Aspectos epidemiológicos da Doença de Chagas canina no semiárido paraibano / Epidemiological aspects of canine Chagas disease in the semi-arid region of Paraiba

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.

Chagas disease in prehistory

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.

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.

Pre-Columbian Chagas disease in Brazil: Trypanosoma cruzi I in the archaeological remains of a human in Peruaçu Valley, Minas Gerais, Brazil

We evaluated the presence and distribution of Trypanosoma cruzi DNA in a mummy presenting with megacolon that was dated as approximately 560 ± 40 years old. The mummy was from the Peruaçu Valley in the state of Minas Gerais, Brazil. All samples were positive for T. cruzi minicircle DNA, demonstrating the presence and broad dissemination of the parasite in this body. From one sample, a mini-exon gene fragment was recovered and characterized by sequencing and was found to belong to the T. cruzi I genotype. This finding suggests that T. cruzi I infected humans during the pre-Columbian times and that, in addition to T. cruzi infection, Chagas disease in Brazil most likely preceded European colonization.

Specific antibody levels and antigenic recognition of Wistar rats inoculated with distinct isolates of Trypanosoma evansi

"Mal de Cadeiras", an enzootic disease caused by Trypanosoma evansi, is one of the most important trypanosomiases in the Brazilian Pantanal region. The disease affects mainly horses, which are widely used in extensive cattle production, an activity of greatest economical significance for the region. The parasite also infects sylvan (coatis and capybaras) and domestic (dogs) animals, respectively considered wild and domestic reservoirs of T. evansi. For a better understanding of the interaction of T. evansi with its rodent host, we evaluated the differences in the specific antibody level patterns and in the parasitic peptides recognition patterns of experimentally infected Wistar rats. The rats experimentally infected with T. evansi isolates obtained from coatis, dogs and horses were submitted to indirect immunofluorescence test (IgM e IgG) and Western blotting. The serological titers for IgM and IgG ranged between 1:40 and 1:160. The most recognized polypeptide profiles were in a range of 17 and 74 kDa. Our data suggest that the humoral immune response in Wistar rats is not sufficient for granting an effective control of T. evansi infections

Trypanosoma cruzi infection in Leontopithecus rosalia at the Reserva Biológica de Poço das Antas, Rio de Janeiro, Brazil

Wild golden lion tamarins (Leontopithecus rosalia) -- endangered primates that are native to the Brazilian Atlantic coastal forest -- were surveyed for the presence of Trypanosoma cruzi with the use of Giemsa-stained blood smears, hemocultures and an indirect immunofluorescence assay (IFAT). Positive IFAT with titers ranging from 1:20 to 1:1280 were observed in 52 per cent of the 118 wild tamarins examined and the parasite was isolated from 38 tamarins. No patent parasitemia was observed among the tamarins from which T. cruzi was isolated. Serum conversion and positive hemoculture was observed for three animals that had yielded negative results some months earlier, which indicates that T. cruzi is actively transmitted among tamarins. In contrast to observations with other sylvatic isolates, those from the tamarins were significantly more virulent and most of them produced mortality in experimentally infected Swiss mice. Some variation in the kDNA restriction profiles among the isolates was observed. Electrophoresis with GPI, G6PDH, IDH, MDH and ME enzymes showed a Z2 profile.

Trypanosoma cruzi infection in the opossum Didelphis marsupialis: absence of neonatal transmission and protection by maternal antibodies in experimental infections

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

Infection of a mammal by monogenetic insect trypanosomatids (Kinetoplastida, 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 näo houve evidência de invasäo dos tecidos pelos parasitas

From a mono to a digenetic life-cycle: how was the jump for flagellates of the family trypanosomatidae?

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 evoluçäo da família Trypanosomatidae