Comparative survival of the engorged stages of Amblyomma dubitatum and Amblyomma sculptum in the laboratory: Implications for Brazilian spotted fever epidemiology

Author(s)

Luz, Hermes R. ^[1] ; Ramirez-Hernandez, Alejandro ^[2] ; Benatti, Hector R. ^[2] ; Ramirez, Diego G. ^[2] ; Szabo, Matias P. J. ^[3] ; Labruna, Marcelo B. ^[2]

Affiliation

^[1] Univ Fed Maranhao, Ponto Focal Maranhao, Programa Posgrad Biotecnol Renorbio, Sao Luis, Maranhao - Brazil

^[2] Univ Sao Paulo, Fac Med Vet & Zootecnia, Dept Med Vet Prevent & Saude Anim, Sao Paulo, SP - Brazil

^[3] Univ Fed Uberlandia, Fac Med Vet, Lab Ixodol, Uberlandia, MG - Brazil

• Document type: Journal article
• Source: TICKS AND TICK-BORNE DISEASES; v. 11, n. 2 MAR 2020.
• Web of Science Citations: 0

Abstract

Brazilian spotted fever (BSF), caused by the bacterium Rickettsia rickettsii, is transmitted to humans mainly by the tick Amblyomma sculptum in southeastern Brazil. In most BSF-endemic areas A. sculptum populations are sustained chiefly by capybaras (Hydrochoerus hydrochaeris), which are also the host of another tick species, Amblyomma dubitatum, not implicated in R. rickettsii transmission. Herein, we evaluated the effects of relative humidity (RH), temperature, and water immersion on the successful development of the engorged stages of A. dubitatum and compared them with recently published data under the same experimental conditions for A. sculptum. We showed that free-living developmental stages (engorged larvae, nymphs and females, and eggs) of A. dubitatum had higher survival rates when these stages were submerged in water for different periods of times (24-72 h). On the other hand, higher survival rates were observed for A. sculptum when ticks were incubated at lower RH values, 65 or 78 %, regardless of summer or winter mean temperatures. These results suggest that A. dubitatum is more adapted to humid habitats and seasonally flooding soils than A. sculptum, whereas this latter species should be more adapted than A. dubitatum to drier habitats. The implications of these results for the spatial distribution of A. dubitatum and A. sculptum, in relation to BSF epidemiology, are discussed. (AU)

• FAPESP's process: 13/18046-7 - Capybaras, ticks, and spotted fever
• Grantee: Marcelo Bahia Labruna
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 13/13650-3 - Comparative biology of ticks of the species groups Rhipicephalus sanguineus and Amblyomma cajennense
• Grantee: Marcelo Bahia Labruna
• Support type: Regular Research Grants
• FAPESP's process: 17/00117-6 - Population structure and dynamics of free-living capybara associated with tick infestation and Rickettsia spp. infection
• Grantee: Hermes Ribeiro Luz
• Support type: Scholarships in Brazil - Post-Doctorate