Malaria info from MSF
13 February 2002
In countries where malaria is endemic it usually is one of the five major causes of death in any emergency situation. The others are diarrhoea, malnutrition, measles and pneumonia. Each day, malaria kills some 3,000 children. In a single year it kills up to two million people. The tragedy of this is that malaria is treatable. If people had access to basic health care most of these deaths could be prevented. Unlike many other infectious diseases malaria is spreading. Deforestation, especially, creates new habitats for the Anopheles mosquito, which is the vector. Apart from the deaths and suffering it causes, malaria leads to economic and social hardship. Adults weakened by the parasite cannot properly work or tend their fields, or care for their children. Among refugee populations it may even render an otherwise desirable settlement site uninhabitable, forcing the refugees to move elsewhere. How malaria kills The Anopheles mosquito breeds in fresh water like ponds, puddles or slow-moving streams. So malaria tends to occur during the wet season. The female mosquito needs a blood feed in order to nourish her own eggs. If she happens to bite a person already infected with malaria the parasite can then proceed to the next stage of its life cycle, which takes place within the stomach of the mosquito. The next night, when the mosquito feeds again, she injects the malaria parasites into the next person's skin, along with her saliva. Once in the blood stream, the parasite invades the red blood cells and then develops and multiplies. An infected red blood cell has a characteristic appearance under the microscope - the malaria parasite is quite clearly visible within it, looking like a blue signet ring. The presence of the parasites in the blood causes the symptoms of fever, chills, body aches and headache. Malaria can also cause diarrhoea, vomiting, cough and blood-stained urine. Infected red blood cells are not as elastic as they should be. This means that they can no longer fit through the smallest blood vessels, called capillaries. Because of this they tend to clog up the circulation in the major organs - especially the brain, kidneys and lungs. The higher the parasite count (i.e. the proportion of the red blood cells that are infected), the more extensive will be this clogging process. In falciparum malaria it is so extensive that it leads to failure of the organs. Death follows quickly. The malaria parasite also makes the red blood cells more fragile, which means that their life span is much reduced. The resulting haemolysis, or destruction of red cells, leads to anaemia. This means that there are not enough red cells in the body to transport oxygen. The result is that the infected person may become easily fatigued and short of breath. A pregnant woman who is anaemic is more likely to die of post-partum haemorrhage, which means blood loss during delivery. Managing a malaria outbreak Sometimes when refugees are forced to flee their homes they take refuge in a low-lying area near swamps or a river, so as to have access to water. This puts them in close proximity to vectors of malaria and other diseases. When an MSF team notices a rise in the number of patients presenting with symptoms of fever and chills, the first thing they must do is to establish the diagnosis. If malaria is known to be endemic in the area, this may well be the cause. However, other diseases such as dengue fever and typhoid can present in a similar fashion. The MSF approach is to take a sample of approximately 100 consecutive patients with fever and to perform a blood film examination of them. This means making a finger prick in the patient and putting two drops of their blood on a microscope slide. The slide is then treated with a stain and examined under a microscope. If a significant proportion of the patients are found to have malaria parasites in their red blood cells then this is assumed to be the diagnosis. From then on, all patients with fever will be given presumptive treatment against malaria. The reason that we do not examine the blood of every patient under the microscope is that during an outbreak of malaria there are many cases and this would place too much of a burden on the local laboratory. It might even delay treatment. In terms of preventing deaths it more efficient and effective to make the presumptive diagnosis and give people the treatment they need. Preventing malaria Children are the most at risk of dying of malaria, because they have not has a chance to develop any immunity to the parasite. Pregnant women are also at risk, because they tend to lose the immunity they had previously acquired. It is difficult to prevent malaria. Anopheles mosquitoes can breed in many places, and are becoming increasingly resistant to insecticides. The mosquitoes tend to feed at night, while people are asleep and unaware that they are being bitten. One of the most effective strategies used by MSF is the promotion of permethrin-treated bed nets. Permethrin is a biodegradable insecticide, safe to use around humans. Use of these mosquito nets for sleeping has been shown to reduce child deaths from malaria. For the future, there is hope for the development of a malaria vaccine. However, this is proving to be very difficult technically and a useful vaccine, especially one that is cheap enough to be used in developing countries, may still be decades away. An example - Preventing malaria deaths in Africa In the tropical belt of Africa it has always proven difficult to prevent transmission of malaria. This is for several reasons:
in rural villages people live in traditional mud huts with grass rooves, called tukuls. This type of dwelling offers no barrier at all to the night-biting Anopheles mosquitoes;
the species of Anopheles mosquito there is extremely hardy, able to breed almost anywhere - even in a rain-filled footprint. Thus it is almost impossible to control mosquito numbers;
malaria tends often to be endemic all year round.
Because of these difficulties the approaches taken by MSF teams in Africa include:
in some circumstances, not trying to prevent transmission (as this is too difficult), and concentrating instead on stopping people from dying of malaria. This means ensuring that they have access to appropriate presumptive treatment;
using prophylaxis for certain at-risk groups, for example children under five and pregnant women. These groups are at especial risk of dying of malaria, and therefore in some circumstances it is justifiable to give them regular chloroquine tablets on a preventive basis;
use of permethrin-treated bed-nets. One of the problems with these is their cost, which is well beyond the means of most rural families. In some circumstances MSF has been able to have a programme funded by donors so that nets can be distributed either free of charge or at a subsidised cost.
How MSF teams treat malaria patients
The most dangerous form of malaria, the one caused by falciparum parasites, tends over time to develop resistance to antimalarial drugs. In a new emergency situation MSF teams will collaborate with local health authorities in determining which drugs are most appropriate for treating cases. In many instances this information is known empirically (that is, from clinical experience) but in some instances it is necessary to carry out field testing of drug sensitivity.
The drugs in common use for treatment include chloroquine, doxycycline, quinine and mefloquine.
The proper management of malaria cases follows several steps:
training all health workers on the case definition of malaria - the usual one is "any a person with fever and chills";
promptly giving all people who meet the case definition presumptive treatment - so as to prevent the malaria infection from progressing to complications such as cerebral malaria;
admitting as inpatients anyone with symptoms of cerebral malaria and treating them immediately with an intravenous infusion of quinine and glucose. The latter element is important because many patients with cerebral malaria suffer from severe hypoglycaemia (low blood sugar); afterwards, educating families about how to avoid catching malaria in the future.