Areas with the highest prevalence of<unk>  are tropical and subtropical areas including sub-Saharan Africa, central and east Asia, and the Americas. Neglected tropical diseases Some types of<unk>  are classified as neglected tropical diseases. They include: * Soil-transmitted<unk>  * Roundworm infections such as lymphatic filariasis, dracunculiasis, and onchocerciasis * Trematode infections, such as schistosomiasis, and food-borne trematodiases, including fascioliasis, clonorchiasis, opisthorchiasis, and paragonimiasis * Tapeworm infections such as cysticercosis, taeniasis, and echinococcosis Prevalence The soil-transmitted helminths (A. lumbricoides, T. trichiura, N. americanus, A. duodenale), schistosomes, and filarial worms collectively infect more than a quarter of the human population worldwide at any one time, far surpassing HIV and malaria together. Schistosomiasis is the second most prevalent parasitic disease of humans after malaria. In 2014–15, the WHO estimated that approximately 2 billion people were infected with soil-transmitted<unk> , 249 million with schistosomiasis, 56 million people with food-borne trematodiasis, 120 million with lymphatic filariasis, 37 million people with onchocerciasis, and 1 million people with echinococcosis. Another source estimated a much higher figure of 3.5 billion infected with one or more soil-transmitted helminths. In 2014, only 148 people were reported to have dracunculiasis because of a successful eradication campaign for that particular helminth, which is easier to eradicate than other helminths as it is transmitted only by drinking contaminated water. Because of their high mobility and lower standards of hygiene, school-age children are particularly vulnerable to<unk> . Most children from developing nations will have at least one infestation. Multi-species infections are very common. The most common intestinal parasites in the United States are Enterobius vermicularis, Giardia lamblia, Ancylostoma duodenale, Necator americanus, and Entamoeba histolytica. Variations within communities Even in areas of high prevalence, the frequency and severity of infection is not uniform within communities or families. A small proportion of community members harbour the majority of worms, and this depends on age. The maximum worm burden is at five to ten years of age, declining rapidly thereafter. Individual predisposition to<unk>  for people with the same sanitation infrastructure and hygiene behavior is thought to result from differing immunocompetence, nutritional status, and genetic factors. Because individuals are predisposed to a high or a low worm burden, the burden reacquired after successful treatment is proportional to that before treatment. Disability-adjusted life years It is estimated that intestinal nematode infections cause 5 million disability-adjusted life years (DALYS) to be lost, of which hookworm infections account for more than 3 million DALYS and ascaris infections more than 1 million. There are also signs of progress: The Global Burden of Disease Study published in 2015 estimates a 46 percent (59 percent when age standardised) reduction in years lived with disability (YLD) for the 13-year time period from 1990 to 2013 for all intestinal/nematode infections, and even a 74 percent (80 percent when age standardised) reduction in YLD from ascariasis. Deaths As many as 135,000 die annually from soil transmitted<unk> . The 1990–2013 Global Burden of Disease Study estimated 5,500 direct deaths from schistosomiasis, while more than 200,000 people were estimated in 2013 to die annually from causes related to schistosomiasis. Another 20 million have severe consequences from the disease. It is the most deadly of the neglected tropical diseases. Helminth genera Common name Infections (million per year) Direct deaths per year Regions where common Soil transmitted<unk>  (STH) (classified as neglected tropical disease): Ascaris lumbricoides Roundworm 1000 to 1450 807 to 1,121 20,000 Many regions of South-east Asia, Africa, and Central and South America Trichuris trichiura Whipworm 500 604–795 In moist, warm, tropical regions of Asia, Africa, Central and South America, and the Caribbean islands. Ancylostoma duodenale Hookworm 900 to 1300 576–740 (hookworm in general) In tropical and subtropical countries (Sub-Saharan Africa) Necator americanus Strongyloides stercoralis Hookworm, pinworm 50 to 100 Thousands In moist rainy areas of the tropics and subtropics, in some areas of southern and eastern Europe and of the United States of America All STH together 1500 to 2000 135,000 Tropical and subtropical areas, in particular sub-Saharan Africa, the Americas, China and east Asia. Not transmitted via soil but classified as neglected tropical disease: Schistosoma mansoni Blood fluke All types of Schistosoma together: 160 to 200 (210 "affected") 12,000 150,000 deaths from kidney failure 200,000 indirect deaths from "causes related to" Schistosomiasis In tropical and subtropical regions Schistosoma haematobium 112 (in Sub-Saharan Africa alone) Echinococcus granulosus 3 Developing countries Not transmitted via soil and not classified as neglected tropical disease: Toxocara canis Dog roundworm 50 Many regions of South-east Asia, Africa, and Central and South America Taenia solium Pork tapeworm 50 South America, Southeast Asia, West Africa and East Africa Taenia saginata Beef tapeworm 50 (all types of Taenia: 40 to 60) Hymenolepis nana Dwarf tapeworm 100 Hymenolepis diminuta Rat tapeworm Fasciola hepatica,Fascioloides magna Liver fluke 50 Largely in southern and eastern Asia but also in central and eastern Europe Fasciolopsis buski Giant intestinal fluke Dracunculus medinensis Guinea worm Nowadays negligible thanks to eradication program Formerly widespread in India, west Africa and southern Sudan Trichostrongylus orientalis Roundworm 1–3 ("several") Rural communities in Asia Other 100 Worldwide Total (number of infections) Approx. 3.5 billion Worldwide
Helminthiasis
Trichiasis
Soil-transmitted helminthiasis
Trichuriasis
Toxocariasis
Trichomoniasis
Isosporiasis
Tungiasis