Malaria Parasite
Malaria is a mosquito-borne infectious disease of humans and other animals caused by parasitic protozoans (a type of single cellmicroorganism) of the Plasmodium type. Malaria causes symptoms that typically include fever, fatigue, vomiting and headaches. In severe cases it can cause yellow skin, seizures, coma or death. These symptoms usually begin ten to fifteen days after being bitten. In those who have not been appropriately treated disease may recur months later. In those who have recently survived an infection, re-infection typically causes milder symptoms. This partial resistance disappears over months to years if there is no ongoing exposure to malaria.
Commonly, the disease is transmitted by the bite of an infected female Anopheles mosquito.
LIFE CYCLE
- Sickle cell sporozoites enter blood stream of man with
saliva of female anopheles mosquito when it pierces the skin.
- They remain in the blood stream for an hour before they
enter the liver.
- In the liver, they penetrate the liver cells.
- They feed on
liver cells then they divide mitotically and repeatedly to form merozoites.
- The whole
cells containing the merozoites is now called a meront.
- The meront
(liver cells) burst releasing the merozoites.
- Some
merozoites re-enter the liver cells (Pre-erythrocytic cycle)
- Others enter
the blood cells, into the RBC's
- inside the RBC's the merozoites feed and grow to become
ameoboid in shape. Large vacuole appear on the central region and pushes the
nucleus to the sides forming a signet ring.
- Multiple division takes place forming merozoites and some excretory granules which
are formed in the cytoplam of the RBC. As it burst open. the merozotes and the
excretory granules are released to the plasma.
- Some merozoite re-enter the RBC (erythrocytic cycle)
- The toxic effect takes abt 48h which causes a
characteristic fever
- Some merozotes stop dividing and grow to form
gametocytes.
- Female gametocytes have large nuclues and cytolpasm is
rich in food materials and granulated
- Male gametocytes have large nucleus and clear
cytoplasm.
- If the gametocytes are ingested by a female anopheles
mosquito, they develop into male and femle gametes which unite to form a
zygote.
- From the zygote, multi-nuclei structures called
sporocysts develop onto the stomach wall of the mosquito which within a few
days divide into thousands of tiny spindle shaped cells called sporozoites. On
rupturing of the cyst, the sporozoites migrate to the mosquito salivary gland.
- When the mosquito bites another victim, the
cycle begins again..
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