Malaria is a massive problem. There are 300-500 million cases a year, and close to one million people die of it annually. The parasite responsible is a master of disguise, readily fooling the body’s defences. The only real hope for eradication is through immunisation – and this possibility has recently moved one step closer.
How malaria operates
Malaria parasites are hard to detect. They go undercover immunologically seconds after entering the blood by way of a mosquito bite. They not only hide inside red blood cells or the liver, but their shape-shifting nature means that the body is always several days behind in finding, identifying and mounting a malaria-specific immune response. An ‘unprimed’ or naive body is hopelessly ill-equipped to defend itself.
The parasite’s most vulnerable at the moment of infection – when the mosquito bites. But it is only ‘naked’ and vulnerable in the blood for a matter of seconds.
Malaria symptoms take at least a week to appear; these include headache, fever, chills, muscle aches and weakness, vomiting, cough, diarrhoea and abdominal pain.
The malaria vaccine?
Huge reductions in cases and deaths have been achieved recently – more than 50% in the worst-hit African countries. This is at least in part due to the activities of the Roll Back Malaria partnership. This promotes rapid diagnosis and treatment, supply of insecticide-impregnated bednets (to 140 million homes), spraying and other strategies.
There is also a vaccine, developed by GlaxoSmithKline, which is contributing to a significant reduction in deaths in African children. This vaccine is a long way from being useful for travellers but, in November, Cambridge scientists announced a breakthrough that could be the first step to making a universally effective vaccine.
The scientists, led by Dr Julian Rayner, have identified the protein that the malaria parasite uses to unlock red blood cells and disappear beyond physiological surveillance. Interfering with this ‘key’ could be a route to rendering the malaria parasite impotent.
Even though this is exciting news, and progress continues on many fronts, it will be a long time before travellers can drop their guards and abandon preventative measures. Indeed, home-grown Plasmodium vivax malaria cases in northern Spain in 2010 and Greece in 2011 underline the fact that this disease isn’t going to go down without a fight.
In the meantime…
While we’re waiting for a world-changing malaria vaccine, it’s still vitally important to employ good malaria prophylaxis and know about the enemy we’re dealing with.
There are five different types of malaria (though some unfortunate victims can harbour two kinds at once). All malaria mosquitoes tend to bite between dusk and dawn, and avoidance strategies are similar for each. Here’s the lowdown…
1. The biggest killer: Plasmodium falciparum
Danger rating: High – this is the biggest killer globally. It can cause cerebral malaria. More than 1% of those infected die, even in hospital; away from good hospital care, the death rate is up to 20%. Approximately 1,200 cases are imported into the UK each year, of whom around eight die.
Where? So called ‘Tropical malaria’ – common in Africa and parts of Asia; most UK cases originate from West Africa.
Incubation & fever pattern: Incubation is usually between seven days and three months. Victims often experience frequent fevers within a three-day period.Recommended prophylaxis: Malarone, Lariam or doxycycline.
2. The most widespread: Plasmodium vivax
Danger rating: Rarely kills but wide-ranging. There are around 400 cases imported into the UK each year.
Where? Tropics, subtropics and some temperate regions (present in the UK until 1920s; found in Italy until Mussolini eradicated it in the Second World War); most UK cases originate from India and Pakistan.
Incubation & fever pattern: The disease can take months to emerge. When it does, victims suffer fevers about every third day.
Recommended prophylaxis: Malarone, Lariam or doxycycline; chloroquine in some regions.
3. The Old World foe: Plasmodium ovale
Danger rating: Generally benign; more than 100 cases brought back to the UK each year.
Where? Old World tropics and subtropics.
Incubation & fever pattern: The incubation period is often long. Victims suffer fevers every third day.
Recommended prophylaxis: Malarone, Lariam or doxycycline.
4. The slow burner: Plasmodium malariae
Danger rating: Generally benign; ten cases brought back to the UK each year.
Where? Tropics and subtropics.
Incubation & fever pattern: Incubation is often many weeks. Sufferers tend to experience fevers every fourth day.
Recommended prophylaxis: Malarone, Lariam or doxycycline.
5. The new killer: Plasmodium knowlesi
Danger rating: The newly recognised ‘monkey malaria’ is probably the most dangerous (at least 2% die) but a less common strain. No UK cases – so far.
Where? South-East Asia only.
Incubation & fever pattern: Symptoms appear nine to 12 days after the infective bite. It takes only 24 hours for each generation of parasites to replicate, which is why the disease is so much quicker and more deadly.
Recommended prophylaxis: Chloroquine.
Malaria in numbers
40% Proportion of the world’s population is at risk of malaria
3-5 million malaria cases a year
50 Number of UK travellers who brought home malaria from The Gambia in 2010, most of these between Nov-Dec; roughly 36% had not taken antimalarials
109 countries currently considered malarious
1 million die of malaria a year, mostly the under fives in sub-Saharan Africa
125 million people a year from non-malarious countries that visit malaria-endemic areas, of whom around 30,000 contract malaria 1,500 metres
Risk is less above this altitude, although with favourable conditions malaria can be spread at altitudes up to almost 3,000m
The A B C D of avoidance
Awareness: know if malaria is a risk at your destination (see www.nathnac.org or www.fitfortravel.nhs.uk)
Bite Avoidance: apply repellent at dusk; sleep under an impregnated net
Comply: take the right pills (see prophylaxis info on right-hand page)
Diagnosis: report any fever symptoms to a doctor if you’ve also been to a malaria zone
Dr Jane Wilson-Howath’s How to Shit Around the World has been updated and is back in print.
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