Improving the evidence base for pre-travel advice: the importance of surveillance of travel-associated infection.

WHY IS SURVEILLANCE OF TRAVEL-ASSOCIATED INFECTION IMPORTANT? Foreign travel by UK residents is increasing, especially to destinations with more tropical climates that are often lowincome countries with a high burden of infectious diseases. In 2003, 61.4 million visits abroad were made by UK residents; this is greater than the estimated UK population for that year and nearly three times the number of visits in 1983. Most visits are to European Union countries (around 70%), but the number of UK residents visiting more exotic destinations such as Africa, Asia, the Caribbean, and south and central America, increased annually by an average of 11% between 1995 and 2002 compared with only a 5% increase for Europe. These trends are likely to continue and through travel, UK residents are at risk of contracting infectious diseases to which they are not normally exposed in the UK. The increasing importance of travel-related illness has been highlighted by recent articles in the literature, and primary care is very often the first point of contact both for pretravel advice and for travellers returning to the UK with an illness. Primary care practitioners need the best quality information about specific risks associated with particular destinations, both to be able to advise the patients who consult them before they travel and also to be able to manage those who return unwell. The National Travel Health Network and Centre (NaTHNaC) was established in 2003 with the key goal of ‘protecting the health of British travellers’ by promoting clinical standards in travel medicine. To do this, NaTHNaC provides expert guidance and training for health professionals on pre-travel health issues, administration and quality assurance of yellow fever vaccination centres in England, and a telephone pre-travel advice service for queries about travellers with special health needs and those with complicated travel itineraries (Monday to Friday 9am–12pm and 2pm–4.30pm: 020 7380 9234). General travel advice information is also available free on the NaTHNaC website at http:// www.nathnac.org/ and is updated regularly. As part of NaTHNaC, the Travel Health Surveillance Section (THSS) at the Health Protection Agency, Communicable Disease Surveillance Centre was established to provide surveillance data on the number and types of illnesses in England, Wales, and Northern Ireland that are associated with travel. This is important both to improve the current evidence base on which pre-travel advice is given (for example, what immunisations are necessary for which destinations), and also to improve clinicians’ awareness of likely illnesses in returning travellers so that prompt and accurate diagnoses may be made. There are additional reasons why surveillance of travel-associated infection is important. Although estimates have been made, there is little accurate information available about the financial costs to the NHS, travellers and society that arise from travel-associated infectious disease. Good quality surveillance data may enable the costs associated with travel-associated diseases to be defined more accurately, and may help to determine the costeffectiveness of preventive measures. Furthermore, surveillance data helps to determine the most appropriate public health responses to imported infections in particular groups (for example, distinguishing between illness in new entrants to the UK, as opposed to illness acquired by UK residents through travel) or to global disease threats (for example, pandemic influenza or Severe Acute Respiratory Syndrome). In addition, for infections that can be contracted either in the UK or abroad, it is important to be able to determine how much disease is ‘home grown’ in order for public health