Malaria
Symptoms and effects: Malaria is a parasitic infection of the blood spread by the bites of the infected female anopheles mosquito, which tends to strike at dawn and dusk. Malaria produces fever alternating with chills, flu-like symptoms and, in some cases, complications affecting the kidneys, liver, brain and blood. If the condition is not correctly treated, the parasites may persist in the liver. The first attack can be delayed and relapses may occur over several years. Malaria can be fatal.
Areas at risk: Africa, Asia, India, Latin America and the Caribbean.
Prevention and cure: Avoid mosquito bites and take a course of anti-malaria tablets. Tablets are usually taken regularly from two or three weeks before travel and continued for four weeks after return from a region with malaria. Use insect repellent, preferably one containing DEET (diethyltoluamide). Keep your arms and legs covered after sunset.

SARS (Severe Acute Respiratory Syndrome)
Symptoms and effects: A new viral disease first reported in Asia in February 2003. About 11% of those who develop SARS will die, but the proportion is higher amongst the elderly. Symptoms include high fever of 38C or greater and one or more of the following respiratory symptoms: dry cough, breathing difficulties caused by shortness of breath and severe pneumonia. Other symptoms may include headache, muscular stiffness, loss of appetite, tiredness, confusion, rash and diarrhoea.
Areas at risk: Originated in China, but cases reported in several other countries all over the world.
Prevention and cure: Regular hand-washing could reduce the risk of infection. Isolation and specialist hospital treatment is required if infected.

West Nile virus
Symptoms and effects: Transmitted between birds, animals and humans by infected mosquitoes. West Nile virus is usually spread by the Culex mosquito which bites between dusk and dawn. Most people do not experience symptoms but a few will suffer from flu-like symptoms (headaches, fever, body aches). A small number (less than 1%) may experience severe illness with encephalitis or meningitis (swelling of the brain). This can cause severe headaches, disorientation, convulsions and coma. The disease can be fatal with over-50s most at risk.
Areas at risk: Africa, the Middle East, parts of the Far East, Russia and, more recently, Canada and the United States.
Prevention and cure: There is no specific treatment for West Nile virus. Infection is thought to lead to long lasting immunity.

Bilharzia
Symptoms and effects: Bilharzia is also known as schistosomiasis. It is caused by infestation by a type of flatworm, or fluke, which penetrates the human skin and matures into an adult. Female flukes may lay eggs that cause inflammation. Over a billion humans are at risk worldwide and approximately 300 million people are infected. Symptoms include muscle pains, diarrhoea, fever, vomiting, coughing, burning when passing urine, passing urine more frequently and blood in the urine. Untreated bilharzia may cause life-threatening urinary system or liver damage. It may also cause bladder tumours and bowel cancer.
Areas at risk: Africa, south-east Asia, the Caribbean, the Middle East and Latin America.
Prevention and cure: Avoid swimming or wading in fresh water when you are in countries in which schistosomiasis occurs. Drink safe water. Drug treatment is available if infection occurs.

Yellow fever
Symptoms and effects: Viral infection that causes flu-like illness. Symptoms are headaches, muscular pain and chills. In its most severe form, yellow fever can affect the liver, causing jaundice and bleeding. It is transmitted by mosquito bites. The death rate can be over 50% in western travellers.
Areas at risk: Principally a jungle disease, but there have been occasional outbreaks in cities and towns. The disease is found in Africa, the Americas, and parts of the Caribbean.
Prevention and cure: Vaccination gives almost 100% protection for up to 10 years. Avoid mosquito bites.

Dengue
Symptoms and effects: Virus transmitted by the Aedes aegypti mosquito, which bites during daylight hours. There is no direct person-to-person transmission. Monkeys act as a reservoir host in south-east Asia and west Africa. Symptoms are a sudden onset of fever, followed sometimes by a skin rash and severe muscular pains. For this reason it is also known as "breakbone fever". Most patients recover after a few days and the illness is rarely fatal. Dengue haemorrhagic fever (DHF), on the other hand, is a potentially deadly complication that can, in severe cases, result in circulatory failure.
Areas at risk: Dengue is widespread in tropical and subtropical regions of central and south America and south and south-east Asia. It also occurs in Africa. In these regions, dengue is limited to altitudes below 600 metres (2,000ft). DHF now occurs in most of Asia.
Prevention and cure: No specific treatment for dengue, but rest and painkillers can help relieve the symptoms. Aspirin is generally avoided. DHF sufferers need careful clinical management by experienced medical staff. With appropriate therapy, the mortality rate may be reduced to less than 1%.

Bird flu
Symptoms and effects: Bird flu, or avian influenza, is a viral disease which normally only affects birds (and, less commonly, pigs). On rare occasions, the virus has jumped to humans. Certain strains of the virus are more likely to be linked to serious disease in humans. Outbreaks caused by the H5N1 strain, currently present the greatest concern. When human cases of avian influenza have been reported, the illness has been severe (respiratory illness) and sometimes fatal (23 deaths out of 34 cases in the outbreak in early 2004).
Areas at risk: Vietnam, Thailand, China, Republic of Korea, Indonesia, Laos, Cambodia and Japan.
Prevention and cure: Avoid contact with livestock in outbreak countries. Wash hands regularly. Antiviral drugs have been used to manage human cases of bird flu.

Sleeping Sickness
Symptoms and effects: Sleeping sickness is transmitted by the bite of an infected tsetse fly. Tsetse flies are attracted to moving vehicles and will often follow safari trucks. First symptoms of the disease are seen at the site of the bite, where a painful nodule can develop. Fever, headache, enlarged lymph nodes and rashes may also be noted. If left untreated, the disease will progress to cause body wasting, sleepiness and eventually death.
Areas at risk: Africa
Prevention and cure: To prevent bites, keep the doors and windows of safari vehicles closed when possible. Kill any flies that enter with a "knock down" fly spray. Repellents offer limited protection. Drug treatments are available.

Tick fever
Symptoms and effects: Tick bite fever is caused by a bacterial infection transmitted by ticks. Symptoms vary but usually the illness is characterised by high fever, headache, rash and swollen lymph nodes.
Areas at risk: Africa, but also transmitted by domestic European ticks.
Prevention and cure: Wear long-sleeved garments, including trousers, in scrub land, pastures and forests. Use repellent on exposed skin. Ticks should be removed by gentle steady pulling, using tweezers or fingers protected by tissues. Take care to remove all of the tick as the mouth parts cause local infection if they are not fully removed. Apply antiseptic to the bite site and, if a tick has been touched with bare hands, wash thoroughly with soap and water. Infections respond well to treatment with antibiotics such as Doxycycline.

Ebola
Symptoms and effects: Ebola haemorrhagic fever (EHF) is a virus caused by the filoviridae family of viruses. The disease causes death in up to 90% of all cases. Transmitted by direct contact with the blood, secretions, organs or other bodily fluids of infected persons. Characterised by the sudden onset of fever, intense weakness, muscle pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, impaired kidney and liver function, and, in some cases, both internal and external bleeding.
Areas at risk: Zaire and Sudan.
Prevention and cure: None.