RESUMO
Long-term control of triatomine bugs in Chagas endemic regions will depend on a full understanding of vector-parasite-host interactions. Herein we describe a cytochrome b multiplex polymerase chain reaction (PCR)-based strategy for blood meal source identification in bug foregut contents. This technique discriminates human from animal blood, and has been tested in five Triatoma species from México. Host identification has been validated for human, four rodent species, two bat species, dog, rabbit, sheep, and opossum. In addition, Trypanosoma cruzi can be identified simultaneously using S34/S67-specific kinetoplast DNA primers. Both host and parasite identification were possible as long as 10 weeks after bug feeding, and in samples stored up to 6 years. The blood meal identification procedure described here represents a powerful tool for large-scale studies identifying the biological, ecological, and environmental variables associated with Chagas disease transmission.
Assuntos
Sangue , Doença de Chagas/parasitologia , Citocromos b/genética , Insetos Vetores/parasitologia , Triatoma/parasitologia , Trypanosoma cruzi/fisiologia , Animais , Doença de Chagas/transmissão , Comportamento Alimentar , Feminino , Interações Hospedeiro-Parasita , Humanos , Insetos Vetores/classificação , Insetos Vetores/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Reação em Cadeia da Polimerase , Fatores de Tempo , Triatoma/classificação , Triatoma/metabolismo , Trypanosoma cruzi/genética , Trypanosoma cruzi/isolamento & purificaçãoRESUMO
In several districts of Boa Vista, state of Roraima, Brazil we found Anopheles (Nyssorhynchus) albitarsis E to be the primary vector of human malaria parasites, and during 2001-2002 it was significantly more abundant than An. darlingi (p < 0.001). Other species sampled were An. (Nys.) braziliensis, An. (Ano.) peryassui, An. (Nys.) nuneztovari, An. (Nys.) oswaldoi s.l., and An. (Nys.) triannulatus. As determined by the ELISA technique An. darlingi had a higher overall infection rate (2.1%) compared with An. albitarsis E (1.2%). However a marginally higher proportion of An. albitarsis E was infected with Plasmodium vivax compared with An. darlingi, and the An. albitarsis E biting index was also much higher These results suggest the importance of An. albitarsis E in malaria transmission in a savannah ecoregion of northern Amazonian Brazil, and reconfirm the importance of An. darlingi even if at lower abundance.
Assuntos
Anopheles/parasitologia , DNA de Protozoário/análise , Insetos Vetores/parasitologia , Malária/transmissão , Plasmodium/isolamento & purificação , Animais , Anopheles/classificação , Brasil , Ensaio de Imunoadsorção Enzimática , Humanos , Malária/parasitologia , Plasmodium/classificação , Plasmodium/genética , Estações do AnoRESUMO
In several districts of Boa Vista, state of Roraima, Brazil we found Anopheles (Nyssorhynchus) albitarsis E to be the primary vector of human malaria parasites, and during 2001-2002 it was significantly more abundant than An. darlingi (p < 0.001). Other species sampled were An. (Nys.) braziliensis, An. (Ano.) peryassui, An. (Nys.) nuneztovari, An. (Nys.) oswaldoi s.l., and An. (Nys.) triannulatus. As determined by the ELISA technique An. darlingi had a higher overall infection rate (2.1 percent) compared with An. albitarsis E (1.2 percent). However, a marginally higher proportion of An. albitarsis E was infected with Plasmodium vivax compared with An. darlingi, and the An. albitarsis E biting index was also much higher. These results suggest the importance of An. albitarsis E in malaria transmission in a savannah ecoregion of northern Amazonian Brazil, and reconfirm the importance of An. darlingi even if at lower abundance.
Assuntos
Humanos , Animais , Anopheles/parasitologia , DNA de Protozoário/análise , Insetos Vetores/parasitologia , Malária/transmissão , Plasmodium/isolamento & purificação , Anopheles/classificação , Brasil , Ensaio de Imunoadsorção Enzimática , Malária/parasitologia , Plasmodium/classificação , Plasmodium/genética , Estações do AnoRESUMO
An evaluation of malaria transmission and epidemiology in the Amazonian city of Belém over the last 70 years shows that (1) Anopheles darlingi, reported to be eradicated in 1968, reappeared in the mid 1990s, with a marked increase in abundance between 1997 to 1999 in two of three districts sampled; (2) An. darlingi and An. aquasalis are each implicated in current malaria transmission in different districts of the city; (3) mosquito species diversity (in Anopheles subgenus Nyssorhynchus) has increased from two in the 1930s to six in the 1940s to 10 in the 1990s; (4) there is no overall correlation between malaria case incidence and human population size from 1940 to 1996 in Belém; (5) however, the total number of malaria cases has increased significantly since the late 1970s and over the short term from 1993 to 1999; and (6) interestingly, the short term increases are due solely to cases of Plasmodium vivax infection; cases of P. falciparum malaria are declining (significantly for Pará state only). The reappearance of An. darlingi may be a result of the continued expansion of Belém into the surrounding forest in the 1990s. In the absence of preventative measures, we predict an increase in local outbreaks of malaria in the DAENT and DAICO districts where the population sizes of An. darlingi are increasing.
Assuntos
Anopheles , Insetos Vetores , Malária/epidemiologia , Densidade Demográfica , Animais , Brasil , Geografia , Humanos , Incidência , Malária/transmissão , Análise de RegressãoRESUMO
In the present study, domestic dogs in a Leishmania endemic area in the Peten Region of Guatemala were sampled to determine if they are a potential reservoir for Leishmania parasites. Blood from 100 dogs from six villages was tested with two different antibody-capture assays for Leishmania-specific antibodies and a 28% seroprevalence was determined. Tissue scrapings from six dogs presenting with chronic lesions characteristic of Leishmania infection were sampled and four dogs were positive by a genus-specific fluorogenic PCR assay. Histopathology by giemsa stain confirmed the presence of amastigotes in one of these dogs. These findings support the hypothesis that dogs may play an important role in the transmission of Leishmania in a region where no mammal has ever been implicated as a reservoir.
Assuntos
Reservatórios de Doenças/veterinária , Doenças do Cão/parasitologia , Leishmania braziliensis/isolamento & purificação , Leishmania donovani/isolamento & purificação , Leishmaniose Cutânea/veterinária , Animais , Anticorpos Antiprotozoários/sangue , DNA de Protozoário/química , DNA de Protozoário/genética , Doenças do Cão/epidemiologia , Cães , Doenças Endêmicas , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Guatemala/epidemiologia , Histocitoquímica/veterinária , Leishmania braziliensis/genética , Leishmania donovani/genética , Leishmaniose Cutânea/sangue , Leishmaniose Cutânea/epidemiologia , Leishmaniose Cutânea/parasitologia , Masculino , Reação em Cadeia da Polimerase/veterinária , Estudos Prospectivos , Estudos SoroepidemiológicosRESUMO
In a region of northeastern Amazonia, we find a species previously of minor importance, Anopheles marajoara, to be the principal malaria vector. In a total of five collections during 1996-97 in three replicated sites near the city of Macapá, Amapá state, this species occurs in much greater abundance compared with the presumed vector Anopheles darlingi. Also, a significantly higher proportion of An. marajoara is infected with malaria parasites, determined by the ELISA technique. This appears to be the result of increased abundance of An. marajoara due to alterations in land use, invasion of its primary breeding sites by human immigrants, and its anthropophilic behavior. This discovery highlights one of the challenges of Neotropical malaria control, namely that the targeting of specific vectors may be complicated by a changing mosaic of different locally important vectors and their interactions with human populations.