Q fever in Brazil: assessing the exposure of small mammals to Coxiella burnetii in the state of São Paulo and in the Pantanal wetlands

• Grant number: 24/09309-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2024
• End date: August 31, 2025
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Marcelo Bahia Labruna
• Grantee: Henrique do Nascimento Cunha
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Q fever is a zoonosis caused by the bacterium Coxiella burnetii, which has a cosmopolitan distribution and infects humans and domestic and wild mammals. In Brazil, where several human cases have already been described, including in the form of epidemic outbreaks, epidemiological studies have mostly involved domestic ruminants. Despite the growing number of human cases of Q fever diagnosed in Brazil in recent years, little is known about the epidemiology of the disease in the country, especially about the involvement of wild animals in the epidemiological chain of the disease. In several countries in the Northern Hemisphere, the fundamental role of domestic animals, especially ruminants, in maintaining C. burnetii infection in endemic foci has been established. In the case of Brazil, a study would be essential to assess the possible involvement of small mammals in the epidemiology of Q fever. In this way, this project aims to carry out a serological survey against crude C. burnetii antigen and a molecular survey to detect C. burnetii DNA in small mammals belonging to the orders Didelmorphia, Rodentia, Cingulata and Carnivora, from different anthropized areas in the state of São Paulo and natural areas in the Pantanal of Mato Grosso do Sul. A total of 524 serum samples and 277 DNA samples from the blood and internal organs of small mammals will be tested. These samples are available in our laboratory, previously collected from animals captured during the years 2015-2018 in seven geographical areas, during another study on the role of small mammals in the epidemiology of Brazilian Spotted Fever, funded by FAPESP (process 2013/18046-7). The animal sera will be tested by indirect immunofluorescence assay (IFA) against crude antigen of C. burnetii strain At12, to detect IgG antibodies reactive to C. burnetii, and the DNA samples extracted from blood and tissues will be tested using a real-time taqman-PCR (qPCR) protocol to amplify a 70 bp fragment of the C. burnetii transposase elements gene (IS1111), according to pre-established protocols in our laboratory. The results of the seroprevalence of animals reactive to C. burnetii, as well as the frequencies of positive animals in the specific qPCR for C. burnetii will be analyzed between the seven geographical areas, as well as between the main groups of mammals (rodents and marsupials), in order to look for any statistically significant differences.