Implementation and Evaluation of a Health-Promotion Strategy for Control of Taenia Solium Infections in Northern Tanzania
Ngowi, H. A., Mlangwa, J. E. D., Mlozi, M. R. S., Tolma, E. L., Kassuku, A. A., Carabin, H., Willingham, A. L., Iii., International Journal of Health Promotion and Education
Human neurocysticercosis, an infection of human central nervous tissue by larvae of a zoonotic parasite, Taenia solium, has been a global public health threat because of the parasite's ability to cause serious neurological syndromes. Clinical manifestations of active neurocysticercosis dependent on the number and location of the larvae include headaches, seizures, focal neurologic deficits, or signs of increased intracranial pressure. Epileptic seizures are by far the most common manifestations of active or inactive stages, accounting for 70-90% of symptoms of neurocysticercosis (Takayanagui and Odashima, 2006). Other potential clinical features of active or inactive infection are mental confusion, visual disturbances, and behavioural abnormalities. In areas endemic for T. solium, neurocysticercosis doubles the prevalence of epilepsy (White, 1997). A recent hospital-based study conducted in Mbulu District, northern Tanzania, established an important association of human neurocysticerosis with epilepsy in the area (Blocher et al., 2007).
Taenia solium poses great economic impact in affected populations due to monetary losses encountered in the livestock and health sectors. However, because of lack of diagnostic facilities especially for human neurocysticercosis, scanty information is available on the actual economic burden caused by the parasite. In South Africa, one of the rare African countries with access to imagery, a recent analysis revealed an important monetary burden due to T. solium in Eastern Cape Province. The overall monetary burden estimated in 2004 ranged from US$18.6 to US$34.2 million based on different methods of analysis (Carabin et al., 2006). In Tanzania, there is little information on the burden of neurocysticercosis in human despite the high prevalence of infection in pigs (Ngowi et al., 2004). A previous study conducted in 21 randomly selected villages in the area determined an incidence rate of porcine cysticercosis of 68.6 per 100 pig-years in sentinel pigs using antigen ELISA (Ag-ELISA) (Ngowi et al., 2007b), which has a sensitivity and specificity of 86.7 and 94.7 per cent, respectively (Dorny et al., 2004). This study also observed lack of knowledge of people with regard to T. solium, as well as high prevalence of potential risk factors for the transmission of the parasite, including lack of pit latrines, allowing pigs to free range, consuming infected pork, and drinking unboiled water. The general population in Tanzania, like that of many other developing countries, is at a high risk of infection with T. solium because of poor living standards and unlimited movements of people and animals between rural and urban areas.
Researchers have tried in the past through various ways to control T. solium in endemic areas. The parasite was formerly eliminated in industrialized countries such as the United States of America because of improved sanitation and industrialization of pig husbandry, with strict control of herds and inspection of pork (Maguire, 2004). However, reemergence of human neurocysticercosis in these countries has now become a common phenomenon because of increased migration of people between countries (Shandrea and Kass, 2006; Sorvillo et al., 2007).
Few control strategies for T. solium have been implemented in areas endemic for porcine cysticercosis using different approaches. One intervention study using chemotherapy for human taeniosis in Mexico led to increased prevalence of porcine cysticercosis after the intervention because of poor compliance of people to recommended treatment regimens and poor disposal of human faecal materials following worm expulsion (Keilbach, 1989). Another study in Mexico involving mass chemotherapy of 70% of population in an endemic village that was repeated one year later, determined a decrease of human taeniosis prevalence from 1.32% to 0% based on stool microscopy (Camacho et al., 1991). Both of these studies did not have a control group, hence failed to establish the actual effect of the intervention. …