• Many infectious diseases that are endemic in foreign countries can be prevented by vaccination. Vaccination is a valuable preventative measure. However, it is estimated that only 10% of travel related illness is preventable by vaccination:
• Travel to subtropical or tropical destinations is becoming more common, and potentially dangerous diseases are more likely to be endemic in these areas.
• Extended holidays abroad are becoming more popular, and may increase exposure to tropical diseases. In addition, holidays involving travel in rural areas and adventure travel can increase the likelihood of contracting an infection, and medical treatment may be hard to obtain.
• A traveller can greatly reduce the risk of contracting certain infections by being vaccinated against them beforehand.
• Some countries require an International Certification of Vaccination as a condition of entry. Many countries will not accept travellers who have recently visited areas (parts of Africa and South America) in which yellow fever occurs unless they can prove that they have been vaccinated or are medically exempt from yellow fever vaccination. Saudi Arabia requires proof of vaccination against meningococcal meningitis ACW135Y prior to visits for Hajj Umrah pilgrims.
• Travellers contracting tropical diseases abroad and importing them back to the United Kingdom pose a significant problem. Many diseases, such as typhoid fever, are occasionally notified in the United Kingdom but are usually contracted abroad. General practitioners are encouraged to report and refer to specialist centres those returned travellers who may have symptoms of tropical disease.

[DH, 2006a; NaTHNaC, 2010b]