Travel related health conditions can be more serious in very young or old patients. For example, children under the age of five years are at an increased risk of being bitten by insects or contracting travellers' diarrhoea. Elderly people and young children are also more susceptible to the effects of dehydration.

Diarrhoea and vomiting, especially in combination with high temperatures can quickly dehydrate a child. In very young children diarrhoea, sunburn and vomiting can be more serious than for older travellers.

Children are also at increased risk of severe or fatal malaria. Appropriate bite avoidance techniques are essential and in areas where malaria is endemic, children should be given appropriate chemoprophylaxis. The dose of chemoprophylaxis should be calculated on a weight basis according to the doses in the BNF or the Summary of Product Characteristics (SPC).

Age limits can apply to certain vaccines and antimalarial drugs that preclude their use in very young children. For example, Dukoral cholera vaccine is only recommended for children over 2 years of age whilst Japanese Encephalitis vaccine is only licensed for children aged two months and over. Parents should be advised to think carefully and to take specific advice regarding the health risks associated with travel for a young child.

Older patients are more likely to have a compromised immune system which puts them at an increased risk of infection such as influenza, meningitis or tuberculosis. They are also more likely to suffer from pre-existing medical conditions that can be aggravated or exacerbated by travelling and necessitate medical treatment whilst abroad. Increasing age also reduces the immune response to vaccination resulting in only partial protection.

Elderly travellers may struggle to cope with high temperatures and humidity as the ability to thermoregulate deteriorates with increasing age. Dehydration caused by the warm humid climate can increase the risk of postural hypotension, which may be aggravated by medication such as diuretics taken for hypertension. Postural hypotension can be an added risk factor for travellers on boat trips or cruise ships, increasing the possibility of a fall.

Elderly travellers should be advised to:

• Check medical facilities before travelling including the availability of replacement medication.
• Ensure facilities are available for the safe storage of medication.
• Assess medication requirements and adjustments for time differences.
• Liaise with their travel provider regarding any special requirements, e.g. provision of a wheelchair.
• Be aware of exercise and mobility to reduce risk of thrombosis.
• Prepare for extremes of climate or environment.
• Ensure they have comprehensive travel insurance.