Taenia solium taeniosis/cysticercosis in Africa: Risk factors, epidemiology and prospects for control using vaccination

Abstract

Poor sanitary conditions, free-roaming of domestic pigs and lack of awareness of the disease play an important role in the perpetuation of the Taenia solium taeniosis and cysticercosis in Africa. Traditional pig production systems known as the source of T. solium taeniosis/cysticercosis complex are predominant in the continent, representing 60–90% of pig production in rural areas. It has been reported that T. solium cysticercosis is the main cause of acquired epilepsy in human population and results in considerable public health problems and economic costs to the endemic countries. Although the socioeconomic impact and public health burden of cysticercosis have been demonstrated, up to now no large-scale control programme has been undertaken in Africa. Most disease control trials reported in the literature have been located in Latin America and Asia. This review discusses the risk factors and epidemiology of T. solium cysticercosis in Africa and critically analyzes the options available for implementing control of this zoonotic disease in the continent.

Introduction

The Taenia solium taeniosis/cysticercosis complex constitutes an important public health problem and a serious socioeconomic obstacle for pig breeders in many African countries (Zoli et al., 2003, Willingham and Engels, 2006, Carabin et al., 2006).

During the 1990s there was optimistic opinion on the control of cysticercosis in developing countries (Cruz et al., 1989). The assumption was based on characteristics of T. solium which suggest it could be eradicated (Schantz et al., 1993, Krecek and Waller, 2006). The failure to control taeniosis/cysticercosis using taeniacidal drug administration (Sarti et al., 2000) and health education through large scale elimination programmes in Latin America (Sarti et al., 1997) and Asia (Allan et al., 2002) has shown that global eradication of this zoonosis is difficult to achieve in the context of persistence of free-roaming pig production. New strategies for controlling cysticercosis have been suggested by Flisser et al. (2006) who argue that intervention measures for control of cysticercosis might involve the international agencies and institutions, such as the World Health Organization, the Food and Agriculture Organization, as well as the commitment of policymakers, scientists and field workers as key means for a sustainable control. Considering the many problems faced by endemic countries and the understandable priority focused on diseases such as malaria, tuberculosis and AIDS, and also the limited resources available in these countries, T. solium is often not provided the attention it deserves and is a particularly neglected disease. In this situation, some researchers suggest that control of T. solium should be focused on the areas with high risk of infection (Molyneux et al., 2004, Ngowi et al., 2010). The objective of this review is to present the predisposing factors and the epidemiological data on T. solium cysticercosis available on the endemic areas of Africa including a critical comparison of various options for the control of this zoonotic disease. Emphasis will be put on the veterinary aspects.