Four species of plasmodium are, reported to cause different types of malaria in human beings viz. P. vivax, P.ovale, P.malariae and P.falciparum.
In human beings, plasmodium attacks the R.B.C. and liver cells and releases a toxic substance. Hemozoin, which causes malaria, is identified by periodic attack of high fever. Death of man is not actually directly due to the parasite make the patient weak, causing anemia ultimately resulting in death.
When a female Anopheles, containing sporozoite stage of plasmodium in her salivary glands, bites a man, the sporozoites are released into the blood stream of human-being. After 3 days of entrance, these sporozoites start in the parenchyma cells of the liver and attain schizont stage. Now these schizonts attack the R.B.C. and get changed into trophozoits.
Now trophozites of ach R.B.C. attain schizont stage and divide into 6 to 36 daughter merozoites. Due to the high pressure, R.B.C. ruptures and releases the merozoites into the blood plasma. These merozoites attack the other R.B.C. After 10 days, the number of parasites becomes large and they produce toxins, which cause fever in man. There are four recognized forms of malaria caused by different species of plasmodium.
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Tertian Malaria: It is caused by P.vivax in which fever is repeated every third day.
Ovale Malaria: It is caused by P. ovale in which fever is repeated every 3rd day.
Quartan Malaria: It is caused by P. malaria in which fever is repeated every fourth day.
Malignant Malaria: It is caused by P. falciparum in which fever is repeated every second day and is fatal to the patient.