A commentary on occupational infectious diseases due to agricultural practices in Sub-Saharan Africa
Introduction
Sub-Saharan Africa (SSA) has over 300 million poor livestock farmers, and 36% of the population in East Africa is livestock keepers. Infectious diseases have contributed substantially to undermining the health status of people and jeopardizing the economic development of nations in SSA [1], [2]. Despite notable examples of success in campaigns to eradicate and control specific diseases in tropical Africa, many remain prevalent. This is due to the combined effects of suitable ecological and climatic factors on the causative microorganisms and their vectors, human behavioural practices, customs, traditions, development of drug resistant microbial strains, and the socioeconomic conditions that prevail in Africa [3], [4]. It has been estimated that the World Health Organization (WHO) spends more than 25% of its budget on the control and treatment of infectious diseases [4]. Limitations to sanitation facilities and manure management strategies, resulting in poor and declining water quality and environmental burdens of infectious organisms, remain unresolved [4], [5], [6].
Despite numerous studies on the epidemiology, pathogenesis, immunology and chemotherapy of infectious disease, the picture across Africa remains unclear [1], [2]. The WHO estimates that more than 80% of infectious diseases in Africa result from poor water and environmental sanitation [4]. Infectious diseases associated with agriculture are playing an increasing role in both communicable and non communicable diseases [7] and this is further complicated by the significant population of immunocompromised individuals in SSA. For instance, Shukla et al. [8] reported high prevalence of Cryptosporidium parvum, transmitted through poor water quality amongst HIV/AIDS patients. It has been apparent from the personal experiences of the author (Yongabi, K.) working with patients at clinics in Bamenda that fevers caused by Plasmodium falciparum and Salmonella enterica serovar Typhi are frequently reported amongst cancer patients in Cameroon. Contact with both of these organisms can be common during farming activities.
The aim of this paper is to provide an overview of occupational diseases related to agriculture in SSA as a precursor to studies on sustainable farm practices that will improve the health of the farmers.
Section snippets
Routes of infection
Infections can be transmitted by foods, fluids, flies, fields, fingers, or sexual contact. They may also arise through vertical (mother to child) transmission. The first five methods of transmission are particularly applicable to agricultural practices [9], [10], [11] where faeco-oral transmission, direct skin contact and infection through biting insects are common [12].
Over two thirds of the population of developing countries in SSA were classed as rural according to World Bank statistics in
Key occupational diseases
Livestock manures [31] and human sewage [19], [34] play host to a number of bacterial, viral, fungal and parasitic diseases including Campylobacter, Listeria monocytogenes, Salmonella, pathogenic Escherichia coli, Yersinia, Leptospira, Coxiella, Mycobacteria, Giardia, Taenia, Cryptosporidium, Entamoeba, Candida, Rotavirus and Hepatitis (Table 1) [19], [34]. These are commonly linked with infection in farmers and agricultural workers. In developing countries, one gram of human faeces contains
Breaking the cycle of transmission
Table 1 demonstrates that many of the occupational diseases associated with farming arise as a result of the close proximity of humans and animals in farming communities in SSA, a general lack of protection from direct contact with soils, faeces and contaminated water and inhalation of dusts and droplets during day-to-day farming. This is combined with a greater exposure to biting insects, partly due to the amount of time spent outdoors and partly because farming frequently takes place close to
Conclusions
There are limited data on the incidence and prevalence of occupational diseases due to agricultural practices in SSA. More effective reporting of these diseases would facilitate research into risk factors and prevention strategies that could significantly reduce the disease burden and transmission rates amongst farmers in SSA. Characterising the association between certain diseases amongst farmers and agricultural practices in SSA would provide valuable information on approaches to manage risk.
Acknowledgements
We are grateful to Department for International Development for supporting the Phase I project “The Potential of Small-Scale Biogas Digesters to Alleviate Poverty and Improve Long Term Sustainability of Ecosystem Services in Sub-Saharan Africa”. DFID NET-RC AO6502 which led to the generation of this review.
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