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Term Paper on Malaria
Term Paper Contents:
- Term Paper on the Introduction to Malaria
- Term Paper on the Types of Malaria
- Term Paper on the Causes of Malaria
- Term Paper on the Life Cycle of Malaria
- Term Paper on the Symptoms of Malaria
- Term Paper on the Diagnosis and Treatment of Malaria
- Term Paper on the Prevention and Disease Control of Malaria
Term Paper # 1. Introduction to Malaria:
The word Malaria is derived from ‘mal’ and ‘aria’ (which means ‘bad air’) and was formerly called ague or marsh fever. Malaria is an infectious disease caused by a parasite that infects the red blood cells. It is a mosquito- borne disease caused by the protozoan, Plasmodium.
The disease is transmitted by the bite of an infected Anopheles mosquito. An infected Anopheles mosquito bites a person and injects the malaria parasites into the blood. The malaria parasites then travel through the bloodstream to the liver and eventually infect the red blood cells.
There are four types of malaria caused by four different species of Plasmodium – P. vivax, P. ovale, P. malariae and P. falciparum. The most serious type is falciparum malaria. It can be life threatening. The other three types of malaria are generally less serious and are not life threatening. About 300 million cases of malaria have been reported from around the world.
Malaria is currently a problem in tropical or subtropical areas of Asia, Africa and Central and South America, the Mediterranean countries, Asia, and many of the Pacific islands. Most black Africans show a natural resistance to some species of malaria. Malaria may also be transmitted by transfusion of blood from infected people or by the use of contaminated needles or syringes.
Plasmodium is found in the salivary glands of the female Anopheles mosquito. When a mosquito bites, the protozoan is transferred into the blood of man. It requires both mosquito and man to complete its life cycle. The female mosquito is the vector.
Term Paper # 2. Types of Malaria:
i. Benign Tertian Malaria:
Period of Attack:
After 48 hours (every 3rd day). Not fatal.
Distribution:
Tropical and Temperate. Most common malaria.
ii. Mild Tertian Malaria:
Period of Attack:
After 48 hours.
Distribution:
West Africa and South America.
iii. Quartan Malaria (also called sub-clinical malaria):
Period of Attack:
After 72 hours (every 4th day).
Distribution:
Tropical and Temperate.
iv. Quotidian Malaria:
Period of Attack:
Daily.
Distribution:
Tropical.
v. Malignant Tertian (Most Serious):
Period of Attack:
After 48 hours.
Distribution:
Tropical.
vi. Irregular Malaria:
Period of Attack:
Not Fixed.
Distribution
Tropical.
Term Paper # 3. Causes of Malaria:
Malaria is caused by a toxic pigment haemozoin formed from Hb of RBC when RBCs are destroyed by developing stages (merozoites) of the malaria parasite, Plasmodium.
Term Paper # 4. Life Cycle of Malaria:
Life cycle of Plasmodium is digenetic (two hosts) and triphasic. Two hosts are man (secondary host) and female Anopheles (primary host).
Three phases of life cycle of Plasmodium are:
(i) Schizogony;
(ii) Gamogony; and
(iii) Sporogony.
(i) Schizogony:
It is the phase of asexual multiplication of the parasites inside the man. Human infection of Plasmodium is indirect and inoculative in which the infective sporozoites are injected in the blood of man along with a drop of saliva (contains anticoagulant) of infected female Anopheles mosquito.
Schizogony is again divided into two sub-phases:
(a) Hepatic Schizogony and
(b) Erythrocytic schizogony.
(a) Hepatic Schizogony:
In this, the sporozoites enter the liver cells, become rounded, feed on the cytoplasm of liver cells, grow and finally undergo multiple fission to form large number of cryptomerozoites. Some of these cryptomerozoites enter the fresh liver cells and repeat the process.
(b) Erythrocytic Schizogony:
In this, cryptomerozoites enter the erythrocytes, feed upon their haemoglobin, grow and undergo multiple fission to form merozoites which repeat the process. The haeme of haemoglobin of RBCs in changed into a toxic substance, called haemozoin, which is responsible for the malarial attack.
(ii) Gamogony:
It is the phase of sexual reproduction of the parasites and occurs partly in the man and partly in the stomach of the mosquito. In this, the merozoites enter the fresh RBCs and change into two types of gametocytes: micro- and macrogametocytes. Further development occurs only when these gametocytes are sucked by female Anopheles mosquito.
In the stomach of mosquito, the gametocytes form two types of gametes: sperms and ova. Fertilization also occurs in the stomach of mosquito and zygote is formed. Later zygote becomes worm-like and motile and is called ookinete. As sexual reproduction occurs in mosquito so it acts primary host while man acts as secondary host.
(iii) Sporogeny:
It is the phase of asexual multiplication which occurs in the mosquito. In this, the ookinete changes into a rounded oocyst in the wall of stomach, feeds, grows and undergoes multiple fission to form large number (about 10,000) sporozoites. Oocyst ruptures and sporozoites are released. Most of sporozoites enter the salivary glands and wait to be injected into another man.
As female Anopheles transmits the parasites from an infected person to another healthy person, so is also called vector or carrier host. As a part of life cycle of Plasmodium is spent in the vector host, so it is also called biological or active vector.
Term Paper # 5. Symptoms of Malaria:
The main symptoms are fever and headache with intermittent sweating and shivering stages.
The symptoms can be divided into three stages:
i. Cold stage – characterised by shivering
ii. Hot stage — characterised by profuse sweating in the body
iii. Sweating stage – characterised by very high temperature, fast heart rate and breathing.
The fever recurs with a specific periodicity depending on the species of the Plasmodium infecting the patient. The patient suffers from anaemia as the red blood cells are affected. The liver and the spleen may also become affected. In some cases, vomiting, diarrhoea, coughing and jaundice of the skin and whites of the eyes is seen. Blood coagulation defects, kidney or liver failure, central nervous system disorders and coma may happen in some cases.
The incubation period ranges from 12 to 30 days depending on the type of Plasmodium involved. One strain of Plasmodium, called P. vivax, may have a prolonged incubation period of 8 to 10 months. When infection occurs by blood transfusion, the incubation period depends on the number of parasites transferred but is usually less than two months.
Term Paper # 6. Diagnosis and Treatment of Malaria:
Microscopic examination of blood films is the standard diagnostic technique for malaria. Each of the four parasite species has distinguishing physical characteristics visible under the microscope. Antigen detection tests and polymerase chain reaction are sophisticated techniques available to detect malaria. However it is expensive and requires a special laboratory.
Malaria has been treated with quinine extracted from the bark of Cinchona. After the World War II, it was replaced by a synthetic analog, chloroquine. In the 1960, however many strains of the parasite developed resistance to the drug. This problem was complicated with the growing immunity of mosquitoes to DDT and caused malaria to be a leading infectious disease.
There are several families of drugs used to treat malaria. The treatment of malaria depends upon the geographical area where a person has been infected with the disease. Different areas of the world have malaria types that are resistant to certain medications. So, it is important to take the correct medicine prescribed by a doctor.
Some drugs used are artemisinin, amodiaquine, sulfadoxine, pyrimethamine, etc. Vaccines against malaria are still in an experimental stage. Spraying is still used to control malaria-transmitting mosquitoes, but fish that feed on mosquito larva also have been employed.
The French army doctor, Charles Louis Alphonse Laveran was awarded the Nobel Prize for physiology or Medicine for his discovery of the cause of malaria in 1907. Sir Ronald Ross also received a Nobel Prize in 1902 for describing the life cycle stages of the malaria parasite that develop within the mosquito host.
Term Paper # 7. Prevention and Disease Control of Malaria:
Several methods are used to prevent the spread of disease and to protect individuals in areas where malaria is endemic. The preventive measures include prophylactic drugs, mosquito eradication and the prevention of mosquito bites.
i. Mosquito Eradication:
The ideal method of vector control is elimination of breeding places by providing adequate sanitation and underground waste water disposal system. The vector can be eradicated either in the adult stage or larval stage.
1. Mosquito larvicidal oil and pyrethrum oil help in eradicating the larva when it is sprayed on breeding grounds.
2. The use of insecticides such as DDT and BHC kills the adult mosquitoes. However, because of the negative effect of these chemicals in the environment, there is great controversy in their use, especially DDT.
3. Sterile insect technique is a potential method to control mosquitoes.
4. Biological control is also done by introducing fish like Gambusia, trouts, etc into ponds which eat the mosquito larvae.
5. A new approach involves the spraying of inert spores of the fungus, Beauveria bassiana on the walls and nets. This method has been found to be very effective in killing the mosquitoes as the insects do not develop resistance to fungal infections.
ii. Prevention of Mosquito Bites:
Use of mosquito nets, mosquito repellents, and spraying interior walls with DDT are also effective in most areas, where the mosquitoes are not DDT-resistant. Wire gauzes are used on windows and doors to prevent entry of mosquitoes.
Vaccines for malaria are under development, with no completely effective vaccine yet available till January 2006. Sterile insect technique is emerging as a potential method of controlling mosquitoes. No vaccine is yet available.