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Epidemiology of capybara-associated Brazilian spotted fever

2019; Public Library of Science; Volume: 13; Issue: 9 Linguagem: Inglês

10.1371/journal.pntd.0007734

1935-2735

Hermes Ribeiro Luz, Francisco B. Costa, Hector Ribeiro Benatti, Vanessa do Nascimento Ramos, Maria Carolina de Azevedo Serpa, Thiago Fernandes Martins, Igor da Cunha Lima Acosta, Diego Garcia Ramirez, Sebastián Muñoz‐Leal, Alejandro Ramírez‐Hernández, Lina C. Binder, Márcio Port Carvalho, Vlamir José Rocha, Thiago C. Dias, Camila L. Simeoni, José Brites‐Neto, Jardel Brasil, Ana Maria Nievas, Patrícia Ferreira Monticelli, Maria Estela Gaglianone Moro, Beatriz Lopes, Daniel Moura de Aguiar, Richard de Campos Pacheco, Celso Eduardo de Souza, Ubiratan Piovezan, Raquel Soares Juliano, Kátia Maria Paschoaletto Micchi de Barros Ferraz, Matias Pablo Juán Szabó, Marcelo B. Labruna,

Mosquito-borne diseases and control

Background Brazilian spotted fever (BSF), caused by the bacterium Rickettsia rickettsii, has been associated with the transmission by the tick Amblyomma sculptum, and one of its main hosts, the capybara (Hydrochoerus hydrochaeris). Methods During 2015–2019, we captured capybaras and ticks in seven highly anthropic areas of São Paulo state (three endemic and four nonendemic for BSF) and in two natural areas of the Pantanal biome, all with established populations of capybaras. Results The BSF-endemic areas were characterized by much higher tick burdens on both capybaras and in the environment, when compared to the BSF-nonendemic areas. Only two tick species (A. sculptum and Amblyomma dubitatum) were found in the anthropic areas; however, with a great predominance of A. sculptum (≈90% of all ticks) in the endemic areas, in contrast to a slight predominance of A. dubitatum (≈60%) in the nonendemic areas. Tick species richness was higher in the natural areas, where six species were found, albeit with a predominance of A. sculptum (≈95% of all ticks) and environmental tick burdens much lower than in the anthropic areas. The BSF-endemic areas were characterized by overgrowth populations of A. sculptum that were sustained chiefly by capybaras, and decreased populations of A. dubitatum. In contrast, the BSF-nonendemic areas with landscape similar to the endemic areas differed by having lower tick burdens and a slight predominance of A. dubitatum over A.sculptum, both sustained chiefly by capybaras. While multiple medium- to large-sized mammals have been incriminated as important hosts for A. sculptum in the natural areas, the capybara was the only important host for this tick in the anthropic areas. Conclusions The uneven distribution of R. rickettsii infection among A. sculptum populations in highly anthropic areas of São Paulo state could be related to the tick population size and its proportion to sympatric A. dubitatum populations.