ABSTRACT
ABSTRACT: The study aimed to investigate Leishmania infection in a population of dogs (92 animals) in a fishing area of Bonito Municipality, and evaluate comparatively the serological methods used, immunoenzymatic assay (ELISA), indirect immunofluorescence antibody test (IFAT), and rapid Dual Path-Platform test (DPP®). Blood and aspirate of bone marrow samples were used and parasitological investigation was also performed, such as parasite isolation in Neal, Novy, Nicolle (NNN) medium culture, Woo technique, Giemsa stained smears and specific identification by polymerase chain reaction (PCR). IFAT revealed 56/92 seropositive, the ELISA 8/92 and the DPP®41/92. Regarding the agreement between the serological tests by the Kappa index, there was a slight agreement between ELISA/IFAT and ELISA/DPP®, and fair agreement in IFAT/DPP®. The NNN culture was positive in three out of 21 dogs, and identified by PCR as Leishmania infantum chagasi. No samples were positive by the Woo technique. Our results showed low agreements between the serological tests recommended by the Brazilian Ministry of Heath, and it is necessary to associate other diagnostic techniques, such as parasitological tests and PCR, to increase the sensitivity for canine visceral leishmaniosis diagnosis, mainly regarding asymptomatic dogs in endemic areas.
RESUMO: O estudo teve como objetivo verificar a infecção por Leishmania em uma população de cães (n=92 animais) de uma área de turismo de pesca no município de Bonito e avaliar comparativamente os métodos sorológicos utilizados, ensaio imunoenzimático (ELISA), reação de imunofluorescência indireta (RIFI) e teste rápido de plataforma dupla (DPP®). Testes parasitológicos também foram realizados, como o isolamento do parasita em meio de cultura Neal, Novy, Nicolle, técnica de Woo, esfregaços em lâminas coradas com Giemsa e identificação específica pela reação em cadeia da polimerase (PCR). A RIFI revelou sorologia positiva de 56/92, ELISA 8/92 e DPP®41/92. Quanto à concordância entre os testes sorológicos pelo índice Kappa, houve um ligeiro acordo entre ELISA/RIFI e ELISA/DPP®, e uma concordância razoável entre RIFI/DPP®. A cultura NNN foi positiva em três cães, e identificada por PCR como Leishmania infantum chagasi. Nenhuma amostra foi positiva pela técnica de Woo. Nossos resultados mostraram baixas concordâncias entre os testes sorológicos recomendados pelo Ministério da Saúde, sendo necessário associar a outras técnicas de diagnóstico, como testes parasitológicos e PCR, para aumentar a sensibilidade ao diagnóstico de leishmaniose visceral canina, principalmente, com relação aos cães assintomáticos em áreas endêmicas.
ABSTRACT
Background Bonito municipality, known as an area of ecoturism, in Mato Grosso do Sul state, Brazil, is also a focus of visceral and cutaneous leishmaniases, with cases registered in both human and canine populations. This study sought to investigate natural infection by flagellate forms of Leishmania in phlebotomines of the urban area of Bonito.Findings Sand flies were collected fortnightly from October 2005 to July 2006 with modified automatic light traps installed in peridomiciles and animal shelters in the center and on the outskirts of the city. The females were dissected and their guts observed under an optical microscope. A total of 1977 specimens were captured, Lutzomyia longipalpis (88.4 %) and Bichromomyia flaviscutelata (3.0 %) being the most frequent species. Bi. flaviscutellata was found infected by flagellates that were identified as Leishmania (Leishmania) amazonensis by indirect immunofluorescence reaction, employing monoclonal antibodies and the biotin-avidin system. This is the first report of natural infection by L. amazonensis in Bi. flaviscutellata in a Brazilian urban area.Conclusions As Bi. flaviscutellata is only slightly attracted by humans, the transmission of L. amazonensis in the study area may have a zoonotic character; however, the sympatric occurrence of this parasite andLu. longipalpis should be taken into consideration by the local health authorities since this sand fly has already been found with L. amazonensis DNA in a focus of canine visceral leishmaniasis in Bonito municipality.
Subject(s)
Leishmania , Leishmaniasis , PsychodidaeABSTRACT
O objetivo do trabalho foi identificar a fauna flebotomínea em áreas do perímetro urbano do município de Bonito, Mato Grosso do Sul, Brasil. O estudo foi desenvolvido de março de 2005 a fevereiro de 2006, em 17 ecótopos distribuídos em 12 locais, três no Centro e nove em diferentes bairros. As capturas foram realizadas quinzenalmente com armadilhas automáticas luminosas. Capturou-se 2.680 espécimes, 2.283 machos e 397 fêmeas, de 12 espécies, Brumptomyia avellari, Brumptomyia brumpti, Bichromomyia flaviscutellata, Evandromyia corumbaensis, Evandromyia sallesi, Lutzomyia longipalpis, Micropygomyia acanthopharynx, Micropygomyia quinquefer, Nyssomyia whitmani, Psathyromyia aragaoi, Psathyromyia punctigeniculata e Psathyromyia shannoni. Lutzomyia longipalpis, vetora do agente da leishmaniose visceral americana, foi a espécie mais freqüente e a mais abundante, representando 93,5 por cento dos flebotomíneos capturados e índice de abundância padronizado de 0,85. Com freqüência mais expressiva nos ecótopos próximos de galinheiro e de pocilga, esta espécie foi capturada em todos os meses do ano, com picos no verão, inverno e primavera. As demais espécies foram pouco freqüentes. Ressalta-se que a captura de Bichromomyia flaviscutellata, no intradomicilio e peridomicílio, nas proximidade de mata remanescente, tem grande significado epidemiológico uma vez que essa espécie é a principal vetora da Leishmania (Leishmania) amazonensis, agente etiológico da leishmaniose cutânea difusa anérgica. Portanto, na área urbana de Bonito foram encontradas duas espécies que comprovadamente participam da transmissão de leishmanioses, Lutzomyia longipalpis e Bichromomyia flaviscutellata, ambas encontradas naturalmente infectadas pelos respectivos agentes.
The objective was to identify the urban phlebotomine sandfly fauna of the Bonito municipality, Mato Grosso do Sul, Brazil. The captures of insects were undertaken fortnightly from March 2005 to February 2006, with automatic light traps in 17 ecotopes distributed in 12 sites: three in the Central district and nine in different outskirt districts. A total of 2,680 specimens were captured (2,283 males and 397 females) belonging to 12 species, Brumptomyia avellari, Brumptomyia brumpti, Bichromomyia flaviscutellata, Evandromyia corumbaensis, Evandromyia sallesi, Lutzomyia longipalpis, Micropygomyia acanthopharynx, Micropygomyia quinquefer, Nyssomyia whitmani, Psathyromyia aragaoi, Psathyromyia punctigeniculata and Psathyromyia shannoni. Lutzomyia longipalpis, vector of the American visceral leishmaniasis agent, was the most frequent species (93.5 percent) and also the most abundant with the standardized index of species abundance (SISA) = 0.85. Its most expressive frequencies occurred near to hen-houses and pigpens, and was captured in all months of the year, with peaks at summer, winter or spring. Nyssomyia whitmani presented low frequency (0.22 percent) and it was captured only at the border of urban perimeter in forest fragments and peridomiciles surroundings of savannah and forests. Bichromomyia flaviscutellata was captured inside and close to remaining forests, peri and intradomicile. That fact is of high epidemiological relevance, considering that this species is the most important vector of Leishmania (Leishmania) amazonensis, etiological agent of anergic diffused cutaneous leishmaniasis. Therefore, two vector species of leishmaniasis were found in the urban area of Bonito: Lutzomyia longipalpis and Bichromomyia flaviscutellata, both naturally infected by the respective agents.