Global distribution of Taenia saginata
The zoonotic helminth Taenia saginata relies on humans, as the only definitive host in its life-cycle. Infected people are responsible for dissemination of infective eggs excreted in the faeces into the environment, potentially contaminating pastures, fodder, or water sources, from where eggs are ingested by the intermediate hosts. Domestic cattle are the most common intermediate hosts, but domestic yak, buffalo and reindeer are also important intermediate hosts in certain geographical regions. Following ingestion of eggs by the intermediate host, they hatch and the oncospheres migrate to the musculature where they develop into cysticerci. The consumption of raw or undercooked meat containing cysticerci by humans completes the life-cycle.
The public health impacts of T. saginata are generally limited to mild abdominal discomfort with occasional reports of intestinal obstruction or perforation. The economic burden upon endemic counties, however, can be substantial, with major losses occurring through the condemnation, compulsory freezing, or downgrading of meat products. Despite acknowledgement of the economic impact of this parasite, there has yet to be a comprehensive overview of its worldwide distribution. This collection aims to provide such a resource, and we hope that it will be of use to researchers and policy makers alike.
The systematic reviews included in this collection synthesise the current evidence on the occurrence and prevalence of T. saginata taeniosis and cysticercosis in different world regions. The data have been gathered from both peer-reviewed and grey literature, published between 1990–2017. The 2009 PRISMA guidelines have been followed and methods are fully reported within each publication, along with region-specific discussion. As often cited, this exercise has confirmed the near-ubiquitous distribution of this parasite, while highlighting some striking regional, and intra-regional, differences in prevalence.
This project was conceived through the EU COST Action ‘CYSTINET: The European Network on Taeniosis/Cysticercosis’ (TD 1302) and we are grateful to the network funders and organisers for facilitating this collaborative effort.