Plasmodium Malaria

Malaria

There are four human malaria species - P. falciparum, P. ovale, P. vivax and P. malariae.

P. falciparum is by far the most dangerous. Unfortunately, it is also the most common in Africa.

Malaria is transmitted by certain Anopheles mosquitoes. The parasite has to undergo a crucial development process in the mosquito, and this can only happen in certain mosquitoes.

Signs and symptoms of malaria:

Fever

Body aches/ muscle pains

Fatigue/ tiredness

Headache

Cough or Diarrhoea

These symptoms may be subtle and may mimic other diseases such as flu, gastroenteritis or sinusitis.

Malaria kills over one million people each year, most of whom are children under 5, and almost 90% of whom live in Africa, south of the Sahara. Each year there are over 300 million clinical cases of malaria, that is five times as many as combined cases of TB, AIDS, measles and leprosy. Malaria is responsible for one out of every four childhood deaths in Africa.

Women are four times more likely to get sick, and twice as likely to die from malaria if they are pregnant.

In humans, the parasite multiplies in two stages: first in the liver cells, then in the blood cells.

Fever is caused by release of waste material when infected cells rupture in the blood. Cerebral malaria is caused by clotting of red blood cells in the brain blood capillaries as a result of the malaria infection. Severe anaemia is caused by destruction of both infected and uninfected cells by the parasite or by the body itself. The failure of other organs, like kidneys, liver and spleen, is caused by the flood of waste materials and the clotting of blood capillaries, to the point where the body can no longer cope.

Immunity is only acquired under conditions of frequent infection. The more frequently a person is infected, the greater the immunity. It does not prevent infection, but decreases the rate and severity of the disease, and increases the rate of recovery. Immunity can be lost when a person leaves the malaria area. Immunity is also specific to a particular species and stage of the parasite. It is transferred from the mother to the infant but remains active only for 3-6 months

                                                                   Common Myths

"It is better not to take any prophylaxis, as it masks the symptoms and makes diagnosis difficult"This is incorrect. Not to take prophylaxis when visiting a malaria area puts travellers at risk of contracting a dangerous and life-threatening disease.

Prophylactic drugs suppress parasite development, and therefore, even if not totally effective (due to partial drug resistance or non-compliance), symptoms tend to take longer to appear, may be less severe at first and development of complications is retarded. In the complete absence of drugs, parasites are able to multiply at phenomenal rates, and malaria can quickly get out of hand, and lead to severe complications and death.

Malaria is sometimes difficult to diagnose the standard way (by microscope) because malaria parasites are present in the peripheral blood only during a fever spell. If a finger prick is taken between fever spells, it is possible that the parasites are not picked up. As prophylaxis retards the parasite multiplication, it may indeed make diagnosis more difficult initially, but repeated blood smears or new and very sensitive dip-stick type tests will usually confirm malaria well before the patient is dangerously ill.

"There is this new deadly strain of malaria"

Cerebral malaria is not a new strain; it is a complication of untreated Falciparum malaria. Early diagnosis and appropriate treatment should ensure that no one gets cerebral malaria.

 "Malaria cannot be cured"

Malaria can indeed be cured with the appropriate drugs. Due to drug resistance to certain drugs, it may take several attempts with different (combinations of) drugs to effect a complete cure.

Also, because most common drugs only deal with the blood and not the liver stages of the disease, the two malaria species that have dormant liver stages (Vivax and Ovale) often do not get removed initially. If the parasite species is not identified correctly, or if there were two species present in the blood, of which one was missed, malaria can flare up again, sometimes many months later. However, once the species has been correctly identified, the liver stage can be successfully removed with Primaquine.

"Prophylaxis need only be taken while in a malaria area"

The drugs that we have to prevent malaria are known as blood schizontocides, which means that they work on the parasite once it enters the red blood cells. This does not occur until 10-14 days after being bitten by an infected mosquito. If the drug is stopped before the parasites reach the blood cells, there will not be enough in the blood to kill the parasites and the prophylaxis will fail. It is therefore extremely important to continue taking prophylaxis for 4 weeks after leaving a malaria area.

"I wasn't bitten, can I stop taking my prophylaxis?"

The female anopheles mosquito is not known as 'the silent killer' for nothing. She does not buzz around your head at night, irritating you. You may not be aware of her presence at all. The reaction to her bite may also not be as pronounced as it is with other bloodsucking insects and you may be unaware of having been bitten.