The immunocompromised traveller.
Increasing numbers of immunocompromised people are travelling abroad to areas where the risks of some infections are increased. HIV positive people respond reasonably well to most vaccines when asymptomatic but response is less predictable when symptomatic disease is present. Generally, live vaccines should be avoided in all stages of HIV disease. Patients with anatomic or functional asplenia are at particular risk of severe sepsis due to encapsulated bacteria and from malaria. They should be immunised against the pneumococcus, meningococcus, and haemophilus and should avoid travel to areas where the probability of malaria transmission is high. Patients receiving cancer chemotherapy or transplant recipients on long-term immunosuppression should avoid live virus vaccines but may benefit from bacterial polysaccharide vaccines such as the pneumococcal vaccine. All patients with potentially impaired immunity should be assessed on an individual basis in terms of the risks and benefits involved in travel and available prophylactic measures. Immunisations useful in their native regions can be reviewed at the same time. Such travellers should carry a physician's letter and contact address in case of medical problems encountered abroad.