Leishmanias and Leishmaniasis of the New World, with Particular Reference to Brazil’ * 2

LEISHMANIAS AND LEISHMANIASIS OF THE NEW WORLD, WITH PARTICULAR REFERENCE TO BRAZIL’ * 2 Ralph Lainson, B.Sc., Ph.D., D.SC.;~ and J.J. Shaw, B.Sc., D.A.P.E., Ph.D.4 Problems in understanding leishmaniasis in the Americas stem partly from ignorance concerning the protozoan parasites (Leishmania) causing the disease. Until about 1960, relatively little was known of their epidemiology, their vectors, or their host species. Since that time, however, a good deal of research has been completed. On the basis of this the authors have presented a revised classification of the major species and sub- species of leishmanias in the Western Hemisphere. This new taxonomy, given in the following article, is not intended to be rigid or restrictive; rather, it is designed to help stimulate inter- est in unearthing the large amount of significant information about these important organisms that still remains unknown5 Introduction economic importance, since the country is pres- ently making major efforts to promote devolop- It is our intention here to discussthe para- ment by exploring and clearing large areasof sites responsible for cutaneous and mucocuta- virgin forest for farming or mining, and by con- neous leishmaniasisin the Americas,rather than structing extensive new road systems: the clinical manifestations of the diseasesthey may cause in man. Particular referencewill be made to the taxonomy of the organism-and to Classification Problems the epidemiologic situation in Brazil-in the light of recent research. Clinical Classifications Leishmaniasis remains a major problem in Brazil. There, as in most other parts of the New Past emphasison the clinical aspectsof leish- World, it is principally an occupational hazard maniasis has resulted in a bewildering array of of the forest worker. This makesit of particular terms but little progressin understanding the organismscausing the disease.Thus, textbooks ‘Paper presented at the Twelfth Meeting of the refer to “Chiclero’s ulcer,” “Bay-sore,” “pian- PAHO Advisory Committee on Medical Research held bois,” “framboesiform,” “verrucosal” or “nod- in Washington, D.C., on 2529 June 1973. Also ap- pearing in Spanish in Boletin de la Oficina Sanitaria ular” leishmaniasis, “simple” and “mucocuta- Panamericana. neous” leishmaniasis, “espundia,” “ulcera de 2These studies were carried out under the auspices of the Wellcome Trust, London, in collaboration with Bauru,” “uta,” and “diffuse cutaneous leish- the foIlowing: The Evandro Chagas Institute; the maniasis.” Superintendency of Amazon Development; the Pan American Health Organization, and the Walter Reed If infection with Leishmaniu were restricted Army Institute of Research. to man, there might be some excuse for such SDirector, Wellcome Parasitology Unif, Evandro Chagas Institute, C.P.3, 66.000, Belem, Para, Brazil. classification; but the various forms of the dis- 4Assistant Director, Wellcome Parasitology Unif, ease in the Americas are zoonosesinvolving a Evandro Chagas Institute, C.P.3, 66.000, Belem, Para, wide variety of wild or domesticated animals. Brazil. ‘Additional information on the general subject of Man is more correctly regarded,therefore, as an leishmania classification is cited on p.79. accidental host who plays no important role in 2 PAHO BULLETIN . Vol. VII, No. 4, 1973 maintaining the parasitesin nature. It should be brasiliensis . has been an important obstacle remembered,too, that while a given variety of in the path of research.”Velez (61) established Leishmania may produce a generally consistent a separatename, Leishmania peruviana, for the clinical picture, individual persons may react parasite responsiblefor uta in the Peruvian An- differently to the sameparasite. des, but most authors still referred to it as L. Extreme examples of this are patients with braziliensis, even though each type of organism diffuse cutaneous leishmaniasis.Due to their had a perfectly distinct ecology and epidemi- anergid condition, these unfortunate persons ology of its own. develop a particularly disfiguring and incurable The first seriousattempts to separatethe dif- infection in which large nodules may be scat- ferent leishmaniaswere made by Biagi (7) and tered over most of the body. But when the Floch (15). The former author referred to same parasite infects immunologically compe- Leishmania tropica mexicana as the cause of tent subjectsit produces a single ulcer or a lim- Chiclero’s ulcer in Mexico, Guatemala, and ited number of lesions that are relatively easy British Honduras, and the latter author referred to treat. to L. tropica braziliensis as the parasite asso- Moreover, the diseasesymptoms may vary ciated with mucocutaneous leishmaniasis in greatly at different stagesof infection. Thus the Brazil. The organism responsible for pian-bois mucocutaneousdisease starts with a primary le- in the Guianas,uta in Peru, and cutaneousleish- sion that can develop anywhere on the body; maniasis generally in Panama and Costa Rica, nasopharyngealdestruction may begin as much was referred to simply asL. tropica guyanensis. as 1.5to 20 years later, after the initial ulcer has Pessoa,on the other hand (45) preferred to disappearedand been forgotten. Pian-bois may consider all these parasites as subspeciesof involve metastatic spread from the primary Leishmania braziliensis, and called them L. bra- sore, particularly along the lymphatics, pro- ziliensis mexicana, L. braziliensis guyanensis, ducing ulcers scatteredall over the body. and L. braziliensis peruviana. He also gave the In general, then, classifying leishmaniason a name L. braziliensis pifanoi to the organismiso- clinical basis is unsound. Unfortunately, how- lated from a case of diffuse cutaneous leish- ever, classification on a firmer, biological basis maniasis in Venezuela (39). A few years later has proved difficult in the past, becauseof the Garnham (23) assignedthe parasite responsible close similarity of both amastigote and pro- for Chiclero’s ulcer the rank of a separatespe- mastigote stages6of most of the parasitesand cies,Leishmania mexicana. our relative ignorance of their biology. The Need for Revised Classification of the Past Classification Leishmanias In the New World, leishmaniasis extends Up to now, one of the major obstaclesin the from Mexico’s Yucatan Peninsula in the north way of classifying the leishmaniasof the Ameri- to Argentina in the south. Despite the immense cas was our poor knowledge of their life cycles. geographic area involved and the obvious eco- Nor was much known about their comparative logical differences existing within it, there was serologic and immunologic features. However, for a long time a tendency to attribute all the Adler (2) differentiated L. tropica, L. mexica- diseaseforms to a single parasite, Leishmania na, and L. braziliensis by serologic techniques, braziliensis (62). As consistently stressedby the and Lainson and Shaw (28) found that whereas late Saul Adler (I), “ . use of one name L. a previous infection by L. braziliensis panamensis would protect humans againstL. mexi- %‘he amastigote (unflagellated) stage is found in cana mexicana, the reversedid not apply. That the vertebrate hosts, including man; the promastigote (flagellated) stage is found in the sandfly vectors that is, a L. m. mexicana infection did not protect transmit the organism to the vertebrate hosts. againstL. b. panamensis. Lainson and Shaw . LEISHMANIAS OF THE NEW WORLD 3 During the 1960’s, efforts were largely de- usually restricted to that tissue. Using this ap- voted to the epidemiology of the various leish- proach L. mexicana was finally isolated from manias of the WesternHemisphere in the hope numerous specimensof forest rodents, includ- that better understanding of their life cycles ing membersof the generaUtotylomys, Heter- might throw some light on ways to control the omys, and Nyctomys, the parasitesbeing local- diseasesthat they cause-and incidentally pro- ized in discrete skin lesions on the rodents’ vide a basisfor better classification. tails. Inoculation of the isolated parasitesinto volunteers produced L. mexicana-type lesions; Isolation of Leishmanias from Rodents in Pana- the organismswere also successfully transmit- ma and Brazil ted to another volunteer by the bite of an expe- rimentally infected sandfly of the species In Panama(4), workers at the GorgasMemo- Lutzomyia pessoana. Subsequent work in rial Laboratories (using N.N.N. culture me- Belize and on the Yucatan Peninsula showed dium) isolated a leishmania from the heart- the natural vector of L. mexicana to be Lutzo- blood of forest rodents belonging to the genera myia olmeca (8,14, 67). Proechimys and Hoplomys. This leishmaniawas generally considered to be the sameas that in- Similar Isolation of Other Leishmanias fecting man in Panama,but attempts to find the parasite in other animals of these genera These observationsserved as a stimulus that failed, and the significance of the blood infec- quickly produced results elsewherein the New tions in Proechimys and Hoplomys remained World. In 1963 there arose an opportunity to obscure. discussour Belize findings with Dr. Otis Causey In Brazil Forattini (16), also using N.N.N. in his arbovirus laboratory at the Evandro culture medium, tested the heart-blood of over ChagasInstitute in BelCm,Brazil. He mentioned 900 wild animals belonging to severaldifferent having seen skin lesions on the tails of someof species.Amastigotes were observed in skin le- the rodents captured during his work in the sions of one agouti (Dasyprocta sp.) and one forests around

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