Depending on the travel destination, travellers may be exposed to a number of infectious diseases; exposure depends on the presence of infectious agents in the area to be visited.
The risk of becoming infected will vary according to the purpose of the trip and the itinerary within the area, the standards of accommodation, hygiene and sanitation, as well as the behaviour of the traveller.
In some instances, disease can be prevented by vaccination, but there are some infectious diseases, including some of the most important and most dangerous, for which no vaccines exist.
General precautions can greatly reduce the risk of exposure to infectious agents and should always be taken for visits to any destination where there is a significant risk of exposure. These precautions should be taken regardless of whether any vaccinations or medication have been administered.
Modes of transmission of food- and waterborne disease
Food- and waterborne diseases are transmitted by consumption of contaminated food and drink. The risk of infection is reduced by taking hygienic precautions with all food, drink and drinking-water consumed when travelling and by avoiding direct contact with polluted recreational waters.
Examples of diseases transmitted by food and water are hepatitis A, typhoid fever and cholera.
Some facts on cholera:
Cause: Vibrio cholerae bacteria, serogroups O1 and O139.
Transmission: Infection occurs through ingestion of food or water contaminated directly or indirectly by faeces or vomitus of infected persons. Cholera affects only humans; there is no insect vector or animal reservoir host.
Nature of the disease: An acute enteric disease varying in severity. Most infections are asymptomatic (i.e. do not cause any illness). In mild cases, diarrhoea occurs without other symptoms. In severe cases, there is sudden onset of profuse watery diarrhoea with nausea and vomiting and rapid development of dehydration. In severe untreated cases, death may occur within a few hours due to dehydration leading to circulatory collapse.
Geographical distribution: Cholera occurs mainly in poor countries with inadequate sanitation and lack of clean drinking-water and in war-torn countries where the infrastructure may have broken down. Many developing countries are affected, particularly those in Africa and Asia, and to a lesser extent those in central and south America.
Risk for travellers: Very low for most travellers, even in countries where cholera epidemics occur. Humanitarian relief workers in disaster areas and refugee camps are at risk.
Prophylaxis: Oral cholera vaccines for use by travellers and those in occupational risk groups are available in some countries.
Precautions: As for other diarrhoeal diseases. All precautions should be taken to avoid consumption of potentially contaminated food, drink and drinking-water. Oral rehydration salts should be carried to combat dehydration in case of severe diarrhoea.
Source: WHO - Infectious diseases of potential risk for travellers
- Health24, updated November 2010