The transmission of visceral leishmaniasis in the municipality of Guarujá, on the Coast of São Paulo state, Brazil

ABSTRACT OBJECTIVE To perform an entomological survey, evaluating the circulation of Leishmania spp. in sand flies captured from the new foci of visceral leishmaniasis (VL) in the coastal region of São Paulo state. METHODS Sand flies were captured from November 2016 to September 2018 using light traps of the Centers for Disease Control (CDC), in the neighborhood where VL cases were reported. Leishmania spp. circulation was evaluated by gut dissection and molecular analysis of the females captured. RESULTS Nyssomyia intermedia was the more frequent species (90,7%) within the 1,203 sand flies captured. We found no flagellates in dissected females, but two pools containing females of Ny. intermedia presented DNA of L. infantum. CONCLUSION Our results suggest that Ny. intermedia might be involved in the establishment of this new VL focus in Sao Paulo. However, before incriminating this species as a L. infantum vector, further studies should investigate other vectorial capacity parameters, including competence, survival, and feeding habits.

Natural infection of Lutzomyia longipalpis (Cembrene-1 population) with Leishmania infantum in a new visceral leishmaniasis focus in the eastern region of São Paulo State, Brazil

Abstract INTRODUCTION Visceral leishmaniasis (VL) transmission has been associated with two different populations of the Lutzomyia longipalpis complex in São Paulo state. METHODS In a recent focus of VL, we captured and dissected sand flies and investigated Leishmania infantum infection by parasitological, PCR, and sequencing analysis. RESULTS Flagellates were observed in 2 of 47 (4.2%) cembrene-1 Lu. longipalpis females. The sequences obtained matched those of Le. infantum. CONCLUSIONS We found that the transmission of Le. infantum by cembrene-1 females may occur at a high rate in this focus of VL and presented new data on the vector capacity of this population.

Investigação de fatores ecológicos relacionados ao potencial de transmissão de Leishmania infantum por dois quimiotipos do complexo Lutzomyia longipalpis / Investigation of ecological factors related to the potential transmission of Leishmania infantum by two chemotypes of the Lutzomyia longipalpis complex

Introdução: A leishmaniose visceral é causada por Leishmania infantum e tem Lutzomyia longipalpis como o principal vetor no Brasil. Análises químicas de feromônios produzidos por machos da espécie sugerem que Lu. longipalpis é um complexo de espécies, formado por quatro quimiotipos: 3α-himachaleno, (S)-9-metilgermacreno-B, cembreno-1 e cembreno-2. No estado de São Paulo, dois quimiotipos estão presentes: (S)-9-metilgermacreno-B e cembreno-1, e é notável a rápida expansão urbana de ambas populações, associada à LV, tanto canina como humana. Por outro lado, a LV associada à população cembreno-1 de Lu. longipalpis tem um perfil mais rural e está relacionada a população canina. Na dinâmica de transmissão da LV é reconhecido o papel do cão doméstico (Canis familiaris) como fonte de infecção para os flebotomíneos e a presença de cães infectados tem sido apontada como fator de risco para a LV em humanos. Todavia, o papel de outras populações de animais presentes em áreas urbanas é desconhecido. Gatos (Felis catus) frequentemente estão presentes em domicílios e infecções destes animais com Le. infantum têm sido relatadas, mas o seu papel como fonte de infecção para os flebotomíneos não está esclarecido. Objetivo: Investigar aspectos ecológicos relacionados ao potencial de duas populações do complexo Lu. longipalpis: (S)-9-metilgermacreno- B e cembreno-1, em se infectarem por Le. infantum, com base em infecção natural ou se alimentando em modelo artificial, e também para a população (S)-9-metilgermacreno-B alimentando em modelo animal representado por gatos comprovadamente infectados por Le. infantum. Métodos: Foram realizadas capturas nos municípios de Dracena e Valinhos, no estado de São Paulo, para obtenção de amostras das duas populações alvo do estudo para a investigação de infecção natural, realização de infecção experimental por meio de alimentação sanguínea em modelo artificial e animal. Resultados: A infecção natural foi detectada apenas na população de Lu. longipalpis cembreno-1, com taxa de 4,4%. Nos experimentos de infecção em modelo artificial as duas populações de Lu. longipalpis apresentaram infecção após o repasto. Nas fêmeas que realizaram repasto sanguíneo em gatos infectados não foram observadas formas flageladas. Conclusão: A detecção de fêmeas naturalmente infectadas no município de Valinhos sugere um alto risco de transmissão de leishmaniose na área de estudo. As populações utilizadas no estudo não apresentaram diferenças na susceptibilidade de infecção por Le. infantum em modelo artificial. Gatos infectados por Le. infantum não se mostraram como fonte de infecção para Lu. longipalpis no xenodiagnóstico.

Introduction: Visceral leishmaniasis is caused by Leishmania infantum having Lutzomyia longipalpis as the main vector in Brazil. Chemical analyzes of pheromones produced by males suggest that Lu. longipalpis is a species complex composed of four chemotypes: 3α-himachalene, (S) -9-methylgermacrene-B, cembrene-1 and cembrene-2. In the state of São Paulo, two chemotypes are present: (S)-9-methylgermacrene-B and cembrene-1, and has been observed the rapid urban expansion of both populations associated with LV canine and human. On the other hand, the LV associated with the cembreno-1 population of Lu. longipalpis has a more rural profile and is related to the canine population. In the transmission dynamics of LV, the role of the domestic dog (Canis familiaris) as a source of infection for sandflies is recognized and the presence of infected dogs is a factor of risk for LV in humans. However, the role of other animal populations present in urban areas as infection source is unknown. Cats (Felis catus) are often present in households and infections of these animals with Le. infantum have been reported, but their role as a source of infection for sandflies is unclear. Objective: To investigate ecological aspects related to the potential of two populations of the Lu. longipalpis complex, (S) -9-methylgermacrene-B and cembrene-1, to be naturally infected by Le. infantum or acquire the infection by feeding in an artificial feeder, and also for the (S) -9-methylgermacrene-B population feeding in an animal model represented by cats proven to be infected by Le. infantum. Methods: Captures were carried out in the municipalities of Dracena and Valinhos, in the state of São Paulo to obtain samples of the two target populations of the study for the investigation of natural infection, experimental infection by means of blood supply in artificial and animal models. Results: The natural infection by L. infantum was only observed in the population cembreno-1, with a 4.4% rate. In the experiments of infection in artificial model the two populations of Lu. longipalpis presented infection after repast. In females that have fed in infected cats, no flagellated forms were observed. Conclusion: The detection of naturally infected females in the city of Valinhos suggests a high risk of transmission of leishmaniasis in the study area. The populations used in the study did not show differences in the susceptibility of infection by Le. infantum in artificial model. Cats infected by Le. infantum did not show up as a source of infection for Lu. longipalpis in xenodiagnosis.