RESUMO

A precipitin test was employed to study the alimentary tract content of Lutzomyia longipalpis in the intra- and peridomiciliary environments in the municipality of Raposa, Maranh o State, a transmission area for visceral leishmaniasis or kala azar. Out of 2,240 female sandflies captured, 547 (24.4%) had fed on vertebrate blood, with the following proportions: avian (87.9%); rodent (47.2%); human (42.4%); canine (27.6%); opossum (26.6%); and equine (22.5%). Based on a survey of 120 human dwellings, chickens were found to be the most common domestic animals in the peridomicile (28.3%), followed by dogs (21.7%), cats (17.5%), donkeys (13.3%), pigeons (7.5%), rabbits (3.3%), ducks (3.3%), and horses, mallards, and pigs (1.7% each). Synanthropic animals included opossums (39.3%), followed by rats (37.9%), bats (14.3%), raccoons (3.6%), foxes (2.1%), snakes (1.4%), and frogs (1.4%). The peridomiciliary presence of domestic and synanthropic animals as well as sandflies that had fed on human, opossum, and canid blood supports the hypothesis that kala azar transmission has been taking place in the anthropic environment in the municipality of Raposa.

BackgroundThe new epidemiological scenario of orally transmitted Chagas disease that has emerged in Brazil, and mainly in the Amazon region, needs to be addressed with a new and systematic focus. Belém, the capital of Pará state, reports the highest number of acute Chagas disease (ACD) cases associated with the consumption of açaí juice.Methodology/Principal FindingsThe wild and domestic enzootic transmission cycles of Trypanosoma cruzi were evaluated in the two locations (Jurunas and Val-de Cães) that report the majority of the autochthonous cases of ACD in Belém city. Moreover, we evaluated the enzootic cycle on the three islands that provide most of the açaí fruit that is consumed in these localities. We employed parasitological and serological tests throughout to evaluate infectivity competence and exposure to T. cruzi. In Val-de-Cães, no wild mammal presented positive parasitological tests, and 56% seroprevalence was observed, with low serological titers. Three of 14 triatomines were found to be infected (TcI). This unexpected epidemiological picture does not explain the high number of autochthonous ACD cases. In Jurunas, the cases of ACD could not be autochthonous because of the absence of any enzootic cycle of T. cruzi. In contrast, in the 3 island areas from which the açaí fruit originates, 66.7% of wild mammals and two dogs displayed positive hemocultures, and 15.6% of triatomines were found to be infected by T. cruzi. Genotyping by mini-exon gene and PCR-RFLP (1f8/Akw21I) targeting revealed that the mammals and triatomines from the islands harbored TcI and Trypanosoma rangeli in single and mixed infections.Conclusion/SignificanceThese findings show that cases of Chagas disease in the urban area of Belém may be derived from infected triatomines coming together with the açaí fruits from distant islands. We term this new epidemiological feature of Chagas disease as “Distantiae transmission”.

Belminus ferroae (Hemiptera: Reduviidae) was collected from houses in the localities of San Alberto and Santa Catalina in the municipality of Toledo, Department of Norte de Santander, Colombia. Precipitin tests revealed that the main hosts of B. ferroae are insects belonging to the order Blattodea, whose haemolymph serves as food (89.43%). A low rate of haematophagy was indicated on rodents, dogs and humans (7.32%) and no natural infection with Trypanosoma cruzi was found by either microscopic examination or polymerase chain reaction. The finding of B. ferroae inside houses, feeding primarily on Blattodea with only a minor tendency to feed on vertebrate blood, is indicative of both the evolutionary path from predator to blood-sucker taken by Triatominae and their tendency to adapt from silvatic to domestic habitats.

A leishmaniose visceral (LV) possui distribuição mundial, sendo encontrada nas Américas, África, sul da Europa, Ásia e Oriente Médio 13. Nas Américas, a LV ocorre desde o México até a Argentina, sendo que o Brasil contribui com 90% dos casos do continente 12 24 27 . Nesse continente, as leishmanioses têm algumas características epidemiológicas comuns, ocorrendo em pessoas residentes em áreas rurais ou que tiveram contato com habitats silvestres. As mudanças no comportamento humano, as alterações do ambiente, ou ambas, podem ter um maior impacto na prevalência e no padrão de transmissão da LV 11 . ABSTRACTStudies on the feeding habits and intestinal content of sandflies make it possible to identify hosts, thereby indicating potential reservoirs for Leishmania. The present study had the aim of determining the feeding preferences of Lutzomyia longipalpis and its relationship with the transmission of visceral leishmaniasis. Specimens were caught every month in a transmission area of visceral leishmaniasis, in the municipality of Várzea Grande, State of Mato Grosso, from January 2004 to June 2006, using CDC light traps. 2,376 females of Lutzomyia longipalpis were caught, of which 104 (4.4%) were engorged. Among these, 32 (30.8%) were caught inside homes and 72 (69.2%) in areas surrounding homes. From the precipitin reaction, it was observed that Lutzomyia longipalpis females fed preferentially on birds (30.8%) and rodents (21.2%), but they were also found to have fed on blood from humans, opossums, oxen, horses and dogs, thus demonstrating the opportunist nature of this species.