The Taenia solium cysticercosis/taeniosis lifecycle

Taenia solium cysticercosis/taeniosis (TSCT), an emerging but neglected parasitic and zoonotic disease, is caused by the tapeworm T. solium. Humans become infected when they consume undercooked pork meat infected with cysts. The cysts evaginate in the upper small intestine, attach to the mucosa and develop into adult tapeworms. This condition, with the presence of adult worms in the intestine is referred to as Taeniasis. The adult tapeworm, which is hermaphrodite, produces thousands of infective eggs after about two months. The eggs are expelled via the stool into the environment by the tapeworm carrier. These eggs are infective for pigs (normal intermediate host). Once ingested by pigs, the embryos in the eggs hatch, enter the bloodstream and are distributed in muscle, subcutaneous and many other tissues, where they mature into the larval stage or cysticercus. Cysticerci establish as cysts 10 – 12 weeks after ingestion (porcine cysticercosis). Humans can also develop cysticercosis after ingestion of food contaminated with the eggs present in the environment, or through auto-infection (human cysticercosis). In humans, cysticercosis of the central nervous tissue causes neurocysticercosis (NCC).

Impact

Human cysticercosis clinically manifests itself mainly as neurocysticercosis (NCC) which is considered as the most common parasitic helminth infection of the human nervous system and the most frequent preventable cause of epilepsy in sub-Saharan Africa, where it is estimated that approximately 6 million people suffer from the disease. NCC is not only the major cause of acquired epilepsy in low-resource countries, but it is also of increasing concern in as yet non-endemic European countries, due to globalization and the migration of infected people. TSCT, for instance, represents a high-burden disease for the endemic African countries. Although TSCT is detrimental to both human and animal health and causes major loss in pig populations and thus livelihood in communities relying on animal productivity, it is a potentially eradicable disease.

Solution Approach

On the way to effective and sustainable disease control, important gaps need to be closed. These gaps pertain, on the one side, to human health, e.g. lack of precise data of the epidemiology of NCC and its pathomechanisms, the lack of diagnostic facilities and best standard of care including treatment with locally available means and, on the other side, to disease prevention, which not only includes animal health but also education of affected communities. An additional priority component for building a framework for control and elimination of TSCT is to strengthen health systems in poor endemic countries in order to enable them to better detect and manage cases as there is current lack of technical and policy guidance on best practices for management of TSCT/NCC. Therefore, the suggested research approach aims at bridging the above described gaps by

– applying biomedical research to various disease aspects, ranging from basic human immunology to an experimental T. solium pig model, and

– establishing a big consortium (CYSTINET-Africa) to facilitate joint research efforts with an envisaged impact not only on data collection but also on capacity building and data dissemination overarching four African partners of three eastern and southern African countries and two German partners.