Malaria: Types, Symptoms, pathogenicity, Control, Treatment and Prevention
Posted on : 27-08-2018 Posted by : Admin

Types of Malaria

On the basis of period of recurrence of fever the following are five different types of malaria,

Tertian malaria: It is caused by Plasmodium vivax. This type of malaria is not fatal. The fever in this type of malaria is repeated after every 48 hours.

Quartan malaria: It is caused by Plasmodium malariae. If untreated, this malaria can be in dormant stage for more than 40 years. Though it actually not fatal, it may sometimes lead to lethal kidney conditions. The fever in this type of malaria is repeated after every 72 hours.

Mild tertian malaria: It is also known as ovale malaria. This is very much similar to tertian malaria. It is caused by Plasmodium ovale. This malaria is not generally harmful. The fever in this type of malaria is repeated after every 48 hours.

Malignant tertian malaria: It is also known as Aestivo-autumnal or pernicious malaria. The causative organism of this malaria is Plasmodium falciparum. This malarial fever is often fatal as it infects the brain. The fever in this type of malaria is repeated after every 48 hours.

Quotidian malaria: This type of malaria occurs when more than one type of malarial parasite infects the patient. This type may also occur when 2-3 generations of parasites mature on successive days. The fever in this type of malaria is repeated after every 24 hours.

Type of Malaria	Caused by	re-occurrence	fatal (?)
Tertian Malaria	P. vivax	after every 48 hours	No
Quartan Malaria	P. malariae	after every 72 hours	Often
Mild tertian Malaria	P. ovale	after every 48 hours	No
Malignant tertian Malaria	P. falciparum	after every 48 hours	Yes
Quotidian Malaria	more than one malarial parasite	after every 24 hours	Often

Symptoms and pathogenicity of Plasmodium

Symptoms of malaria appear several days after infection. This time interval between the infection and appearance of first symptom is called incubation period. This incubation period is used by the parasite to increase their number as to establish the symptoms, a large parasite population is required.

The clinical features of malaria include, febrile paroxysm (spells of fever) followed by anemia and enlargement of spleen. A febrile paroxysm includes three stages,

Cold stage: At the first onset of malaria, patient suffers severe shaking chills, headache and giddiness. The patient feels so cold that his teeth chatter though covered by huge blankets. Cold stage lasts for about 20 minutes to 1 hour.

Hot stage: When the chills of the cold stage subside, the temperature of the body goes to as high as 106°F. Patient fees very hot with terrible headache. Hot stage lasts for 1-4 hours. There will also be considerable increase in breathing rate and pulse rate.

Sweating stage: As the heat from the hot stage subsides, the patient sweats plentifully. With body temperatures receding to normal, patient feels comfortable until next episode which would onset after 48-72 hours depending on the species of the malarial parasite.

Malarial fever occurs when schizonts in the RBC burst and set free their merozoites and haemozoin into the blood plasma. Haemozoin is toxic in nature and induces high fever.

For more detailed notes on life cycle of plasmodium click below...

Life cycle of plasmodium

Why does malaria cause Anemia?

Malaria is often known to cause anemia because of the following reasons,

Due to destruction of RBCs for liberation of merozoites
Infected RBCs become delicate. They rupture easily and get destructed.
The spleen which gets enlarged due to the infection releases lytic substance called lysolecithin. This substance destroys RBCs
Malarial parasites produce haemolysin which destroys normal RBCs
Falciparum infection also causes black water fever which results in extensive destruction of RBCs and excretion of liberated hemoglobin in urine.

Duration of infection and its relapse

If the patient is not treated or even if treated and death does not occur after variable number of erythrocytic schizogonic cycles, the host antibodies will destroy all or most of the erythrocytic schizonts. With this the symptoms may disappear, but the parasite may persist in the liver cells or capillaries.

The parasite may relapse in all malarias except in ovale malaria. Relapse may be after 6-12 months as in case of tertian malaria whereas in Quartan malaria the relapse may be after long periods of latency.

Control of malaria

Malaria is very dangerous disease and poses a serious threat throughout the world. The control measures may be classified into three categories;

Destruction of vector
Prevention of infection
Treatment of infected patient

Destruction of vector: If the malarial vector Anopheles mosquito is destroyed, the spread of disease from one person to another can be checked. This can be the most effective way of controlling the disease. This can be done in the following ways,

Destruction of adult anopheles mosquitoes through mosquito traps, repellents, spraying insecticides and fumigation.
Sterilization of mosquitoes is also proving to be an effective way of controlling mosquito population.
Mosquito breeding places like stagnant water, swampy and marshy places must be drained off. Use of insecticides in the mosquito breeding places to kill the larvae is also effective.
Biological control is one of the most effective methods of destructing the mosquito larvae. Use of larvivorous fishes like Gambusia is one such biological method.
Kerosene and pyrethrum oil are sprayed on the stagnant waters like sewage gutters and ditches were the mosquitoes lay their eggs. The oil film on the water surface affects the respiration of the larvae and the larvae die of suffocation.

Prevention of infection:

Protection of healthy individuals in the mosquito prone areas
We must protect ourselves from mosquito bites through use of insect repellents, nets, gloves, screening and mesh windows.
Chances of infection can be minimized by maintaining proper health. We must eat healthy food and must avoid exposing ourselves to bad atmosphere.

Treatment of infected patient: As malarial parasites do not produce any antibodies we cannot have vaccinations for this disease.

For as long as 300 years, Quinine is used as an effective drug against malaria. Quinine is extracted from the bark of Cinchona trees growing in Java, Peru, Ceylon and India. But after World War II, Japan got control of the Quinine producing areas. And this led to quinine scarcity. Hence, synthetic drugs like Atabin, Camoquin, CHloroquine, Pamaquine and Primaquine were developed. Daraprim is the most potential drug invented so far for treating malaria.