Chapter 26 : Helminths in Meat

Abstract:

There are four meat-borne helminths of medical significance: Trichinella species, Taenia solium, and Taenia asiatica, which occur primarily in pork; and Taenia saginata, which is found in beef. There are a variety of reasons for this, including animal management systems that perpetuate infection, inadequate or poorly enforced inspection requirements for slaughtered animals, new sources of infection, and demographic changes in human populations that introduce new culinary practices of preparing meats. Lower infectivity of other Trichinella species for the domestic pig diminishes their importance in the domestic cycle. As cooking, freezing, and other processing methods kill Trichinella larvae in meat, most human infections have resulted from instances where meat preparation was not adequate. Pork products such as fresh sausage, summer sausage, and dried or smoked sausage have all been implicated as sources of human trichinellosis. Diagnosis is based on a history of eating infected meat, symptoms, laboratory findings, and recovery of larvae from muscles. After the mid-1980s, pigs are putatively identified as the intermediate host for a unique taeniid (similar to T. saginata and T. solium) that had a predilection for liver tissue in a multitude of experimental hosts. For this reason, both T. asiatica and T. saginata asiatica have appeared and continue to appear in the literature as the scientific names identifying this organism. Although most cases of taeniasis are asymptomatic, up to one-third of patients complain of nausea or abdominal “hunger” pain that is often relieved by eating.