Comparative analysis of the microbiota composition of Amblyomma ovale ticks collected in two areas of Atlantic Forest with differences in the prevalence of Rickettsia parkeri

• Grant number: 24/16436-7
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: August 01, 2025
• End date: August 31, 2027
• Field of knowledge: Biological Sciences - Parasitology - Entomology and Malacology of Parasites and Vectors
• Principal Investigator: Andréa Cristina Fogaça
• Grantee: Beatriz Iglesias Alonso
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Bacteria of the genus Rickettsia (family Rickettsiaceae; order Rickettsiales) are obligate intracellular alfa-proteobacteria known to cause severe diseases in their vertebrate hosts. Among these diseases, rickettsiosis caused by Rickettsia parkeri (FM-Rp) has been gaining attention in the Americas since 2009. In Brazil, R. parkeri (Atlantic Forest strain) is primarily present in Atlantic Forest regions, where it is transmitted to humans by the tick Amblyomma ovale, which are brought into homes by domestic dogs with access to the forest. FM-Rp presents mild symptoms, not causing death like infections with Rickettsia rickettsii, which causes Brazilian spotted fever (BSF). However, due to the lack of specific serological tests, diagnosis is easily confused with BSF and other diseases. On the coast of São Paulo, the prevalence of ticks infected with R. parkeri infesting dogs shows marked differences depending on the city analyzed. For example, the prevalence of ticks positive for R. parkeri in São Sebastião was 13%, while no infected ticks were detected in Peruíbe. It is known that the microbiota of arthropods, including ticks, can interfere with their vector competence. Thus, this research project aims to determine the load and composition of the bacterial microbiota of A. ovale ticks collected from two different locations on the São Paulo coast to evaluate if there is a correlation with the prevalence of R. parkeri infection.