Malaria - Causes, Symptoms, Diagnosis and Prevention
The term ‘malaria’ has been derived from two Italian words – ‘mala’ means ‘bad’ and ‘aria’ means ‘air’. It was also believed previously that the disease was caused due to foul or poisonous or bad air coming at night from marshy or swampy places. Although the disease was causing the death of many people all over the world, particularly in the tropical countries, the real causative agent was not known until 1880. Later it was discovered that malaria fever is caused by a unicellular organism of the genius Plasmodium (Malaria parasite).
Now-a-days the disease has posed to be a serious national problem in India, because of its destructiveness. It has been estimated that more than 10,00,000 persons die of malaria every year in India. Indian Council of Medical Research (ICMR) in collaboration with World Health Organization (WHO) has taken up the problem seriously under the National Malaria Eradication Programme (NMEP) to control Malaria.
Plasmodium vivax is commonly known as malarial parasite. It is an intracellular, blood parasite of man and causes malaria fever in human being. Plasmodium was first discovered by Charles Laveran in the year 1880. He observed the malarial parasites in the blood corpuscles of malarial patients. His observations were later confirmed by Golgi and Cellie. But the exact mode of transfer of the parasites from one human being to the other was not known till 1897. In 1897, Sir Ronald Ross, an Indian military surgeon discovered the presence of oocysts of malarial parasite in the stomach wall of female Anopheles mosquito. Ross got the Nobel Prize award in medicine in the year 1902 for this important discovery.
Plasmodium completes its life cycle in two host namely, man and female anopheles mosquito. Man is known as the primary host and the female anopheles mosquito as the secondary host. The female anopheles mosquito transmits the malarial parasites from one human being to the other and therefore known as the vector or carrier host. Due to the requirement of two hosts for the completion of the life cycle, Plasmodium is known as digenetic parasite.
Symptoms of malaria
The onset of malaria fever is easily recognized because the person suffers from recurring chillness and fever. This is followed by the rapid increase in the body temperature up to about 103 to 140 F and in some cases up to 106 F, accompanied by violent shivering, headache, muscular pains, nausea and sometimes insomnia. Tongue becomes thickly coated, mouth becomes dry and the patient losses appetite. The high temperature remains for about 6 to 10 hours, after which it decreases to become normal. Then profuse sweating takes place on the part of the patient. The cycle of fever, chillness and sweating is repeated at regular intervals.
The disease is diagnosed by taking the blood of the patient when he shows acute chillness and examining the blood in the laboratory. This is because of the fact that the symptoms of malaria are seen after the incubation period when more and more haemozoin granules and erythrocytic merozoites are released into the blood stream.
1. Offensive measures against malarial parasite: There is no immunization against malaria. Malaria is neither treated nor controlled by vaccination nor by inoculation. Rather the treatment of the disease is possible by killing the different stages of the parasite with the help of several antimalarial drugs. Previously Quinine was used for the purpose, as it is proved to be the most useful drug, in spite of several of its disadvantages. Another drug, Atebrine shows to be the supplement of Quinine. Now-a-days several anti-malarial drugs such as Chloroquine, Plasmochin, Camoquine, Pentaquine, Isopentaquine etc. are used for the treatment of malaria. But out of these the most effective ones for the complete cure of malarial fever are Chloroquine and Primaquine. The World Health organization has already started a research programme for developing an effective vaccine for the complete eradication of malaria.
2. Defensive measures: Prevention of infection of malaria parasite can be achieved by using small doses of quinine daily and taking proper care by sleeping under mosquito net and applying mosquito repellant cream or odomus over the body. It has been observed that Atebrine at the rate of 0.1 gm everyday I quite effective in preventing the malaria infection. It is also recommended that a single pill of 0.15 gm of Chloroquine once a week prevents the disease satisfactorily.
3. Offensive measures against mosquitoes: Malaria can be controlled by taking measures to control the insect vectors, i.e. mosquitoes. This can be achieved in the following ways.
1. Mosquito should be killed from human habitations by spraying DDT.
2. Ditches, ponds and drains should be dried or insecticides should be applied to these places so that breeding of the mosquitoes can be stopped.
3. Kerosene oil should be sprayed on the surface of the stagnant water so that the larvae and pupae of the mosquito will be killed.
4. Larvivorous fishes like Gambusia and Lebistes should be introduced into the ponds and drains.
5. Mosquito net should be used at nights while sleeping.
Types of Malaria
In human beings, principally four types of malaria are seen which are caused by four different species of Plasmodium. But the life history of these four species of Plasmodium is very much similar except some minor differences in the life cycle, stages and the time required for schizogony.
1. Benign tertian malaria: This type of malaria is caused by Plasmodium vivax. So it is also known as vivax malaria. In benign tertian malaria, fever comes at an interval of every 48 hours due to the formation of new generation of merozoites. Incubation period is 12 to 14 days. It is most widespread in both tropical and temperate zones.
2. Mild tertian malaria: It is caused by Plasmodium ovale. Fever comes at an interval of every 48 to 50 hours due to formation of new generation of merozoites. Incubation period varies from 11 to 16 days. The attacks are milder in this kind of malaria. It is found in West Africa and South America.
3. Quartan malaria: this is caused by Plasmodium malariae. Here fever comes at an interval of every 72 hours and relapses occur. Incubation period varies from 28 to 37 days. It is found in both tropical and temperate zones but not very widespread.
4. Malignant tertian malaria: This kind of malaria is caused by Plasmodium falciparum. So it is also known as falciparum malaria. In this case, fever comes irregularly at an interval of every 36 to 48 hours and the death rate is high in this type. Therefore this species is known as the killer variety of malaria parasite. Incubation period varies from 7 to 27 days. It is most dangerous type with almost continuous fever but its course is shorter and without relapses. This malaria fever is very common in the tropical countries.
In addition to the above species of Plasmodium causing malaria fever in man, the species invading the other vertebrates are Plasmodium praecox, causing bird malaria and Plasmodium berghei causing malaria in rat.
NMEP (National Malarial Eradication Programme)
Since past several years a massive Malarial Eradication programme is operating in our country. It aims for complete control and eradication of malaria. In this programme 3 effective methods are employed for successful control.
1) Destruction of mosquito: This is being carried out in three ways.
1- Mass killing of adult mosquitoes in residential areas by spraying insecticides like DDT or Flit or by burning sulphur, pyrethrum etc.
2- Construction of proper drain for the removal of sewage water where mosquitoes breed.
3- Destroying eggs and larvae of mosquitoes in stagnant ponds or tanks without drainage system. This is accomplished by periodic cleaning of weeds, oil spraying and introducing insectivorous predators such as ducks, fishes.
2) Prevention of infection: This consists of protection from infection by the bite of the mosquito. One way of the protection is to build human dwellings on high grounds, keeping the house clean and well ventilated, and covering windows and doors with wire meshes and screens. Use of mosquito nets during night, application of mustard oil and mosquito repellant creams on the exposed part of the body should be practiced. Regular use of prophylatic drugs like quinine by all the members of the family in mosquito infected area is also recommended.
3) Treatment: Simultaneous treatment of all patients in large area is an effective method for eradication of malaria, since it minimizes the availability of infective stages of the parasites to the mosquito.
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