Outbreak of toxoplasmosis in a logging industry in the municipality of Lages, Santa Catarina, Brazil, March to August 2022: a retrospective cohort study

Abstract

Background

An outbreak of toxoplasmosis occurred among workers in a timber industry in the municipality of Lages, Santa Catarina, Brazil, between March and August 2022.

Population and Methods

We carried out a retrospective cohort study among all active workers at the logging site. We collected data using a semi-structured questionnaire. A blood sample was collected from each worker to measure immunoglobulin M (IgM), G (IgG) antibodies and IgG avidity testing. Confirmed cases were those with IgM+ and IgG- or IgM+ and IgG+ with low avidity. Measures of absolute and relative frequency, central tendency and dispersion were calculated. The risk ratio for the potential sources of exposure was calculated, and samples of water, food and mud were collected for Toxoplasma gondii DNA testing.

Results

The attack rate was 39.3%. The epidemic curve suggested the occurrence of a continuous common source outbreak. Of the cases of acute toxoplasmosis, 47 (73.4%) were male, 38 (59.4%) were non-white race, their median age was 31 years (interquartile range: 25 - 40 years). Drinking water from drinking fountains had a risk ratio (RR) of 3.7 (95%CI: 1.1-14.4). T. gondii was not found in samples of water, food, or mud.

Discussion

An outbreak of toxoplasmosis was confirmed among workers in a logging site, due to a continuous exposure to a common source, associated with drinking water from the company's drinking fountains. It was recommended to intensify surveillance of the quality of drinking water in the state and municipality.