No abstract

Neurocysticercosis (NCC) is a major cause of seizures/epilepsy in countries endemic for the disease. The objectives of this study were to spatially map the burden of active epilepsy (AE), NCC, taeniasis, seroprevalence for cysticercal antibodies and positivity to circulating cysticercal antigens in Kaniyambadi block (approximately 100 villages comprising 100 000 population) of Vellore district and to detect spatial clusters of AE, NCC, taeniasis and seroprevalence. Using geographic information system (GIS) techniques, all 21 study villages with over 8000 houses (population of 38 105) were mapped. Clustering of different indices of Taenia solium infection was determined using a spatial scan statistic (SaTScan). There was a primary spatial cluster of AE with a log likelihood ratio (LLR) of 10.8 and relative risk (RR) of 22.4; however, no significant clustering for NCC was detected. Five significant spatial clusters of seropositivity for cysticercal antibodies, two clusters of seropositivity for cysticercal antigens and one for taeniasis were detected (LLR of 8.35 and RR of 36.67). Our study has demonstrated the use of GIS methods in mapping and identifying 'hot spots' of various indices of T. solium infection in humans. This spatial analysis has identified pockets with high transmission rates so that preventive measures could be focused on an intensive scale.

We evaluated the exposure of a community in Vellore district of south India to Taenia solium infection and its relationship to the prevalence of neurocysticercosis (NCC) causing active epilepsy. Seroprevalence of Taenia cysticercus antigens and antibodies were determined in 1064 randomly chosen asymptomatic individuals, antibodies to T. solium ova in 197 selected sera, and prevalence of taeniasis by a coproantigen test in 729 stool samples. The prevalence of NCC causing active epilepsy in Vellore district was determined in a population of 50 617. Coproantigens were detected in 0.8% (6 samples), Taenia cysticercus antigens in 4.5% (48 sera) and cysticercus IgG antibodies in 15.9% (169 sera) of the population. Cysticercus antibodies were directed against relatively low molecular weight cyst glycoprotein antigens in 14.9% (158 sera) of the population. IgG antibodies to Taenia ova were found in 81 (41.1%) of the selected samples. Prevalence of NCC causing active epilepsy was 1.3 per 1000 population. These results show high exposure of the population to the parasite and a relatively high prevalence of active infections (4.5% antigen positives) but a low prevalence of NCC causing active epilepsy (0.13%). These findings may indicate that the population is protected against developing neurocysticercosis. IgG antibodies directed against Taenia ova and low molecular weight cyst antigens may contribute to protection.

The high prevalence of porcine cysticercosis recorded in the study areas mandates public health measures, which includes meat inspection.

Summaryobjective To evaluate the cost-effectiveness of three strategies for the control of taeniasis in a community, in terms of cost per case treated.methods A study was conducted in South India to determine the prevalence of taeniasis by screening stool samples from 653 randomly chosen subjects, for coproantigens. The costs incurred in the project were used to estimate the cost per case screened and treated. A one-way sensitivity analysis was carried out for varying rates of taeniasis, different screening strategies and mass therapy. Further sensitivity analysis was carried out with different manpower and test costs.results The rate of taeniasis as detected by ELISA for coproantigen was 3 per 1000 (2 of 653 samples). Our study showed that mass therapy without screening for taeniasis would be the most economical strategy in terms of cost per case treated if field workers are employed exclusively for either mass therapy or screening. For each strategy, costs per case treated are higher at low prevalence of taeniasis, with a sharp rise below 15%.conclusions In places that are endemic for taeniasis and neurocysticercosis, mass therapy or screening for taeniasis should be considered. Screening by stool microscopy is not cost-effective in terms of cost per case of taeniasis treated owing to its low sensitivity. Although the cost per case of taeniasis treated is high at low prevalence of taeniasis for all options, incorporating mass therapy into existing mass drug distribution programmes might prove to be the most cost-effective control strategy.