Toxoplasmosis, leptospirosis, and brucellosis seroepidemiology in veterinary medical students and their relation with unique health

Abstract

Toxoplasmosis, leptospirosis, and brucellosis are global zoonoses, with humans as accidental participants in their transmission cycles. The can also be considered occupational diseases, because certain professionals are at greater risk of contact and infection by such zoonoses. These three diseases have different epidemiological characteristics because of the distinct environmental, social, cultural, and economic conditions where these pathogens circulate. Because of the importance of these diseases and their associations with specific occupations, we performed a seroepidemiological survey of Toxoplasma, Leptospira, and Brucella antibodies, with an analysis of the association between positive serum and certain occupational and environmental variables, in students of a veterinary medicine course (1st, 2nd, 3rd, 4th, and 5th year) in a university in the northwestern region in the state of Paraná, Brazil. From May to November 2014, blood samples were collected from 157 volunteers by professionals trained in nursing and biomedicine from the same university as the veterinary students. At the time of blood collection, the students did not present any clinical signs of the three diseases of interest. To detect anti-Toxoplasma gondii, anti-Leptospira spp., and anti-Brucella antibodies, indirect immunofluorescence test (IIF), microscopic agglutination test (MAT), fast agglutination test (a screening test), and enzyme-linked immunosorbent assay (ELISA) were performed. To determine variables associated with these infections, the students were interviewed to complete an epidemiological questionnaire with environmental, behavioral, and occupational information. The associations between these variables and infections were assess by chi-square or Fischer's exact tests, with a 5% significance level (?). Of the 157 serum samples analyzed, 29.29% reacted to Toxoplasma antigens, with titers ranging from 16 to 4096 by IIF, 1.27% to Leptospira antigens, with titers ranging from 100 to 800 by MAT using Hardjo and Wolffi serovars, and 0.63% to Brucella antigens by ELISA; however, no variables were found to be associated with infection with any of these pathogens. The results of this study show that one-third of the students in the veterinary medicine course were exposed to Toxoplasma gondii, Leptospira spp., and Brucella spp. at some stage in their lives; however, it is not possible to determine whether these infections were acquired at the university, because no associations between occupational risk variables and these infections were found. An understanding of the transmission of each etiological agent and methods to prevent infection is important to maintain low prevalence levels of these zoonotic diseases during the veterinary medicine course and extra-curricular internships, when there is increased exposure to these pathogens.