dracunculiasis main article: dracunculiasis dracunculus medinensis larvae dracunculiasis is also known as guinea-worm disease. in 2019, 53 cases were reported across four countries, a substantial decrease from 3,500,000 cases in 1986. it is not fatal, but can cause months of inactivity. it is caused by drinking water contaminated by water fleas infected with guinea-worm larvae. approximately one year after infection, a painful blister forms and one or more worms emerge. worms can be up to 1 metre long. it is usually treated by world health organization volunteers who clean and bandage wounds caused by worms and return daily to pull the worm out a few more inches. dracunculiasis is preventable by water filtration, immediate case identification to prevent spread, health education, and treating ponds with larvicide. an eradication program has been able to reduce prevalence. as of 2014, the four endemic countries are chad, ethiopia, mali, and south sudan. echinococcosis main article: echinococcosis lifecycle of echinococcus the rate of echinococcosis is higher in rural areas, and there are more than one million people infected currently. it is caused by ingesting parasites in animal feces. there are two versions of the disease: cystic and alveolar. both versions involve an asymptomatic incubation period of several years. in the cystic version, liver cysts cause abdominal pain, nausea, and vomiting, while cysts in the lungs cause chronic cough, chest pain, and shortness of breath. in alveolar echinococcosis, a primary cyst develops, usually in the liver, in addition to weight loss, abdominal pain, malaise, and signs of liver failure. untreated alveolar echinococcosis is fatal. surgery and drugs can be used to treat echinococcosis. it can be prevented by deworming dogs, sanitation, proper disposal of animal feces, health education, and livestock vaccination. cystic echinococcosis is found in the eastern portion of the mediterranean region, northern africa, southern and eastern europe, the southern portion of south america, and central asia. alveolar echinococcosis is found in western and northern china, russia, europe, and northern north america. it can be diagnosed through imaging techniques and serological tests. yaws main article: yaws a child with yaws there are limited data available on the prevalence of yaws, although it primarily affects children. the mortality risk is very low, but the disease causes disfigurement and disability if untreated. the most common symptom is skin lesions. it is a chronic bacterial infection, transmitted by skin contact, and caused by the spirochete bacterium treponema pallidum pertenue. it is treated with antibiotics and can be prevented through hygiene and sanitation. yaws is most prevalent in warm, moist tropical regions of the americas, africa, asia, and the pacific. foodborne trematodiases foodborne trematode infections include clonorchiasis, opisthorchiasis, fascioliasis, and paragonimiasis. these infections are all zoonotic, primarily affecting domestic or wild animals, but can also be transmitted to humans. they are acquired by eating food, such as raw fish, contaminated with the larval stages of the parasites. at least 40 million people are thought to be infected. fasciola hepatica human african trypanosomiasis main article: african trypanosomiasis african trypanosomiasis (african sleeping sickness) is a somewhat rare protozoal disease, with fewer than 10,000 cases currently. human african trypanosomiasis is vector-borne and spreads through the bite of the tsetse fly. the most common symptoms are fever, headache, lymphadenopathy, sleeping disturbances, personality changes, cognitive decline, and coma. the disease is always fatal if untreated. the current forms of treatment are highly toxic and ineffective, as resistance is spreading. it is diagnosed through an inexpensive serological test. lifecycle of african trypanosomiasis leishmaniasis main article: leishmaniasis lifecycle of leishmaniasis the three forms of leishmaniasis, a protozoal disease, are visceral (kala-azar), cutaneous, and mucocutaneous. there are an estimated 12 million people infected. it is fatal if untreated, and 20,000 deaths from visceral leishmaniasis occur annually. it is a vector-borne disease caused by the bite of sandflies. at least 90 percent of visceral leishmaniasis occurs in bangladesh, brazil, ethiopia, india, south sudan, and sudan. cutaneous leishmaniasis occurs in afghanistan, algeria, brazil, colombia, iran, pakistan, peru, saudi arabia, and syria. around 90 percent of mucocutaneous leishmaniasis occurs in bolivia, brazil, and peru. the only method of prevention is a vaccine that is under development and prevention of sandfly bites. diagnosis can be made by clinical signs, serological tests, or parasitological tests. leishmaniasis can be treated with expensive medications. leprosy main article: leprosy according to recent figures from the who, 208,619 new cases of leprosy were reported in 2018 from 127 countries. it is most prevalent in india (69% of cases), brazil, indonesia, nigeria, the democratic republic of the congo, madagascar, and east africa from mozambique to ethiopia, with the highest relative incidence in india, brazil, and nepal. there are one to two million individuals currently disabled or disfigured due to past or present leprosy. it is caused by bacteria and transmitted through droplets from the mouth and nose of infected individuals.hands deformed by leprosy leprosy causes disfigurement and physical disabilities if untreated. it is curable if treated early. treatment requires multidrug therapy. the bcg vaccine has some preventative effect against leprosy. leprosy has a 5–20 year incubation period, and the symptoms are damage to the skin, nerves, eyes, and limbs. lymphatic filariasis main article: lymphatic filariasis elephantiasis lymphatic filariasis is also known as elephantiasis. there are approximately 120 million individuals infected and 40 million with deformities. approximately two-thirds of cases are in southwest asia, and one-third are in africa. lymphatic filariasis is rarely fatal but has lifelong implications, such as lymphoedema of the limbs, genital disease, and painful recurrent attacks. most people are asymptomatic but have lymphatic damage. up to 40 percent of infected individuals have kidney damage. it is a vector-borne disease, caused by nematode worms that are transmitted by mosquitoes. it can be treated with cost-effective antihelminthic treatments, and washing skin can slow or even reverse damage. it is diagnosed with a finger-prick blood test. onchocerciasis main article: onchocerciasis onchocerca volvulus emerging from a blackfly onchocerciasis is also known as river blindness. there are 20.9 million people infected, and prevalence is higher in rural areas. over 99 percent of cases are in sub-saharan africa. it causes blindness, skin rashes, lesions, intense itching, and skin depigmentation. it is a vector-borne disease, caused by blackflies infected with filarial worms. it can be treated with ivermectin and prevented by insecticide spraying or preventative dosing with ivermectin. rabies main article: rabies rabies virusthere are two forms of rabies: furious and paralytic. it is mostly found in asia and africa. there is a higher prevalence in rural areas, and it disproportionately affects children. rabies is fatal after symptoms develop. it is caused by a lyssavirus transmitted through wounds or bites from infected animals. the first symptoms are fever and pain near the infection site, which occur after a one- to three-month incubation period. furious rabies (the more common type) causes hyperactivity, hydrophobia, and aerophobia; death by cardio-respiratory arrest occurs within days. paralytic rabies causes a slow progression from paralysis to coma to death. there are 60,000 deaths from rabies annually. it can be prevented in dogs by vaccination and by cleaning and disinfecting bite wounds (post-exposure prophylaxis). rabies is undiagnosable before symptoms develop. it can be detected through tissue testing after symptoms develop. schistosomiasis main article: schistosomiasis 11-year-old filipino boy with ascites due to schistosomiasisthere are over 200 million cases of schistosomiasis. approximately 85 percent of cases are in sub-saharan africa. the disease can be fatal by causing bladder cancer and hematemesis. schistosoma species have a complex life cycle that alternates between humans and freshwater snails. infection occurs when the skin comes into contact with contaminated fresh water in which the snails that carry the parasite are living. symptoms for schistosomiasis are not caused by the worms but by the body's reaction to the eggs. the eggs that do not pass out of the body can become lodged in the intestine or bladder, causing inflammation or scarring. children who are repeatedly infected can develop anemia, malnutrition, and learning difficulties. the symptoms are usually haematuria, bladder obstruction, renal failure, bladder cancer, periportal fibrosis, bladder fibrosis, liver fibrosis, portal hypertension, cervical lesions, ascites, and esophageal varices. inexpensive praziquantel can be used to treat individuals with schistosomiasis, but it cannot prevent reinfection. the cost of prevention is us$0.32 per child per year. mass deworming treatment with praziquantel, better access to safe water, sanitation, and health education can all be used to prevent schistosomiasis. vaccines are under development. it can be diagnosed through a serological test, but the test often produces false negatives. soil-transmitted helminthiasis main article: soil-transmitted helminthiasis adult ascaris worms being removed from the bile duct of a patient in south africa soil-transmitted helminthiasis is the most prevalent neglected tropical disease. the three major worm species responsible for soil-transmitted helminthiasis are ascaris (roundworms), trichuris (whipworm), the hookworms necator americanus and ancylostoma duodenale, and strongyloides stercoralis. there are 1.5 billion people currently infected. soil-transmitted heminthiasis occurs in sub-saharan africa, the americas, china, and east asia. the mortality risk is very low. the most common symptoms are anemia, stunted growth, intestinal problems, lack of energy, and compromised physical and cognitive development. infected children often fall behind in schooling. the severity of symptoms depends on the number of worms in the body. parasitic worms are generally transmitted via exposure to infected human feces and soil that are spread in the environment, for example, due to open defecation. the most common treatment is medicine. it can be prevented through hygienically prepared food and clean water, improved sanitation, periodic deworming, and health education. the world health organization recommends mass deworming without prior diagnosis. taeniasis/cysticercosis main article: cysticercosis cysticercosis is a tapeworm larvae infection, while taeniasis is infection with adult tapeworms. both are found in asia, africa, and latin america, particularly on farms in which pigs are exposed to human excrement. cysticercosis is the most common preventable cause of epilepsy in the developing world. cysticercosis occurs after ingestion of contaminated food, water, or soil. cysts and lesions can cause headaches, blindness, seizures, hydrocephalus, meningitis, and dementia. neurocysticercosis, or the parasitic infection of the nervous system, can be fatal. taeniasis is not fatal. it is usually contracted after eating undercooked contaminated pork. taeniasis has mild symptoms, including abdominal pain, nausea, diarrhea, or constipation. drugs are used to treat both diseases. infection can be prevented through stricter meat-inspection standards, livestock confinement, improved hygiene and sanitation, health education, safe meat preparation, and identifying and treating human and pig carriers. trachoma main article: trachoma there are 21.4 million people infected with trachoma, of whom 2.2 million are partially blind and 1.2 million are blind. it is found in africa, asia, central and south america, the middle east, and australia. the disease disproportionately affects women and children. the mortality risk is very low, although multiple re-infections eventually lead to blindness. the symptoms are internally scarred eyelids, followed by eyelids turning inward. trachoma is caused by a micro-organism that spreads through eye discharges (on hands, cloth, etc.) and by "eye-seeking flies". it is treated with antibiotics. the only known prevention method is interpersonal hygiene. chromoblastomycosis and other deep mycoses main article: chromoblastomycosis scabies this section is an excerpt from scabies. magnified view of a burrowing trail of the scabies mite. the scaly patch on the left was caused by scratching and marks the mite's entry point into the skin. the mite has burrowed to the top-right, where it can be seen as a dark spot at the end. scabies (/ˈskeɪbiːz, ˈskeɪbiiːz/; also sometimes known as the seven-year itch) is a contagious skin infestation by the mite sarcoptes scabiei. the most common symptoms are severe itchiness and a pimple-like rash. occasionally, tiny burrows may appear on the skin. in a first-ever infection, the infected person usually develops symptoms within two to six weeks. during a second infection, symptoms may begin within 24 hours. these symptoms can be present across most of the body or just certain areas such as the wrists, between fingers, or along the waistline. the head may be affected, but this is typically only in young children. the itch is often worse at night. scratching may cause skin breakdown and an additional bacterial infection in the skin. snakebite envenoming main article: snakebite snakebite was added to the list in 2017, after years of criticism of the who by activists for not making it a priority. the greatest burden of snakebite