During travel in tropical and subtropical regions, a number of diseases can be transmitted by mosquitoes, sand flies, tsetse flies and other insects. Some of these diseases can be prevented by vaccination or medication, but protection against insect bites remains one of the most important preventive measures.

Malaria

Malaria is a serious infectious disease caused by parasites and transmitted by mosquitoes. It occurs particularly in large parts of Africa, but also in parts of Asia, Central and South America and the Indian subcontinent.

Symptoms may resemble influenza and include fever, chills, headache, muscle aches, nausea and a general feeling of illness. Severe malaria can develop rapidly, cause serious complications and become life-threatening within a short period of time. Prompt diagnosis and treatment are therefore essential.

Japanese Encephalitis

Japanese encephalitis is a viral infection transmitted by mosquitoes, primarily in parts of Asia and the western Pacific. Risk is generally greatest in rural and agricultural areas, particularly where rice cultivation and pig farming are common. Most people who become infected have no symptoms or only mild illness, but a small proportion develop encephalitis, which can cause severe neurological complications or death.

Vaccination may be recommended for longer stays in risk areas and may also be considered for shorter trips when the itinerary, season, destination or planned activities increase the risk of exposure. Vaccinated travellers should still protect themselves against mosquito bites.

Yellow Fever

Yellow fever is a viral disease transmitted by mosquitoes in tropical parts of Africa and Central and South America. The disease can be very serious and, in severe cases, cause jaundice, liver and other organ failure, bleeding and death.

Dengue Fever

Dengue is caused by viruses transmitted by mosquitoes and occurs widely throughout tropical and subtropical regions, including parts of Asia, Africa, the Caribbean, Central and South America and the Pacific. The mosquitoes that transmit dengue are common in urban as well as rural environments and are primarily active during the daytime, with particularly intense biting activity often occurring in the early morning and late afternoon.

Common symptoms include high fever, headache, pain behind the eyes, muscle and joint pain, nausea and skin rash. Most people recover, but some develop severe dengue, which can cause bleeding, shock and other serious complications.

Dengue vaccines are available in some countries, but recommendations, approved age groups and eligibility vary between countries and vaccines. Vaccination may be appropriate for some travellers depending on previous dengue infection, destination, age and individual risk. Advice should therefore be obtained from a vaccination clinic or other healthcare professional familiar with current recommendations.

Chikungunya

Chikungunya is transmitted by mosquitoes and occurs in many tropical and subtropical regions. The illness typically begins suddenly with fever and often severe joint pain, together with headache and muscle pain. Joint symptoms can sometimes persist for months or longer.

There is no specific antiviral treatment for chikungunya, making protection against mosquito bites particularly important. Vaccines against chikungunya are available in some countries. Vaccination may be recommended or considered for certain travellers, particularly during outbreaks or when the destination, duration of travel and individual risk increase the likelihood or consequences of infection.

Zika Virus

Zika virus is transmitted mainly by mosquitoes and occurs in tropical and subtropical regions. Infection often causes no symptoms at all. When symptoms occur, they are usually mild and may include fever, skin rash, conjunctivitis and joint pain. Zika virus can also be transmitted sexually.

Other Insect-Borne Diseases

Sand Fly Fever

Sand fly fever is a viral infection transmitted by sand flies and occurs in parts of the tropics and subtropics as well as in some areas around the Mediterranean. The illness typically causes fever, headache and muscle pain and usually resolves within several days to about a week.

Leishmaniasis

Leishmaniasis is caused by parasites transmitted by sand flies. Sand flies are small and often fly close to the ground, although bites are not limited to the feet and lower legs. The most common form in travellers is cutaneous leishmaniasis, which can cause persistent skin sores that may take a long time to heal. The disease is uncommon among ordinary tourists but the risk may increase with longer stays, outdoor activities or accommodation that provides limited protection against sand flies.

African Sleeping Sickness

African sleeping sickness (African trypanosomiasis) is transmitted by tsetse flies and occurs in parts of sub-Saharan Africa. Infection in travellers is very rare, but the disease is serious and requires medical treatment.

Chagas Disease

Chagas disease occurs mainly in parts of Latin America and is caused by a parasite that can be transmitted by triatomine bugs. These insects may live in cracks in the walls and roofs of certain types of rural housing. The risk to most travellers is very low but may be higher during prolonged stays in poorly constructed accommodation in endemic areas.