Natural infection of Lutzomyia longipalpis (Lutz & Neiva, 1912) by Leishmania infantum in a municipality with a high incidence of visceral leishmaniasis in the Brazilian Midwest.

BACKGROUND: Here, Leishmania presence in sand flies from Três Lagoas, Mato Grosso do Sul, Brazil, after visceral leishmaniasis (VL) was investigated. METHODS: In April 2022, two light traps were deployed within and around the residence for two days post-VL case report. RESULTS: A total of 120 Lutzomyia longipalpis were collected. Suprapyloric flagellates were found in a female sand fly with eggs and residual blood during midgut dissection. Sequencing of ITS1 and cytb fragments confirmed Leishmania infantum DNA and identified Homo sapiens as the blood source, respectively. CONCLUSIONS: This study emphasizes the importance of monitoring sand flies in VL endemic areas.

Natural infection of Lutzomyia longipalpis (Lutz & Neiva, 1912) by Leishmania infantum in a municipality with a high incidence of visceral leishmaniasis in the Brazilian Midwest

ABSTRACT Background: Here, Leishmania presence in sand flies from Três Lagoas, Mato Grosso do Sul, Brazil, after visceral leishmaniasis (VL) was investigated. Methods: In April 2022, two light traps were deployed within and around the residence for two days post-VL case report. Results: A total of 120 Lutzomyia longipalpis were collected. Suprapyloric flagellates were found in a female sand fly with eggs and residual blood during midgut dissection. Sequencing of ITS1 and cytb fragments confirmed Leishmania infantum DNA and identified Homo sapiens as the blood source, respectively. Conclusions: This study emphasizes the importance of monitoring sand flies in VL endemic areas.

Flebotomíneos (Diptera: Psychodidae: Phlebotominae) no Município de Três Lagoas, área de transmissão intensa de leishmaniose visceral, Estado de Mato Grosso do Sul, Brasil / Survey of phlebotomine sand flies (Diptera: Psychodidae: Phlebotominae) in Três Lagoas Municipality, Mato Grosso do Sul State, Brazil, an area of intense transmission of American visceral leishmaniasis

O estudo objetivou identificar a fauna flebotomínica urbana e rural; determinar sua distribuição espaço-temporal; investigar a infecção natural por Leishmania dos flebótomos fêmeas; verificar o impacto da aplicação de inseticidas sobre a população vetorial; correlacionar dados entomológicos, epidemiológicos e biogeográficos para compreensão das condições favoráveis à ocorrência da doença; e fornecer informações para o controle da leishmaniose nessa área. As coletas foram efetuadas um dia por mês, entre agosto de 2000 e dezembro de 2006, com armadilhas do tipo CDC. Foram capturados 4.277 espécimes, pertencentes a 14 espécies de flebotomíneos (76,61 por cento no peridomicílio), sendo 3.071 machos e 1.206 fêmeas. Lutzomyia longipalpis, a espécie mais frequente (87,02 por cento), teve índice de constância estandardizado igual a 1,0. Os padrões temporo-espaciais de distribuição dessa espécie ratificaram seu importante papel na transmissão da leishmaniose visceral americana. Infecção por flagelados sugestivos de Leishmania spp. foi encontrada em 1,18 por cento das fêmeas dissecadas de Lu. longipalpis. Análises estatísticas mostraram correlação significativa (p < 0,05) entre o número de vetores, precipitação e umidade. O teste de regressão linear demonstrou associação significante entre o número de Lu. longipalpis capturados e os casos de leishmaniose visceral americana humana e canina (p < 0,001). A população de vetores foi reduzida em 2002, com a aplicação de inseticidas, mas elevou-se nos anos subsequentes, devido à irregularidade das borrifações. Estratégias que poderão ser utilizadas no controle da doença nessa área são sugeridas na conclusão.

The objectives of this study were to survey urban and rural sandfly species; to investigate the spatiotemporal distribution of sandflies in the studied area; to determine the levels of natural infection of female sandflies with Leishmania; to determine the impact of the application of insecticides on the vector population; to correlate entomological, epidemiological, and biogeographic data to identify conditions that are favorable to the occurrence of leishmaniasis; and to provide information for the control of leishmaniasis in the studied area. Specimen collection was carried out once a month between August 2000 and December 2006, using CDC traps. In total, 4,277 specimens were captured (3,071 males and 1,206 females), comprising 14 sandfly species. Of these specimens, 76.61 per cent were found in peridomestic areas. Lutzomyia longipalpis, the most frequent species (87.02 per cent), had a standardized constancy index of 1.0. The spatiotemporal distribution pattern of this species confirmed its important role in the transmission of American visceral leishmaniasis. Infection by flagellates suggestive of Leishmania spp. was found in 1.18 per cent of dissected Lu. longipalpis females. Statistical analyses showed a significant correlation (p < 0.05) between the number of sandflies and the precipitation and humidity levels. Linear regression tests showed a significant association between the number of Lu. longipalpis captured and the cases of human and canine American visceral leishmaniasis in a given area (p < 0.001). The vector population was reduced in 2002 by the application of insecticides; however, it increased in subsequent years due to the irregularity of spraying. Strategies that can be used for disease control in this area are suggested in the conclusion.