Epidemiology

Taenia saginata and T solium are prevalent throughout the world. T saginata is commonly found in the US, Europe, South America, and Africa, and infection usually occurs among those whose diets consist of raw or undercooked meat from infected animals.T solium is endemic in areas of the world where pigs have access to human fecal material (e.g., Latin America, Eastern Europe, sub-Saharan Africa, India, and elsewhere in Asia).[4][5][6][7] WHO Taenia solium endemicity map - 2022 update Opens in new window​​ The prevalence of taeniosis is estimated to be between 0.04% and 8.8% in the Americas, with cases reported in 13 of the 54 countries and territories.[8] More than 2000 cases of neurocysticercosis are diagnosed in the US each year. Between 2003 and 2012, neurocysticercosis led to an estimated 18,584 hospitalizations and cost in excess of US $908 million. Risk of hospitalization was reported to be highest in those of Hispanic ethnicity, male sex, and age 20 to 44 years.[9] Globally, the total number of people with neurocysticercosis is estimated to be between 2.56 and 8.3 million (based on available epilepsy prevalence data). It is responsible for approximately 30% of cases of epilepsy in endemic countries.[10] Between 1990 and 2015, 275 cases of human cysticercosis and 22 cases of taeniosis were reported in Western Europe.[11]

Diphyllobothrium latum infection is prevalent in areas of the north temperate and subarctic zones, where freshwater fish are commonly consumed. The worldwide prevalence is approximately 20 million people.[12] Infected fish have been reported worldwide. In North America, highly endemic areas have been found in Alaska and Canada among Native American populations. In the US, infected fish have been found in regions of the Great Lakes (especially Minnesota and Michigan) and in Florida and California. Transmission has been brought under control in Western Europe, although cases have been reported in Finland. Humans are the primary definitive host and the most important reservoir of infection.

The dwarf tapeworm Hymenolepis nana is found in most warm regions of the world. It is the most common tapeworm infection in the southeastern US and in Latin America, and it is common throughout southern Europe, the Indian subcontinent, Russia, and the former Soviet republics.[13][14][15][16] Patients infected with H nana are often children, who present with loose bowel movements.

The greatest prevalence of cystic echinococcosis in humans is found in countries of temperate zones, including southern South America, the entire Mediterranean littoral, the southern and central areas of the former Soviet Union, central Asia, China, Australia, and areas of Africa.[1][17]​​​​​ The prevalence may reach 5% to 10% in parts of Argentina, Peru, East Africa, Central Asia, and China. It is commonly found among populations involved with sheep raising. In the US, most infections are diagnosed in immigrants from countries in which hydatid disease is highly endemic.

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