Travellers

Antimalarial guidelines - advising travellers

Precautions

There are four key principles of malaria protection:

Be aware of the risk, incubation period and main symptoms
Make sure that all non-immune travellers to endemic areas are aware of the risk of malaria in the areas they visit. This includes previously semi-immune travellers who may have lost immunity during stays of 6 months or more in non-endemic areas. The risk of travellers contracting malaria varies highly from country to country and even between areas in a country. If specific information is not available before travelling, it is recommended that travellers prepare as if the highest reported risk for the area or country applies throughout. This applies particularly to individuals backpacking to remote places and visiting areas where diagnostic facilities and medical care are not readily available. Travellers staying overnight in rural areas may be at highest risk.

Children of people who have migrated to non-endemic areas are particularly at risk when they return to malarious areas to visit friends and relatives. Emphasise that they should take action to reduce the risk, and seek medical advice urgently if they develop a fever or flu-like symptoms. Travellers should understand that malaria can be treated effectively early in the course of the disease, but that a delay in treatment can have serious or fatal consequences.

Avoid being bitten by mosquitoes, especially between dusk and dawn
Explain to all travellers that individual protection from mosquito bites between dusk and dawn is their first line of defence against malaria. Suggest that they take the following personal protective measures to avoid bites by mosquitoes:

• Sleep in rooms that are properly screened with close-fitting gauze over windows and doors, no holes in the gauze, and no unscreened entry points.
• Spray the room with a knockdown insecticide before evening to kill any mosquitoes that may have entered the room during the day.
• Use mosquito nets around the bed at night when sleeping outdoors or in an unscreened room, checking that there are no holes in the net. The net should be impregnated with pyrethroids, for example, permethrin 0.2g/m² of material every 6 months, and should be long enough to fall to the floor all round the bed or be tucked under the mattress.
• Vaporise synthetic pyrethroids overnight, using an electrically heated mat. Alternatively mosquito coils (slow burning mixture of repellent and insecticide) may be burned. Electronic buzzers are sometimes marketed as repellents, but do not work.
• Wear long-sleeved clothing, long trousers, and socks out of doors after sunset. Light colours are less attractive to mosquitoes.
• Apply insect repellents containing over 10% DEET to exposed skin. Do not, however, exceed the manufacturer’s recommendations, particularly with small children. Impregnating cotton garments with 30 ml of DEET in 250 ml of water makes them repellent. Refined lemon eucalyptus oil on skin also repels mosquitoes.

Travellers should take antimalarial drugs (chemoprophylaxis and/or standby emergency treatment) when appropriate to the risk and destination(s), to prevent infection developing into clinical disease. Note that most cases of malaria in travellers occur because of poor compliance with prophylactic drug regimens, or use of inappropriate medicines or no chemoprophylaxis at all, combined with poor prevention of mosquito bites. Locally purchased antimalarials are often suspect, due to the high level of counterfeiting in some countries.

Seek diagnosis. Travellers should immediately seek diagnosis and treatment if a fever develops one week or more after entering an area where there is a malaria risk, and up to 3 months after departure from a risk area.

Also see Riamet^®

Healthcare workers should avoid giving unnecessary medication and be aware of contraindications. The choice of drug will depend on previous history, presence of pregnancy, relevant family history, and concomitant illness or medication.

Note: In high-risk areas prophylaxis may be recommended. Nevertheless, it is now accepted that chemoprophylaxis in multi-drug resistant areas is often ineffective. Even in less hazardous areas, variability of transmission rates within a single country mean that it is not always possible to decide upon the risk of contracting the disease. In addition, people may travel at short notice from areas of low transmission to areas of much higher risk. Therefore, it is prudent for travellers to countries with any significant malaria risk to carry standby emergency treatment with them. This is particularly true if they are visiting areas with a significant risk of multidrug-resistant malaria.

If chemoprophylaxis is required, the choice of drug for a particular traveller depends on an assessment of the following variables: ²

• countries and localities to be visited and their malaria risk, which may vary during the year
• whether destination is rural or urban
• type of accommodation
• duration of intended stay in malarious areas
• activities (beach/jungle explorations/safaris, etc.), particularly between dusk and dawn, when the risk of being bitten is greater
• style of travel (business/backpacking/package tour/visiting relatives, etc.)
• age, sex, pregnancy and intended conception, breastfeeding
• weight of young children, a better guide than age to the dose of antimalarials
• previous travel and experience with antimalarials
• previous reaction to an antimalarial drug
• sensitivity patterns or drug resistance in intended area of travel
• current illnesses (renal and hepatic function, cardiac conduction, myasthaenia gravis, psoriasis)
• current medication (anticoagulants, anticonvulsants, cimetidine, cyclosporine, cardiac glycosides, cytotoxic drugs, antibacterials, probenecid)
• relevant previous illnesses or medication (fits, psychiatric disorders, drug reactions, psoriasis)
• family history of epilepsy in first-degree relatives
• history of psychiatric disorder, depression, anxiety requiring treatment.

When prescribing chemoprophylaxis make sure that the patient is aware that no antimalarial prophylactic regimen gives complete protection, but good chemoprophylaxis does reduce the risk of fatal disease. The following should also be taken into account¹ :

• Dosing schedules for children should be based on body weight.
• Antimalarials that have to be taken daily should be started the day before arrival in the risk area (but see below for weekly treatments).
• When first using weekly mefloquine it is advisable to start at least one week but preferably two to three weeks before travelling, to achieve higher pre-travel blood levels and so that if adverse events occur, there will be time to switch to an alternative before travelling.
• Antimalarial drugs must be taken with food and swallowed with plenty of water.
• All prophylactic drugs should be taken with unfailing regularity while in the malarious risk area and for 4 weeks after the last possible exposure to infection, since parasites may still emerge from the liver during this period. The single exception is atovaquone/proguanil, which can be stopped one week after return.