Seasonal variation of Lutzomyia longipalpis in Belo Horizonte, State of Minas Gerais

Abstract

Between October, 1997 and September, 1999 in Belo Horizonte, Minas Gerais a study of seasonal variation of Lutzomyia longipalpis was carried out in three distinct areas of the municipality. Sand flies were sampled at 15-day intervals in three residences, in each of which two CDC light traps were installed, one indoors and the other in the peridomicile. A total of 397 sand flies were captured in the three areas, with 65%, 30% and 1% of specimens collected in the eastern, northeast and Barreiro districts, respectively. The overall proportions of sand flies collected inside and around the houses were similar (57% vs 43%) and this pattern was seen for both Lutzomyia longipalpis and Lutzomyia whitmani. The highest population levels during the two years of the study were from October to March. From October onwards, numbers increased constantly until February. A gradual fall was seen from April onwards until the lowest levels were reached in the months of June, July and August. Key-words: Sand fly. Seasonal variation. Control. Leishmaniasis. RESUMOEntre outubro de 1997 e setembro de 1999, em Belo Horizonte, Minas Gerais foi conduzido um estudo de variação sazonal de Lutzomyia longipalpis em três áreas distintas do município. Os flebotomíneos foram coletados quinzenalmente em três residências, em cada área, nas quais foram instaladas duas armadilhas luminosas CDC, sendo uma no intradomicílio e a outra no peridomicílio. Um total de 397 flebotomíneos foi capturado nas três áreas, com 65%, 30% e 1% exemplares coletados nos distritos Leste, Nordeste e Barreiro, respectivamente. A proporção total de flebotomíneos coletados no intradomicílio e peridomicílio foi semelhante (57% vs 43%) e este padrão foi visto para Lutzomyia longipalpis e Lutzomyia whitmani. Durante os dois anos de estudo, o nível da população foi maior no período de outubro a março. A partir de outubro o número de flebotomíneos aumenta constantemente até fevereiro. Uma gradual redução foi observada a partir de abril até alcançar o nível mais baixo nos meses de junho, julho e agosto. Palavras-chaves: Flebotomíneos. Variação sazonal. Controle. Leishmanioses.

Phlebotomine sand flies (Diptera: Psychodidae) in the municipality of Várzea Grande: an area of transmission of visceral leishmaniasis in the state of Mato Grosso, Brazil

“…The predominance of L. longipalpis found in the present study showed to be in accordance with Missawa and Lima (2005) in the same municipality and other localities as reported by Oliveira et al (2003Oliveira et al ( , 2006 for Campo Grande, MS, Resende et al (2006) and Souza et al (2004) for Belo Horizonte, state of Minas Gerais (MG), Barata et al (2004Barata et al ( , 2005, and França- for Porteirinha, MG, Monteiro et al (2005) for Montes Claros, MG.…”

“…The closeness between the houses and the domestic animal shelters may account for the presence of insects indoors together with their capacity of endophilia. The high frequency of male insects found in both intra-and peridomiciliary areas has corroborated data provided by Oliveira et al (2003Oliveira et al ( , 2006, Resende et al (2006), Barata et al (2004Barata et al ( , 2005, evidencing the high adaptation capacity of sand flies enabling the disease transmission. The process of urbanization of insects and, consequently, of the disease is correlated with disorganized urban growth, followed by human migration from rural to urban regions and the environmental destruction.…”

“…The insects' preference for the peridomiciliar area has also been observed in several Brazilian states , Souza et al 2004, Resende et al 2006, which provides evidence of the insect domiciliation influenced by human socio-ecological modifications in the sand fly habitat and the adaptive power of the insects' species (Oliveira et al 2003, Aguiar & Medeiros 2003, Souza et al 2004), although Resende et al (2006) have observed roughly equal proportions of phlebotomine sand flies, mainly L. longipalpis, in both intra-and peridomiciliary areas.…”

“…França-Silva et al (2005) showed no correlation between vector density and the climatic variables, temperature and ARH. On the other hand, Resende et al (2006) reported an increased number of phlebotomine sand flies, mainly L. longipalpis, when the combination of high temperature averages and regular rain periods occurred, as well as Monteiro et al (2005), Barata et al (2004) and Oliveira et al (2003), who have associated phlebotomine density with the first rainy periods and high ARH.…”

“…According to Resende et al (2006), the pattern of distribution of L. longipalpis coincides with the occurrence of human VL cases, and such correlation has been used to validate autochthony of the cases. Correspondence between human VL cases and high phlebotomine density was not observed between 2004 and 2006 in VG, although Barata et al (2004) and Souza et al (2004) have measured correlations between phlebotomine density, prevalence of VL human cases and presence of domestic animals in Porteirinha and Belo Horizonte, MG. Monteiro et al (2005) and França- have correlated the presence of high vector density and high VL canine prevalence in Montes Claros and Porteirinha, MG.…”