Elizabeth Nduta Mbugua
Department of Science and Engineering
School of Science, Engineering and Health
In Partial Fulfillment of the Requirement for
BIOLOGY (BIO 111)
19th March 2014
Malaria affects 10%of the world’s population with 300-500 million new cases each year and 2 million deaths annually. It is called the worlds invisible pandemic. It is transmission of the disease by a mosquito vector that depends on temperature and rainfall and thus survives well in tropic areas. The people at significant risk for malaria include those who have little or no immunity to the parasite. Children, pregnant women and travelers are most likely to fall victim to the disease. CAUSATIVE AGENT
The parasite that causes malaria belongs to the genus plasmodium. There are four species of plasmodia that causes malaria in man. i.
It is believed to account for 80%of all malaria infections, widely distributed because it can develop in mosquitoes at lower temperatures and is the cause of the most prevalent forms of malaria benign tertian with frequent relapses. The cycle of paroxysms occurs every 2 days and the patients generally survive even without treatment. Plasmodium ovale and plasmodium Malariae
Also causes relatively benign malaria but even so the victims lack energy.These latter two malarial types are lower in incidence and rather restricted geographically. Plasmodium Falciparum
The most dangerous malaria is that caused by Plasmodium Falciparum.It is believed that humans have been exposed to this parasite(through contact with birds)only in relevant recent history.Reffered to as “malignant”malaria , untreated it eventually kills about half of those infected. The highest mortality rates occur in young children. More red blood cells are infected and destroyed than in other forms of malaria. The resulting anemia severely weakens the victim. Furthermore, the red blood cells develop surface knobs that cause them to stick to the walls of the capillary vessels, which become clogged. This clogging prevents the infected red blood cells from reaching the spleen, where phagocytic cells would eliminate them. The blocked capillaries and subsequent loss of blood supply leads to death of the tissues, kidneys and liver damage is caused in this fashion. The brain is frequently affected and Plasmodium Falciparum is the usual cause of cerebral malaria. Transmission
Human malaria is transmitted by the female anopheles mosquito. Half of the life cycle occurs in the human and the remainder happens in the mosquito. The male mosquito feed exclusively on fruit juices but the female needs at least two blood meals before the first batch of eggs can be laid. As the female feeds on the human blood she injects saliva containing an anticoagulant along with the parasites. Infected humans also infect one another by using unsterilized syringes and needles or blood transfusion from people who have been in an endemic area. Life cycle
The life cycle of malaria parasites comprises of two stages an asexual phase occurring in humans and sexual phase occurring in the mosquito. i.
In the asexual phase the parasite multiplies by division or splitting, a process designated Schizogony.Because this asexual phase occurs in man it is also called the vertebrate phase. In humans, schizogony occurs in two locations in the red blood cells and in the liver cells. Because schizogony in the liver is an essential step before the parasites can invade erythrocytes, it is called pre-erythrocytic schizogomy.The products of schizogomy,whether erythrocytic or exoerythrocytic are called merozoites. ii.
The sexual phase takes place in the female anopheles mosquito, even though the sexual forms of the parasite originate in human blood cells.Maturation and...
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