Revista da Sociedade Brasileira de Medicina Tropical 18(1): 47-56, Jan-Mar, 1985
R E V IS Ã O
OURPRESENT KNOWLEDGE OF THE ECOLOGY AND CONTROLOF LEISHMANIASIS
IN THE AMAZON REGION OF BRAZIL
R. La inson
S p e c ie s o f
Leishmania
R o s s , 1 9 0 3 49 , a re e x c lu s iv e ly p a ra s itic p r o to z o a o f th e O r d e r K in e to - p la s tid a , F a m ily T ry p a n o s o m a tíd a e . T h e y a re dige - n e tic (h e te ro x e n o u s ) o rg a n is m s , w ith p ro m a s tig o te s a n d p a ra m a s tig o te s (w ith a sin gle , fre e flag ellu m ) in the a lim e n ta ry tr a c t o f th e in s e c t h o s t, a n d ro u n d -o v a l a m a s tig o te s (n o fre e flag e llu m ) in th e m a c ro p h a g e s o f v e rte b ra te h o s ts : a s fa r a s is k n o w n th e re is n o s e x u a l sta g e in th e p a r a s ite ’s life c y c le . T h e in s e c t h o s ts a p p e a r to b e lim ite d to sp e c ie s o f th e h a e m a to p h a g o u s p h le b o to m in e “ s a n d flie s ” (D ip te ra : P s y c h o d id a e : P h le b o to m in a e ), a n d th e v e rte b ra te h o s ts to a v a rie ty o f m a m m a ls . T h e la tte r fu n c tio n a s re s e rv o irs o f in fe c tio n fo r th e sa n d fly , a n d tr a n s m is s io n to th e n e x t m a m m a lia n h o s t is p re d o m in a n tly b y in je c tio n o f the p a ra s ite d u rin g th e b ite o f th e in fe c te d in se c t.T h e p rim itiv e n a tu re o f th e p ro m a s tig o te fo rm h a s le d to th e w id e ly a d o p te d v ie w th a t th e sa n d fly v e c to rs o f
Leishm ania
( o r th e ir a n c e s to rs ) re p re s e n t th e p rim itiv e a n d p rim a ry h o s ts o f th e p a ra s ite : a su g g e stio n w h ic h fin d s s u p p o rt in a d e fin ite c y c le o f d e v e lo p m e n t w h ic h ta k e s p la c e w ith in th e sa n d fly gut, a n d so m e tim e s a tta c h e d to th e g u t w a ll.Leishmania
p ro b a b ly a d a p te d to su rv iv e in m a m m a ls , a fte r th e in o c u la tio n o f th e o rg a n is m du rin g th e e v o lu tio n o f the b lo o d -su c k in g h a b it o f a n c e s tra l sa n d flie s. T h e m a m m a lia n h o s ts n o w a c t n o t o n ly a s a su p p ly o f b lo o d for th e sa n d fly , b u t a s a so u rc e o f in fe c tio n fro m th e a m a s tig o te s lo c a te d in th e sk in o r b lo o d o f th e s e a n im a is .
A la rg e n u m b e r o f m a m m a lia n sp e c ie s a c t a s re s e rv o irs o f
Leishmania.
T h e p a ra s ite s a re c o m m o n - ly fo u n d in ro d e n ts , c a n id s , m a rs u p ia is , e d e n ta te s , p ro c y o n id s , p rim itiv e u n g u la te s (h y ra x e s ) a n d p rim a - te s ; ra re in fe c tio n s h a v e e v e n b e e n re c o rd e d in b a ts . N o le is h m a n ia s h a v e y e t b e e n re c o rd e d in a m p h ib ia n s o r b ird s (a lth o u g h th e re a re so m e sa n d fly sp e c ie s w h ic h fe e d o n th e s e a n im a is ), a n dLeishmania
-like p a ra s ite s o f re p tile s (Sauroleishm ania
) h a v e n o w b e e n re m o v e d fro m th e g e n u sLeishmania.
T h e W ellc om e P arasitolog y U nit, U nida d e s de E stu dos E s pe ciais, Ins tituto E v an d ro C h a ga s, F u n d a ç ã o S E S P , C a ix a P o sta l 3, 6 6 .0 0 0 B elém , P a rá , B razil.
E c o lo g ic a l a n d e p id e m io lo g ic a l stu d ie s o v e r the p a s t 25 y e a rs h a v e sh o w n th a t th e re a re m a n y m o re le is h m a n ia l p a ra s ite s th a n w e p re v io u sly su sp e c te d , a n d fu rth e r e v id e n c e is ra p id ly a c c u m u la tin g to su gg est th a t e a c h s p e c ie s is n o t, as c o m m o n ly su p p o se d , ra n d o m ly d is trib u te d in a m is c e lla n e a o f sa n d fly a nd m a m m a lia n h o s ts , b u t th a t th e re a re n a tu ra l b a rrie rs lim iting c e rta in le is h m a n ia s to c e rta in sa n d fly /m a m - m a lia n c o m b in a tio n s 20
2S.
In th e n a tu ra l m a m m a lia n re s e rv o ir h o st,
Leishm ania
ra re ly p ro d u c e s d is e a s e , th e infe c tio n u s u a lly re m a in in g ben ig n a n d i n a p p a r e n t- as is u su a lly th e c a s e in a n a n c ie n t a n d w e ll b a la n c e d h o s t-p a ra s ite re la tio n s h ip . I n th e w ro ng h o s ts , h o w e v e r, in c lu d in g m a n a n d so m e o f h is d o m e s tic a n im a is su c h a s th e dog a n d d o n k e y s , in fe c tio n m o s t c o m m o n ly p ro d u c e s ugly skin le s io n s, o r a v is c e ra l d is e a s e w hic h is u s u a lly o f a fa ta l n a tu re u n le s s a d e q u a te ly tre a te d . L u c k ily , m a n y s a n d fly sp e c ie s a p p e a r to b e h o s t-re s tric te d , o r a re a t le a s t u n a ttr a c te d to m a n , a n d a g re a t m a n y le is h m a n ia s (p ro b a b ly th e m a jo rity ) th u s re m a in w ith n o o p p o rtu - n ity to in fe c t him . I t is q u ite p o s sib le th a t th e y w o u ld in a n y c a s e be in c a p a b le o f e s ta b lis h in g th e m se lv e s in his tis s u e s . N e v e rth e le s s , th o s e s p e c ie s o fLeishmania
th a t w e k n o w to in fe c t m a n a re o f v e ry g re a t m e d ic a i im p o rta n c e : so m u c h so th a t le is h m a n ia s is is ra n k e d a m o n g th e six m o s t im p o rta n t tro p ic a l d is e a s e s , w ith a n e s tim a te d g lo b a l in c id e n c e o f so m e 4 0 0 ,0 0 0 new c a s e s o c c u rrin g e a c h y e a r 3. T h e e n d e m ic re gio ns c o v e r a v a s t a r e a o f o u r p la n e t; th ro u g h o u t m o s t o f tro p ic a l A fric a , ín d ia , e a s te m A s ia (b u t u n k n o w n in A u s tra la s ia ), c e n tra l A s ia , th e M e d ite rra n e a n b a sin , a n d so m e n e ig h b o u rin g E u r o p e a n c o u n trie s , a n d m o st o f L a tin A m e ric a .
Le ish m a n ia sis in Brazil
Revisão. Ourpresentknowledgeoftheecologyandcontrolofleishmaniasis in theAmazon region ofBrazil. R. Lainson. Revista da Sociedade Brasileira de Medicina Tropical 18: 47-56, Jan-Mar, 1985
w e c a n still s tu d y th e a n c ie n t s a n d fly /m a m m a lia n life- c y c le s o f th e s e p a ra s ite s , re la tiv e ly u n c o m p lic a te d by m a n ’s in flu e n c e .
V ia n n a 54 ga ve th e n a m e (h is sp e llin g ) o f
Leishmania brazilienses
to a le is h m a n ia l p a ra s itec a u sin g d is s e m in a te d c u ta n e o u s le is h m a n ia s is in A lé m P a ra ib a , on th e b o rd e rs o f M in a s G e r a is a n d R io d e J a n e iro S ta te s , B ra zil: a la p s u s c a la m i g e n e ra lly o v e rlo o k e d , a n d la te r c o rre c te d to
L. braziliensis
b y M a tta 40.W ith d e s p e ra te ly fe w ta x o n o m ic c rite ria w ith w h ic h to
idenúiy Leishm ania
s p e c ie s , it lon g re m a in e d th e c u s to m to re fe r to ali c a s e s o f c u ta n e o u s a n d m u c o c u ta n e o u s le is h m a n ia s is in B ra z il a n d n e ig h b o u r- ing c o u n trie s a s d u e toL. braziliensis.
I t w a s n o tu n til 1 9 5 4 , in fa c t, th a t a n e w n a m e a p p e a re d , a s s o c ia te d w ith c u ta n e o u s le is h m a n ia s is in th e G u y a n a s a n d n o rth A m a z o n ia n B ra z il, w h e n F lo c h 13 re fe rre d t o L .tropica guyanensis
a s th e c a u s a i a g e n t o f “ p ia n -b o is ” in th o se re g io n s, a n d re s e rv e d th e n a m e o fL. t.
braziliensis
fo r th e p a ra s ite s a s s o c ia te d w ith a li form s o f th e c u ta n e o u s a n d /o r m u c o c u ta n e o u s d is e a s e so u th o f th e A m a z o n R iv e r. P e s s ô a 44 c o rre c tly a m e n d e d th e s e n a m e s to o u r p re s e n t-d a yL. braziliensis
guyanensis
a n dL. b. braziliensis.
W ith th e e x c e p tio n o f “ c h ic le ro ’s u lc e r ” , in the Y u c a ta n re gio n o f C e n tra l A m e ric a , it is fa irly sa fe to s a y , h o w e v e r, th a t u p to th e la te 1 9 6 0 ’s few p ro - to z o o lo g ists (a n d e v e n fe w e r d e rm a to lo g is ts ) a c c e p te d th e su g g e stio n th a t a n y fo rm o f d e rm a l le is h m a n ia s is in B ra z il - o r th ro u g h o u t th e A m é ric a s , fo r th a t m a tte r - m ig h t b e d u e to m o re th a n o n e p a ra s ite , n a m e ly
L.
braziliensis.
T h is w a s in sp ite o f a d d itio n a l n e w n a m e s given to th e p a ra s ite s a s s o c ia te d w ith “ u t a ” in th e P e ru v ia n A n d e s(L. peruviana
V e le z , 1 9 1 3 53), “ c h ic le ro ’s u lc e r” (L . mexicana
B ia g i7 e m e n d . G a m h a m 17) a n d “ d iffu se c u ta n e o u s le is h m a n ia s is ” in V e n e z u e la(L. pifanoi
M e d in a & R o m e ro 42, e m e nd . M e d in a & R o m e ro 43). H e re th e s itu a tio n re s te d un til th e la te 1 9 6 0 ’s, w h e n th e in c rim in a tio n o f fo re s t ro d e n ts a s re s e rv o ir h o s ts o fL. mexicana
in B e liz e 26 27 p ro m p te d s im ila r fie ld s tu d ie s in B ra z il.L e is h m a n ia s is in A m a z o n ia n B ra zil
Leishmania mexicana amazonensis
L a in s o n &S h a w , 197223.
W o rk in g in P a r á a n d M a to G r o s s o S ta te s , L a in so n & S h a w 22 n o te d strik in g b io lo g ic a l diffe r- e n c e s b e tw e e n a
Leishmania
c o m m o n ly fo u n d in ro d e n ts a n d th e p a ra s ite s m o s t fre q u e n tly is o la te d from m a n . T h e ro d e n t p a ra s ite w a s sh o w n to b e so s im ila r toL. mexicana
o f n o rth e m C e n tra l A m e ric a , th a t it w a sg iv e n th e n e w s u b -s p e c ific n a m e o f
L. m. am a
zonensis.
T h e sa n d fly h o s t w a s sh o w n 21 51 to be
Lut-zom yia Jlaviscutellata
( M a n g a b e ira 1 9 6 9 39), a low -flying a n d e s s e n tia lly n o c tu m a l in s e c t w h ic h is lu ck ily n o t m u c h a ttr a c te d to m a n . H u m a n in fe c tio n is th u s u n c o m m o n , a n d la rg e ly re s tric te d to nig h tim e h u n te rs a n d fish erm e n , a n d oth e rs p e n e tra tin g low -lying sw am p fo re s t (ig a p ó ) o r riv e rin e fo re s t (v á rz e a ), a t nig h t, w h e re th e
Lu. Jlaviscutellata
p o p u la tio n is p a rtic u la rly d e n s e . D u e to th e lo w -le v e l fligh t ra n g e o f th is sa n d fly (it is ra re ly e n c o u n te re d a b o v e 1 m e tre ) th e w ild re s e rv o ir h o s ts a re la rg e ly fo u n d a m o n g te rre s tria l o r s e m ite rre s tria l a n im a is , p a rtic u la rly ro d e n ts a n d m a rsu p ia is : th e prin c ip a l v e rte b ra te h o s t is th e ech im y id ro d e n t,Proechimys
spp.I n sp ite o f th e re la tiv e ra rity o f h u m a n d is e a s e d u e to
L. m. amazonensis,
th is p a ra s ite is o f c o n si- d e ra b le im p o rta n c e fo r tw o re a s o n s . I n th e firs t p la c e , h u m a n in fe c tio n n o t in fre q u e n tly p ro c e e d s to in c u ra b le “ diffus e c u ta n e o u s le is h m a n ia s is ” (D C L ) . A lth o u g h th is c o n d itio n h a s b e e n sh o w n to b e lin k e d w ith a d e fic ie n t c e ll-m e d ia te d im m u n ity in th e p a tie n t, it h a s till no w b e e n fo u n d a s s o c ia te donly
w ith in div id u a is in fe c te d w ith p a ra s ite s o f th eL. mexicana
c o m p le x , a n d o n n o o c c a s io n h a v e w e re c o rd e d D C L in th e m a n y h u n d re d s o f o th e r p a tie n ts in fe c te d w ithL. brazilien
sis
o r rela ted pa ra site s in n o rth B razil. I n the second place, b o th th e sa n d fly a n d v e rte b ra te h o s ts o fL. m. am azo
nensis
a re c o m m o n ly fo u n d in a w ide v a rie ty o f h a b ita ts ; fro m high p rim a ry fo re s t to th e lo w , d e n se s e c o n d a ry g ro w th w h ic h fo llo w s d e fo re s ta tio n (p a rti c u la rly fa v o u re d b y ro d e n ts ). T h e e n z o o tic h a s e v e n a d a p te d re m a rk a b ly w e ll to c o m p le te ly n o n -in d ig e - n o u s p in e a n d g m e lin a tre e p la n ta tio n s in th e A m a z o n R e g io n o f B ra z il46, su gg estin g th a t a lth o u g h d e s tru c - tio n o f p rim a ry fo re s t m a y c u t th e in c id e n c e o f h u m a n le is h m a n ia s is d u e to so m e p a ra s ite s , e.g.L. b.
guyanensis,
it m a y re s u lt in a n in c re a s e in th e d is e a s e d u e to o th e rs , s u c h a sL. m. amazonensis.
T h is is a p a rtic u la rly s o m b re th o u g h t in v ie w o f th is o rg a n is m ’s a s s o c ia tio n w ith D C L .Leishmania braziliensis guyanensis
F lo c h , 1 9 5 4 13.T h e p ro c e s s o f u n ra v e llin g th e e p id e m io lo g y o f “ p ia n -b o is ” h a s m a d e a fa s c in a tin g sto ry in w h ic h field o b s e rv a tio n s , b a sic p a ra s ito lo g y a n d e n to m o lo g y , a n d m o d e m b io c h e m ic a l te c h n iq u e s h a v e ali p la y e d an e q u a lly im p o rta n t p a rt.
Revisão. Ourpresent knowledge ofthe ecology and control o f leishmaniasis in the Amazon region o f Brazil. R. Lainson. Revista da Sociedade Brasileira de Medicina Tropical 18: 47-56, Jan-Mar, 1985
id e n tifie d (e rro n e o u s ly , a s it tra n s p ire d ) a s
Lutzom yia
anduzei
(R o z e b o o m ), a n d F lo c h in tu itiv e ly fe lt th a t th is sa n d fly m ig h t b e th e v e c to r o f “ p ia n -b o is ” . S o m e y e a rs la te r, in n e ig h b o u rin g S u rin a m , W ije rs & L in g e r58 a ls o n o te d th is p h e n o m e n o n , a g a in id e n tifie d th e fly a sLu. anduzei,
a n d d e m o n s tra te d p ro m a s ti- g o te s in 12 s p e c im e n s a m o n g a n u n sp e c ifie d n u m b e r th e y d is s e c te d . F la g e lla te s fro m tw o flie s w e re ino- c u la te d in to a h a m s te r, b u t th e a n im a l fa ile d to b e c o m e in fe c te d .A rm e d w ith th is kn o w le d g e , L a in s o n e t a l29 stu d ie d a n a r e a o f fo re s t n e a r M o n te D o u ra d o in P a r á S ta te , B ra z il, n o rth o f th e A m a z o n R i ve r. T h e y d is s e c te d 55 s p e c im e n s
o i "Lu. anduzei”,
fo u n d 4 to be h e a v ily in fe c te d , a n d o n th is o c c a s io n th e p a ra s ite w a s e s ta b lis h e d in h a m s te rs a n d la te r in b lo o d -a g a r c u ltu re m e d iu m . D u rin g the se ' stu d ie s s u s p ic io n s w ere a ro u s e d th a t th e sa n d fly c o n c e m e d w as n o t in fa c tL u .anduzei
R o z e b o o m , b u t a c lo s e ly re la te d a n d p re - v io u sly u n d e s c rib e d sp e c ie s, w h ic h W a rd & F ra ih a ^ S s u b s e q u e n tly n a m e dLu. umbratilis.
A d d itio n a l s tu d ie s in th e s a m e a n d o th e r a re a s o f n o rth B ra z il, a n d in F r e n c h G u y a n a , p ro v id e d fu rth e r e v id e n c e in c rim in a t- ing th is sa n d fly a s th e m a jo r v e c to r o fL. b.
guya-nensis
4 37 38 a n d , fo llo w ing a v e ry d e ta ile d s tu d y o f the e c o lo g y o f th e sa n d fly fa u n a in th e M o n te D o u ra d o a re a o v e r a n u m b e r o f ye ars'*7, it w a s c o n c lu d e d th a t “ o n ly th e fe m a le s o fLu. umbratilis
h a v e th e h a b its ... a n d a b u n d a n c e ... c o n s is te n t w ith a m a jo r v e c to r to m a n o fL . b. guyanensis”.
In 1 9 8 0 th e a u th o r’s la b o ra to ry 28 34 tu m e d its a tte n tio n to a s e a rc h fo r th e w ild a n im a l re s e rv o ir o f th e p a ra s ite a n d , in view o f th e v e c to r’s h a b its , c o n c e n - tra te d p rin c ip a lly o n a rb o re a l a n im a is c a p tu re d in p rim a ry fo re s t o f th e M o n te D o u r a d o a re a . T h e o rg a n ism w a s fin a lly is o la te d fro m 2 7 o u t o f 5 9 ( 4 6 % ) tw o -to e d slo th s (
Choloepus didactylus)
a n d 6 o u t o f 27 ( 2 2 .2 % ) le s s e r a n te a te rs (Tamandua tetradactyla
), w ith ra re in fe c tio n s o c c a s io n a lly fo u n d in te rre s tria l o r s e m i-te rre s tria l a n im a is s u c h a s ro d e n ts a n d m a rs u p ia is : a h ig h ra te o f in fe c tio n h a s a ls o b e e n fo u n d inC.
didactylus
in F r e n c h G u y a n a 1*. F in a lly , to c o m p le te th e e p id e m io lo g ic a l p ic tu re , b io lo g ic a l a n d b io c h e m i- c a l (e n z y m e p ro file s ) c o m p a ris o n h a s fa ile d to d e te c t a n y d iffe re n c e s b e tw e e n th e p a ra s ite s fro mLu. um
bratilis,
th e w ild a n im a l re s e rv o irs a n d m a n .In th e fo re s t c a n o p y , th e n , th e re is a c o n s ta n t c y c le o f tra n s m is s io n m a in ta in e d b y th e sa n d fly
Lu.
umbratilis,
a t n ig h t, a m o n g a rb o re a l a n im a is , p a r- tic u la rly th e s lo thC. didactylus
a n d th e a n te a te rT.
tetradactyla.
G r a v id sa n d flie s d e s c e n d to th e fo re s t flo o r to o v ip o s it, a n d th e n m ig ra te b a c k to th e c a n o p y fo r fu rth e r b lo o d -m e a ls o n th e ir a rb o re a l h o s ts . T h e m ig ra tio n s re s u lt in u n u s u a lly la rg e c o n c e n tra tio n s o ffe m a le
Lu. umbratilis
o n th e b a s e s o f th e la rg e r tre e s (th o se w h o se u p p e r b ra n c h e s fo rm p a r t o f th e c a n o p y ), p a rtic u la rly in th e e a rly h o u rs o f da y lig h t, a n d m a n y o f th e s e w ill be in fe c te d . T h e s e flie s a re n o rm a lly disin - c lin e d to fe e d o n m a n , b u t w h e n d is tu rb e d b y his a c tiv itie s (fellin g o f tre e s , o r b y th e sim p le p ro c e ss o f le a n in g a g a in s t a tre e ) th e y w ill a tta c k h im avidly. T h u s , d u rin g a d a y tim e c a p tu re o f sa n d flie s fro m tree - tru n k s (fo r a b o u t o n e h o u r, a t 8 .0 0 a m ), tw o field- w o rk e rs c o lle c te d 77 s p e c im e n s a tta c k in g th e ir arm s: o f th e s e , 7 2 ( 9 2 .5 % ) w e re L u .umbratilis,
o f w hic h 16 w e re h e a v ily in fe c te d . I t is sm a ll w o n d e r th a t th e tw o m e n , b e tw e e n th e m , de v e lo p e d 13 le sio n s d u e toL. b.
guyanensis
o n th e ir w rists a n d fo re a rm s 37. P e rh a p sth e m o s t o v e rw h e lm in g e v id e n c e to in c rim in a te a sa n d fly v e c to r th a t o ne c o u ld w ish for!
A s m o s t fo re st-w o rk e rs e ng a g e d in tre e-fe lling o p e ra te o n ly d u rin g th e d a y , w e feel th a t m o s t tra n s m is sio n to m a n ta k e s p la c e a t g ro u n d le ve i, in the d a y lig h t h o u rs a n d p a rtic u la rly in th e e a rly m o m in g . T h is is n o t to s a y th a t so m e tra n s m is s io n to m a n d o e s n o t o c c u r a t n ig h t, a n d in d e e d w e h a v e p e rso n a l e v id e n c e th a t i t d o e s, b u t o n a sm a ll sc a le , fo r th e follo w ing re a s o n s . F irs tly , th e re is re la tiv e ly little hum ain a c tiv ity a t n ig h t in th e fo re s t (m a in ly o c c a s io n a l h u n te rs ) a n d , se c o n d ly , a t n ig h t m o s t o f th e fe m a le
Lu.
umbratilis
p o p u la tio n is a c tiv e ly se e k in g b lo o d am o ng (re s e rv o ir) h o s ts hig h u p in th e fo re s t c a n o p y .I n c o n c lu s io n , A ria s & N aiff5 n o te d an inte re st- ing v a ria tio n in th e e c o lo g y o f “ p ia n -b o is ” n e a r M a n a u s , A m a z o n a s S ta te , w h e re fo re s t w a s be in g c u t fo r th e d e v e lo p m e n t o f a n e w re s id e n tia l a re a . F iv e o u t o f 7 c o m m o n o p o s s u m s
(Didelphis marsupialis)
w ere fo u n d in fe c te d w ithL. b. guyanensis
a n d it w a s su g g e ste d th a t th is hig h in fe c tio n ra te w a s d u e to the d is a p p e a ra n c e o f th e p rim a ry e d e n ta te h o s ts follow ing m a n ’s d e s tru c tio n o f th e ir h a b ita t, a n d a re su ltin g in c re a se in the n u m b e ro fo p o s s u m s , w hich a re notorious sc a v e n g e rs a n dattracted
b y m a n ’s p re se n c e . A n a n a ly s is o f b lo o d fro m 9 7 5 e ng o rg e dLu. umbratilis
Revisão. Ourpresent knowledge ofthe ecology and control o f leishmaniasis in the Amazon region o f Brazil. R. Lainson. Revista da Sociedade Brasileira de Medicina Tropical 18: 47-56, Jan-Mar, 1985
Leishmania braziliensis braziliensis
V ia n n a ,1 9 1 1 54 em e n d . M a tta , 1 9 1 6 40.
E lu c id a tin g th e e c o lo g y a n d e p id e m io lo g y o f le is h m a n ia sis d u e to th is p a ra s ite h a s p ro v e d a m u c h m ore d iffic ult p ro p o s itio n , a n d th e s itu a tio n re m a in s c o n fu se d b o th in th e A m a z o n R e g io n a n d in re la tio n to h u m a n le is h m a n ia s is c a u s e d b y
L . b. braziliensis
se n su la to in o th e r g e o g ra p h ic re g io n s o f B ra z il a n d e ls e w h e re in S o u th a n d C e n tra l A m e ric a . T h e re a re a n u m b e r o f re a s o n s fo r th is . F ir s d y , a s is u n fo rtu n a te ly th e c a s e w ith m o s t re c o g n iz e d sp e c ie s o f p ro to z o a l p a ra s ite s , th e re is n o ty p e m a te ria l o f V ia n n a ’s p a ra s ite o r, b y m o d e m sta n d a rd s , a n a d e q u a te d e s c rip tio n w ith w h ic h w e c a n d ire c tly c o m p a re o u r p re s e n t d a y is o la te s o f
“L. b. braziliensis
s e n s u la to ” . E v e n th e a ssu m e d linkag e o f th e o rg a n is m w ith th e c lin ic a i c o n d itio n o f m u c o c u ta n e o u s le is h m a n ia s is , o r “ e s p u n d ia ” , d o e s n o t h e lp u s , fo r V ia n n a ’s p a tie n t w a s d e s c rib e d a s suffering fro m d is s e m in a te d c u ta n e o u s le sio n s. I t in fa c t re m a in s d is tin c tly p o s sib le th a t th e in fe c tio n w a s n o t d u e to w h a t w e a re n o w c a llin g L .b.
braziliensis,butXo
a p a r a s i t o f th emexicana
c om ple x!A li th a t it is p o ssib le to d o a t th e m o m e n t is to c o n tin u e sto c kp ilin g a n d c o m p a rin g ali a v a ila b le is o la te s o f
Leishmania
fro m m a n , w ild m a m m a ls a n d sa n d flie s, in give n g e og ra p h ic a re a s o f L a tin A m e ric a , u n til w e c a n d e sig n a te a n e o ty p e w hic h c a n se rv e a s a firm b a s is w ith w h ic h to s o rt o u t th e c o n s id e ra b le n u m b e r o f p e rip y la ria n le is h m a n ia s a t p r e s e n t b e in g u n c o v e re d . A n o th e r p ro b le m c o n fro n tin g u s is th e d iffic ü lty in h a n d lin g m a n y o f th e s e is o la te s in th e la b o ra to ry , w ith c o n sis te n tly p o o r g ro w th o f s u c h p a ra s ite s in ali m a nn e r o fin vitro
culture m ed ia a n d in the h a m s te r 19 24.S tu d ie s o n th e e p id e m io lo g y o f
L. b. braziliensis
s. 1. in th e A m a z o n R e g io n o f B ra z il h a v e la rg e ly b e e n lim ite d to M a to G r o s s o a n d P a r á , p rin c ip a lly in th e ra n g e o f hills k no w n a s th e S e rra d o s C a ra já s , in th e d e n s e ly fo re s te d s o u th e m p a r t o f th e la tte r S ta te . H e re , a high in c id e n c e o f c u ta n e o u s le is h m a n ia s is su ffe re d b y a m in in g c o m p a n y , in th e e a rly 1 9 7 0 ’s, p ro m p te d a su rv e y o f th e sa n d fly f a u n a ^ 7 , re su ltin g in th e re la tiv e ly s p e e d y p in p o in tin g o f th e lo c a l v e c to r33.
T h e sa n d fly in q u e s tio n ,
Psychodopygus
wellcomei
F ra ih a e t al, is a m e m b e r o f thesquamiventris
gro up , n o ta b le fo r its in c lu sio n o f a n u m b e r o f s p e c ie s o r su b sp e c ie s w ith m o rp h o lo g ic a lly in d is tin g u is h a b le fem ale form s: id e n tific a tio n o f th e s e a t p re s e n t re s ts on th e n io rp h o lo g y o f th e m a le s .
Ps. wellcomei
is a n e x tre m e ly a n th ro p o p h ilic sa n d fly , a tta c k in g m a n n o t on ly a t n ig h t b u t a ls o d u rin g th e d a y , p a rtic u la rly in th e e a rly h o u rs a n d in o v e rc a s t w e a th e r. A to ta l o f 16infected flies w a s re co rd e d during a n u m b e r o f visits to th is re g io n 30.
O u r e a rly w o rk in th e C a ra já s a r e a w a s c a rrie d o u t high u p o n the hills, a t a b o u t 5 0 0 -7 0 0 m : th e on ly fo re s t a c c e s s ib le a t th a t tim e , b y a ir. R e c e n t r o a d c o n stru c tio n , h o w e ve r, h a s n o w e n a b le d s im ila r stu d ie s to b e m a de do w n to the foothills, w ith a m o st in te re stin g find ing . T h e b re e d in g -o u t o f g ra v id fe m a le s in th e la b o ra to ry (D r. P . D . R e a d y , u n p u b lis h e d o b s e rv a tio n s ) s h o w e d th a t o u r h ig h e r a ltitu d e p o p u la - tio n o f
“Ps. wellcomei
” w a s in fa c t c o m p ris e d o f 9 5 % tru ewellcomei
a n d5% o i Ps. complexus
(M a n g a b e ira ), a n o th e r m e m b e r o f th esquamiventris
g ro up . B e lo w a b o u t 3 0 0 m th e p o s itio n slo w ly re v e rs e d , w ith a n m c re a s in g p ro p o rtio n o fPs. complexus
a s o n e d e s c e n d s th e h ills. W e fe e l th a t th is is, h o w e v e r, u n lik e ly to in v a lid a te o u r e a rlie rin c rim in a tio no f Ps. wellcomei
a s th e m a jo r v e c to r, a s ali o iir o b s e rv a tio n s w e re m a d e a b o v e 5 0 0 m : it is s ig n ific a n t, to o , th a t p a ra s ite s is o la te d fro m m a n in th e lo w la n d s a p p e á r to b e d iffe re n t fro m th a t in th e h ig h e r a ltitu d e ,wellcomei
h a b ita t. M o re re c e n ü y , D r . L . R y a n (u n p u b lis h e d o b s e rv a tio n s ) h a s c o n tin u e d th is s tu d y , in th e sa m e a re a , a n d e n c o u n te re d a fu rth e r 35 su p p o s e d
Ps.
wellcomei
w ith fla ge lla te in fe c tio n s. T o d a te , 14 o f th e s e a re c o n s id e re d as d u e t oL. b. braziliensis
s. 1. on m ono clona l a ntib od y serology (S h a w & L a in so n , unp ub lishe d obse rva tio ns). A tte m p ts to ra ise ofFspring fro m th e eggs o f th e s e flies h a v e u n fo rtu n a te ly fa ile d b u t, w h ile th e p o s s ib ility th a t so m e m a y h a v e b e e nPs.
complexus
c a n n o t b e e n tire ly ru le d o u t, th e n u m e ric a l su p e rio rity o fPs. wellcomei
a t t h e c a p tu re site m a k e s it m o s t lik e ly th a t a li o r m o s t w e re th is sp e c ie s. R e c e n t (u n p u b lish e d ) re su lts o n c u tic u la r h y d ro c a rb o n a n a ly sis in co lla boration w ith P rof. D a v id M o ly ne u x’s laborato ry , a t S a lfo rd U n iv e rs ity , in d ic a te s th e te c h n iq u e to h a v e g re a t p ro m is e in d iffe re n tia tin g sa n d fly s p e c ie s a n d m a y h e lp so lv e th is p ro b le m in fu tu re field s tu d ie s in th e C a ra já s .F o r so m e tim e th e k n o w n d is trib u tio n o f
Ps.
wellcomei
w a s re s tric te d to th e S e rra d o s C a ra já s , P a r á , b u t th is sa n d fly h a s n o w b e e n sh o w n to b e a p re d o m in a n t sp e c ie s in s im ila r ra n g e s o f fo re s te d h ills in th e n o rth e a s te m S ta te o f C e a r á 4 8 . I n th is re s p e c t it is sig n ific a n t th a t p a ra s ite s is o la te d fro m m a n in C e a r á a n d B a h ia h a v e p ro v e d to b e in d is tin g u is h a b le fro m L .Revisão. Ourpresent knowledge ofthe ecology and control o f leishmaniasis in the Amazon region o f Brazil. R. Lainson. Revista da Sociedade Brasileira de Medicina Tropical 18: 47-56, Jan-Mar, 1985
A lth o u g h a v e ry lim ite d n u m b e r o f w ild ro d e n ts h a v e b e e n fo u n d in fe c te d w ith L .
b. braziliensis -
like p a ra s ite s in M a to G r o s s o a n d S ã o P a u lo S ta te s 15 16 22^ w e h a v e b e e n s in g u la rly u n s u c c e s s fu l in d e te c tin g in fe c tio n in a w id e ra n g e o f m a m m a ls (p rin c ip a lly te rre s tria l ro d e n ts , a n d a v a rie ty o f m a rs u p ia is ) in o u r S e rra d o s C a ra já s stu d y a re a , a n d th e se a rc h c o n tin u e s. T h e v e c to r,Ps. wellcomei
h a s b e e n sh o w n to be e s s e n tia lly a fo re s t-flo o r s p e c ie s , h o w e v e r, a n d w e r e m a in c o n v in c e d th a t th e re s e rv o ir h o s t o f th e p a ra s ite is te rre s tria l in h a b its , o r a t le a s t c o m e s fre q u e n tly to th e g ro u n d .T h e e x is te n c e o f b io c h e m ic a lly a n d se ro lo gic a lly v e ry s im ila r o r in d is tin g u is h a b le le is h m a n ia s o f m a n in g e o g ra p h ic a lly w id e ly s e p a ra te d p a r ts o f B ra z il a n d in o th e r p a rts o f S o u th a n d C e n tra l A m e ric a , h a s b e e n d is c u s s e d e ls e w h e re 20 24 52. S o m e o f th e s e lo c a litie s a re so d is ta n t, o r s o e c o lo g ic a lly d iffe re n t (p a rtic u la rly in te rm s o f th e p h le b o to m in e a n d /o r m a m m a lia n fa u n a ) th a t in sp ite o f th e p re v io u s ly d is c u s s e d e v id e n ce fo r th e h o s t-s p e c ific ity in th e p a ra s ite /s a n d f ly / m a m m a l c o m b in a tio n s , it is d iffic u lt to c o n c lu d e o th e r th a n th a t
L. b. braziliensis
h a s d iffe re n t s a n d fly / m a m m a lia n h o s ts in th e s e g e o g ra p h ic re g io ns . T h is c o n c lu s io n m u s t b e v ie w e d w ith c a u tio n , h o w e v e r: w h ile it is re la tiv e ly e a s y to s a y th a t tw o o rg a n is m s a redifferent,
it is m u c h m o re diffic u lt to s a y th e y a re th esame.
F in a lly , d u rin g th e a b o v e -m e n tio n e d e p id e m io - lo gica l s tu d ie s in th e A m a z o n R e g io n , w e h a v e u n c o v e re d w h a t a re u n d o u b te d ly n e w le is h m a n ia l p a r a s ite s 25, tw o o f th e m in m a n . M o s t, ho w e v e r, h a v e b e e n fo u n d in a v a rie ty o f w ild m a m m a l a n d sa n d fly s p e c ie s , a n d th e re a re d o u b tle s s m o re to b e d isc o v e re d : so m e o f th e s e p a ra s ite s c a n c e rta in ly b e e s ta b lis h e d in th e h a m s te r, b u t w h e th e r o r n o t th e y c a n in fe c t m a n re m a in s to b e se e n .
Leishmania donovani chagasi
C u n h a & C ha g a s,193711
V is c e ra l le is h m a n ia s is in th e A m a z o n R e g io n h a s u n til re c e n tly b e e n re g a rd e d a s a r a th e r ra r e , sp o ra d ic d is e a s e o f m a n 20, la rg e ly re s tric te d to th e c o a s ta l v illa g e s o f P a r á S ta te : th e e p id e m io lo g y h a s re m a in e d o b s c u re , a lth o u g h th e fo x ,
Cerdocyon thous,
h a s b e e n in c rim in a te d a s a n a tu ra l h o s t a n d , a s in fe c tio n in th is a n im a l is o f a n in a p p a re n t n a tu re , ith a s b e e n s u g g e ste d th a t “ ... p re s e n t-d a y e n d e m ic a re a s e ls e w h e re in S o u th A m e r ic a m a y h a v e o rig in a te d fro m a n c ie n t s y lv a tic e n z o o tic in vo lv in g
C. thous
o r re la te d c a n id s ” .A s th ro u g h o u t th e r e s t o f th e g e o g ra p h ic ra ng e o f A m e ric a n v is c e ra l le is h m a n ia s is , th e v e c to r h a s long b e e n a s s u m e d to b e th e sa n d fly
Lutzom yia longipalpis
(L u tz & N e iv a ) , a lth o u g h th is c o n c lu s io n h a s b e e n b a se d en tirely o n th e (usually) dom estic a nd peridom estic ab u n d a nc e o f this insect in th e be tte r know n endem ic regions o f the A m é ric a s, th e ra re re c o rd s o f u n id e ntifie d p ro m a s tig o te s in d is s e c te d fe m a le s a n d e x p e rim e n ta l tra n s m is s io n o f th e p a ra s ite to h a m s te rs b y th e b ite s o f la b o ra to ry - b re d
Lu. longipalpis
3 i.S p e c im e n s o f
Lu. longipalpis
fro m P a r á h a v e sh o w n slig h t m o rp h o lo g ic a l d iffe re n c e s fro m th o s e in th e m a jo r e n d e m ic a re a s o f B a h ia a n d C e a r á S ta te s in n o rth e a s t B ra z il32 39 56 in th a t th e m a le s o f th e n o rth e a ste m form h av e tw o pa irs o f w hite spots on the 3 id a nd 4 th a bd om in a l tergites, w hile the m ales o f the P a r á fo rm h a v e o n ly o n e p a ir o f sp o ts , o n th e 4 th te rg ite . W a r d e t al56, fo u n d th e tw o fo rm s to be se x u a lly iso la te d : th e y su g g e ste d th a t th e le ss an th ro p o - p h ilic h a b its o f th e A m a z o n ia n fo rm a n d th e m ore h ig h ly d e v e lo p e d d o m e s tic h a b its o f th e n o rth e a s te m fo rm m ig h t a c c o u n t fo r th e low a n d high e n d e m ic ity of h u m a n v is c e ra l le is h m a n ia s is in th e s e reg io n s, re s p e c tiv e ly .D u rin g fie ld s tu d ie s in a sm a ll focu s o f the d is e a s e o n th e Is la n d o f M a r a jó 32 50 w e d is s e c te d 1 ,5 0 0 fe m a le s o f
Lu. longipalpis
c a u g h t in a n d a ro u n d th e h o u s e s o f p a tie n ts w ith v is c e ra l le is h m a n ia s is , a n d found h e a v y prom astig ote infections in 8 (0 .5 % ). E n z y m e c h a ra c te riz a tio n o f th e fla g e lla te s fro m on e fly sh o w e d th e p a ra s ite to b e in d is tin g u is h a b le fromL. d.
chagasi
fro m m a n a n d fo x e s in th e s a m e lo c a lity , a n d fro m m a n in e n d e m ic a re a s in C e a r á a n d B a hia : p a ra s ite s fro m a n o th e r fly p ro d u c e d fulm in atin g visc eral leishm an iasis w h e n ino cu lated into a h a m ste r36. I n th e s a m e M a ra jó fo c u s, u p to th e tim e o f w riting th is p a p e r,L. d. chagasi
h a s b e e n is o la te d fro m th e v isc e ra o f 5 o u t o f 17 (2 9 .4 % ) spe cim en s o f the fox,C. thous.
S u p e rfic ia lly , a li th e in fe c te d a n im a is a p p e a re d to b e in p e rfe c t h e a lth .
Revisão. Our present knowledge ofthe ecology and control o f leishmaniasis in the Amazon region o f Brazil. R. Lainson. Revista da Sociedade Brasileira de Medicina Tropical 18: 47-56, Jan-Mar, 1985
19 84 : a li b u t 4 o f th e s e w e re in c h ild re n b e lo w th e age o f 15 y e a rs .
E p id e m io lo g ic a l s tu d ie s w e re c o m m e n c e d in S a n ta ré m in F e b ru a ry , 198 4 35 36 a n d qu ickly rev ea led a v e ry d e n se p o p u la tio n o f
Lu. longipalpis
in th o s e su b u rtis fro m w h ic h m o s t o f th e h u m a n c a s e s o f v is c e ra l le is h m a n ia s is w e re re g iste re d . T h u s , in o n e n ig h t it w a s p o s sib le to c o lle c t 3 ,3 2 4 s p e c im e n s o f th is sa n d fly ( 7 0 6 fe m a le s ) in th e b a c k -y a rd o f o n e h o u s e , using a co m b in a tio n o f a single C D C light-trap, pla c e d o v e r a bro oding chic ke n, a n d d ire c t aspira tio n o f flie s fro m a c h ic k e n - h o u s e in w h ic h a n in fe c te d d o g w as sle e pin g . A fu rth e r 15 e n g o rg e d flies w e re c a u g h t in a n o th e r lig h t-tra p p la c e d in th e c h ild re n s ’ sle e pin g qua rte rs. O f th e se ch ildren, on e h a d b e e n tre a te d for visceral le ishm aniasis som e m on th s prev iously, a n d the o th e r tw o w ere show n to be infected during th e p re se n t investigation.A to ta l o f 4 9 1 o f th e Lm.
longipalpis
c a p tu r e d o n th is o c c a s io n w e re d is s e c te d , a n d 35 ( 7 .1 4 % ) w e re fo u nd to b e in fe c te d w ith p ro m a stig o te s. T h e fla ge lla te s fro m 27 o f th e sa n d flie s w e re in o c u la te d in to h a m s te rs , b y th e in tra -p e rito n e a l ro u te , a n d 16 o f th e s e a n im a is d e v e lo p e d ty p ic a l, fu lm in a tin g v is c e ra l le is h m a n ia s is from 3-6 m o nth s late r. In add ition , tra n sm issio n o f the pa ra site b y th e b ite s o f n a tu ra lly infected L u .longipalpis
w a s o btaine d o n fo u r oc c a sio n s, b y placin g an ae sth etise d h a m s te rs in c a g e s c o n ta in in g v a ria b le n u m b e rs o f th e s e w ild -c a u g h t sa n d flie s. F in a lly , 9 o u t o f 16 d og s e x a m in e d in o r n e a r th e stu d y a re a s h o w e d a b u n d a n t to m a ssiv e n u m b e rs o f a m a s tig o te s in sk in -sc ra p in g s, a n d a s u b s e q u e n t se ro lo g ic a l su rv e y ( I F A T ) o f 4 1 6 o th e rs, from th e s a m e s u b u rb , s h o w e d a p o s itiv ity o f 5 6 % .
Iso la te s from m a n , dogs a n d th e infected
Lu.
longipalpis
h a v e b e e n c o m p a re d , b io c h e m ic a lly , b y sta rc h -g e l e le c tro p h o re s is u sin g th e e n z y m e s A S A T , A L A T , P G M , G P I , M D H , a n d M P I 8 a n d fo u n d to b e in d is tin g u is h a b le . F r o m th e s e re s u lts a n d th e e p id e m io lo g ic a l o b s e rv a tio n s , th e re fo re , th e re re m a in s n o re a s o n a b le d o u b t a s to th e im p o rta n t a n d p ro b a b ly unique role o fLu. longipalpis
as the v ec to r o f L .d.
chagasi
in A m a z o n ia n B razil, a n d p re su m a b ly elsew here in th e g e o g ra p h ic ra n g e o f th e p a ra s ite . T h e v e ry h ig h in fe c tio n -ra te in th e S a n ta ré m fo c us o f v is c e ra l le ish m a n ia sis w a s d o u b tle ss d u e to th e larg e p o p u la tio n o f sic k do gs c o n c e n tra te d in o v e rc ro w d e d c on d itio n s.P R E V E N T I O N A N D C O N T R O L
M e th o d s o f a v o id in g c u ta n e o u s le is h m a n ia s is o n th e p a r t o f in d iv id u a l p e rs o n s o c c a s io n a lly p e n e tra
t-in g tro p ic a l ra t-in -fo re s t a re a t p r e s e n t lim ite d to th e u se o f in s e c t re p e lle n ts , p ro te c tiv e c lo th in g o r n e ttin g , a n d a v o id a n c e o f d a n g e r a re a s a t nig ht: n o n e o f th e s e a re v e ry effective. In hot, hum id con ditio ns the effectiveness o f in s e c t re p e lle n t is qu ic kly n e u tra liz e d b y p ro fu se sw e a tin g , a n d th e a u th o r h a s o n m a n y o c c a s io n s w a tc h e d sa n d flie s fe e d in g o n e x p o s e d sk in w h ic h h a d b e e n s p ra y e d o n ly so m e 10 m in u te s e a rlie r. L o n g sle e v e s, glo ve s (!) a n d n e ttin g to p r o te c t th e fa c e m ig h t b e fe a sib le fo r a m o tio n le s s p e rs o n , b u t fo r a c tiv e fo re st-w o rk e rs th e y a re in s u p p o rta b le a b s u rd itie s . C u rta ilm e n t o f n ig htim e a c tiv itie s in a re a s o f hig h risk w ill d o u b tle s s d im in is h c h a n c e s o f in fe c tio n , b u t it w ill b e re c a lle d th a t a n u m b e r o f a n th ro p o p h ilic sa n d flie s, in c lu d in g a t le a s t tw o m a jo r v e c to rs , a ls o fe e d in th e d a y tim e u n d e r c e rta in c irc u m s ta n c e s . A w a re n e s s o f th e po ssibilitie s o f a cq uirin g in fe ctio n, p ro m p t diagn osis a n d m e d ic a i tre a tm e n t, go a lon g w a y in a v o id in g a n u n p le a s a n t a n d p ro tra c te d d is e a s e . T h e re a re
no
a v a ila b le v a c c in e s a g a in s t a n y fo rm o f le is h m a n ia s is o n th e m a rk e t, a n d n o c h e m o p ro p h y la c tic drugs. T r e a tm e n t o f th e d is e a s e is still la rg e ly d e p e n d a n t o n pro lo n g e d c o u rs e s o f in je ctio n s w ith an tim o n y de riv a tiv e s, w h ic h a re c o stly a n d o f v a ria b le to xic ity .
P re ve n tio n a n d /o r control o f sylvatic leishm aniasis am o ng gangs o f labo ure rs, topog ra ph ers and o th e r forestry w orkers (principally during fore st cle a ra n ce ) c a n be effective o n a sm all scale: m e n in fore st en ca m p m e nts c a n to som e e x te n t b e p ro te c te d b y p la c in g th e m in a d e q u a te clearings, sp ra ying th e b a se s o f th e la rger tree s w ith in s e c tic id e s (e . g. in “ p ia n -b o is ” a r e a s ) 1445, a n d by prohibiting nightim e hunting.
V isceral leishm aniasis in the m a jor endem ic areas o f the n orth e a st (C e a rá a n d B a h ia ) h a s b e e n w ell con trolled (bu t
not
elim inated) b y the destru ction o f infected dogs, reg ular insecticide spraying o f house s an d an im al shelters, a n d the tre a tm e n t o f patien ts. In are as w ith a b u n d a n t a dja ce nt forest o r w ood land s, how ever, such a s the Isla n d o f M a ra jó , the re is clearly a sylvatic cycle am ong foxes a n d L u .longipalpis,
b u tb e c a u s e o f the spa rsity o f b o th hu m a n an d can ine pop ulations, dom estic o r p e rid o m e s tic tr a n s m is s io n is s p o ra d ic a n d ra re . A lth o u g h th e a n tim a la ria l s p ra y in g p ro g ra m m e s k e e p th e n u m b e r o fLu. longipalpis
in h o u s e s to a v e ry low le v e i, it is n o t c u s to m a ry to s p ra y th e c h ic k e n -h o u s e s a n d , un fo rtu n a te ly , th e c h ic k en is a n id e a l m a in te n a n c e h o s t for this ins ec t, w hic h a c c u m u la te s in la rg e nu m be rs in th e prim itive sh e lte rs h o u sin g th e s e b ird s . M a ra u d in g fo x e s c o m m o n ly e n te r v illa g e s in s e a rc h o f p re y , b rin g in g in fe c tio n to th is p e rid o m e s tic L u .longipalpis
Revisão. Ourpresent knowledge ofthe ecology and control o f leishmaniasis in the Amazon region o f Brazil. R. Lainson. Revista da Sociedade Brasileira de Medicina Tropical 18: 47-56, Jan-Mar, 1985
d o g s, a n d m o re ra re ly to m a n . C a n in e in fe c tio n re m a in s m u c h m o re c o m m o n th a n th a t o f m a n , s im p ly b e c a u s e th e sa n d fly v e c to r is m u c h m o re h ig hly a ttra c te d to do gs.
W h e n , a s in S a n ta ré m , th e d o g , h u m a n a n d sa n d fly p o p u la tio n s a re ali in c re a s e d to a h ig h le v e i in th e v e ry o v e rc ro w d e d s u b u rb s, in tro d u c tio n o f infec tio n m a y re s u lt in a n e x p lo siv e o u tb re a k o f th e h u m a n d is e a se , sim ply d u e to a “ sp ill-o v e r” fro m th e v a s t re s e rv o ir o f in fe c tio n in th e la rg e n u m b e r o f sick do g s. O n c e a g a in , fo x e s a re p ro b a b ly th e o rig in a l so u rc e o f in fe c tio n , in a d ja c e n t w o o d la n d , w h e re L u .
longipalpis
h a s b e e n ta k e n in lig ht-tra ps. T h u s , a lth ou gh p e rio d iccontrol
o f v is c e ra l le is h m a n ia s is m a y b e p o ss ib le in s u c h s itu a tio n s , th e s y lv a tic c y c le re n d e rs its to ta l e r a d ic a tio n m o s t un lik e ly .W h ile th e d o g se rv e s a s a m a jo r re s e rv o ir o f in fe c tio n fo r m a n in th e e p id e m io lo g y o f v is c e ra l le is h m a n ia s is , th e re is n o firm e v id e n c e th a t it p la y s a n y ro le in th e e p id e m io lo g y o f th e k n o w n c u ta n e o u s d is e a s e s in th e A m a z o n R e g io n , a s re c e n tly su g g e ste d b y A g u ila r e t a l 1. T h e n u m b e r o f do gs p re s e n t in e n d e m ic fo re s te d re g io n s, w ith th e ir s p a rs e h u m ^n p o p u la tio n s , is sm a ll; a n d e v e n th o u g h o c c a s io n a l do gs m a y b e c o m e in fe c te d w h e n o n h u n tin g e x p e d itio n s w ith th e ir o w n e rs , th e y a re , a s a so u rc e o f in fe c tio n fo r sa n d flie s, b u t a d ro p in th e o c e a n c o m p a re d w ith th e v a s t a n d c o n s ta n t re s e rv o ir o f in fe c tio n in th e w ild a n im a is , à n d n o t w o rth y o f c o n s id e ra tio n in th e o v e ra ll e p id e m io lo g y . T h e a u th o r h a s se e n n o in fe c te d d o g d u rin g h is 2 0 y e a rs o f e p id e m io lo g ic a l s tu d ie s o n th e c u ta n e o u s d is e a s e in P a r á , a n d it sh o u ld be re m e m b e re d th a t th e g re a t m a jo rity o f h u m a n infe c tio n s a re fo u n d a m o n g la b o u r fo rc e s , o r m ilita ry p e rs o n n e l u n d e rta k in g ju n g le -w a rfa re tra in in g , n e ith e r o f w h o m a re u s u a lly a c c o m p a n ie d b y d o g s. I n th e S e rra d o s C a r a já s , w h e re h u m a n in fe c tio n is so c o m m o n , do g s a re a c tu a lly p ro h ib ite d in th e n e w ly c o lo n iz e d a re a s (p rin c ip a lly a n a n ti-ra b iç s m e a s u re ).
D o n k e y s, w hic h a re a c o m m o n m e a n s o f tra n sp o rt to fo re s t p la n ta tio n s in c e rta in p a rts o f V e n e z u e la , h a v e frequently b e e n fo und w ith skin ulCers d ue to
Leishmania,
p re s u m a b ly a c q u ire d w h e n p a s s in g th ro u g h e n z o o tic w o o d la n d s . A g u ila r e t a l 1, su g g e st th a t th e s e a n im a is m ig h ta ls o b e c o n s id e re d a s a lte m a tiv e re s e rv o ir-h o sts fo r h u m a n in fe c tio n in th e A m a z o n R e g io n o f B ra z il, “ ...w h e re th e re is a te n d e n c y o f th e lo c a l w o rk e rs to s e a rc h fo r th e in fe c tio n m o s tly in w ild a n im a is ” . T h e s a m e a rg u m e n ts a p p ly a n d , in th e a u th o r ’s e x p e rie n c e , d o n k e y s a re a ra re sig h t in d e e d in A m a z o n ia n fo re sts. T h e p o s s ib le ro le o f d o g s, e q u in e s , o r e v e n m a n , a s
s o u rc e s o f in fe c tio n fo r sa n d flie s m ig ht, it is tru e , b e o f so m e e p id e m io lo g ic a l im p o rta n c e
i f domestic or
peridomestic transmission can beproven',
a n d if it c a nb e sh o w n th a t a n y o n e o f th e s e th re e “ v ic tim ” h o s ts are c a p a b le o f a c tin g a s a sig n ific a n t so u rc e o f infe c tio n for a n a n th ro p o p h ilic sa n d fly s p e c ie s , co m m o n ly fou nd in o r a ro u n d h o u s e s , a n d w h ic h is c a p a b le o f tra n sm ittin g th e v a rio u s aetio logic agents o f c u ta n e o u s leishm a nia sis d is c u s s e d a b o v e . W e h a v e lo o k e d in v a in fo r su c h a fly in th e m a jo r e n d e m ic a re a s w e h a v e stu d ie d in the A m a z o n R e gion .
A C K N O W L E D G E M E N T S
M o s t o f th e e p id e m io lo g ic a l stu d ie s re fe rre d to a b o v e w e re c a rrie d o u t u n d e r th e a u s p ic e s o f the W e llc o m e T r u s t, L o n d o n , a n d th e In s titu to E v a n d ro C h a g a s , F u n d a ç ã o S E S P o f B ra z il.
R E F E R E N C E S
1. A guilar C M , F ern an d e s E , F e m a n d e z R , D ea n e L M . S tudy o f an outbrea k o f cutaneous leishm aniasis in V enezuela. T h e role o f dom estic anim ais. M em órias do Instituto O sw ald o C ru z 79: 181-195, 1984.
2. A le n c a r J E , P e ssô a E P , C o s ta O R . C a la z a r em S anta rém , E sta d o do P a rá . R evista B rasileira de M alariolog ia e D oe nç as T rop ic ais 14: 3 7 1-37 7 , 1962.
3. A nonym ous. R e p ort o f the Steering C om m ittee o f the Scientific W orking G ro u p on the L eishm aniasis, to the S. T. R . C ., G ene va, W H O , 1981.
4. A rias J R , F re ita s R A . S obre os vetores d a leishm aniose c utâ n e a n a A m az ô n ia C e ntral do B rasil. 2. Incidência de flagelados em flebótom os selváticos. A c ta A m azônic a 8: 38 7 -3 9 6, 1978.
5. A rias J R , N aifF R D . T he prjncipal reservoir host of cutane ou s leishm aniasis in the urb an areas o f M an aus, C e n tral A m az on o f B razil. M e m órias do Instituto O s w aldo C ru z 76: 2 7 9-28 6 , 1981.
6. A rias J R . N a iff R D , M iles M A , S o uza A A . T he opossum , Didelphis marsupialis (M arsupialia: D idel- phidae), as a reservoir h o st o f Leishmania braziliensis guyanensis in th e A m az on B a sin o f B rasil. T ransactions o f the R oya l S ociety o f T rop ic al M edicine & H ygiene 75: 5 3 7 -5 4 1 , 1981.
Revisão. Our present knowledge ofthe ecology and control o f leishmaniasis in the Amazon region o f Brazil. R. Lainson. Revista da Sociedade Brasileira de Medicina Tropical 18: 47-56, Jan-Mar, 1985
8. B raga R R , L ainson R , S haw J J , R yan L , S ilveira F T . L eishm aniasis in B razil. X X II. C ha ra cteríz a tio n of Leishmania from m an, dogs an d the sandfly Lutzomyia
longigalpis (L u tz & N eiva, 1912) isolated during an outbreak o f visceral leishm aniasis in S antarém , P a rá State. T ra nsa ctio ns o f th e R oyal S ociety o f T rop ica l M edicine & H ygiene, in press.
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Journal o f T rop ic al M edicine & H ygiene 31: 23 9-242 , 1982.
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12. D ea ne L M . L eishm aniose visceral no B rasil. Serviço N ac iona l de E d u ca çã o S anitá ria, R io de Ja neiro , B rasil, 1956.
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“ p ia n-b ois” in north B razil. T ra n sa ctio n s o f the R oya l S ociety o f T ro pica l M edicine & H ygiene 75: 6 1 1-61 2 , 1981.
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30. L ainson R , W a rd R D , S haw J J . Leishmania in phlebo- tom id sandflies. V I. Im p ortanc e o f hindgut developm ent in distinguishing p ara sites o f the Leishmania mexicana and L. braziliensis com plexes. P roc ee ding o f the R oyal S ociety (B ) 199: 30 9 -3 20 , 1977.
31. L ain son R , W a rd R D , S haw J J . E xperim e nta l tran sm is sion o f Leishmania chagasi, causa tiv e agent o f neotro- pical visceral leishm aniasis, by the sandfly Lutzomyia longipalpis. N a tu re 266: 62 8 -6 3 0, 1977.
32. L ain son R , S haw J J , S ilveira F T , F ra in h a H . L eishm a niasis in B razil. X IX . V isceral leishm aniasis in the A m az on R egion, and th e presence o f Lutzomyia longi palpis o n th e Is la n d o f M ara jó, P a rá S tate. T ran sa ctions
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33. L ain son R , S haw J J , W a rd R D , F ra in h a H . L eishm a nia sis in B razil. I X . C onside ration s on One Leishmania braziliensis com plex: im portance o f sandflies o f the genus Psychodopygus (M ang ab eira) in the transm ission o f L. braziliensis in north B razil. T ra nsa ction s o f the R oy a L S o c ie ty o f T rop ica l M edicine & H yg ie ne 6 7 :1 8 4 -
196, 1973.
34. L ainson R , S haw J J , R e ad y P D , M iles M A , P óvo a M M . L eishm aniasis in B razil. X V I. Isolation and identifica- tion o f Leishmania species from sandflies, w ild m am m als and m an in north P a r á S tate , w ith particula r reference to Leishmania braziliensis guyanensis, c a u sative agent o f “ pian-bois” . T ra n sa ctio n s o f the R oyal S ociety o f T rop ic al M edicine & H ygiene 75: 53 0-53 6, 1981.
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