**1. Introduction**

Tapeworms and cysticerci are mentioned during the time of ancient Egypt and Greece. However, their life cycle, including intermediate and definite hosts, are explained in the nineteenth century. Cysticercosis and taeniosis represent food-borne zoonotic infections by the larvae and adult forms of *Taenia saginata* (beef tapeworm), *Taenia solium* (pork tapeworm), and *Taenia asiatica* (Asian tapeworm). These parasites are unique since their life cycle includes humans as definite hosts.

Adult forms of *T. saginata*, *T. solium*, and *T. asiatica* cause human taeniosis. Transmission occurs via consumption of larvae found in animal tissues (beef or pork) and the consequent development of parasites to adult forms in human intestines. Symptoms of intestinal infection are stomachache, intermittent diarrhea, and weight loss, while anal pruritus manifests due to the active migration of proglottids.

Cysticercosis represents infection of tissues by larval stage of Cysticercus (metacestode) found in pigs, cattle, and humans, who in this case can be both intermediate and definite hosts. Larvae of the *T. saginata* are found in the muscles of cattle, larvae of the *T. asiatica* prefer inner organs of pigs (gut and liver), while larvae of the *T. solium* are usually localized in muscles, inner organs, and brain of pigs and humans. After consumption of *T. solium* egg, parasite evolves by larvae (oncospheres) exiting the eggs, which then penetrate the intestine wall and migrate to the eye, striated muscles, and subcutaneous tissue. This is diagnosed as human cysticercosis (HCC). Neurocysticercosis (NCC), occurs when cysticerci migrate to central nervous system tissues and currently it is the most common helminth infection of the nervous system and the leading cause of acquired epilepsy in the world [1]. Hence, *T. solium* is considered as the sole causative agent of NCC in humans with great public health importance, while *T. saginata* and *T. asiatica* are less clinically important. Their main impact is economic losses in animal production. However, the possibility that *T. asiatica* can cause cysticercosis in humans similar as *T. solium* is under investigation due to indications that *T. asiatica* caused several cases of human cysticercosis in Asia [2].

World Health Organization (WHO) considers human cysticercosis and taeniosis as neglected diseases, especially in undeveloped countries where many people live in poor hygiene conditions. Even though taenia-causing infections in humans have a worldwide distribution, cases are mostly reported in regions where cattle and pigs are reared extensively. Therefore, the distribution of each of the three taenia species depends on the culture and nutritional habits (i.e., consummation of raw or undercooked contaminated meat or organs of pigs and cattle) [3–5]. Occurrence of *T. asiatica* is limited to Asia. It is still not reported in Europe, where *T. solium* occurs but not as often, while infections by *T. saginata* are still common. Even though the life cycle of Cestoda is less likely to maintain with appropriate sanitary conditions and good farming practices, infections in such areas still can occur due to migrations. Imported infections increase global distribution into free areas such as the United States of America and Europe. Here infected people contaminate the environment leading to new infections.

Considering the global public health significance of taenia infections, maintaining vigilant surveillance is still needed as a tool to reduce disease incidence as much as possible, as the first step to the eradication of cysticercosis and taeniosis. This chapter summarizes etiology, pathology, and epidemiology of taeniosis/cysticercosis along with science-based approaches to its surveillance as food-borne parasites.
