# Seroprevalence and risk factors for Brucella species and Coxiella burnetii exposure in a cross-sectional serosurvey of occupationally exposed groups in peri-urban Lomé, Togo

## TL;DR

A study in Togo found that workers in contact with livestock have significant exposure to Brucella and Coxiella burnetii, with risk factors including animal husbandry and raw dairy consumption.

## Contribution

This study identifies specific occupational and dietary risk factors for Brucella and Coxiella burnetii exposure among livestock workers in Togo.

## Key findings

- 9.5% of workers were seropositive for Brucella, and 28% for Coxiella burnetii.
- Consuming raw milk increased Brucella seropositivity odds, while fermented milk and cheese increased Coxiella seropositivity odds.
- Farmworkers had nearly twice the odds of Brucella seropositivity compared to abattoir workers.

## Abstract

Brucella species and Coxiella burnetii have been detected in livestock populations in Togo. Populations exposed to livestock ruminants through their occupation may be at increased risk of infection.

A cross-sectional serosurvey was conducted in 108 abattoir and 81 dairy farm workers (from 52 dairy farms) in peri-urban Lomé, Togo in 2019–2020. Structured questionnaires were used to collect data on participant livestock contact and dairy product consumption. Sera were tested using the Rose Bengal plate agglutination test (RBT) and the indirect Brucella IgG Enzyme-Linked Immunosorbent Assay (ELISA) for Brucella, and the IgG ELISA for Coxiella burnetii in Phase 1 and in Phase 2. Fresh bulk milk samples from farms were tested using an indirect milk ELISA for Brucella IgG. The association between seropositivity and exposure variables was examined using logistic regression with robust standard errors to account for site-level clustering. Eighteen workers (9.5%, 95% CI 5.5-16.0) were Brucella seropositive. Twenty-eight percent (95% CI 22.5-34.3) of workers were seropositive for C. burnetii. Twenty of fifty-one farms which gave milk samples tested positive for Brucella antibodies (39.2%, 95% CI 26.6 - 53.4%). Farmworkers had nearly twice the crude odds of being Brucella seropositive compared to abattoir workers (OR 1.93, 95% CI: 0.94-3.93, p = 0.07). After adjusting for age, working on farms with animal ill health, a positive milk test, participating in small ruminant husbandry and assisting with cattle abortion were all associated with increased odds of seropositivity. Farm and abattoir workers who consumed raw milk at least every month were more likely to be seropositive for Brucella species (OR 3.79, 95% CI: 2.34-6.13, p < 0.001) while participants who consumed fermented milk and cheese had greater odds of being seropositive for C. burnetii (OR 1.59, 95% CI: 1.26-2.00, p < 0.001 and OR 1.70, 95% CI: 0.97-2.98, p = 0.07 respectively).

Livestock workers in peri-urban Lomé have been exposed to both Brucella and Coxiella burnetii bacteria. The widespread consumption of raw dairy products and lack of personal protective equipment (PPE) use is of concern as both dairy consumption and participation in animal husbandry activities have been seen to increase odds of seropositivity for both pathogens. A One Health prioritization of zoonotic disease would help to bring together the relevant sectors to adequately resource prevention and control of zoonoses of public health concern in Togo, which may particularly impact workers in close contact with animals.

Human and animal health are inextricably linked, particularly for those who live and work closely with animals. Brucellosis and Q fever are two zoonotic infections transmitted through animal contact and dairy product consumption, which cause non-specific fevers and for which diagnostic tests are lacking in many Low and Middle-Income Countries (LMIC) contexts. Previous studies have shown that both bacteria circulate in livestock in Togo. We undertook a survey in dairy farm and abattoir workers in peri-urban Lomé, Togo, and found that 9.5% and 28% of workers were seropositive for Brucella and C. burnetii respectively. We found that risk factors included animal husbandry practices and consumption of dairy products. Mitigating practices such as the use of PPE and boiling milk can protect livestock workers from these and other zoonotic diseases. A systematic One Health prioritization of zoonoses for Togo would enable a multisectoral approach and adequate resource allocation for prevention and control of these diseases.