Epidemiological aspects of vector, parasite, and domestic reservoir in areas of recent transmission and no reported human cases of visceral leishmaniasis in Brazil

Abstract

About 97% of the human cases of the American visceral leishmaniasis (VL) occur in Brazil. In the last few years, the disease expanded to medium- and large-sized cities, in which surveillance and control actions have been intensified, in an effort to control VL spreading. Our two-year study was conducted in Belo Horizonte, the sixth most populous city in Brazil, which is endemic for VL. We focused in two particular districts of recent transmission of the disease, with no reported human cases and submitted to minor surveillance and control actions. Our aim was to draw an epidemiological profile of the local situation concerning Lutzomyia vector, Leishmania parasites, and the main domestic reservoirs (dogs). Lutzomyia longipalpis comprised 96.5% of the total phlebotomine sand flies captured and displayed an expressive minimal infection rate by Leishmania infantum (16.7%). Positive correlations were found between the population densities of L. longipalpis, rainfall and temperature. L. infantum was also detected in the cortelezzii complex and, for the first time, in Lutzomyia lloydi. Leishmania braziliensis, an etiological agent of the American cutaneous leishmaniasis, was also identified in L. longipalpis. Among the 1408 dogs serologically tested by standard enzyme-linked and fluorescence immune assays (ELISA/IFA) 3.6% were positive for VL. L. infantum DNA and Leishmania parasites were identified in 100% and 72.5% of the seropositive dogs, respectively. The co-positivity of other diagnostic tests for VL-Leishmania-nested PCR, imprint and myeloculture-was compared to the standard serology. Both symptomatic or asymptomatic dogs displayed an equal average number of positive diagnostic tests for VL. The districts studied display favorable conditions for the rapid spreading of human infection, in terms of L. longipalpis population density, and presence of L. infantum in both vector and main reservoir.

Aspects of the ecology of phlebotomine sand flies (Diptera: Psychodidae) in the Private Natural Heritage Reserve Sanctuary Caraça

“…Others have been detected with Leishmania DNA, such as Evandromyia Lenti , Evandromyia termitophila (Martins, Falcão & Silva, 1964), Micropygomyia ferreirana (Barreto, Martin & Pellegrino, 1956) and Ps . Lloydi [48,49,50,51,52,36,53,54,55,56,57], which may suggest they play a role in maintaining the parasite transmission cycle in wild environments.…”

Epidemiological aspects and spatial distribution of human and canine visceral leishmaniasis in an endemic area in northeastern Brazil

“…As a model, for example, this increase in dogs with VL may be associated with prohibition of euthanasia of infected dogs by the Center for Zoonosis Control of Aracaju, in 2013. The presence of infected dogs maintain the Leishmania transmission among species, increasing the incidence of VL in dogs and humans (Amóra et al, 2006;Felipe et al, 2014;Lara-Silva et al, 2015).…”

Leishmaniasis visceral en América Latina y perspectivas terapéuticas

“…La Organización Mundial de la Salud (OMS) estima que cada año se producen en el mundo entre 200.000 y 400.000 nuevos casos de Leishmaniasis visceral, más del 90% de ellos en países: Bangladesh, Brasil, Etiopía, India, Sudán y Sudán del Sur (5). Inicialmente, la LV se presentaba en contextos rurales, sin embargo, factores como la domiciliación del vector, presencia de reservorios en el intra y peridomicilio, sumado a factores físicos, climáticos y otros derivados de la actividad humana han permitido ciclos de transmisión a nivel urbano (6) …”

“…The World Health Organization (WHO) estimates that each year, between 200,000 and 400,000 new cases of visceral leishmaniasis appear, and over 90% of them in countries such as Bangladesh, Brazil, Ethiopia, India, Sudan, and South Sudan (5). Initially, VL appeared in rural contexts, but factors such as vector domiciliation, the presence of intra and peridomiciliary reservoirs, in addition to physical, climate, and other factors derived from human activity, have given rise to urban transmission cycles (6).…”