A semi-quantitative human exposure assessment to taenia saginata infection through beef consumption in Windhoek, Namibia.

Abstract

Human taeniasis is an internal parasitic disease associated with the handling, preparing, and consuming infected beef or pork with viable cysts. However, the association between exposures to infections and causal factors varies from person to person. Numerous factors are responsible for exposure which may be linked to the socio-economic status of the society, the geographical location of the country or environment, the level of awareness of the society and the health system of a country to combat such diseases. Economic and cultural conditions may contribute to perpetuating exposure to the disease. The risk of exposure and infection may be reduced by routine meat inspection. This study aimed to assess the risk of human exposure to Taenia saginata through beef consumption. To achieve this objective, a three-tier study was conducted to estimate the prevalence of T. saginata in slaughtered cattle, describe the beef consumption pattern among residents in Windhoek, and quantify the risk of human exposure through beef consumption. The first study was a retrospective review of meat inspection records at a selected abattoir to estimate prevalence. The second part was a crosssectional survey to gather beef consumption data from the study population. The final part of the study used primary data inputs and the consumption survey to estimate the risk of exposure to Cysticercus bovis and possible risk factors contributing to the risk of exposure using Monte Carlo simulation-based in the @Risk software embedded in Microsoft Excel. Research ethics was considered and applied in all aspects. The prevalence of bovine cysticercosis was 0.70% among the inspected beef carcasses. Beef consumers were estimated to be 99.5% of the population. The majority consumed 40-50g pieces in a serving, with the largest portion being 300g per serving. The number of cysts that could be found in a 300g portion of beef was 5 (95% CI 1-11). The probability of human exposure to T. saginata was 0.0076%. Although the risk of exposure increased with the absence of home freezing of beef and Post Mortem Inspection (PMI) by 0.0094% and 0.109%, respectively, improving home freezing and routine PMI may reduce the risk of exposure to 0.0038% and 0.0040%, respectively. Hence PMI and home freezing were both protective and contributing factors to the risk of exposure The probability of C. bovis viability after home freezing of beef and C. bovis viability in infected beef after cooking were the most influencing risk factors. Therefore, improving home freezing, efficient PMI and thorough cooking of beef coupled with one health approach are recommended to reduce the risk.