According to the official U.S Department of Health and Human Services records, around 2.7 million people still die of malaria every year and a large percentage of these, sadly, are infants. Malaria, deriving its name from mala aria – the Italian for ‘bad air’ and also known as ague, paludism, jungle fever, marsh fever and periodic fever, is a disease caused by the presence of certain parasites in the blood. Although there is such thing as avian (bird) malaria, the disease is ‘species specific’, meaning it will only affect one species, and the strain that affects humans will only affect humans. The human strain appears in four species, or plasmodium: Plasmodium vivax, Plasmodium ovale, Plasmodium malariae and Plasmodium falciparum. (‘Blacks Medical Dictionary’, 1978, page 530)
The diagram above (taken from the ‘U.S department of health and human services’ reports, 2002) shows, very simply and basically, the life cycle of the malaria parasite as it is transmitted from one infected human to another, via the female mosquito. After an infected human is bitten the malarial parasites develop in oocysts in the gut wall. After the oocysts burst sporozoites of the parasite travel to the salivary glands of the mossquito.
When the mosquito bites another human it injects a small amount of saliva to prevent the blood it feeds on from clotting. This is where the parasite is transferred into the human blood stream. The parasites will then travel to and invade liver cells, where they develop into hepatic trophozoites, which grow and divide into invasive merozoites. When the liver cells burst, merozoites are released into the blood, entering blood cells, and grow into trophozoites. Trophozoites then develop into schizonts, which divide internally to form new merozoites, which emerge into the blood stream when the red blood cells burst. Merozoites may infect further red blood cells to form new trophozoites.
Malaria infection causes many symptoms, and diagnosis is important as Falciparum malaria can rapidly develop into a severe, complicated and life threatening disease. Uncomplicated malaria (early stage) can cause symptoms such as acute fever, headaches, malaise, chills and sweats, abdominal and muscle pain, vomiting and watery diarrhoea. Complicated and severe malaria causes symptoms directly related with deaths caused by malaria. These include coma, pulmonary oedema, renal failure, prostration, jaundice high parasite loads, respiratory distress, severe anemia, convulsions, low blood sugars and shock. (‘Encyclopedia of Arthropod transmitted diseases’, 2001, page 316)
The malarial parasite: Unlike the more easily treated prokaryotic bacterial cells, malarial protozoa are eukaryotic, meaning they have a nucleus. Within the nucleus is stored DNA. With this DNA the malaria parasite can change its surface antigens (surface defense) thus allowing it to keep producing antigens against anti malarial drugs, meaning that the drugs may well become ineffective. Chloroquine resistance is due to the mutation in the gene on the parasite’s chromosome 7, while resistance to pyrimethamine results from a mutation in the gene coding for the enzyme dihydrofolate reductase (DHFR). The ability to swap its surface antigens (camouflage proteins) means, also, that human immune cells fail to recognise the malaria protozoa as an invasive cell, which allows the parasite to slip through the human defense mechanisms and continue causing severe damage to major organs (‘Medicine World.Org’, page 3)
Malaria Hotspots: As the map above (taken from GlaxoSmithKline travel health) shows, the malarial hotspots of the world run along the equator. These areas mainly run through the tropics and are largely made up of swampy areas and wetlands. Looking at world population figures (taken from Internet World Stats), it is easy to see, statistically, why malaria still affects so many people. The map shows hotspot areas in Latin America, a very large area of Africa, Asia and the Middle East. Latin America makes up 8.5% of the world’s population, Africa 14.1%, Asia 56.4% and the Middle East 2.9%. Collectively this makes up a staggering 81.9% of the world population (the total world population being 6,499,697,060) and although only 40% of this number is affected every year, it is this amount of people that are still very much at risk of becoming infected.
In fact, the geography of malarial hotspots makes up for many of the causes of high death rates. Consultant Dr Richard Brindle, of the Microbiology Department of St Mary’s Hospital in Portsmouth, UK, and specialist in malaria and other tropical diseases insists that: – ‘Malaria is very much a ‘social’ disease. It occurs in very specific parts of the world and successful recognition and treatment of the disease depends on many factors. If we look at the areas where malaria is at its most potent we can see that practically all of these areas lie in the tropics, in largely populated and, most importantly, 3rd world areas.’
Preventative Means: Malaria is a potentially fatal disease and remains incredibly complex and difficult to treat. Despite this, some people, if exposed to the infection from birth, may have developed some immunity to the disease. Though these people may never need to be treated for the infection, they will have some level of malaria in their blood and will act as carriers for the disease. According to the U.S Department of Health and Human Services, in the mid 1950’s, the World Health Organisation (WHO) launched a massive worldwide campaign to eliminate malaria. The program combined preventative treatments and drug use. These preventative treatments included the eradication of the mosquitoes, which involved large areas of water being sprayed with oil. This means that mosquito larvae developing under the surface cannot breathe, and therefore die out.
Large amounts of DDT insecticide were also used to kill off the mosquitoes and for a while these tactics seemed to be paying off, but difficulties soon developed. More and more strains of the malaria vector, Anopheles mosquitoes, were developing resistance to DDT and other insecticides. It was around this time that plasmodium parasite began to develop resistance to the anti malarials. Other means of eradicating mosquito populations include draining large water areas and filling them in with mud to clear mosquito breeding grounds and using barrier tactics such as using wind screens and mosquito nets coated in insecticides and using animals, such as fish, to eradicate the problem.
Unfortunately there are two major problems that come with these preventative means. 1) The preventative measures cost money. Government reports show that costs are considerable: Cost to individuals and their families, including drugs, expenses for travel (if they can travel at all, as many third world countries are inaccessible) and treatment at dispensaries and clinics, lost days of work, absence from school, expenses for preventative measures, maintenance of preventative measures (so motivation is also a factor) and cost for funerals in case of death.
Costs to the governments include: maintenance of health facilities, purchase of drugs and supplies, public health interventions such as insecticides, distribution of preventative means, lost days of work, lost days of income and lost opportunities for joint economic ventures and tourism (U.S Department of Health and Human Services, 2002). 2) These measures are still only working with limited success. Mosquitoes are still growing resistant to insecticides, they are moving into cities where humidity is high and breeding conditions may be available. Mosquito nets are flimsy and need constant repairs, plus mosquitoes are still able to feed through them if a person sleeps close enough to the edge of a bed where nets are hung. Many people in third world countries are without schooling and remain ignorant to the risks of malaria and the preventative means that can be used to lower risk of getting bitten. Promotion of this costs more money still. (Dr Richard Brindle, 2006, Black’s Medical Dictionary, 1978 page 533 and U.S Department of Health and Human Services, 2002)
It is also useful to take note of the social structure of many third world countries, many of which remain divided by war. As Dr Richard Brindle points out: – ‘The overall conquest of malaria, if at all, will rely on the cooperation of the countries most badly effected by this, plus the support of outside countries. It is fairly safe to say that this will not happen while these countries remain politically divided. The risk of malaria spreading to other countries with the movement of armed forces and refugees increases greatly. Quite often, the areas affected worst by the disease are near impossible to get to. This means that diagnoses cannot be made and appropriate treatments cannot be administered. With the increase of travel comes the increased risk of resurgence in advanced countries, thus money needed for third world countries to eradicate, or at least control malaria, is being used for pre-travel vaccines.
We also have to take into account that, as well as the malaria infection, we also need to go on treating the symptoms and the damage it causes, which in turn costs even more money.’ Unfortunately, Malaria is far to complex a disease to cover in one essay. In this essay I have covered the main aspects of the disease and I believe I have successfully answered the question ‘why do so many people still die of malaria? Although malaria has been eradicated from most of the new world countries it is still very prominent in 3rd world countries, where over half the world’s population resides. With the increasing popularity of travel the risk of infection becomes higher, as it does with war.
Global warming will continue to increase humidity so breeding grounds for mosquitoes will therefore increase. Also, as Black’s Medical Dictionary states, the increasing popularity of keeping fish and ponds as water features in gardens will create good breeding grounds for mosquitoes and bring them into very close contact with humans. It also points out that there are many species of mosquito so distinguishing between them is made very difficult. Research will also have to be a non stop factor towards treating malaria as the protozoa, as well as the mosquitoes are becoming resistant to all known forms of treatment and preventions and still people are going undiagnosed and without treatment. While this happens and world collaboration against malaria fails to happen people will still continue to die of the infection.