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Thursday, 10 January, 2002, 11:30 GMT
Tropical diseases
Medical workers
Ebola hit the Democratic Republic of Congo in 1995
Health experts warn that tropical diseases pose an increasing problem for the UK.

BBC News Online examines the diseases which are thought to pose the biggest threat.


Malaria kills more people than any other communicable disease except tuberculosis.

It is caused by four species of a single-celled parasite called the Plasmodium protozoa.

These bugs are transmitted to humans by the bite of an infected mosquito.

Most people survive a bout of malaria after a 10-20 day illness, but it is important to spot the symptoms early. The first is high fever, followed a few hours later by chills. Two to four days later, this cycle is repeated.

The most serious forms of the disease can affect the kidneys and brain and can cause anaemia, coma and death.

Malaria is a problem throughout Africa, south Asia and South America.

Dengue fever:

Dengue fever is another disease that is spread to humans from mosquitoes.

It is caused by four distinct, but closely related, viruses.

It is a severe, flu-like illness that affects infants, young children and adults but rarely causes death.

Symptoms of the disease vary, but can include high fever, severe headache, pain behind the eyes, muscle and joint pains, and rash.

Dengue haemorrhagic fever is a potentially deadly complication that can lead to an enlargement of the liver and, in severe cases, failure of the circulation system.

Dengue fever is found in Africa, Southeast Asia and China, the Indian sub-continent, the Middle East, South and Central America, the Caribbean and Australia.


Schistosomiasis, also known as bilharziasis, is a parasitic disease that leads to chronic ill health.

The main forms of human schistosomiasis are caused by five species of flatworms, or blood flukes, known as schistosomes. People are infected by contact with infested water.

Urinary schistosomiasis, which is indicated by the presence of blood in the urine, can lead to bladder cancer or kidney problems.

Intestinal schistosomiasis, a tell-tale sign of which is bloody diarrhoea, can lead to serious complications of the liver and spleen.

Schistosomiasis is found in Africa, Latin America, the Caribbean, the Middle East and South East Asia.

Sleeping sickness:

Sleeping sickness (also called trypanosomiasis) is an infection caused by the single-celled Trypanosoma protozoa.

It is passed to humans through the bite of the tsetse fly.

The first sign of infection may be a sore appearing at the site of the tsetse fly bite about two to tree days after having been bitten.

Two to three weeks later, fever develops, often accompanied by an intensely itchy rash. Other symptoms include headache, mental confusion, swelling of the lymph tissue and enlargement of the spleen and liver.

Eventually, the patient's speech becomes slurred, mental processes slow, and the patient sits and stares for long periods of time, or sleeps.

Untreated, these symptoms eventually lead to coma and then to death.

Sleeping sickness is a particular problem in sub-Saharan Africa, where more than 66m people have the disease.


Ebola is a deadly disease caused by a virus.

Very often, flu-like symptoms such as a sore throat, headache and high temperature are the first sign of infection.

This is followed by nausea, vomiting and diarrhoea.

The victim may start to become delirious and dehydrated. They can begin to bleed internally, either from the major organs themselves or from tiny blood vessels, the digestive tract and gums.

Eventually, this can cause enough blood loss to cause shock and respiratory problems, leading quickly in many cases to death.

Outbreaks of Ebola have occurred in Africa.

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