruzi
e d o en ~ a d e C h ag as.R io d e Jan eiro , G u an ab ara K o o g an , 1 9 7 9 . p . 8 9 -1 5 1 .2 . B U R A L L I, G .M . - E stu d o d o co n tra Ie d o s triato m fn eo s d o m iciliad o s n o E stad o d e S ao P au lo . S ao P au lo 1 9 8 5 . 2 4 0 p . (D issertac;ao d e m estrad o F ac. S au d e P u b lica U S P ). 3 . C H A G A S , C . - N o v a trip an o zo m iase h u m an a. E stu d o s so b
a m o rfo lo g ia e 0cicio ev o lu tiv o d o Schizotl}'pQ11Um cruzi
n .g en .,s.sp . ag en te etio lo g ico d e n o v a en tid ad e m o rb id a d o h o m em . M em In st O sw ald o C ru z 1 : 1 5 9 -2 1 8 ,1 9 0 9 . 4 . C H O C A IR , P .R .; S A B B A G A , E .; A M A T O N E T O ,
v.;
S H IR O M A , M . & G O E S , G .M . - N o v a m o d alid ad e d e tran sm issao d a d o en c;a d e C h ag as. R ev In st M ed tro p S ao P au lo 2 3 :2 8 0 -2 8 2 , 1 9 8 1 .
5 . C O U R A , J.R . - D o en c;a d e C h ag as n a A m azo n ia b rasileira.
R ev S o c B ras M ed T ro p 2 6 (su p l 2 ): 1 5 -7 , 1 9 9 3 . 6 . D IA S , J.c.P . - A d o en c;a d e C h ag as e seu co n tro le n a A m erica
L atin a. U m a an alise d e p o ssib ilid ad es. C ad S au d e P u b l, R io d e Jan eiro 9 :2 0 1 -9 , 1 9 9 3 .
7. D IA S, J.c.P. - Control ofChagas D isease in Brasil. Parasitol.
Today 3: 36-41, 1987.
8. D IA S, J.C.P. - Epidem iology ofChagas D isease in Brazil. In
Brener, RR
&
Stoka, A .M . eds. Chagas'D isease V ectors.Boca Raton, CRC Press Inc 1: 57-81,1987.
9. D IA S, J.C.P. - Epidem iology of Chagas disease. In: W endel,
S.; Brener, Z.; Cam argo, M .E. & Rassi, A eds. Chagas D isease
(A m erican Trypanosom iasis) its im pact of transfusion and
clinical m edicine. Sao Paulo, ISBT 1992. p. 49-80.
10. D IA S, J.C.P. - M ecanism os de transm issao In: Brener, Z.
&
A ndrade, Z. eds.
Trypa1losoma cruz;
e doent;a de Chagas.Rio de Janeiro, G uanabara-K oogan, 1979. p. 152-174.
11. FO RA TTIN I, O .P. - Biogeografia, origem e distribui~ao da
dom icilia~ao de triatom fneos no Brasil. Rev Saude Publ Sao
Paulo 14: 205-29, 1990.
12. FREITA S, J.L.P.; A M A TO -N ETO , Y .; SO N N TA G , R.;
BIA N CA LA N A , A ; N U SSEN ZW EIG , Y . & BA RRETO ,
J.G . - Prim eiras verifica~5es da transm issao acidental da
m olestia de Chagas ao hom em par transfusao de sangue. Rev
Paulista M edicina 40: 36-40, 1952.
13. LITV O C, J.; W A N D ERLEY , D .M .Y . & A RA N H A
CA M A RG O , L.M . - M ortalidade por doen~a de Chagas no
Estado de Sao Paulo (Brasil):Subsfdios para 0planejam ento
da assistencia ao chagasico. Rev Saude Publ Sao Paulo 26:
59-65, 1992.
14. M A RCO N D ES, C.B.; G U ED ES, L.A & M EN D O N <;A , D .
- Surto de doen~a de Chagas de provavel contam ina~ao oral
em Catole do Rocha (Pb ):observa~5es epidem iol6gicas. Rev
Soc Bras M ed Trop 20(supI.2): M ll-3, 1987.
15. M A ZZA , S.; M O N TA N A , A .; BEN ITEZ, C.
&
JU ZIN , E.-Transm isi6n del
Schizotrypanum cnd
al nifio por leche dela m adre con enferm edad de Chagas. M is Est Pat Reg A rg
28: 41-6, 1936.
16. M EN EG U ETTI, L.c. - Epidem iologia da transm issao
congenita da doent;a de Chagas: subsfdios para a
form ulat;ao de urn projeto de pesquisa. Sao Paulo, 1986.
130 p. [D isserta~ao de M estrado, Fac. Saude Publica U SP].
17. M IN ISTERIO D A SA U D E - Estatfsticas de M ortalidade.
Brasilia. 1987.
18. M IN ISTERIO D A SA U D E - Superintendencia de
Cam panhas de Saude Publica-SU CA M . D oent;a de
Chagas-Clfnica e Terapeutica. Brasilia 1990 .p. 1-94.
19. M O RA ES-SO U ZA , H .; W A N D ERLEY , D .M .Y .; BREN ER,
S.; N A SCIM EN TO , R.D .
&
D IA S, J.C.P. - Situa~ao dadoen~a de Chagas transfusional e da hem oterapia no Brasil.
Resultados de urn inquerito nacional. Bol O f Sanit Panam
116: 406-19, 1994.
20. PELLEG RIN O , J. -
0
perigo da transm issao da doen~a deChagas pela transfusao de sangue. Prim eiras com prova~5es
sorol6gicas de esquizotripanose em doadores e em candidatos
a doadores de sangue. Brasil M ed 63: 65-71, 1949.
21. RO CH A E SILV A , E.O .; G U A RITA , O .F.
&
CO RREA ,R-D oen~a de Chagas. A tividades de controle dos transm issores
no Estado de Sao Paulo. Rev Bras M alar 31: 99-119, 1979.
22. SCH M U N IS, G .A . -
Trypanosoma cruzi,
the ethiologic agentof Chagas disease:Status in the blood supply in endem ic and
nonendem ic countries. Transfusion 31: 547-57,1991.
23. SCH O FIELD , c.J.
&
D IA S, J.c.P. - A cost benefit analysisof Chagas disease control. M em Inst O sw aldo Cruz 86:
285-95, 1991.
24. SH A W , J.; LA IN SO N , R
&
FRA H IA , H . - Considera~5essobre a epidem iologia dos prim eiros casos aut6ctones de
doen~a de Chagas registrados em Belem , Para, Brasil. Rev
Saude publ3: 153-57, 1969.
25. SH ERLO CK , LA - V etores In: Brener, Z. & A ndrade, Z.
Trypanosoma cruzi
e D oen~a de Chagas. Rio de Janeiro:G uanabara-K oogan 1979. 83 p.
26. SILV A , N .N .; CLA U SELL, D .T.; N O LIBU S, H .; M ELLO ,
A .L.; O SSA N A I, A .; RA PO N E, T.
&
SN ELL, T. - Surtoepidem ico de doen~a de Chagas com provavel contam ina~ao
oral. Rev Inst M ed trop Sao Paulo 10: 265-76, 1969.
27. SILV EIRA , A .C.
&
SA K A M O TO , T. - Im portancia medico-social da doen~a de Chagas no Brasil e seu controle. Rev
brasil m alariol D trop 35: 127-134, 1983.
28. SO U ZA , A .G .; W A N D ERLEY , D .M .Y .; BU RA LLI, G .M .
&
A N D RA D E, J.C.R. - Consolidation of the control ofChagas disease in the State of Sao Paulo. M em Inst O sw aldo
Cruz 79(supl): 125-132, 1985.
29. W A N D ERLEY , D .M .Y . - A m ilise da atual estratt~gia do
Program a de Controle da doent;a de Chagas no Estado
de Sao Paulo. Sao Paulo, 1987. 103 p. [D isserta~ao de
m estrado, Fac.Saude Publica U SP].
30. W A N D ERLEY , D .M .V . - V igilancia do risco de transm issao
da doen~a de Chagas por vetores secundarios no Estado de
Sao Paulo. Rev Soc Bras M ed trop 26: 38-40, 1993.
31. W A N D ERLEY , D .M .Y . - V igilancia entom ol6gica da doen~a
de Chagas no Estado de Sao Paulo. Rev Saude publ S Paulo
25: 28-32, 1991.
32. W A N D ERLEY , D .M .Y .; G O N ZA LES, T.T.; PEREIRA ,
M .S.C.A ; N A SCIM EN TO , RD .
&
M O RA ES-SO U ZA , H .- Controle da hem oterapia e da doen~a de Chagas
transfusional no Estado de Sao Paulo: 1988 e 1990. Rev Saude
pub I. S.Paulo 27: 430-5, 1993.
33. W EN D EL, S.
&
D IA S, J.c.P. - Transfusion transm ittedChagas disease. In: W endel, S.; Brener, Z.; A ndrade, Z.
&
Rassi, A . eds. Chagas disease (A m erican Trypanosom iasis)
its im pact on transfusion and clinical m edicine. Sao Paulo:
ISBT, 1992. p. 103-133.
34. W H O - Control of Chagas disease. W H O Technical Report
Series 811, W orld H ealth O rganization, G eneva, 1991. 95p.
35. W H O - W kly. Epidem Rec 65: 257-64, 1990.
