Malaria is a parasitic infection of the blood and is transmitted through bites from mosquitoes.
It kills over a million people worldwide each year and is second only to tuberculosis in its impact on world health.
The disease is present in 90 countries and infects one in 10 of the world's population at some point in their lives.
Three-quarters of all malaria cases are in sub-Saharan Africa where it is a main cause of death and a major threat to child health.
Avoiding being bitten by mosquitoes is the best way of avoiding malaria.
Keeping arms and legs covered by clothing in the evening; applying DEET repellent creams and sleeping under a special mosquito net are the best ways of discouraging insect bites.
But travellers should also ensure that they have the appropriate anti-malarial drugs for the specific region to which they are travelling.
Travellers can help to cut their risk by taking anti-malarial drugs before they leave on their trip.
Travellers should contact their GP at least a month before travel to get advice about which particular drugs to take for the areas that they are travelling to.
The tablets, which are taken in either daily or weekly doses, need to be started before travel and continued for up to a month after return from the malarial zone.
If spotted and treated quickly malaria can usually be completely cured.
Most UK travellers do survive a bout of malaria after a 10-20 day illness. Many of those who die do so because the disease has not been spotted early enough.
The death rates are high in areas of sub-Saharan Africa, where medical expertise and malarial drugs are limited.
It is vital that anyone getting "flu-like symptoms" after the first week in a malarious region and for up to a year after returning home should mention this to their GP so that he can organise a test for malaria.
Symptoms of the disease include flu-like illness, diarrhoea, joint pains and fever.