One piece of the puzzle: Modeling vector presence and environment reveals seasonality, distribution, and prevalence of sandflies and Leishmania in an expansion area

Vanete Thomaz-Soccol; André Luiz Gonçalves; Rafael Antunes Baggio; Alceu Bisetto Jr; Adão Celestino; Manuel Hospinal-Santiani; André de Souza; Mario Mychalizen; Marcelo Eduardo Borges; Cláudio Adriano Piechnik

doi:10.1016/j.onehlt.2023.100581

One piece of the puzzle: Modeling vector presence and environment reveals seasonality, distribution, and prevalence of sandflies and Leishmania in an expansion area

One Health. 2023 Jun 9:17:100581. doi: 10.1016/j.onehlt.2023.100581. eCollection 2023 Dec.

Affiliations

¹ Federal University of Paraná (UFPR), Molecular Biology Laboratory, Department of Bioprocess Engineering and Biotechnology, Rua Francisco H. dos Santos, Centro Politécnico, Curitiba, PR, Brazil.
² SESA- Secretary of Health of the State of Paraná and the Ninth Health Region, Paraná, Brazil.
³ Foz do Iguaçu City Hall, Zoonosis Control Center, Foz do Iguaçu, PR, Brazil.
⁴ Graduate Program in Environmental Management, Universidade Positivo, Curitiba, Paraná, PR, Brazil.
⁵ Biological Interactions, Federal University of Paraná (UFPR), P.O. Box 19073, 81531-890 Curitiba, PR, Brazil.
⁶ University of Innsbruck, Institute of Zoology, Technikerstraße 25, 6020 Innsbruck, Austria.

Abstract

The recent geographic spread of Leishmania infantum along the borders of Argentina, Brazil and Paraguay has been highlighted. In our previous study, Lutzomyia longipalpis was found in 55 of 123 patches surveyed, and in some patches, sandflies were found at higher densities, forming hotspots. Based on the One Health approach, we investigated the seasonality of the vector, the presence of parasite DNA, and the environmental factors that contribute to vector and parasite dispersal in these previously described hotspots in Foz do Iguaçu, Brazil. Entomological surveys were conducted monthly for one year. Fourteen hotspots peridomicile and six intradomicile were sampled. PCR was used to assess the prevalence of Leishmania DNA in sandflies. Zero-inflated negative binomial regression was used to determine the association of micro- and mesoscale environmental variables with the occurrence and abundance of the three most abundant sandfly species sampled. A total of 3543 species were captured, with Lutzomyia longipalpis being the predominant species (71.78%) of the 13 species found. Evandromyia edwardsi, Expapillata firmatoi, Micropygomyia ferreirana and Pintomyia christenseni were reported for the first time in the region. NDVI, distance to water, precipitation, west-to-east wind, wind speed, maximum and minimum relative humidity, and sex were significant variables associated with vector presence/abundance in the environment. Vector presence/abundance in the peridomicile was associated with precipitation, altitude, maximum temperature, minimum and maximum relative humidity, west-to-east wind, wind speed, and sex. Leishmania DNA was detected in an average of 21% of Lu. longipalpis throughout the year. Vector abundance is concentrated in urban and peri-urban areas, with some specimens present in different parts of the city and some sites with high vector abundance. This distribution suggests that the risk of actual contact between humans and parasite vectors in urban areas during the epidemic period is associated with patches of peri-urban vegetation and then extends into urban areas.

Keywords: Dispersion; Environment; Epidemiology; Leishmaniasis; Modeling; Psychodidae.