MALARIA PARASITE IN AFRICA
Malaria is a major killer and deserves respect. Every year between 350 and 500 million people are infected with the disease 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 and many remain ignorant of the severity of malaria symptoms and malaria causes.
Obtaining the best information on malaria is essential for all travelers and the ABCD approach is key to avoiding the malaria disease and is essential malaria advice.
A is for Awareness and Advice.
Travellers should be aware of the risks of their journey and how best to minimise them.
B is for Bite prevention.
Travellers should use repellents, mosquito nets and insecticides.
C – Chemoprophylaxis.
Medication should be tailored to the destination, duration of trip and a patient’s pre-existing health problems. It must be taken at the right dose for the correct duration.
D – Diagnosis.
Malaria should be considered in any patient who develops a feverish illness during a visit to a country with the disease or after returning home.
What is malaria?
The Malaria disease is caused by the Plasmodium protozoan, which is transmitted by the bite of the Anopheles mosquito.
Malaria effects in humans is caused by four different types of protozoan:
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.
Life cycle made simple
When someone is bitten by a mosquito, parasites enter the blood and move to the liver where they multiply over the next one to three weeks. They are then released back into the bloodstream where they infect red blood cells.
The parasites grow in the red blood cells until ready for the next stage of their life cycle. They then cause the host cells to rupture, releasing toxins which can cause malaria symptoms and failure of body mechanisms. Male and female gametes are released into the bloodstream where will be sucked up by the next mosquito to bite. Sexual fusion occurs in the mosquito gut, creating a new parasite.
Prophylaxis made simple
Most prophylactic medications work by killing malarial parasites as they emerge from the liver to seek out red blood cells to infect. Parasites can survive in the liver for around three weeks so patients need to take medication for four weeks after leaving a malarial area to ensure they are properly protected. Malarone, a new prophylactic medication, is able to enter the liver and kill parasites there, which means it only needs to be taken for one week after leaving an area with malaria. Primaquine, though not licensed or used much for prophylaxis, also enters the liver.
The risk of malaria varies according to season. Mosquitoes breed in water and thrive after rainy seasons or monsoons.
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 Consider the type of travel. Travel in rural areas, jungle trips and treks, particularly with outdoor sleeping, increases risk. 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.
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 will reduce biting. DEET is still the best and can be used from three months of age. Icaridin in the formulation Autan Active is also effective, while there is some evidence suggesting Eucalyptus citriodora can be an effective natural alternative.
Nets are an excellent way of reducing bites, particularly when impregnated with an insecticide, ideally deltamethrin. Nets can be bought from camping shops, travel clinics or online. Travellers should practice 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.