Infectious diseases of potential risk for travellers
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, regardless of whether any vaccinations or medication have been administered.
Modes of transmission and general precautions
The modes of transmission for different infectious diseases and the corresponding general precautions are outlined in the following paragraphs.
- Foodborne and waterborne diseases
- Vector-borne diseases
- Zoonoses (diseases transmitted by animals)
- Sexually transmitted diseases
- Bloodborne diseases
- Airborne diseases
- Diseases transmitted via soil
Specific infectious diseases involving potential health risks for travellers
The main infectious diseases to which travellers may be exposed, and precautions for each, are detailed on the following pages. Information on malaria, one of the most important infectious disease threats for travellers, is provided in Chapter 7. The infectious diseases described in this chapter have been selected on the basis of the following criteria:
- diseases that have a sufficiently high global or regional prevalence to constitute a significant risk for travellers;
- diseases that are severe and life-threatening, even though the risk of exposure may be low for most travellers;
- diseases for which the perceived risk may be much greater than the real risk, and which may therefore cause anxiety to travellers;
- diseases that involve a public health risk due to transmission of infection to others by the infected traveller.
Information about available vaccines and indications for their use by travellers is provided in Chapter 6. Advice concerning the diseases for which vaccination is routinely administered in childhood, i.e. diphtheria, measles, mumps and rubella, pertussis, poliomyelitis and tetanus, and the use of the corresponding vaccines later in life and for travel, is also given in Chapter 6. These diseases are not included in this chapter.
The most common infectious illness to affect travellers, namely travellers’ diarrhoea, is covered in Chapter 3. Because travellers’ diarrhoea can be caused by many different foodborne and waterborne infectious agents, for which treatment and precautions are essentially the same, the illness is not included with the specific infectious diseases.
Some of the diseases included in this chapter, such as brucellosis, HIV/AIDS, leishmaniasis and TB, have prolonged and variable incubation periods. Clinical manifestations of these diseases may appear long after the return from travel, so that the link with the travel destination where the infection was acquired may not be readily apparent.
The list below does not include vaccine-preventable diseases (Chapter 6).
- Haemorrhagic fevers
- Hantavirus diseases
- Hepatitis C
- Hepatitis E
- HIV/AIDS and other sexually transmitted infections
- Leishmaniasis (cutaneous, mucosal and visceral forms)
- Leptospirosis (including Weil disease)
- Lyme Borreliosis (Lyme disease)
- Lymphatic filariasis
- SARS (Severe Acute Respiratory Syndrome)
- Schistosomiasis (Bilharziasis)
- Typhus fever (Epidemic louse-borne typhus)
- Zoonotic influenza