Malaria is a mosquito-borne infectious disease of human caused by protist plasmodium known as malarial parasite. It is widespread in tropical and subtropical regions, including much of sub-saharan Africa, Asia and the America. The disease results from the multiplication of malaria parasites within red blood cells, causing symptoms that typically include fever and headache, in severe cases progressing to coma, and death.
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| Malaria |
Four species of Plasmodium can infect and be transmitted by humans. Severe disease is largely caused by Plasmodium falciparum. Malaria is also caused by Plasmodium vivax, Plasmodium ovule and Plasmodium malariae.
How is Malaria transmitted?
The life cycle of the Malaria parasite is complicated and involves two hosts, humans and female Anopheles mosquito. The disease is transmitted to human when an infected Anopheles mosquito bites a person and injects the malaria parasites (sporozoites) into the blood.
Life cycle of Malarial parasite in Anopheles mosquito:
Mosquitoes first ingect the malarial parasite while feeding on an infected human. Once ingested, the gametocytes get differentiated into male of female gametes and fuse in the mosquito's gut. This produces an Ookinete that penetrates the gut lining and produces an oocyst in the gut wall. When the oocyst ruptures, it releases sporozoites that migrate to the salivary glands. The sporozoites are injected into the skin, when the mosquito bites a normal person.
Only female mosquitoes feed on blood while male mosquitoes feed on plant sap, thus males do not transmit the disease.
The life cycle of malarial parasites in the human body:
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| Life cycle of Malaria Parasite |
Malaria develops via two phases: An pre-erythrocytic and an erythrocytic phase. The pre-erythrocytic phase involves infection of the liver. The erythrocytic phase involves infection of the erythrocytes, or red blood cells.
When mosquito bites a person sporozoites enter the bloodstream, and migrate to the liver. They infect liver cells (hepatocytes), where they multiply into merozoites. They rupture the liver cells,and escape into the bloodstream. Then, merozoites infect red blood cells, where they develop into ring forms, trophozoites and then schizonts which in turn produce further merozoites.
Within the erythrocytes, the parasites multiply Asexually, periodically breaking out of their hosts to invade fresh red blood cells. Several such amplification cycles occur. Thus, classical descriptions of waves of fever arise from simultaneous waves of merozoites escaping and infecting red blood cells.
Malaria symptoms:
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| Life cycle of Plasmodium |
Symptoms of malaria include fever, shivering, arthralgia (joint pain), vomitting, anemia (caused by hemolysis), hemoglobinuria, retinal damage, and convulsions. The classic symptom of malaria is cyclical occurance of sudden coldness followed by rigor and then fever and sweating lasting four to six hours, occuring every two days in P. vivax and P. ovule infections, while every three days for P. malaria. Severe malaria is almost exclusively caused by P. falciparum infection. Splenomegaly (enlarged spleen), severe headache, cerebral ischemia, hepatomegaly (enlarged liver), hypoglycemia, and hemoglobinuria with renal failure may occur.
So, this are the Malaria symptoms.
Prevention of Malaria:
Malaria transmission can be reduced by preventing mosquito bites by mosquito nets and insect repellents, or by mosquito control measures such as spraying insecticides and draining standing water where mosquitoes lay their eggs. The mosquito larvae cand be controlled by release of Gamobusia fish.
This are the prevention for Malaria.