Occupational Health Risks Among Abattoir Workers in Sub-Saharan Africa: A One Health Systematic Review and Meta-Analysis Protocol

Abstract

Abattoir workers in sub-Saharan Africa work where human, animal and environmental health meet. They are in daily contact with live animals, carcasses, blood, offal, hides and contaminated water. This exposes them to zoonotic infections such as brucellosis, Q fever, bovine tuberculosis and leptospirosis. They also face physical, ergonomic, chemical and psychosocial hazards, including injuries from sharp tools, musculoskeletal strain and smoke from singeing carcasses with scrap tyres. Existing reviews have focused on single pathogens, a small number of infections, or zoonotic agents in one subregion. No review has yet brought together all categories of occupational hazards among abattoir workers across sub-Saharan Africa using a One Health approach. This systematic review and meta-analysis aims to estimate the prevalence of occupational health outcomes among abattoir workers in sub-Saharan Africa, and to identify the occupational, behavioural, animal and environmental factors associated with them. The review is structured using the PECO framework (Population, Exposure, Comparator, Outcome). The primary outcomes are: laboratory-confirmed zoonotic infection or seropositivity; occupational injuries; non-infectious work-related ill health (musculoskeletal, respiratory, dermatological, auditory and psychosocial). The secondary outcomes are factors associated with these outcomes, personal protective equipment (PPE) use, knowledge, attitudes and practices, and measured workplace exposure levels. We will search MEDLINE (PubMed), Scopus, Web of Science, CAB Abstracts or Global Health, African Journals Online, the African Index Medicus and Embase (where accessible), with no date restriction. We will include quantitative observational studies and theses published in English or French. French-language studies will be assessed using machine translation, with numerical data checked against the original articles. Two reviewers will independently screen studies, extract data and assess risk of bias, using the JBI checklists and the Newcastle–Ottawa Scale. Prevalence will be pooled using random-effects logistic (generalised linear mixed) models in Stata 19. Zoonotic infection estimates will be pooled separately for each pathogen and diagnostic test. Heterogeneity will be described with I², τ² and prediction intervals. Subgroup analyses will examine subregion, diagnostic test, facility type and job role. Where pooling is not appropriate, findings will be synthesised narratively following the SWiM guideline. A One Health matrix will link each hazard to its animal source and environmental pathway. The certainty of the evidence will be assessed using GRADE. The review will be reported according to PRISMA 2020. Expected outcomes: pooled prevalence estimates for the main occupational health outcomes among abattoir workers in sub-Saharan Africa; a summary of the factors associated with these outcomes; a map of where evidence is lacking, by country, hazard and outcome; and evidence-based recommendations for occupational safety, veterinary public health and One Health programmes in abattoirs across the region.Abattoir workers in sub-Saharan Africa work where human, animal and environmental health meet. They are in daily contact with live animals, carcasses, blood, offal, hides and contaminated water. This exposes them to zoonotic infections such as brucellosis, Q fever, bovine tuberculosis and leptospirosis. They also face physical, ergonomic, chemical and psychosocial hazards, including injuries from sharp tools, musculoskeletal strain and smoke from singeing carcasses with scrap tyres. Existing reviews have focused on single pathogens, a small number of infections, or zoonotic agents in one subregion. No review has yet brought together all categories of occupational hazards among abattoir workers across sub-Saharan Africa using a One Health approach. This systematic review and meta-analysis aims to estimate the prevalence of occupational health outcomes among abattoir workers in sub-Saharan Africa, and to identify the occupational, behavioural, animal and environmental factors associated with them. The review is structured using the PECO framework (Population, Exposure, Comparator, Outcome). The primary outcomes are: laboratory-confirmed zoonotic infection or seropositivity; occupational injuries; non-infectious work-related ill health (musculoskeletal, respiratory, dermatological, auditory and psychosocial). The secondary outcomes are factors associated with these outcomes, personal protective equipment (PPE) use, knowledge, attitudes and practices, and measured workplace exposure levels. We will search MEDLINE (PubMed), Scopus, Web of Science, CAB Abstracts or Global Health, African Journals Online, the African Index Medicus and Embase (where accessible), with no date restriction. We will include quantitative observational studies and theses published in English or French. French-language studies will be assessed using machine translation, with numerical data checked against the original articles. Two reviewers will independently screen studies, extract data and assess risk of bias, using the JBI checklists and the Newcastle–Ottawa Scale. Prevalence will be pooled using random-effects logistic (generalised linear mixed) models in Stata 19. Zoonotic infection estimates will be pooled separately for each pathogen and diagnostic test. Heterogeneity will be described with I², τ² and prediction intervals. Subgroup analyses will examine subregion, diagnostic test, facility type and job role. Where pooling is not appropriate, findings will be synthesised narratively following the SWiM guideline. A One Health matrix will link each hazard to its animal source and environmental pathway. The certainty of the evidence will be assessed using GRADE. The review will be reported according to PRISMA 2020. Expected outcomes: pooled prevalence estimates for the main occupational health outcomes among abattoir workers in sub-Saharan Africa; a summary of the factors associated with these outcomes; a map of where evidence is lacking, by country, hazard and outcome; and evidence-based recommendations for occupational safety, veterinary public health and One Health programmes in abattoirs across the region.