Rickettsia rickettsii (Rickettsiales: Rickettsiaceae) Infecting Amblyomma sculptum (Acari: Ixodidae) Ticks and Capybaras in a Brazilian Spotted Fever-Endemic Area of Brazil

Autor(es)

Costa, Francisco B. ^{[1, 2]} ; Gerardi, Monize ^[1] ; Binder, Lina de C. ^[1] ; Benatti, Hector R. ^[1] ; de Azevedo Serpa, Maria Carolina ^[1] ; Lopes, Beatriz ^[3] ; Luz, Hermes R. ^{[1, 4]} ; Ferraz, Katia M. P. M. B. ^[3] ; Labruna, Marcelo B. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Fac Med Vet & Zootecnia, Dept Med Vet Prevent & Saude Anim, BR-05508270 Sao Paulo, SP - Brazil

^[2] Univ Estadual Maranhao, Dept Patol, Programa Posgrad Ciencia Anim, BR-65055310 Sao Luis, Maranhao - Brazil

^[3] Univ Sao Paulo, Dept Ciencias Florestais, Escola Super Agr Luiz de Queiroz, BR-13418900 Piracicaba, SP - Brazil

^[4] Univ Fed Maranhao, Dept Patol, Programa Posgrad Biotecnol RENORBIO, BR-65500000 Sao Luis, Maranhao - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Medical Entomology; v. 57, n. 1, p. 308-311, JAN 2020.
• Citações Web of Science: 2

Resumo

The bacterium Rickettsia rickettsii is the agent of Brazilian spotted fever (BSF), a highly fatal disease that is transmitted in Brazil mainly by the tick Amblyomma sculptum Berlese, which uses capybaras (Hydrochoerus hydrochaeris Linnaeus) as major hosts. In 2015, we captured nine capybaras in a BSF-endemic area of southeastern Brazil. From each capybara, we collected blood sera that were tested through the immunofluorescence assay using Rickettsia spp. antigens, and A. sculptum ticks, processed for isolation of R. rickettsii through guinea pig inoculation. All capybaras (100%) were seroreactive to Rickettsia spp., with highest titers to R. rickettsii. A total of 166 A. sculptum ticks were macerated and inoculated into nine guinea pigs, from which only one presented high fever and seroconverted to R. rickettsii. Blood from this febrile animal was inoculated into additional guinea pigs (guinea pig passages), which also became febrile and seroconverted, or when euthanized during the fever period, their internal organs (spleen, lung) were shown to contain R. rickettsii DNA. The present rickettsial isolate has been maintained cryopreserved as infected guinea pig organs. There was at least one R. rickettsii-infected tick among the 166 macerated ticks, giving a minimal infection rate of 0.6% (1/166). This infection rate is within the range of previous studies, which reported that only 0.05% to at most 1.28% A. sculptum ticks were infected by R. rickettsii in other BSF-endemic areas. These low infection rates support the low incidence of BSF, despite of A. sculptum being the most frequent human-biting tick in southeastern Brazil. (AU)

• Processo FAPESP: 14/23176-0 - Estrutura e dinâmica populacional de capivaras de vida livre, associados à infestação por carrapatos e infecção por Rickettsia spp.
• Beneficiário: Francisco Borges Costa
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 13/18046-7 - Capivaras, carrapatos e febre maculosa
• Beneficiário: Marcelo Bahia Labruna
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 14/27078-2 - Diagnóstico e monitoramento de capivaras de vida livre - 1
• Beneficiário: Beatriz Lopes
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica