Zoonotic diseases are those which can infect both humans and animals. Not only do these diseases impose a large burden on human health, but because livestock are often a major source of income and primary asset for many communities, they also impact on the ability of people to pay for the healthcare they need. To tackle these diseases, approaches that bring together a number of different sectors are required.
The Pork tapeworm, Taenia solium, is one example of the detrimental impact of zoonotic organisms and demonstrates the need for cross-sectoral collaboration to achieve control. Taenia solium is transmitted between humans and pigs, but it is the ability of the parasite’s larval stage to encyst in humans causing human cysticercosis, which is of most concern. The parasitic cysts often form in the human brain leading to severe neurological symptoms, such as epileptic seizures.
In 2015, human cysticercosis was estimated to be the foodborne parasitic disease with the highest burden globally. The total number of people suffering from neurocysticercosis, including symptomatic and asymptomatic cases, is estimated to be between 2.56–8.30 million, based on the range of epilepsy prevalence data available. This makes neurocysticercosis the most common parasitic infection of the brain and a leading cause of epilepsy in the developing world, especially Latin America, India, Africa, and China. T. solium cysticercosis was added to the World Health Organization (WHO) list of major Neglected Tropical Diseases (NTDs) in 2010 with NTD roadmap goals of making a validated strategy for control and elimination of T. solium taeniasis/cysticercosis available and for such interventions to be scaled up in selected countries by 2020.
Human cysticercosis is solely contracted by the ingestion of T. solium eggs through either food or water, that has been contaminated with T. solium eggs in faeces of people with T. solium tapeworm. Humans become infected with tapeworm by ingesting undercooked infected pork. The cysts in pig meat significantly reduce the price farmers receive for their pork meat. WHO have identified Cysticercosis as a disease that can be eliminated but, again, this will require a number of sectors to work together.
In the Veterinary Public Health sector, strategies should include vaccination of pigs as well as better housing of pigs to prevent contact with infected human faeces. In the water, sanitation and hygiene (WASH) sector, improved water and sanitation to prevent eggs from human faeces getting into the food chain will be central to this endeavour. Food hygiene will also be important – better meat inspection to prevent people coming into contact with infected pork meat will be an important preventative measure. In terms of human health, treatment to kill the tapeworms will be necessary. Whilst there is no specific drug for T. solium, we can use some of the drugs that are already used to treat other NTDs (e.g. praziquantel for schistosomiasis).
At the Schistosomiasis Control Initiative (SCI), we have partnered with a number of organisations including The University of Copenhagen, The Technical University of Munich, and the Institute of Tropical Medicine Antwerp, to conduct operational research to determine how established platforms may be used to provide treatment for tapeworm infections. These platforms include treatment programmes established against schistosomiasis. Such programmes capitalise on the broad efficacy of praziquantel to treat not only schistosomiasis infections but also tapeworms. It is our hope that through the utilisation of existing platforms to treat other NTDs, we can facilitate the treatment of those infected with T. solium and reduce the burden of this debilitating zoonotic disease in Africa.