Essay/Term paper: Malaria
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Malaria is regarded as one of the world's deadliest tropical parasitic diseases. It claims more lives than any other communicable disease except tuberculosis. In Africa and other developing countries, it also accounts for millions of dollars in medical costs. Malaria, however, is a curable disease if promptly diagnosed and adequately treated.
Malaria is a mosquito-borne disease caused by the parasite plasmodium. In recent years, most cases in the U.S. have been in people who have acquired the disease after travelling to tropical and sub-tropical areas. Over 200 million cases worldwide are reported each year.
Estimates of deaths caused by malaria exceed 1 million each year, with the majority being African children. Other groups at risk include pregnant women, foreign travelers, refugees, and laborers entering endemic areas. Malaria is prevalent in over 100 countries around the world, the most of which located in Africa and South America.
Predominance of Malaria
Today, malaria is a public health problem in more than 90 countries. Worldwide prevalence of the disease is estimated to be over 200 million cases each year. More than 90% of all malaria cases arise from sub-Saharan Africa.
The geographical area affected by malaria has shrunk considerably in the past 50 years. Yet measures to control this epidemic are becoming less and less effective. Increased risk of the disease is linked with expansion projects in undeveloped areas, particularly in the Amazon basin and in Southeast Asia.
The rise of malaria is also linked to factors such as global warming, poor health services, political upheavals and armed conflicts. Other causes of this spread include growing resistance of the parasites that cause the disease to new drugs. And with the growing popularity international travel, malaria is now showing up in developed countries. It is also re-emerging in areas where it has previously been under eradicated.
Symptoms of malaria vary depending on the specific type of parasite involved. These symptoms include high fever, chills, sweats, vomiting, and headaches. This would explain why malaria is often misdiagnosed as the flu.
In severe cases the illness can progress to lethargy, respiratory failure, coma and death. If left untreated, the symptoms may persist for weeks or even months. With some types of malaria, relapses may occur for years after treatment.
Malaria symptoms usually appear from 12 to 30 days after infection. Some strains may not cause symptoms for 10 months or even longer.
Areas Stricken with the Disease
Malaria strikes poverty-stricken with the hardest blow. Malaria prevalent areas include some of the world's poorest nations. In Africa, medical costs and related expenses have been estimated at 1-5% gross domestic product.
Farming communities are particularly affected as well. In rural areas, the rainy season is a time of intense agricultural activity, when poor families earn most of their income. When malaria strikes at this time, these families are unable to make a living.
Malaria and Children
Malaria claims the life of a child every 30 seconds. This disease has reached epidemic proportions in many regions of the world, and continues to grow unchecked. Malaria kills 3,000 children under five years of age every day. This rate exceeds the mortality toll from AIDS.
Young African are chronic victims of malaria, suffering an average of six bouts a year. Too often, severely afflicted children die less than 72 hours after developing the symptoms. Of the children who survive, malaria also drains vital nutrients, impairing their physical and intellectual development.
Malaria is also particularly dangerous pregnant women. It causes severe anemia, and is a major factor contributing to maternal deaths in malaria infected areas. Pregnant mothers who have malaria and are HIV-positive are more likely to pass on their HIV status to the unborn child.
The estimated economic costs of malaria are enormous. In affected countries, up to 30% of beds in hospitals are occupied by victims of malaria. In Africa, where malaria reaches a peak at harvest time, a single case of the disease costs an estimated equivalent of 10 working days.
Research indicates that affected families clear only 40 percent of their land for crops compared to healthy families. Knowledge about malaria is markedly low among affected populations. In a recent survey in Ghana, half the respondents did not know that mosquitoes transmit malaria.
Prevention and Cure
Prevention of malaria includes a variety of measures that may protect against infection or against progression of the disease in infected individuals. Initiatives that protect against infection are directed against the mosquito. These measures can be at the individual or household level including protective clothing, repellents and bed nets. Or they may be community programs that include the use of insecticides or environmental management.
Despite growing drug resistance of parasites, malaria is a curable disease. Although only a limited number of drugs exist, if these are used properly and directed to those at greatest risk, malaria infections and casualties can be profoundly reduced.
Disease management through early diagnosis and prompt treatment is a vital step to controlling malaria. It is a basic right of affected populations and needs to be available wherever malaria occurs. Children and pregnant women, on whom malaria has its greatest impact in most parts of the world, are especially important.
When traveling to areas of the world where malaria is common, specific preventive medicine is prescribed depending on which countries will be visited. Mosquito repellents, bed nets, screens and protective clothing are used in many countries to protect against infection from mosquitoes. Health departments assist travelers in determining what precautions are needed.
Drug and Vaccine Development
Drugs designed to treat malaria are available on a very limited basis. Because of increasing resistance to drugs in many parts of the world, adequate treatment of malaria is becoming increasingly difficult. Although a few new drugs have appeared in the last 20 years, they are not economically available to many people who need them.
In the last decade, considerable progress has been made in the search for a malaria vaccine. An effective vaccine would create a powerful addition to malaria control. More than a dozen candidate vaccines are currently in development, some of them in clinical trial. The hope is that an effective vaccine will be available within the next 7-15 years.
A bibliography on the behavioral, social, and economic aspects of malaria and its control. c1978. World Health Organization. Geneva, Switzerland.
(April 2000). Malaria Foundation International. [On-line]. Available: http://www.malaria.org/
(April 2000). Travel health online. [On-line]. Available: http://www.tripprep.com/travinfo/timala.html
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Here is a term paper on ‘Malaria’. Find paragraphs, long and short term papers on ‘Malaria’ especially written for school and college students.
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.
Tropical and Temperate. Most common malaria.
ii. Mild Tertian Malaria:
Period of Attack:
After 48 hours.
West Africa and South America.
iii. Quartan Malaria (also called sub-clinical malaria):
Period of Attack:
After 72 hours (every 4th day).
Tropical and Temperate.
iv. Quotidian Malaria:
Period of Attack:
v. Malignant Tertian (Most Serious):
Period of Attack:
After 48 hours.
vi. Irregular Malaria:
Period of Attack:
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:
(ii) Gamogony; and
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.
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.
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.