Com o objetivo de determinar os aspectos epidemiológicos que envolvem a doença de Chagas (DC) canina e identificar os principais fatores de risco da enfermidade no semiárido paraibano, foi conduzido um estudo na zona rural de Patos, onde a área foi dividida em três estratos amostrais (Norte, Sul e Oeste) e, em cada estrato foram amostradas aleatoriamente 294 casas, e dessas todos os cães domiciliados representaram as unidades elementares do estudo. Em cada unidade domiciliar foi aplicado um questionário epidemiológico para se obter informações sobre indicadores que favorecem a disseminação da doença no segmento peridomiciliar. O diagnóstico sorológico para DC em cães foi baseado em três métodos (RIFI, ELISA e HAI), sendo consideradas positivas aquelas amostras que apresentassem pelo menos dois testes reagentes e ausência de reatividade cruzada. Para zona rural do município, a prevalência de cães sororreagentes para T. cruzi por estrato amostral foram: Norte 6,05%, Sul 3,59% e Oeste 2,97%, correspondendo a uma prevalência em sua totalidade de 4,08%. Os fatores de riscos (odds ratio, OR) evidenciados em análise multifatorial foram: tipo de parede (OR=2,59 [1,24-5,4]), presença de armazém (OR=1,89 [1,31-3,0]), presença de galinheiros (OR=8,31 [1,29-61,7]), contato com animais (OR=9,11 [1,12-73,9]), contato com aves (OR=9,7 [1,81-52,83]), triatomíneos capturados (OR=16,58 [3,43-80,23]) e antropismo (OR=4,35 [1,36-14,0]. Diante dos resultados foi possível se obter informações inerentes à situação epidemiológica da Doença de Chagas ressaltando características biogeográficas da zona rural do semiárido paraibano, elevando a espécie canina e os fatores de risco evidenciados, em destaque ao contato com aves e ecótopos artificiais, operacionalizando indicadores a serem assistidos e considerados na cadeia de transmissão da doença na região.

In order to determine the epidemiological aspects involving canine Chagas disease (CD) and to identify major risk factors for the disease in the semi-arid region of Paraiba, a study was conducted in the rural area of Patos/Paraíba, Brazil, where the area was divided into three sampling strata (North, South and West) and, in each stratum we randomly sampled about 294 houses, and all the pet dogs represented the elementary units of study. In each household an epidemiological questionnaire was administered to obtain information on indicators that favor the spread of the disease in peridomestic segment. Serological diagnosis for CD in dogs was based on three methods (IFA, ELISA and HAI), considering positive samples that had at least two tests reagents and absence of cross-reaction. For the rural area, the prevalence of seropositive dogs for Trypanosoma cruzi by sampling stratum was: North 6.05%, South 3.59% and West 2.97%, corresponding to a total prevalence of 4.08%. The risk factors (odds ratio, OR) were evidenced in multifactorial analysis: wall type (OR=2.59 [1.24-5.4]), presence at warehouse (OR=1.89 [1.31-3.0]), present at chicken stall (OR=8.31 [1.29-61.7]), contact with animals (OR = 9.11 [1.12-73.9]), contact with birds (OR=9.7 [1.81-52.83]), captured triatomines (OR=16.58 [3.43-80.23]) and anthropogenic (OR=4.35 [1.36-14.0]. From the results it was possible to obtain information pertaining to the epidemiological situation of Chagas Disease highlighting biogeographical characteristics of rural semi-arid region of Paraiba, raising dogs and the risk factors disclosed in the highlighted contact with birds and ecotopes operationalizing indicators to be watched and considered in the chain of transmission of the disease in the region.

The Pantanal is a South American biome characterized by extensive plains and stark environmental seasonality. Several habitats are subject to annual flooding, forcing small mammal species to aggregate in dry forest patches, which most likely influences their population dynamics and life history strategies. In order to investigate the seasonal influence on the life history traits of these small mammals, we conducted a 2-year mark-recapture study in the southeastern region of the Brazilian Pantanal (Nhecolândia) and analyzed the population dynamics of the most abundant small mammal species with the jackknife estimator. A trapping effort of 21,560 trap-nights resulted in 615 individuals in 1,171 captures (success = 5.43%). Three species of rodents - Oecomys mamorae (Thomas, 1906), Thrichomys pachyurus (Wagner, 1845), and Clyomys laticeps (Thomas, 1841) - and three species of marsupials - Gracilinanus agilis (Burmeister, 1854), Thylamys macrurus (Olfers, 1818), and Monodelphis domestica (Wagner, 1842) - were obtained. The most abundant species was O. mamorae, followed by G. agilis and T. pachyurus. Oecomys mamorae was more abundant in the wet season and presented an opportunistic reproductive strategy. Gracilianus agilis displayed increased population sizes in the dry season and synchronized, seasonal reproduction during the rainy season. Thrichomys pachyurus had a small population size, delayed response to variations in environmental conditions and higher reproductive rates in the dry season. All species revealed different life history strategies (seasonal, opportunistic or delayed response to environmental variations), coinciding with periods of higher resource availability in order to maximize survival.

A hipótese clássica sobre a origem da doença de Chagas propõe que tenha surgido entre as populações pré-históricas dos Andes quando começaram a domesticar animais, mudaram para hábitos sedentários e adotaram a agricultura. Estas mudanças em seus hábitos de vida aconteceram há aproximadamente 6.000 anos. Entretanto, os dados da paleoparasitologia, baseados na biologia molecular, mostraram que a infecção por Trypanosoma cruzi e a doença de Chagas eram comuns tanto em populações pré-históricas da América do Sul e América do Norte muito antes deste período. De acordo com os dados paleoparasitológicos, a doença de Chagas pode ser tão antiga quanto a presença humana no continente americano. O estudo sobre a origem e dispersão da infecção por Trypanosoma cruzi entre populações humanas pré-históricas pode auxiliar na compreensão de questões clínicas e epidemiológicas sobre a doença de Chagas que ainda permanecem sem resposta.

The classical hypothesis proposes that Chagas disease has been originated in the Andean region among prehistoric people when they started domesticating animals, changing to sedentary habits, and adopting agriculture. These changes in their way of life happened nearly 6,000 years ago. However, paleoparasitological data based on molecular tools showed that Trypanosoma cruzi infection and Chagas disease were commonly found both in South and North American prehistoric populations long before that time, suggesting that Chagas disease may be as old as the human presence in the American continent. The study of the origin and dispersion of Trypanosoma cruzi infection among prehistoric human populations may help in the comprehension of the clinical and epidemiological questions on Chagas disease that still remain unanswered.

Barra de Guaratiba é uma região litorânea da cidade do Rio de Janeiro onde a leishmaniose visceral americana é endêmica. Apesar das medidas de controle aplicadas nessa localidade, incluindo sacrifício de cães e borrifação de inseticidas, a soroprevalência canina está estimada em 25% e durante 1995 e 1997, 8 casos humanos autóctones foram notificados. Para avaliar fatores de risco relacionados com o aumento da infecção por Leishmania (Leishmania) chagasi em cães, nós examinamos 365 cães utilizando a técnica de Imunofluorescência Indireta (IFAT) e capturamos flebótomos em ambientes doméstico e peridoméstico. Algumas variáveis relacionadas à infecção foram avaliadas por análise uni e multivariada. A distância da residência a borda da floresta, sua altitude e presença do gambá Didelphis marsupialis no quintal, foram considerados fatores preditores da infecção por Leishmania (Leishmania) chagasiem cães de Barra de Guaratiba. A presença de Lutzomyia longipalpis em ambiente peridoméstico indica a possibilidade de ocorrência de novos casos humanos. Nossos dados também sugerem a presença de um ciclo enzoótico nessa localidade.

Barra de Guaratiba is a coastal area of the city of Rio de Janeiro where American visceral leishmaniasis (AVL) is endemic. Although control measures including killing of dogs and use of insecticides have been applied at this locality, the canine seroprevalence remains at 25% and during 1995 and 1997 eight autochthonous human cases were notified. In order to evaluate factors related to the increase of the risk for Leishmania (Leishmania) chagasi infection in dogs we have screened 365 dogs by anti-Leishmania immunofluorescent antibody test (IFAT) and captured sandflies in the domestic and peridomestic environment. Some variables related to the infection were assessed by uni- and multivariate analysis. The distance of the residence from the forest border, its altitude and the presence of the opossum Didelphis marsupialis in the backyard, were found predictor factors for L. (L.) chagasi infection in dogs in Barra de Guaratiba. The presence of Lutzomyia longipalpis in the peridomestic environment indicates the possibility of appearence of new human cases. Our data also suggest the presence of a sylvatic enzootic cycle at this locality.

The high rate of natural Trypanosoma cruzi infection found in opossums does not always correlate with appreciable densities of local triatomid populations. One alternative method which might bypass the invertebrate vector is direct transmission from mother to offspring. This possibility was investigated in five T. cruzi infected females and their litters (24 young). The influence of maternal antibodies transferred via lactation, on the course of experimental infection, was also examined. Our results show that neonatal transmission is probably not responsible for the high rate of natural T. cruzi infection among opossums. In addition antibodies of maternal origin confer a partial protection to the young. This was demonstrated by the finding of a double prepatency period and 4,5 fold lower levels of circulating parasites, in experimentally infected pouch young from infected as compared to control uninfected mothes. On the other hand, the duration of patent parasitemia was twice as long as that observed in the control group.

Foi verificado que tanto espécies digenéticas do gênero Trypanosoma como espécies de tripanosomatídeos monogenéticos de insetos, podem desenvolver-se no lúmen das glândulas de cheiro do gambá, reproduzindo o ciclo que fazem no tubo digestivo dos insetos que lhes servem de hospedeiros e/ou transmissores. Com base nesses achados especula-se sobre o ciclo incompletamente conhecido de muitos tripanosomas de mamíferos e sobre a evolução da família Trypanosomatidae.

It has been found that species of the digenetic genus Trypanosoma as well as species of monogenetic trypanosomatids of insects can grow in the lumen of the scent glands of opossums reproducing the cycle they perform in the intestinal tract of their insect hosts. Based on these findings, speculations are made on the incompletely known cycles of many mammalian trypanosomes and on the evolution of the family Trypanosomatidae.

Tripanosomatídeos monogenéticos de insetos, dos gêneros Crithidia, Leptomonas e Herpetomonas foram inoculados no lumen das glândulas de cheiro do gambá ae aí se multiplicaram como em culturas axênicas durante muitos meses. No soro dos animais foram detectados anticorpos específicos mas não houve evidência de invasão dos tecidos pelos parasitas.

Monogenetic insect trypanosomatids of the genera Crithidia, Leptomonas and Herpetomonas, multiplied as in axenic cultures, for many months, in the lumen of the scent glands of the opossum Didelphis marsupialis. Specific antibodies were detected in the serum of the animals but there was no evidence of invasion of their tissues by the parasites.