Briefing: travellers at risk from drug-resistant malaria
News that the leading antimalarial drug failed to cure four British tourists has sparked fears that the mosquito-borne parasite that causes the disease has developed resistance to current treatments. In a study published last week, the London School of Hygiene and Tropical Medicine said that, for the first time, artemisinin had proved powerless against infections in the four patients, who had recently returned from Africa.
The findings added to concern that drug-resistant malarial “superbugs” are gaining ground in a number of tropical countries — many of them popular tourist destinations.
So how bad are the risks? “This is an early sign and we need to take it quite seriously, as it may be snowballing into something with greater impact,” says Dr Colin Sutherland, who led the study. “It absolutely doesn’t mean travellers should avoid these countries. But malaria is a very serious disease and travellers heading into those areas should be very serious about the precautions they take.”
Malaria is endemic in 91 countries, in regions as diverse as South America, the Caribbean and Southeast Asia. Popular holiday destinations where it is a significant risk include the Dominican Republic, Jamaica, Peru, Burma and almost all of sub-Saharan Africa.
In a paper published in the Lancet Infectious Diseases last week, researchers from the University of Oxford warned that an artemisinin-resistant variant of malaria has become the dominant strain in parts of Thailand, Laos and Cambodia.
There is a very low risk of contracting milder versions of the disease in Greece and Turkey, but otherwise malaria does not occur in Europe. (For a full country guide, see fitfortravel.nhs.uk.) Infection rates vary from country to country and season to season, with transmission much reduced during dry periods — but while some tourist authorities play down the risks, the advice from official agencies such as the National Travel Health Network and Centre (NaTHNaC) is unequivocal: if malaria is present, it’s present all year round, regardless of the weather.
Symptoms of malaria may not appear until months after infection, so many travellers do not realise they are ill until they’re back home. Fever, chills, diarrhoea and hot sweats are the most common early signs. If untreated, the parasites target red blood cells, causing anaemia and compromising blood flow to vital organs. The most severe cases can lead to coma and death.
No malaria tablet is considered 100% effective
Infection levels in a number of popular destinations are alarming: in Kenya, for example, the WHO estimated 6.5m infections and 12,000 deaths in 2015. Yet the gobal risk to British travellers is still relatively low. Government figures show that 1,400 returned from overseas with the parasite in 2015, of whom six died.
Despite the evidence that malaria is becoming resistant to certain drugs, there are still other treatments that are usually effective. But, as Dr Dipti Patel, of NaTHNaC, says: “Prevention is always better than cure. You should never rely on being treated for malaria after you come home.”
So, how can travellers protect themselves against infection? A range of prophylactic drugs is available, including Malarone, doxycycline and Lariam, and with reputable online pharmacies such as Boots.com, Superdrug. com and Lloydspharmacy. co.uk offering click-through consultations, obtaining effective medication has never been so easy. While these drugs are recommended, they offer widely varying levels of protection, and some can have unpleasant side effects, from heartburn to panic attacks. Lariam, in particular, has been associated with cases of severe anxiety, depression and even hallucinations.
Fitfortravel.nhs.uk warns that “no malaria tablet is considered 100% effective”, so avoiding mosquito bites remains essential. Effective measures include wearing long-sleeved clothing and long trousers (Craghoppers’ Nosilife-impregnated shirts are especially good), using diethyltoluamide (Deet)-based insect repellent and sleeping beneath insecticide-treated bed nets. And by taking measures to avoid being bitten at all times of the day and night, regardless of the malaria risk, you’re also minimising the chances of contracting the full range of exotic mosquito-borne diseases, including dengue fever, chikungunya and the zika virus.
Alternative measures, such as eating garlic, taking large doses of vitamin B and the use of ultrasonic mosquito deterrents, are unlikely to prevent bites. As for citronella, widely touted as a natural alternative to Deet, a 2011 study in the US concluded that “travellers to disease-endemic areas should not be recommended citronella-based repellents”.