Malaria is a major killer and deserves respect. Every year between 350 and 500 million people suffer the effects of Malaria and 1 million die (predominantly in sub-Saharan Africa). Yet many travellers ignore the need to take anti-malarial medication or fail to take it properly. Of 80 million travellers to areas with a high malaria risk, 30,000 will contract the disease .
What is malaria?
Malaria is a disease caused by a protozoan parasite called Plasmodium transmitted by a bite from the Anopheles mosquito.
How is Malaria Spread?
Malaria in humans is caused by four different types of parasite:
- P. falciparum – A common and dangerous form, sometimes called malignant malaria, which is found in sub-Saharan Africa, New Guinea, the Amazon basin and increasingly in the Indian subcontinent.
- P.vivax - Persistent but not life-threatening, and common in the Indian subcontinent.
- P.ovale - Benign form of malaria common in Africa.
- P.malariae - Another benign form that occurs everywhere but only rarely.
Plasmodium falciparum kills - sometimes rapidly. The others cause fever and can be difficult to cure but do not kill.
The ABCD approach is key to avoiding malaria.
- A - awareness and advice
- B - bite prevention
- C - chemoprophylaxis
- D - diagnosis
A - awareness and advice
Malaria occurs throughout the world in tropical areas. The symptoms of malaria can be vague and any feverish illness should be taken seriously when travelling to a malarious area. It is sensible to look at advice for individual countries, but as a general rule:
Higher risk West Africa, Solomon Islands, New Guinea, Amazon basin
Moderate risk East and southern Africa, South America, Indian subcontinent
Lower risk South-east Asia (with exceptions), Central America
Travel in rural areas, jungle trips and treks, particularly with outdoor sleeping, increases the risks. High altitude may eliminate risk – there is no risk of malaria in Nairobi, Addis Ababa or Machu Picchu because they are so far above sea level.
The risk of malaria varies according to season. Mosquitoes breed in water and thrive after rainy seasons or monsoons.
B - bite avoidance – how to prevent malaria
- bite at dusk (though African ones bite later than Amazonian ones)
- are attracted by dark colours
- are attracted by exhaled carbon dioxide
- like large male adults
For Malaria control, travellers should wear white, long sleeves and trousers in the evening to minimise risk. Loose-fitting clothes are more difficult for mosquitoes to bite through.
Repellents such as DEET, which can be used from 3 months of age, and Autan Active can be effective at preventing bites. Eucalyptus citriodora may be a good natural alternative.
Nets are an excellent way of reducing bites, particularly when impregnated with deltamethrin. Nets can be bought from camping shops, travel clinics or on-line. Travellers should practise putting them up.
Insecticides are useful in hotel rooms. A knock-down spray will kill insects and a coil or electrical device that vaporises an insecticide will reduce the chances of being bitten.
C - chemoprophylaxis
Medication must be taken as directed to gain the benefits of effective chemoprophylaxis. It is important that patients understand the benefits and risks of the medicine.
Chloroquine (2 x 150mg tablets weekly) and proguanil (2 x100mg tablets daily)
- can be bought over the counter
- mainly used where P.vivax is the main risk
- not particularly effective except in certain areas with low risk of resistance or of P.falciparum
- may be used for up to five years
- can sometimes react with other drugs
- safe in pregnancy
- may cause rashes and exacerbate psoriasis and should not be used in patients with epilepsy
Mefloquine (250mg weekly) is:
- prescription only
- effective in most malarial areas
- effective against P. falciparum
- has a poor public image (although only 1 in 1,000 suffers major psychiatric side-effects)
- licensed for 1 year though evidence of safety for 3 years
- taken weekly
- does not usually cause side-effects until the third dose, so it is worth taking 3 weekly doses before departure
- best avoided in early pregnancy and by those with epilepsy or cardiac conduction defects.
Doxycycline (100mg daily):
- prescription only
- highly effective in all malarial areas and active against P. falciparum
- excellent when acne treatment is also needed
- can be used for 1 year (though patients with acne use it for 2 years without problems)
- can make skin more susceptible to sunburn and may raise women's risk of thrush
- should not be taken by children under 12 or pregnant women, since it can damage developing bones and discolour teeth.
- must be swallowed with plenty of water as it can irritate the oesophagus
Malarone (250mg atovaquone/100mg of proguanil daily):
- prescription only
- only needs to be taken 2 days before departure and 1 week after
- effective in all areas against P. falciparum and all other malarial types
- licensed for up to 28 days but evidence of safety for 3 or even 6 months' use
- should not be taken by patients on warfarin
- side-effects are minimal but include anorexia, rashes and nausea
- drug too new for safety to be assured in pregnancy and breast-feeding.
D - diagnosis
- Travellers should seek medical attention if they have a fever within 3 months of returning from a malarial area.
- A blood test will normally be taken.