Natural infection by Trypanosoma cruzi in triatomines and seropositivity for Chagas disease of dogs in rural areas of Rio Grande do Norte, Brazil

Abstract INTRODUCTION: Chagas disease is caused by the protozoa Trypanosoma cruzi. Its main reservoir is the domestic dog, especially in rural areas with favorable characteristics for vector establishment and proliferation. The aims of this study were to collect data, survey and map the fauna, and identify T. cruzi infection in triatomines, as well as to assess the presence of anti-T. cruzi antibodies in dogs in rural areas of the municipality of Mossoró, Brazil. METHODS: An active entomologic research was conducted to identify adult specimens through an external morphology dichotomous key. The analysis of natural infection by T. cruzi in the insects was performed by isolation in culture and polymerase chain reaction. The antibody testing for T. cruzi in dogs was performed by enzyme-linked immunosorbent assay and indirect immunofluorescence assay. RESULTS: A total of 68 triatomines were captured, predominantly the Triatoma brasiliensis brasiliensis (Neiva 1911) species. The vector mapping displayed areas with greater risk for parasite transmission. Of the examined triatomines (51 specimens), 41.2% (21/51) were positive on polymerase chain reaction, and all were negative on culture. In the serum testing, 11% (25/218) of dogs were seropositive, but no association was found between the serologic results and the presence and infection by T. cruzi in triatomines. CONCLUSIONS: This study demonstrated the movement of T. cruzi in the studied area, by the presence of vectors and naturally infected domestic reservoirs. The mapping of the studied rural area demonstrates the risk of disease transmission.

Awareness of visceral leishmaniasis and its relationship to canine infection in riverside endemic areas in Northeastern Brazil

Introduction An awareness of visceral leishmaniasis (VL) is necessary to encourage the population to participate in prevention and control in collaboration with more efficient, centrally organized health programs. The aim of this study was to evaluate the awareness of the riverside population regarding VL and the association between awareness and the prevalence of canine visceral leishmaniasis (CVL). Methods In total, 71 people living in riverside areas in the City of Mossoró in State of Rio Grande do Norte participated of the study, and 71 dogs were tested for CVL by polymerase chain reaction (PCR). Association analysis of several variables related to knowledge of the riverside population regarding CVL positivity was performed, yielding odds ratios (OR) and 95% confidence intervals (CI), and significance was determined using chi-square (χ2) and Fisher's exact tests. Results Among individuals whose dogs tested positive for CVL, 60% did not know the cure for CVL, and these subjects were three times more likely to have a dog test positive for CVL than those who were aware the cure for CVL. Knowledge of CVL cure was the only variable that remained in the logistic model after the successive removal of variables, with an adjusted OR of 3.11 (95%CI: 1.1-8,799; p=0.032). Conclusions Insufficient awareness regarding VL in riverside areas with CVL-positive dogs was associated with increased rates of canine infection, which suggests that changes in habits and the adoption of attitudes and preventive practices may contribute to the control and prevention of this disease. This study reinforces the need to invest in better health education programs regarding VL. .

Sandflies (Psychodidae: Phlebotominae) survey in an urban transmission area of visceral leishmaniasis, Northeastern Brazil / Pesquisa de flebotomíneos (Psychodidae: Phlebotominae) em área urbana de transmissão de leishmaniose visceral no Nordeste do Brasil

Visceral leishmaniasis (VL) is a major public health challenge in Brazil, especially in states where it is endemic. The aim of this study was to investigate the relationship of sand fly population density with environmental variables (temperature, rainfall and relative humidity) in urban areas of the city of Mossoró, Rio Grande do Norte, Northeastern Brazil. Sand flies were captured with Center Disease Control (CDC) traps installed monthly in the intra and peridomicile of three houses. Data analysis was based on the chi-square test and linear regression. A total of 7,347 sand flies were captured, being 93.85 percent Lutzomyia longipalpis and 6.15 percent Lutzomyia evandroi. Sand flies were more commonly found in the peridomicile and there was no difference between the number of males and females. The variables rainy season as well as relative humidity and rainfall, alone or together, did not have an effect on sand fly population density. However, high temperatures had a negative effect. The study of the behavior of sand flies in specific units of endemic areas can provide input to public health authorities for planning appropriate VL vector control measures.

A leishmaniose visceral (LV) é um grande desafio para a saúde pública no Brasil, particularmente nos estados onde é endêmica. O objetivo deste estudo foi verificar a relação da densidade populacional de flebotomíneos com as variáveis ambientais (temperatura, precipitação de chuva e umidade relativa do ar) em bairros urbanos de Mossoró, Rio Grande do Norte. Os flebotomíneos foram capturados com armadilhas CDC instaladas mensalmente no intra e peridomicílio de três casas. A análise dos dados foi baseada no teste Qui-quadrado e na regressão linear. Foram capturados 7.347 flebotomíneos, sendo 93,85 por cento Lutzomyia longipalpis e 6,15 por cento Lutzomyia evandroi. Os flebotomíneos foram encontrados mais comumente no peridomicílio e nenhuma diferença significativa entre o número de machos e fêmeas foi observada. As variáveis estação chuvosa, bem como a umidade relativa e precipitação de chuva, associadas ou isoladas, não influenciou a densidade populacional dos flebotomíneos. No entanto, a alta temperatura afetou essa densidade de forma negativa. Portanto, este estudo específico em áreas endêmicas é importante, porque as agências de Saúde Pública podem usar essas informações para um planejamento adequado das medidas de controle de vetores LV.

Monitoring of Lutzomyia longipalpis Lutz & Neiva, 1912 in an area of intense transmission of visceral leishmaniasis in Rio Grande do Norte, Northeast Brazil / Monitoramento de Lutzomyia longipalpis Lutz & Neiva, 1912 em área de transmissão intensa de leishmaniose visceral no Rio Grande do Norte, Nordeste do Brasil

Urban increase of visceral leishmaniasis (VL) in Brazil is associated with the adaptation of its vector, Lutzomyia longipalpis, to environments modified by humans. The present study reports the results of an entomological monitoring of L. longipalpis and the effect of environmental variables on its population density. Sandflies were captured in the municipality of Mossoró, State of Rio Grande do Norte, Northeastern Brazil, from January 2005 to December 2006. Two CDC light traps were placed monthly for four consecutive nights in the peridomicile of selected households. Data analysis was based on the chi-square test and linear regression. A total of 2,087 sandflies were captured, 99.86 percent of which were L. longipalpis. A higher proportion of females were captured (p < 0.05). Monthly analysis of the variables temperature, relative humidity and rainfall did not show a significant influence on population density. However, there were seasonal differences: approximately 70 percent of sand flies were captured during the rainy season (p < 0.05). The predominant species, L. longipalpis, is present in substantial number, representing a public health risk. Therefore, because of higher prevalence during the rainy season, we recommend intensified VL control measures before and during this season to reduce the risk of disease transmission.

No Brasil, o crescimento urbano da leishmaniose visceral (LV) está associado com a adaptação do seu vetor, Lutzomyia longipalpis, aos ambientes modificados pelo homem. Este estudo relata a vigilância entomológica de L. longipalpis e os efeitos das variáveis ambientais sobre a sua densidade populacional. Os flebotomíneos foram capturados no município de Mossoró, Rio Grande do Norte, no Nordeste do Brasil, a partir de janeiro de 2005 a dezembro de 2006. Duas armadilhas tipo CDC foram colocadas mensalmente durante quatro noites consecutivas no peridomicílio das casas escolhidas. A análise dos dados foi baseada no teste Qui-quadrado e regressão linear. Um total de 2.087 flebotomíneos foram capturados, dos quais 99,86 por cento foram L. longipalpis. Mais fêmeas do que machos foram capturados (p < 0,05). Na análise mensal das variáveis ambientais a temperatura, umidade relativa e a chuva não tiveram impacto significativo sobre a densidade populacional de L. longipalpis. No entanto, houve diferenças sazonais: aproximadamente 70 por cento dos flebotomíneos foram capturados durante a estação chuvosa (p < 0,05). Assim, L. longipalpis, a espécie predominante, representa um risco à saúde pública. Portanto, devido à maior prevalência no período chuvoso, recomendamos intensificar as medidas de controle da LV antes e durante este período para reduzir o risco de transmissão da doença.

Fatores relacionados com a positividade de cães para leishmaniose visceral em área endêmica do Estado do Rio Grande do Norte, Brasil / Factors related to positive testing of dogs for visceral leishmaniasis in endemic area in the state of Rio Grande do Norte, Brazil

O presente estudo objetivou descrever alguns fatores relacionados à positividade de cães para leishmaniose visceral, em área endêmica do Estado do Rio Grande do Norte. Foram analisados 198 cães, dos quais 62 foram recrutados de propriedades rurais e 136 de residências urbanas. O diagnóstico foi realizado através dos testes de imunofluorescência indireta e imunoadsorção enzimática. Dos cães analisados, 45 por cento dos positivos eram provenientes da área rural e 35 por cento da área urbana. Analisando a função dos animais, a prevalência foi de 50 por cento dos cães de guarda nas áreas rural e de 43 por cento na área urbana. Quanto aos cães que tinham contato com outros cães de origem rural ou urbana, a prevalência observada de foi 54 por cento e 32 por cento, respectivamente. No que se refere ao sexo, as fêmeas da zona rural foram mais prevalentes. Estes resultados sugerem uma atenção maior sobre o papel destes animais como reservatório dessa zoonose, como também na urbanização da leishmaniose visceral e o inquérito epidemiológico desta doença, no qual estas informações poderão contribuir para o planejamento de estratégias de controle do cão como reservatório doméstico.

This study aimed at describing several factors related to positive testing of dogs for visceral leishmaniasis, in an endemic area of the state of Rio Grande do Norte. Sera of 198 dogs were analyzed, 62 from rural properties and 136 from urban residences. Diagnosis was performed through indirect immunofluorescence and enzyme-linked immunosorbent assay. Forty five percent of positive dogs were from the rural area and 35 percent came from the urban area. Concerning the analysis of dogs' function, the watchdogs showed greater prevalence, with 50 percent prevalence in the rural area and 43 percent in the urban area. With regard to contact with other dogs and origin in rural or urban areas, the prevalence was 54 percent and 32 percent respectively. In relation to gender, females from the rural area were more prevalent. These results suggest more attention should be paid to dogs as reservoirs for this zoonosis, as well as their important role in the urbanization of Leishmaniasis and in epidemiological survey of the disease. These data can contribute to the planning of strategies for control, targeting dogs as domestic reservoirs.