Athletes and their support staff increasingly travel to competitions and camps where infections uncommon in the UK are a real risk. Most are preventable, and several, travellers' diarrhoea above all, are common and performance-limiting enough to derail a trip. For the sport and exercise medicine (SEM) clinician, preparing a travelling squad sits alongside injury care in protecting health and performance. This topic covers the four areas that matter most: travellers' diarrhoea, pre-travel immunisation, malaria prevention, and insect bite avoidance and vector-borne disease, with the thread that preparation weeks before departure prevents most problems.
Travellers' diarrhoea (TD) is the most common illness in travellers, usually bacterial, most often from enterotoxigenic Escherichia coli, and typically caught from contaminated food or water. It is generally self-limiting over a few days, but the fluid and electrolyte loss, cramps and disturbed sleep can badly affect training and competition, and dehydration in a hot climate compounds it.
Prevention rests on sensible food and water hygiene and good hand hygiene, though even careful travellers are often affected. The mainstay of management is rehydration, using oral rehydration solution (ORS) where losses are significant, and most cases need nothing more. In sport this matters twice over, because intravenous infusions of more than 100 millilitres in 12 hours are prohibited under anti-doping rules except as part of hospital care, so oral rehydration must stay the default and an intravenous drip in a hotel or team room would need a therapeutic use exemption. Loperamide can reduce stool frequency for short periods, for example around travel or competition, but is limited to about two days and avoided if there is blood or mucus in the stool, a high fever or severe abdominal pain. Antibiotics are not needed for most cases; a standby course, azithromycin in current UK guidance, is reserved for those at high risk of severe illness or heading somewhere remote, since routine use drives resistance.
Vaccination should be reviewed well ahead of travel, ideally four to six weeks before, both to allow protection to develop and because some courses need several doses over weeks. Routine UK immunisations are checked and brought up to date, and destination-specific vaccines are added according to the country and the activities planned, which may include hepatitis A, typhoid, hepatitis B, rabies, Japanese encephalitis, tick-borne encephalitis, cholera, meningococcal disease and yellow fever.
A few vaccines are live, including yellow fever, the measles, mumps and rubella (MMR) vaccine, varicella and oral typhoid, and these need particular care in anyone significantly immunosuppressed and may need spacing from one another. For athletes the practical point is timing: mild reactions such as a sore arm, malaise or a low-grade fever can interfere with a key session, so vaccines are best given with enough time before departure and away from important training or competition. Yellow fever is given only at designated centres, and proof of vaccination is required for entry to some countries.
Malaria is a serious and sometimes fatal infection from the bite of an infected mosquito, and many imported UK cases are linked to a failure to take recommended precautions. Prevention follows a simple framework often summarised as Awareness of risk, Bite avoidance, Chemoprophylaxis and prompt Diagnosis. No approach is completely protective, so all of these matter, and fever or a flu-like illness within a year of travel to a malaria area needs urgent, same-day testing, even if prophylaxis was taken.
Chemoprophylaxis is chosen for the destination, weighing drug resistance, length of stay, tolerability, cost and contraindications, and the timing differs by drug. Atovaquone with proguanil is started one to two days before travel and continued for one week after leaving, and is well tolerated. Doxycycline is started one to two days before and continued for four weeks after, and its main athlete-relevant drawback is photosensitivity, a real issue for those competing outdoors, along with stomach upset. Mefloquine is ideally started two to three weeks before and continued for four weeks after, and can cause neuropsychiatric effects such as vivid dreams, anxiety or low mood, so it is avoided with a relevant psychiatric history and reviewed carefully in athletes. Each is taken exactly as directed, including the continuation period after leaving the malaria area.
These infections are spread by mosquitoes, and for most the mainstay of protection is avoiding bites. Dengue, causing fever, headache, marked muscle and joint pain and a rash, is spread by Aedes mosquitoes, as are Zika and chikungunya. Vaccines are now available for selected travellers against dengue, mainly those with previous dengue infection, and against chikungunya, but none exists for Zika, so bite avoidance still matters for all three. Chikungunya can leave lasting joint pain, directly relevant to return to sport, and aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) are avoided until dengue is excluded because of the bleeding risk. Zika is usually mild but can seriously harm pregnancy and can be sexually transmitted, so it is an important part of counselling for athletes who are or may become pregnant, or whose partner is.
Bite avoidance uses repellents containing DEET (N,N-diethyl-meta-toluamide), covering exposed skin, treating clothing with permethrin, sleeping under an insecticide-treated net, and choosing screened or air-conditioned accommodation. Timing matters: the mosquitoes that carry malaria bite mainly from dusk to dawn, whereas the Aedes mosquitoes that carry dengue, Zika and chikungunya bite largely by day, so protection is needed around the clock rather than only at night.
Bringing this together, the SEM clinician arranges an early pre-travel review for the squad, individualised to each person's health, destination and role, covering vaccines, malaria measures, bite avoidance and a plan for managing diarrhoea. Any standby antibiotic is prescribed individually after a risk assessment, with written indications and cautions, rather than carried as unrestricted team stock, and every prescribed medicine is checked against anti-doping rules, for example using Global Drug Reference Online (Global DRO), before travel. A team kit still carries rehydration salts, simple analgesia and repellents. After an infection, return to full training is graded once the athlete has recovered and rehydrated, with particular patience where a viral illness has caused prolonged fatigue or joint pain.
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