Malaria , types and control of Malaria

Malaria

• Malaria is caused by a Protozoan Plasmodium vivax.

• It is a digenetic parasite because it completes its life cycle in two hosts. First host is Human and second is Female Anopheles.

• Asexual phase of life cycle of plasmodium take place in Human whereas Sexual phase takes place in Mosquito. 

• Due to the occurrence of sexual phase, Mosquito is regarded as the primary host.

Sexual phase of life cycle of plasmodium

• When an infected Anopheles mosquito bites a healthy person then it introduces sporozoite in the body of the person.

• This sporozoite has a single nucleus and is covered by an elastic cuticle.These sporozoites make entry into the liver where they produce cryptozoite.

• Now these cryptozoites multiply asexually by the Schizogony and form crypto merozoites.

• Crypto merozoite enter into new liver cells and produce asexually Meta crypto merozoites and micro crypto merozoite.

• Out of these, Micro crypto merozoite enter into the blood stream and make target to Red blood cells. .

• Here these Micro crypto merozoites assume disc-like shape with single vacuole and give ring-like appearance. This stage is called signet ring stage.

• Now parasites start to feed Red blood cells and assume amoeboid stage or trophozoite stage.

• The mature trophozoite develops into a Schizont. Schizont multiplies asexually by the erythrocytic schizogony.

• Schizont loses its pseudopodia and its nucleus divides to form a large number of merozoites . This stage is called the rosette stage.

• Merozoite again makes entry in fresh RBC and produces more merozoite.

• During this stage,A chemical is also released  due to bursting of RBC called is responsible for chilling and high fever during Malaria. 

• Few merozoites produce two of gametocytes. Macro gametocyte and microgametocyte.

• Macro and micro gametocyte are considered as female and male gametocytes

Asexual phase of life cycle of plasmodium

• When a female anopheles bites a patient of malaria , gametocytes are ingested by mosquito and reach in the stomach.

• Where macro and micro gametocytes are fused after the further development and a zygote is formed.

• After some period of inactivity, Zygote is changed into ookinete stage and covered by a cyst.

• This stage undergoes  sporogony. In the sporogony, its nucleus divides repeatedly and forms a large number of sporozoite.

• After the bursting of cyst, sporozoite is liberated and stored in the salivary gland of the mosquito.

• When Anopheles bites a healthy person sporozoite is injected into the body of the person and ready for the next life cycle.

 

Types of Malaria

• Benign and tertian malaria caused by the P. Vivax in tropical and subtropical countries.

• Quartan Malaria is caused by the P. malariae and tertian malaria is caused by the P.ovale in West Africa and South America.

• Malignant tertian malaria is caused by P.falciparum.It is most fatal and also called Percinious or Estivo Autumnal malaria.  

Control of Malaria 

• It can be controlled by destroying  the secondary host .

• Mosquitoes can be killed by the spraying of pyrethrum and other insecticides at mosquito breeding places like pools, ditches and drains . The larva of mosquitoes can be killed by the larvicides..

• Antimalarial drugs Quinine, Darapine, paludrine are used to kill sporozoite stage before development .

• Some natural enemies like GAMBUSIA fish  are introduced in mosquito inhabiting place under the Biological control.