Man-biting Species Research Articles

American Cutaneous Leishmaniasis in Panama: a historical review of entomological studies on anthropophilic Lutzomyia sand fly species.

We review existing information on the epidemiology of American Cutaneous Leishmaniasis (ACL) in Panama, with emphasis on the bionomics of anthropophilic Lutzomyia sand fly species. Evidence from Panamanian studies suggests that there are six anthropophilic species in the country: Lutzomyia trapidoi, Lu. panamensis, Lu. gomezi, Lu. ylephiletor, Lu. sanguinaria and Lu. pessoana (Henceforth Lu. carrerai thula). In general, these taxa are abundant, widespread and feed opportunistically on their hosts, which make them potential transmitters of pathogens to a broad range of wildlife, domesticated animals and humans. Furthermore, nearly all man-biting species in Panama (with the exception of Lu. gomezi) expand demographically during the rainy season when transmission is likely higher due to elevated Leishmania infection rates in vector populations. Despite this, data on the distribution and prevalence of ACL suggest little influence of vector density on transmission intensity. Apart from Lu. trapidoi, anthropophilic species seem to be most active in the understory, but vertical stratification, as well as their opportunistic feeding behavior, could vary geographically. This in turn seems related to variation in host species composition and relative abundance across sites that have experienced different degrees of human alteration (e.g., deforestation) in leishmaniasis endemic regions of Panama.

Clinical and histopathological study of Simulium (blackfly) dermatitis from North‐Eastern India – a report

Simulium dermatitis is a common problem in humans and animals in areas where Simulium species occur. It is characterized by chronic eruptions of pruritic papules, vesicles, and erythematous wheals resulting from a hypersensitivity reaction to biting of simuliids or blackflies. It can result in severe skin complications where the man-biting species of Simulium are available. We report two clinical cases of Simulium dermatitis from the North-Eastern region of India. Histopathological study was carried out in one of the cases and the other one was successfully treated with medication. Clinical features like intense itching, which accompanies the eruption, resulting in excoriations, scarring, and permanent hyperpigmentation were reported. Histopathological study revealed the characteristic features of Simulium bite reaction, such as vesicles filled with serous fluid, dermal edema, and perivascular infiltrates rich in eosinophils and lymphocytes. The clinical manifestations and severity of Simulium dermatitis are serious matters of concern in hypersensitive persons.

Virus isolations and high population density implicate Culex antennatus (Becker) (Diptera: Culicidae) as a vector of Rift Valley Fever virus during an outbreak in the Nile Delta of Egypt

In June, 2003, Egypt's hospital-based electronic disease surveillance system began to record increased cases of acute febrile illness from governorates in the Nile Delta. In response to a request for assistance from the Egyptian Ministry of Health and the World Health Organization (WHO), the U.S. Naval Medical Research Unit No. 3 (NAMRU-3) provided assistance in identifying the cause and extent of this outbreak. Testing of human clinical samples (n=375) from nine governorates in Egypt identified 29 cases of RVF viremia that spanned the period of June to October, and a particular focus of disease in Kafr el Sheikh governorate (7.7% RVF infection rate). Veterinary samples (n=101) collected during this time in Kafr el Sheikh and screened by immunoassay for RVFV-specific IgM identified probable recent infections in cattle (10.4%) and sheep (5%). Entomologic investigations that focused in rural, rice growing villages in the Sidi Salim District of Kafr el Sheikh during August–September, 2003, collected, identified, and tested host-seeking female mosquitoes for the presence of pathogenic viruses. Three isolates of RVF virus (RVFV) were obtained from 297 tested pools of female mosquitoes and all three RVFV isolates came from Cx. antennatus (Becker). While Cx. pipiens has been considered the primary vector of RVF virus in Egypt and is often the most common man-biting species found, Cx. antennatus was the dominant species captured at the 2003 outbreak location in Kafr el Sheikh governorate. This is the first time that Cx. antennatus has been found naturally infected with RVFV in Egypt.

Natural Infections of Man-Biting Sand Flies byLeishmaniaandTrypanosomaSpecies in the Northern Peruvian Andes

The natural infection of sand flies by Leishmania species was studied in the Andean areas of Peru where cutaneous leishmaniasis caused by Leishmania (Viannia) peruviana is endemic. Sand flies were captured by human bait and Center for Disease Control (CDC) light trap catches at Nambuque and Padregual, Department of La Libertad, Peru, and morphologically identified. Among 377 female sand flies dissected, the two dominant man-biting species were Lutzomyia (Helcocyrtomyia) peruensis (211 flies) and Lutzomyia (Helcocyrtomyia) caballeroi (151 flies). Another sand fly species captured by light trap was Warileya phlebotomanica (15 flies). The natural infection of sand flies by flagellates was detected in 1.4% of Lu. (H.) peruensis and 2.6% of Lu. (H.) caballeroi, and the parasite species were identified as Le. (V.) peruviana and Trypanosoma avium, respectively, by molecular biological methods. The results indicated that the vector species responsible for the transmission of leishmaniasis in the study areas is Lu. (H.) peruensis. In addition, the presence of Trypanosoma in man-biting sand fly species means that more careful consideration is necessary for vector research in areas of Andean Peru where leishmaniasis is endemic.

Species Diversity and Relative Abundance of Phlebotomine Sand Flies (Diptera: Psychodidae) on Three Army Installations in the Southern United States and Susceptibility of a Domestic Sand Fly to Infection With Old WorldLeishmania major

Leishmania infections in American veterans of Iraq and Afghanistan have raised concern that veterans could serve as reservoirs of Old World parasites for domestic vector populations. A survey of sand flies on three U.S. Army facilities in the southern United States was conducted to identify potential vectors. Five species, including two new state records, are reported for Fort Hood, TX. Very few flies were detected in Fort Bragg, NC. Large numbers of a man-biting species, Lutzomyia shannoni, were trapped on Fort Campbell, KY. Weekly activity patterns for dominant species are presented. In addition, an infection experiment was conducted to determine if a domestic sand fly is susceptible to infection with Old World Leishmania major. Lu. shannoni became infected and supported Le. major up to 6 days postprandial. Metacyclogenesis and actual transmission of Le. major to an uninfected mouse did not occur because infected flies did not take subsequent blood meals.

An indigenous malaria transmission in the outskirts of Addis Ababa, Akaki Town and its environs

Background: In recent years malaria is becoming endemic in highland areas beyond its previously known upper limit of transmission. Assessment of the situation of the disease in such areas is necessary in order to institute appropriate control activities. Objectives: The objectives of the study were to determine the prevalence of malaria, the parasite species involved and Anopheles species responsible in local malaria transmission. Methods: A systematic sampling technique was used to select survey households. Blood films were collected monthly between October and December 1999 from all household members by a trained and experienced laboratory technician. Larval and adult mosquitoes were monthly collected using different methods from September 1999 to October 2000. Results: Among 2136 examined blood films, 78(3.7%) of them were malaria positive of which 54(69%) were due to Plasmodium vivax and 24 (31%) due to P. falciparum. Anopheles gambiae s. l. (presumably An. arabiensis) and An. christyi were the dominant man-biting species, with the former being the major vector in the area. Both these species were found to be more of exophagic and active in the early evening, unlike An. pharoensis, which showed an endophagic tendency. Conclusion: This study indicated that indigenous transmission of malaria occurs in the study area. Transmission is reckoned to be maintained by low density of vector species for short period of time under favorable conditions. Therefore, the acquisition of communal immunity is interrupted by long duration of non-malaria season leading to the occurrence of recurrent malaria epidemics. [Ethiop.J.Health Dev. 2004;18(1):2-7]

Distribution of sand flies (Diptera: Psychodidae) at different altitudes in an endemic region of American cutaneous leishmaniasis in the State of Espírito Santo, Brazil.

The involvement of different sand fly species in the transmission of American cutaneous leishmaniasis (ACL) at different altitudes was evaluated in the municipality of Afonso Cláudio in the State of Espírito Santo, Brazil, from November 1995 to February 1997. CDC light traps and Shannon traps baited with human volunteers were hung simultaneously at three altitudes of a river valley: (a) 650-750 m in an area of active ACL transmission; (b) 750-850 m in a transitional area; and (c) 850-950 m in an area where no ACL transmission occurred. A total of 13,363 specimens belonging to 28 species was collected. The five most abundant man-biting species were Lutzomyia intermedia, which constituted 24.3% of the total, Lu. migonei (22.3%), Lu. whitmani (15.4%), Lu. fischeri (14.9%) and Lu. monticola (5.8%). Analysis of the distribution of these species at the three altitudes provided evidence that Lu. fischeri and Lu. monticola were not involved in ACL transmission, whereas Lu. migonei and Lu. whitmani might act as secondary vectors of Leishmania (Viannia) braziliensis and Lu. intermedia was probably the principal vector of the parasite. These results reinforce those published in the existing literature, which indicate that Lu. intermedia is the main vector of Le. (V.) braziliensis in Southeast Brazil, while Lu. migonei and Lu. whitmani are of secondary importance.

Sand fly vectorial ecology in the State of São Paulo.

Ecological aspect of sand fly distribution in the State of São Paulo, Brazil are described. The main man-biting species are Lutzomyia whitmani, Lu.pessoai, Lu.intermedia, Lu.migonei and Lu.fischeri. Their primary habitat is the forest but latter three of the above species are also encountered in domiciliary environment. Sylvatic species such as Lu.flaviscutellata bite man only rarely and Psychodopygus ayrozai seems to be more anthropophilic. The survival of sand flies in the residual forest and in cultivated areas where man has nearly destroyed the forest almost completely is analyzed. Over the last ten years the incidence of human American cutaneous leishmaniasis (ACL) has been increasing: human cases occurring within several municipalities in which there is overlapping with the distribution of domiciliary Lu.intermedia. New ACL microfoci are appearing in the State of São Paulo and these call for further study.

Epidemiology of cutaneous leishmaniasis in Merida, Venezuela. III. Altitudinal distribution, age structure, natural infection and feeding behaviour of sandflies and their relation to the risk of transmission.

An entomological survey revealed that the distribution of the Lutzomyia species in Merida, Venezuela, varies with altitude. Of the 21 species encountered, 12 (57%) are known to be anthropophilic. The significance of the predominant man-biting species at any altitude is discussed in terms of the risk of transmission of cutaneous leishmaniasis. The general parous rate (and perhaps the ability of a female sandfly to survive oviposition and transmit Leishmania parasites during a second or subsequent bloodmeal) was found to be related to rainfall and altitude. The finding of Leishmania infections in wild-caught parous females of anthropophilic species indicates the high risk of acquiring leishmaniasis in the study area. Observations on the feeding habits of the sandflies indicate that some species are opportunistic feeders, attracted to a variety of hosts, including man.

Isolation and characterization of Leishmania major from Phlebotomus papatasi and military personnel in north Sinai, Egypt

Abstract : Cutaneous leishmaniasis (CL) was repeatedly diagnosed among members of the Multinational Forces and Observers (MFO) in the north Sinai. Leishmania parasites were isolated from both sandflies and suspected human cases of (CL). This study revealed that Phlebotomus papatasi is the only man-biting species in this area. Leishmania parasites produced lesions in the footpads of BALB/c mice, their excretory factor (EF) gave the serotype A1B2, and each isolate yielded isoenzyme profiles identical to those of the L. major reference strain. This is the first report of repeated, concurrent isolation of L. major from both sandflies and humans in Egypt. Cutaneous leishmaniasis, Diagnosis, Leishmania major, Phlebotomus papatasi, MFO personnel, North Sinai, Egypt.

The Brazilian focus of onchocerciasis: new observations in the areas of the Mucajaí and Catrimâni rivers, Territory of Roraima

A recent survey for onchocerciasis conducted among the Yanomami Indians living on the middle reaches of the Mucajaí and Catrimâni Rivers (Territory of Roraima) has failed to show any alteration in the local pattern of the disease. In fact, after a decade from the first surveys in these areas located at the periphery of the Yanomami focus, the prevalence and the intensity of infection have not experienced a significant change. Considering only the residents in the villages inside the surveyed areas, the prevalence varied from zero in the neighbourhood of the Catrimâni mission to 3.1 per cent near the Mucajaí mission. Had there been a competent vector of Onchocerca volvulus in the region higher rates might be expected due to the Yanomami custom of periodic visits among the groups of the tribe. In some of these visits, numbers of highly infected Indians from the central and mountainous part of the Yanomami territory--where more than 90 per cent of the adults have onchocerciasis--come to the villages in the lowland area, attracted by the facilities offered by the mission posts. As the visitors stay in the host villages for several days or weeks, the residents could become exposed to the disease. Simulium oyapockense s.1., a man-biting species of black fly, widely distributed in Northern Brazil, is the only possible vector of O. volvulus in the investigated areas, on the grounds of its local abundance.(ABSTRACT TRUNCATED AT 250 WORDS)

Seasonal abundance of adult Culicoides spp. (Diptera: Ceratopogonidae) in a salt marsh in Florida, USA.

New Jersey light traps and emergence traps were used to determine species composition and seasonal prevalence of adult biting-midge populations at Yankeetown, Florida, USA. Twenty-one species of Culicoides were collected in light traps. Culicoides mississippiensis (57%) and C.furens (36%) were the prevalent species in these collections. Culicoides barbosai was the next most abundant species. These 3 species and C. floridensis and C. melleus were the only man-biting species collected. Only C. furens (73%) and C. mississippiensis (27%) were collected in the emergence traps. Analysis of the overall distribution of C. mississippiensis by plant cover (based on mean number flies/trap/day) revealed that 58% were in Spartina, 22% in Juncus, and 20% in Distichlis; for C.furens, 20% were in Spartina, 12% in Juncus, and 68% in Distichlis. Some C. mississippiensis were present throughout the year, but this species was most abundant during the spring from mid-March through May and in the fall from mid-September through November. Most of the C. mississippiensis collected in emergence traps in the spring were from Spartina areas, and in the fall most specimens were from Juncus and Distichlis areas. Culicoides furens was present in light-trap collections from early April through early November. The largest peak usually occurred in September. Most of the specimens collected in emergence traps from June through October were from Distichlis areas.

Natural infections with promastigotes in man-biting species of sand flies in leishmaniasis-endemic areas of Ecuador.

In order to determine the vectors of leishmaniasis in Ecuador, 1,054 man biting sand flies from the Department of Cañar were dissected and examined for promastigotes. There were 2 man-biting species, Lu. trapidoi and Lu. hartmanni in this endemic area of the disease. The infection rates were 7.7% in the former and 3.9% in the latter species, demonstrating the different rates in various localities and altitudes of the study areas. There was an association between infection rates and the time of day, suggesting some connection with biting activity of sand fly species. In collections using human bait at 7 study areas in 5 Departments, 6 man-biting species were recognized, indicating different dominant species in each area. It was assumed that the dominant species would play an important role as the principal vector of leishmaniasis in each endemic area. As to species determination of the present Leishmania promastigotes, suffice it to say that the parasites are Leishmania sp., presumably L. braziliensis s.l., until the isolates have been typed.

The man-biting activity of phlebotomine sand flies (Diptera: Psychodidae) in a tropical wet forest environment in Colombia

The purpose of this study was to investigate the temporal and spatial attributes of the man-biting activity of phlebotomine sand flies in a Tropical Wet Forest environment. The study was undertaken in a sparsely populated region of the east central portion of the Department of Antioquia, Colombia. With three two-man teams as bait, catches of approximately 10 hours duration during the day and approximately 13 hours for the night and twilight period were made at three separate forest locations and six diverse clearing sites. In the forest series of catches, the predominant man-biting species and their percentage of the catch were Lutzomyia hartmanni (56%), L. trapidoi (22%), and L. yuilli (13%). In the clearing series of catches the predominant species were L. hartmanni (56%), L. gomezi (16%), L. yuilli (9%), and Warileya rotundipennis (9%). For most species, both the magnitude and vertical stratification of their man-biting activity tended to be quite variable between the three forest sites. These differences were thought to be related to local variations in forest structure. Between-site differences in the magnitudes of biting activity were ieast pronounced in the understory. L. trapidoi, and to a lesser extent L. yuilli, were reluctant to bite at ground level in either the forest or clearing habitats. Their diminished biting activity at ground level appeared to primarily account for the greater similarity of the clearing catches to the forest floor catches than to those in the understory and canopy. In the clearing series of catches, the biting activity of L.hartmanni, L. trapidoi, and L. yuilli was detected to be significantly greater at the two forest edge sites than at those sites within the clearing. Diversity of man-biting activity in the clearing habitat was determined to be greatest at a site situated at the edge of pioneer vegetation and pasture. The pioneer vegetation extended to this location from the forest about 130 m away. The man-biting activity of phlebotomine sand flies in the Providencia study area was primarily nocturnal although crepuscular patterns were exhibited by L. bifoliata within the forest and by L. gomezi at the clearing sites. The temporal pattern of biting activity of each of the predominant forest species, i.e., L. hartmanni, L. trapidoi, and L. yuilli, was quite variable from one night to another and there was often a sharp peak in the biting activity. When such variations were averaged, the summarizing pattern tended to distort the true nature of the biting activity and only defined a rather broad interval of time in which biting activity was likely to be concentrated. There was no indication of a nightly pattern of vertical movement by any of these three species. The biting activity of most species appeared to be concentrated at a somewhat earlier time in the clearing habitat than in the forest. The magnitude of man-biting activity for all species combined was relatively uniform throghout the year; however, the dry season was unusually wet. Most of the individual species also did not appear to have pronounced seasonal fluctuations in biting acitivity although L. panamensis was a notable exception. The patterns of man-biting activity exhibited by L. gomezi suggest that it is the species most likely to transmit dermal leishmaniasis to man in the region where our study was conducted. The phlebotomine sand fly assemblage of the Providencia study area is compared with that described from other locations in Colombia and Panama. For each of the common man-biting species in the study area, a review of the literature pertaining to their biology is included.

Microclimate as Background Environment for Ecological Studies of Insects in a Tropical Forest

Microclimate data collection and analyses were made in support of an ecological study of changes in transmission cycles of insect-borne disease during a three-year period of construction of a hydroelectric dam. The dam will cause impoundment of some 300 km2 of tropical forest in the Bayano River Basin, Panama. The pre-impoundment microclimate appeared to be one of strong seasonality with appreciable changes in the wind flow, sensible and latent heat flux, evaporation, rainfall and humidity. Average daily net radiation balance was 106 W m−2 above the forest canopy and 46 W m−2 on the floor of the forest. The moisture balance of the forest indicates an annual rainfall of 2 m of which 1 m reaches the floor of the forest. An appreciable amount of rain is intercepted in the forest canopy. The evaporation and runoff on the forest floor are both about 0.5 m. Average daily wind speeds are light, varying from 8 km day−1 in the rainy season to 126 km day−1 in the dry season. Ecological significance was found in the nocturnal unstable vertical temperature profile of the forest and the associated small updrafts and downdrafts which may permit easier vertical migration of forest insects at night. Rainfall and light wind speeds during 24 h periods of collection seem to appreciably affect the activity of the most abundant man-biting species of insects.

The distribution in Oregon of Ixodes pacificus, Dermacentor andersoni, and Dermacentor occidentalis with a note on Dermacentor variabilis (Acarina: Ixodidae).

Numerous tick collections from areas throughout Oregon between 1967 and 1975 have clarified the distribution of 3 man-biting species, Ixodes pacificus, Dermacentor andersoni , and D. occidentalis . Additional unpublished Oregon records at the Rocky Mountain Laboratory are included (a total of 11,839 ticks) to give full county (spatial) and monthly (temporal) species distributions. A possible new focus of D. variabilis is also included.

Man-biting species of Chrysops Meigen, Culicoides Latreille and Simulium Latreille in Ethiopia, with discussion of their vector potentialities

Human filariasis and its vectors are little known in Ethiopia. Wuchereria bancrofti is confined to the western lowlands and cannot be the aetiological agent of elephantiasis in the highlands. Onchocerca volvulus is widespread in the south-western highlands. Loa loa and Dipetalonema persians are reported here for the first time and appear to be uncommon. Studies were conducted in 1973, mostly near Jimma in Kaffa Province, on potential vectors of all but the first of these parasites. Among Simuliidae, the only blackflies of apparent medical importance were S. woodi ethiopiense and a possibly new member of the S. damnosum complex. The former is less seasonal and much less numerous than the latter, but may be more widespread and important along smaller and higher streams. Onchocerca larvae were recovered from “damnosum”, but not from the small number (46) of ethiopiense examined. In August, at the height of the rainy season, the biting-rate of ethiopiense at 1,710 m altitude on the Gilgil Ghibe river reached 9·5/man-hour at 10–1100 hours and about 12/man-hour at 14–1600 hours. At the same time and place, the attack of “ damnosum” reached a midday climax of about 1,800/man-hour; this peak could be delayed or suppressed by rain. Another possibly anthropophilic blackfly, S. dentulosum, tended to become most common in December after the rainy season had passed, but proved incompetent to bite man successfully. The only feasible loiasis vector found in Ethiopia was Chrysops streptobalius; however, this tabanid was not closely associated with man. Up to 34/man-day were caught in watermeadows by the Gojeb river (altitude 1, 160m) in October. Man-biting species of Ceratopogonidae in various parts of Ethiopia were Culicoides fulvithorax, C. grahamii, C. kingi and C. milnei. The first two of these were anthropophilic in lowlands, but apparently not so in highlands. C. milnei was extremely abundant biting man and domestic animals both indoors and outdoors at Jimma and was widespread elsewhere in the highlands. Its biting cycle was irregular, usually displaying a succession of ill-defined nocturnal peaks; sometimes it attacked in daylight. Up to 35,000 C. milnei per trap-night were caught in light traps. Most of the females entering light traps in a stable were already engorged with blood. It seemed very likely that C. milnei would prove to be of veterinary importance. No firm indication was obtained as to what may transmit D. perstans in Ethiopia.

Epidemiological patterns of cutaneous leishmaniasis in Panama. II. Incidental occurrence of cases in non-endemic settlements.

Epidemiological studies on cutaneous leishmaniasis were carried out in a settlement in the Bayano region, Republic of Panama, during 1971-72. This settlement was established about 12 years earlier for the purpose of cattle raising by small groups of settlers. The primary forest was cut and cleared and the area planted with grass. The presence of active cases of cutaneous leishmaniasis among humans and animals, both domestic and ferals, was investigated. In addition, phlebotomine sandflies were collected to determine their species composition. In 1971, nine of the 161 persons interviewed had active lesions; all but one of the patients were males and of these seven were adults. Five (9%) of 55 dogs and one (3%) of 33 feral mammals examined also were found infected. Strains of the parasite infecting both humans and animals were characterized as Leishmania braziliensis. About 60% of the sandflies collected belong to four man-biting species previously incriminated as vectors of human cutaneous leishmaniasis in Panama. The extensive pasture, together with periodic applications of insecticides in the houses by the antimalarial agency in this country, provided an effective barrier against transmission within the settlement itself. However, both humans and dogs acquired the disease during excursions into the surrounding forest. No new cases were found in 1972.

Preliminary Entomological and Parasitological Studies in Humboldt, Aripuanã, Mato Grosso State, Brazil.

ABSTRACT The preliminary results are given of studies on the sandfly fauna (Diptera: Psychodidae) in forest surrounding the Humboldt Research Centre, Municipio of Aripuanã, Mato Grosso State, Brazil. A total of 712 sandflies were obtained, including 26 different species: of these, 387 were caught off human bait; 317 from tree-trunks; 4 in a malaise-trap; 3 in rodent baited oil traps; and 1 in a light-trap. Man-biting species were absent or very rare during studies in the dry season (August and September, 1974), but relatively abundant at the end of the rainy season (June, 1975): this suggests a seasonal transmission of leishmaniasis. The species at present known as Lutzomyia anduzei of Floch & Abonnenc (1942) was a major man-biter, this species is an important vector of cutaneous leishmaniasis in North Pará, Brazil, and could be responsible for transmission in Aripuanã. Among a total of 349 female sandflies dissected, promastigote flagellates were found in 2 Lutzomyia yuilli; epimastigote flagellates in 1 L. yuilli; a microsporidian in Psychodopygus (1) complexus; a gregarine, probably Monocystis chagasi, in P. davisi; and a nematode larva in P. complexus. Inoculation of the promastigote flagellates into the skin of hamsters failed to give Leishmania infections: possibly they were developmental stages of some other parasite. Two research workers of Project RADAM acquired cutaneous leishmaniasis in the Humboldt area; and 6 cases of malaria were diagnosed, 3 due to P. falciparum and 3 to P. vivax. Transmission of malaria was shown to be taking place in the camp site itself. Finally, man-biting "black-flies" (Diptera: Simuliidae) were found to be a serious problem, necessitating constant use of insect repellent.

Epidemiological patterns of cutaneous leishmaniasis in Panama. III. Endemic persistence of the disease.

Endemic persistence of cutaneous leishmaniasis is described in El Aguacate, a community established in the forest of central Panama about 75 years ago. Physiographic pecularities partially isolate El Aguacate from other villages in the region. Some of the original forest environment has been preserved and man-biting species of phlebotomine sandflies were abundant as was the two-toed sloth, Choloepus hoffmanni, the principal reservoir host of Leishmania braziliensis in Panama. The inhabitants, as well as their dogs, were examined for natural leishmaniasis in 1969 and 1973. Mammals and phlebotomine sandflies were collected from 1968 to 1973 in a search for reservoir hosts and potential vectors of the disease. Similar studies were undertaken in two nearby villages during 1968 and 1969. L. braziliensis has persisted for many years in El Aguacate, and infection is acquired during childhood. Dogs also were found naturally infected, and the two-toed sloth showed yearly infection rates up to 47.8%. Parasites were demonstrated from a night monkey, Aotus trivirgatus.