Domestic dogs as amplifying hosts of Rickettsia rickettsii for Amblyomma aureolatum ticks

Author(s)

Binder, Lina C. ; Ramirez-Hernandez, Alejandro ; de Azevedo Serpa, Maria Carolina ; Moraes-Filho, Jonas ; Pinter, Adriano ; Scinachi, Claudia A. ; Labruna, Marcelo B.

• Document type: Journal article
• Source: TICKS AND TICK-BORNE DISEASES; v. 12, n. 6, p. 8-pg., 2021-11-01.

Abstract

Brazilian spotted fever (BSF) is an acute infectious disease caused by the bacterium Rickettsia rickettsii, which is transmitted by different tick species. Due to deleterious effects caused on ticks, the horizontal transmission of R. rickettsii through amplifying hosts is crucial for its maintenance in tick populations among B SF-endemic areas. The tick Amblyomma aureolatum is the main vector of R. rickettsii in the Sao Paulo metropolitan area; nevertheless, it is not known which vertebrate could act as an amplifying host for this tick species. Herein, we evaluated the potential of domestic dogs - primary hosts for A. aureolatum adults in BSF-endemic areas - to act as amplifying hosts. For this purpose, A. aureolatum non-infected adults were allowed to feed on two groups of dogs: the control group (G1), composed of one dog not exposed to R. rickettsii; and, the infected group (G2), composed of three dogs infected with R. rickettsii via tick parasitism. All G2-dogs became ill, semconverted to R. rickettsii, and rickettsial DNA was detected in 87% of the engorged females that fed on them. Transovarial transmission rate was estimated to be 25% and infected larvae successfully transmitted R. rickettsii to guinea-pigs, confirming transovarial transmission and vector competence. No rickettsial DNA was detected in individual samples of eggs or larvae, which precluded the estimation of filial infection rate, but implies that it was low. Our results suggest that domestic dogs act as amplifying hosts of R. rickettsii for A. aureolatum ticks in BSF-endemic areas in Brazil. (AU)

• FAPESP's process: 18/01596-8 - Evaluation of possible epidemiological variables associated with the spatial distribution of Rickettsia rickettsii infection in dogs and ticks in an area endemic to Brazilian Spotted Fever in the Metropolitan Region of São Paulo
• Grantee: Lina de Campos Binder
• Support Opportunities: Scholarships in Brazil - Master