Studies on Trypanosoma rangeli Tejera 1920: VI. Developmental pattern in the haemolymph of Rhodnius prolixus

The morphological sequence of Trypanosoma rangeli development in the body cavity of Rhodnius prolixus is described. The metacyclic trypanosome is the product of successive division and transformation during the intra and extracellular development in the haemocoele. The significance of the early invasion of T. rangeli into the haemolymph is discussed. The epidemiological importance of the developmental pattern of T. rangeli in the vectors haemolymph and the host-response to the parasite are considered.

A rewiew of the subgenus Trichopygomyia Barretto, 1962; with description of a new species from the brazilian Amazon Basin (Diptera: Psychodidae, Phlebotominae)

The subgenus Trichopygomyia Barreto, 1962 of the phlebotomine genus Lutzomyia França, 1924 is reviewed. This subgenus corresponds to the informal species group longispina of Theodor (1965). Lutzomyia (Trichopygomya) ratcliffei n.sp. from the Brazilian Amazon Basin is described. Figures, keys, distribution maps and notes on ecology are presented for all the known forms. The better known species are most frequently encountered in armadillo burrows and, therefore, could well be vectors of Leishmania.

Bolivian phlebotomines. II Psychodopygus Yucumensis n.sp., a new man-biting phlebotomine sandfly from subandean region (Diptera, Psychodidae)

Psychodopygus yucumensis n.sp., a new species of Phlebotomine sandfly belonging in genus Psychodopygus mang., is described from specimens collected from human bait, in Beni dept., Bolivia. The male is characteristic of the series panamensis, but the female, closely related to P. carrerai carrerai, can be confused with this species ("cryptic species"). Isozyme characterization can determine any specimen of either species, while morphometric analysis shows statistical differences between the two species. P. yucumensis is strongly anthropophilic. A Leishmania braziliensis braziliensis stock was isolated from this new species, indicating that it is one of the vectors of mucocutaneous Leishmaniasis in the lowland subandean area.

Leishmaniasis in Bolivia: II. The involvement of Psychodopygus yucumensis and Psychodopygus llanosmartinsi in the selvatic transmission cycle of Leishmania braziliensis braziliensis in a lowland subandean region

An epidemiological survey of the vectors of cutaneous leishmaniasis ("espúndia" type) was caried out in the Alto Beni region of Bolivia, an area of Andean foothills at the Eastern limit of the Amazonian lowlands. The climate is typical wet tropical (15ºS latitude). Anthropophilic phlebotomine sandfly species were sampled at 20 sites, all forested. The importance of species from the Psychodopygus group, already suspected as a vector in the transmission of Leishmania from the braziliensis complex, was confirmed by: 1) the aggressiveness and diversity of the species encountered (83% of catches, nine species), 2) the discovery of a new anthropophilic species, P. yucumensis and 3) the isolation of a strain of Leishmania braziliensis braziliensis indistinguishable from human strains from the same area, from two species, P. llanosmartinsi and P. yucumensis.

Infective stages of Leishmania in the sandfly vector and some observations on the mechanism of transmission

Infective stages of Leishmania (Leishmania) amazonensis, capable of producing amastigote infections in hamster skin, were shown to be present in the experimentally infected sandfly vector Lutzomyia flaviscutellata 15, 25, 40, 49, 70, 96 and 120 hours after the flies had received their infective blood-meal. Similarly, infective stages of Leishmania (L.) chagasi were demonstrated in the experimentally infected vector Lu. longipalpis examined 38, 50, 63, 87, 110, 135, 171 and 221 hours following the infective blood-meal, by the intraperitoneal inoculation of the flagellates into hamsters. The question of whether or not transmission by the bite of the sandfly is dependent on the presence of [quot ]metacyclic[quot ] promastigotes in the mouthparts of the vector is discussed.

Evaluation of the rabbit as a model for chagas' disease: I. Parasitological studies

In order to investigate the value of the rabbit as an experimental model for Chagas' disease, 72 animals have been inoculated by intraperitoneal and conjunctival route with bloodstream forms, vector-derived metacyclic trypomastigotes and tissue culture trypomastigotes of Trypanosoma cruzi strains Y, CL and Ernane. In 95.6% of the animals trypomastigotes had been detected at the early stages of infection by fresh blood examination. The course of parasitemia at the acute phase was strongly influenced by the parasite strain and route of inoculation. At the chronic phase parasites had been recovered by xenodiagnosis and/or hemoculture in 40% of the examined animals. The xenodiagnosis studies have shown selective interactions between the T. cruzi strains and the four species of vectors used, inducing significant variability in the results. The data herein present are consistent with the parasitological requirements established for a suitable model for chronic Chagas' disease.

Virological study of a dengue type 1 epidemic at Rio de Janeiro

A dengue outbreak started in March, 1986 in Rio de Janeiro and spread very rapidly to other parts of the country. The great majority of cases presented classical dengue fever but there was one fatal case, confirmed by virus isolation. Dengue type 1 strains were isolated from patients and vectors (Aedes aegypti) in the area by cultivation in A. albopictus C6/36 cell line. The cytopathic effect (CPE) was studied by electron microscopy. An IgM capture test (MAC-ELISA) was applied with clear and reproducible results for diagnosis and evaluation of virus circulation; IgM antibodies appeared soon after start of clinical disease, and persisted for about 90 days in most patients. The test was type-specific in about 50% of the patients but high levels of heterologous response for type 3 were observed. An overall isolation rate of 46,8% (813 virus strains out of 1734 specimens) was recorded. The IgM test increased the number of confirmed cases to 58,2% (1479 out of 2451 suspected cases). The importance of laboratory diagnosis in all regions where the vectors are present is emphasized.

Zoonotic cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis associated with domestic animals in Venezuela and Brazil

After outbreaks of cutaneous leishmaniasis in Solano State, Venezuela, 5% of the population had parasitized ulcers while after similar outbreaks in Mesquita, Rio de Janeiro State, Brazil, 9% had the disease. In these foci children, including some under six years of age, wre affected. There was no significant difference in the occurence of the disease according to sex or type of employment. In Solano, 3% of dogs and 28% of donkeys had parasitized lesions, while in Mesquita these indices were 19.8% and 30.8% respectively. The parasite from man, dogs and equines was identified as Leishmania (Viannia) braziliensis, by zymodeme and serodeme characterization. In these foci there is evidence suggesting that leishmaniasis is a zoonosis, possibly with equine and dogs as reservoirs, although both a wild enzootic cycle and the role of man as a source of infection can not be ruled out. Transmission is assumed to occur peridomestically by sandfly vectors such as Lutzomyia panamensis in Venezuela and Lutzomyia intermedia in Brazil. Information about the origin of these foci suggests that infected equines may be an important factor in the dissemination of the parasite in a peridomestic situation where these sandflies are abundant.

Anopheline species, some of their habits and relation to malaria in endemic areas of Rondônia State, Amazon region of Brazil

In view of recent studies incriminating several species of anophelines, besides Anopheles darlingi, as malaria vectors in the Brazilian Amazon, we performed an anopheline survey in four localities - Ariquemes, Cujubim, Machadinho and Itapoã do Oeste - in Rondônia, the most malarious State in the Country. Twenty species were found. An. darlingi was, by far, the dominant species and the only one whose density coincided with that of malaria. On human baits it was more numerous in the immediate vincinity of houses than indoors whre, however, it was almost the only species encountered. On both situations it fed mostly at sunset and during the first half of the night. It was less numerous far from houses and scarce inside the forest. Other species (An. triannulatus, An. evansae, An. albitarsis, An. strodei) appeared in appreciable numbers only in Ariquemes, both in areas with and without malaria. The remaining species were scanty. An. darlingi was confirmed as the primary local vector.

Mass migration of juvenile Biomphalaria glabrata snails bred under semi-natural conditions

For the development of studies on snail interspecific competition special in-door laboratory channels were built. In the all five channels seeded with adult specimens of Biomphalaria glabrata mass migration of juvenile snails outside the water was observed. Most of the migrant snails presented apertural lamellae. Data collected during the period of two years, showed the regression of the migration phenomenon and the disappearance of the lamellate snails.

A cronologia da descoberta dos transmissores da malária na Amazônia brasileira

In the Amazon Region of Brazil, during the first three decades of this century, anophelines of the subgenus Nyssorhynchus not precisely identified to species were regarded as the probable malaria vectors. In 1931 and 1933 Anopheles darlingi, and in 1942-1946 An. aquasalis were confirmed as carriers, the former in the interior, the latter along the coast, because of their habits and salivary gland infection. An. albitarsis and An. braziliensis seemed to be occasional, secondary vectors. Forty years later, through immunological tests, other species are being pointed as naturally infected: An. triannulatus, An. nuneztovari, An. oswaldoi, An. strodei, An. galvaoi and An. peryassui. The importance of all incriminated species except An. darlingi (the main vector wherever present) and An. aquasalis has yet to be measured.

Estudo comparado do ciclo evolutivo de triatomíneos a duas temperaturas

We studied the life cicle of several triatominae species: Dipetalogaster maximus (Uhler, 1894); Panstrongylus herreri Wygodzinsky, 1948; Panstrongylus megistus (Burmeister, 1835); Rhodnius ecuadoriensis Lent & Leon, 1958; Rhodnius nasutus Stal, 1859; Rhodnius neglectus Lent, 1954; Rhodnius pictipes Stal, 1872; Rhodnius prolixus Stal, 1859; Rhodnius robustus Larrousse, 1927; Triatoma brasiliensis Neiva, 1911; Triatoma infestans (Klug, 1834); Triatoma maculata (Erichson, 1848); Triatoma matogrossensis Leite & Barbosa, 1953; Triatoma platensis Neiva, 1913; Triatoma protracta (Uhler, 1894); Triatoma sordida (Stal, 1859); Triatoma tibiamaculata (Pinto, 1926) e Triatoma vitticeps (Stal, 1859) (Hemiptera, Reduviidae). The main purpose of the study was to obtain information to improve control measures specially in those peridomiciliar species. The experiments were performed in two climatized chambers, both with an humidity of 70 ± 5% and photoperiod of 12 hours. One was maintained at 25 ± 0,5ºC and the other at 30 ± 1ºC.

Observations on the distribution of anophelines in Suriname with particular reference to the malaria vector Anopheles darlingi

A study was made on the distribution of anophelines in Suriname with special emphasis on the principal malaria vector Anopheles darlingi and on the occurrence of other possible vector species. Peridomestic human bait collections of adult mosquitoes and collections of larvae were made in many localities with a recent history of malaria transmission. Stable population of An. darlingi were only found in the interior, south of the limit of tidal influence, due to year-round availability of breeding habitats in quietly sunlit places in flooded forest areas and along river banks. In the area with tidal movement of the rivers, breeding is limited to flooded areas in the west season. Anopheles darlingi was only incidentally collected in low densities. In the interior, malaria transmission occurred in all places where An. darlingi was found. The absence of malaria transmission along the Upper Suriname River could be explained by the absence of An. darlingi. In the malaria endemic areas, An darlingi was the most numerous mosquito biting on man. In the tidal region, malaria outbreak are infrequent and might be explained by the temporary availability of favourable beeding habitats for An. darlingi. However, evidence is insufficient to incriminate an. darlingi as the vector of malaria in this region and the possible vectorial role of other anophelines is discussed.

Potential schistosome-vector snails and associated trematodes in ricefields of Corrients province, Argentina: preliminary results

Considering the possibility of introduction of schistosomiasis mansoni into Argentina as a consequence of dam construction on the Rio De La Plata basin, preliminary studies have been carried out on agrosystems such as ricefields in Corrientes province with the following purposes: 1) to survey and estimate the relative abundance of planorbids and identify potential vector species; 2) to identify environmental factors capable of influencing Biomphalaria population dynamics; and 3) to find out snail-parasite associations and estimate snail infection rates in order to detect possible competitive interactions between larval stages of native trematodes that could be used in biological control of Schistosoma mansoni. Three potential schistosome vectors were detected in ricefields, namely Biomphalaria straminea, B. tenagophila and B. peregrina, although B. orbignyi, a species refractory to infection with S. mansoni, proved the most frequent and abundant. Positive correlations (P<0.05) were found between Biomphalaria abundance and some environmental parameters: conductivity, hardness, calcium, nitrites plus nitrates, ammonium and bicarbonates. Water temperature correlation was negative (P<0.05). No correlation (P>0.05) was found in total iron, phosphates (SRP), pH and soil granulometry. Echinocercariae developed from rediae and belonging to Petasiger sp., Paryphostomum sp., and other undetermined species were found.

Trypanosomatid protozoa in fruit of solanaceae in southeastern Brazil

Fruits of cultivated and indigenous Solanaceae from Southeastern Brazil have been examined for the presence of trypanosomatid flagellates. The 14 species found infected were: Capsicum annum, C. praetermissum, Lycopersicon esculentum, Nicandra physaloides, Physalis angulata, Solanum sp., S. americanum, S. concinnum, S. diflorum, S. erianthum, S. gilo, S. robustum, S. variable and S. viarum. The pentatomid hemipteran Arvelius albopunctatus experimentally transmitted flagellates to fruits of some species. Cultures of flagellates were obtained form fruits of eight species of Salonaceae and from A. albopunctatus.