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Dracunculiasis -

Also known as Guinea worm disease, dracunculiasis is caused by a parasitic worm. A person becomes infected by drinking water containing water fleas infected with guinea worm larvae. Dracunculiasis is a neglected tropical disease (NTD). These are medical conditions that are mainly prevalent in tropical areas and typically affect people who live in impoverished communities.

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African trypanosomiasis -

African trypanosomiasis is a sleeping sickness caused by microscopic parasites transmitted by the tsetse fly. The disease occurs throughout sub-Saharan Africa.

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Onchocerciasis -

This NTD that's also known as "river blindness" is a major cause of visual impairment in the developing world. The disease is transmitted through repeated bites by blackflies. There is no effective vaccination or drug prophylaxis for onchocerciasis. Pictured clutching walking sticks are villagers in West Africa stricken with onchocerciasis.

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Schistosomiasis -

Schistosomiasis, also known as bilharzia, is an acute and chronic parasitic disease caused by blood flukes (trematode worms). The World Health Organization (WHO) recognizes schistosomiasis as the second most prevalent tropical disease after malaria. It's estimated that at least 90% of those requiring treatment for schistosomiasis live in Africa.

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Filarial lymphangitis -

Filarial lymphangitis is caused by an infection of thread-like parasitic worms, which are spread from person to person by mosquitoes. The worms reside in the lymph system. In extreme cases, the condition can develop into elephantiasis, a painful and profoundly disfiguring disease. According to WHO, filarial lymphangitis affects over 120 million people in 72 countries throughout the tropics and sub-tropics of Asia, Africa, the Western Pacific, and parts of the Caribbean and South America.

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Balantidiasis -

Balantidiasis is almost exclusive to the tropics and is usually passed to humans from animals, for example pigs and monkeys. Common symptoms include intermittent diarrhea and constipation.

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O'nyong'nyong virus -

O'nyong'nyong virus, the name of which comes from the Nilotic language of Uganda and Sudan, means "weakening of the joints" virus. Common symptoms of infection, spread by the bite of anopheline mosquitoes, are polyarthritis, rash, and fever.

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Brazilian purpuric fever -

Almost always affecting children under 10, Brazilian purpuric fever begins with a severe, pustular conjunctivitis, or pink eye. Untreated, life-threatening septicemia can develop.

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Chikungunya virus -

Occurring in Africa, the Indian subcontinent, and Southeast Asia, chikungunya virus is spread to people by the bite of an infected mosquito. Besides fever, sufferers typically display a stooped posture caused by joint pains.

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Leishmaniasis -

Female sand flies are responsible for the spread of leishmaniasis, a parasitic disease that is found in parts of the tropics, subtropics, and southern Europe. Leishmaniasis is classified as a NTD.

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Ciguatera -

Ciguatera is a foodborne illness that occurs after eating reef-dwelling fish who have fed on a particular type of toxic plankton. The fish most often implicated include grouper (pictured), barracuda, moray eel, amberjack, sea bass, and sturgeon.

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Eastern equine encephalitis -

A rare and infectious disease passed to people from vertebrates (typically horses) by mosquitoes, Eastern equine encephalitis is known in the Caribbean and parts of Central and South America. Isolated outbreaks have also been recorded along the eastern seaboard of the United States and Canada.

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Dengue fever -

Dengue fever is spread by the female Aedes aegypti mosquito (pictured). Outbreaks of the disease typically occur in most tropical and subtropical regions of the Far East, the Middle East, South America, and Africa. Symptoms include an alarmingly high temperature—40°C (104°F)—vomiting, and muscle, bone, or joint pain.

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Lassa fever -

Lassa fever is an acute viral illness spread by the common African rat. Prevalent in parts of West Africa including Sierra Leone, Liberia, Guinea, and Nigeria, the disease is extremely dangerous in anyone who is severely affected.

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Leptospirosis -

A bacterial disease that affects humans and animals, leptospirosis occurs anywhere in the world. In the tropics, outbreaks take hold during and after the rainy season. Dogs, pigs, and rats are the principle animal hosts to the microbes that cause it.

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Fasciolopsiasis -

The fasciolopsiasis fluke, or giant intestinal fluke, is commonly found in pigs and humans in south China, Taiwan, and across Southeast Asia. Heavy infections of this, the largest intestinal fluke found in humans, cause diarrhea, abdominal pain, and fever, among other symptoms.

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Rift Valley fever -

As its name suggests, this disease originates in Africa's Great Rift Valley region. A mosquito-borne viral hemorrhagic fever, the infection is mainly found in domesticated animals, but can strike down humans through contact with the meat, blood, and milk of infected livestock.

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Gnathostomiasis -

A worm infection contracted by eating raw freshwater fish contaminated with larvae, gnathostomiasis occurs mostly in Asia, but has also been recorded in Peru, Ecuador, and Mexico. Eels, frogs, birds, and reptiles can also carry the disorder.

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Tropical sprue -

Tropical sprue occurs throughout most of Asia, some Caribbean islands, certain areas of Africa and India, and pockets of South America. It's a malabsorption disease that causes interference in the absorption of some chemicals and nutrients from the small intestine.

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Mycetoma -

A serious condition, mycetoma is a chronic fungal infection relatively common in Africa, India, and Sri Lanka. It's caused by certain types of bacteria and fungi found in soil and water, and usually affects the skin, muscle, and bones of the lower leg.

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Trachoma -

According to WHO, trachoma is the commonest form of blindness. A bacterial infection that affects the eyes, it's caused by the bacterium Chlamydia trachomatis. Trachoma is contagious, spreading through contact with the eyes, eyelids, and nose or throat secretions of infected people. Most trachoma cases occur in poor areas of Africa.

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Oropouche fever -

A scourge of Brazil, Peru, Trinidad, and Panama, oropouche fever is transmitted to humans by the bites of midges and mosquitoes from the blood of sloths. Symptoms include sudden-onset of high fever with muscle and joint pains, intense headache, nausea, and diarrhea.

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Myiasis -

Myiasis is defined as the parasitic skin infestation of live vertebrates (humans and/or animals) by larvae of flying insects. The tumbu fly and Lund's fly in Africa, and the human bot fly (pictured) in Central and South America and the Caribbean are common vectors.

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Barmah Forest virus -

Named after the Barmah Forest in the northern Victoria region of Australia, Barmah Forest virus was first isolated in mosquitoes. It has gradually spread from the subtropical northern areas of Victoria to the coastal regions of New South Wales, Queensland, and Western Australia. While there is no specific treatment for infection with the Barmah Forest virus, the symptoms of which include fever, malaise, rash, and muscle tenderness, the disease is non-fatal and most infected people recover.

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Paragonimiasis -

Paragonimiasis is a dangerous food-borne parasitic disease caused by several species of lung flukes (flatworms). Larvae hatched in water develop in snails, crabs, or crayfish. Consuming an undercooked crustacean hosting the eggs can lead to the onset of paragonimiasis. The condition is often recorded throughout the Far East, parts of Africa, Southeast Asia, and Central and northern South America.

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Tungiasis -

Tungiasis is caused by a species of flea known as the chigoe. It occurs when the flea burrows into the skin and lays eggs. Tungiasis can cause abscesses, secondary infections, gangrene, and disfigurement. It's found in most tropical and subtropical areas of the world.

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West Nile fever -

West Nile fever is a tick and mosquito-borne virus often carried by birds. While it mostly occurs in Egypt, Israel, India, and Pakistan, the disease has also been recorded in eastern Europe and the northern Mediterranean, and North America.

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Yellow fever -

Almost all reported cases of yellow fever occur in Africa, but the disease is also endemic in South and Central America. It's caused by the yellow fever virus and spread by the bite of an infected mosquito. The condition is named for the sallow, yellowish complexion of the skin left by liver damage.

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Ross Valley virus -

So named for the river in northern Queensland where it was first identified, Ross Valley virus is endemic throughout Australia. It's spread to people by the bite of an infected mosquito. Illness is similar in nature to dengue fever, and there is no vaccination against the disease.

Sources: (WHO) (CDC)

See more: Stars who suffer from rare diseases

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