Designing a Minimal Intervention Strategy to Control Taenia solium

Abstract

Neurocysticercosis is an important cause of epilepsy in many developing countries. The disease is a zoonosis caused by the cestode parasite Taenia solium. Many potential intervention strategies are available, however none has been able to be implemented and sustained. Here we predict the impact of some T. solium interventions that could be applied to prevent transmission through pigs, the parasite's natural animal intermediate host. These include minimal intervention strategies that are predicted to be effective and likely to be feasible. Logical models are presented which reflect changes in the risk that age cohorts of animals have for their potential to transmit T. solium. Interventions that include a combined application of vaccination, plus chemotherapy in young animals, are the most effective.

Mapping the residual incidence of taeniasis and cysticercosis in Colombia, 2009–2013, using geographical information systems: Implications for public health and travel medicine

“…Therefore veterinary controls and pig-meat inspection are interventions needed especially in places where meat is just for local consumption [18]. Also, international organizations and national ministries should be aware of prevention mechanisms by improving control measures to stop transmission among humans and pigs including the chance for swine vaccination programs among risk population that have shown to be very effective and provides significant levels of protection [41,49–51]. …”

Implementation of a practical and effective control program for Taenia solium in the Banke District of Nepal

“…As the animals selected for assessment were based on them being of a size and age at which pigs from the area are generally sold or slaughtered, most of the animals assessed had been present for at least two of the interventions (Table 4). The treatment schedule which was assessed was determined to be the most effective in an area where animals are consumed from 7 months of age [14]. Available evidence suggests that immunity stimulated by the TSOL18 vaccine requires two immunizations with the currently available vaccine [15].…”

“…Also, the farmer’s requirements about selling animals can change rapidly; a family illness or other unforeseen event can impose an urgent need to sell animals. The T. solium transmission modelling presented by Lightowlers and Donadeu [4] predicted that a 3-monthly program of vaccination plus oxfendazole treatment of pigs between one and 7 months of age would eliminate T. solium infection entirely from pigs >7 months of age such that they would not require further oxfendazole treatment. Cessation of drug treatment of animals that are approaching slaughter age would reduce or prevent the risk that animals with high levels of drug residues could be consumed as well as reducing the cost.…”

“…Introduction of a new 3-monthly treatment program in an area would necessarily involve all pigs to start, so as to treat and protect all the existing animals. However, immunity induced by 2 immunizations with the Cysvax vaccine, together with a natural resistance to T. solium infection in animals >1 year of age (mentioned above), may allow a continuing program involving vaccination plus oxfendazole medication to be effective if it were only implemented in animals up to 7 months of age [4].…”

“…A major limitation to achieving a long-lasting reduction in neurocysticercosis has been the sustainability of T. solium control activities. Lightowlers and Donadeu [4] presented a logical model for control of T. solium transmission using a combination of vaccination and medication in pigs. Combined use of the TSOL18 vaccine [5] and oxfendazole treatment [6] in all pigs at 3-monthly intervals was predicted to lead to a cessation of T. solium transmission by slaughter-age pigs within a year of initiation of the program [4].…”