It's a trick question beloved by travel health medics: What's the most dangerous animal in Africa?
Lion? Croc? Hippo? Snake?
Fearsome beasts, but the puny mosquito beats them all. Or more precisely, the even tinier malaria parasite the mosquito carries.
Malaria is the disease Travel Doc gets asked about most by readers heading into Africa, and with good reason. Of the million-plus people malaria kills and the hundreds of millions more it sickens annually, 90% are African.
Especially vulnerable are small children, pregnant women, HIV-positive people – and travellers from malaria-free areas. If your body has never encountered the disease, your immune system has no experience in fighting it, making you poorly-defended territory to invasion by the parasite.
The reason inhabitants of malarial areas don't take prophylaxis (malaria prevention drugs) is because it's impractical and expensive to do so long-term. But it's also because they've usually survived a few bouts and have built up some immunity.
Travellers are vulnerable
Travellers from outside the malaria high-danger zone have no such protection, and each year thousands contract this life-threatening disease. But you can drastically lower your risk:
Check in advance with your doctor whether your destination falls into a malaria zone or season. These areas shift, so get the latest expert advice. Most endemic areas are tropical or sub-tropical, but as mosquitos spread due to climate change, malaria transmission may increase, “engulfing” countries like Zimbabwe in coming decades. Greece, which last had malaria in 1974, has seen several cases this year.
Take prophylaxis. You should only risk not doing so (and most doctors will advise against this) if you're going to be indoors at night in an air-conditioned, mosquito-free building.
Even on prophylaxis, always avoid bites: use nets and sprays, wear long trousers and sleeves, and stay indoors dusk to dawn if possible.
Know the symptoms and monitor your health closely in the month following your trip.
Don't take kids under 5 into malarial areas, but if you must, put them on paediatric anti-malarials. Also avoid these areas if you're pregnant or immunocompromised e.g. if you have HIV/Aids or are on chemotherapy.
- Olivia Rose-Innes, Enviro and Travel Health Editor, Health24, updated April 2012