Madagascar: Halting pig-transmitted tapeworm
In Madagascar, backyard pig rearing is common in rural and semi-urban areas, contributing to the livelihood of households. However, like in many other countries, living in close proximity to domesticated animals raises health challenges, where viruses, bacteria and parasites flow freer between animals and humans. Infection with T. solium (TS) tapeworm occurs when humans eat raw or undercooked, infected pork.
When a disease infects both animals and humans, it is called a zoonosis. Many zoonoses can be prevented by improved personal hygiene, safe food preparation and access to improved water and sanitation facilities. In Madagascar, typically, few pigs are raised per household and are either sold or slaughtered during holidays to celebrate family reunions. When pigs are raised in backyards, where they can roam freely, they may become infected by eating food contaminated with human faeces, which maintains the life cycle of Taenia solium – the pig tapeworm. This parasite is hosted by pigs and humans.
Infection with T. solium (TS) tapeworm occurs when humans eat raw or undercooked, infected pork. People who have tapeworms in the intestine will shed tapeworm eggs. They can unknowingly infect themselves and other people with tapeworm eggs through dirty hands or contaminated food or water with devastating effects on human health. Tapeworm larvae (cysticerci) develop in the muscles, skin, eyes and the central nervous system. When cysts develop in the brain, the condition is known as neurocysticercosis.
Neurocysticercosis is the cause of more than 30% of epilepsy cases in areas with endemic TS tapeworm. It can be averted by preventing people from getting infected with tapeworm eggs, but most of the time the tapeworm carriers remain undiagnosed and therefore unreported. Preliminary data from parasitological surveys indicate that TS is endemic in many districts in Madagascar.
It is essential that different sectors – including human, veterinary health and environment – work together to control and eliminate the parasite. WHO is supporting an intersectoral initiative led by the Ministry of Health of Madagascar to implement a pilot study to demonstrate how selected interventions against TS can reduce taeniasis prevalence to a level below 1%.
The 3-year project is being implemented in Antanifotsy a rural district southeast of the capital, Antananarivo, where preliminary data indicated a high prevalence (above 6%) of TS. One of the main interventions is large-scale treatment of all eligible individuals (children under 5 are not treated) with praziquantel. For two consecutive years, in 2015 and in 2016 about 65 000 individuals were treated, representing more than 95% coverage of the targeted population.
An important part of the intervention is education, awareness-raising and social mobilization. The population is informed about risks of the disease and benefits of treatment by community health workers. Additional information is made available in leaflets, posters and on banners in public places. At the start of the current campaign in Madagascar in 2016, awareness was amplified by a folk dance group who performed a special song about the parasite.
As baseline to evaluate the success of the intervention, stool specimens of people are tested for TS. Pigs from the pilot communities are also tested for cysticercosis antibodies in their blood. Two rounds of large-scale treatment already show a decrease in the prevalence of TS. If this trend continues, final results at the end of the 3-year pilot study will demonstrate whether this strategy can reduce TS in humans and eventually halt its transmission. In combination with preventative measures in pigs (confinement, antiparasitic treatment, meat inspection) and the use of latrines, the chances of controlling the parasite will be higher.