Taenia spp.

Tapeworms of the genus Taenia include over 100 species. Members of the genus are characterised by a ribbon-like appearance comprised of multiple, eggcontaining segments called ‘proglottids’. Taenia spp. lifecycle relies on a vertebrate intermediate host in which the infective larvae (cysticerci) develop and a definitive host which ingests the uncooked flesh of the intermediate host containing the cysticerci which develops in the smallintestine into the adult tapeworm. The tapeworm proglottids are released from the definitive host and
intermediate hosts are infected by ingesting the tapeworm eggs from the proglottids. Taenia spp. eggs have been demonstrated to survive for periods of months or years on pasture, with low to moderate temperatures and high
humidity being associated with long survival times. Humans are the definitive host for three Taenia species (T. saginata, T. solium, T. asiatica). The accidental ingestion of T. solium eggs by humans, through poor hand hygiene, contaminated water or faecal contamination of food, can result in the aberrant larval infection human cysticercosis.
Neurocysticercosis, infection of the nervous system, is one of the most common causes of preventable epilepsy in endemic countries and has been estimated to be responsible for a loss of 503,000 (379,000-663,000) DALYs
yearly. Human taeniosis infections (with the adult tapeworm) have generally rather mild clinical effects and are susceptible to praziquantel, niclosamide or triple dose albendazole. Neurocysticercosis, however, requires careful surgical or
medical management due to the sensitive location of the larval cysts and potential critical complications that can occur.
As well as anthelmintic treatment of the definitive or intermediate hosts, the control of Taenia spp. relies on stringent meat inspection, education on safe meat preparation, personal hygiene and, importantly, the careful management of potentially contaminated domestic effluent and sewage sludge.
The zoonotic tapeworms Taenia saginata and Taenia solium, are known as the beef tapeworm and pork tapeworm, respectively, depending on their intermediate host. A third species, Taenia asiatica, the Asian tapeworm, although genetically closest to T. saginata, also utilises a porcine intermediate host (Flisser, 2006). In the definitive, human, host infections with the adult stage of Taenia spp. (taeniosis) have only mild health implications through gastro-intestinal disturbance. The larval stage of T. solium, can however infect humans as aberrant intermediate hosts, an infection known as cysticercosis. This can result in severe disease including epileptic seizures due to cyst development in the brain (neurocysticercosis). Humans acquire cysticercosis through ingestion of T. solium eggsfor instance in excreta or through contaminated water and
food-stuffs. Correct treatment and handling of excreta, raw sewerage and sewerage sludge is therefore of incredible importance for the safety of both sanitation workers and the public.