Overview of Malaria
Malaria is an infectious disease caused by parasitic protozoan which is transmitted by mosquito bite. Malaria is a historical disease and affects humans and other animals. It causes fever, chills and flu-like symptoms and severe complications in case of delayed treatment. Five species of Plasmodium can infect and spread by humans; these are P. falciparum, P. vivax, P. ovale, P. malariae and P. knowlesi. P. falciparum causes severe cases of disease while other produce milder symptoms. This disease is prevalent in tropical and sub-tropical region which include Asia, Sub-saharan Africa and Latin America. About 90% of cases occur in Africa affecting mostly children. It is usually associated with poverty and impact economic development negatively.
Causes and Risk Factors of Malaria
Malarial parasite belongs to genus Plasmodium and phylum Apicomplexa. It is transmitted by female Anopheles mosquito which feeds on human blood. The mosquito bite introduces the motile infective form (sporozoite) of parasite from mosquito’s saliva into a person’s blood. Sporozoites are taken up by blood vessels to liver cells where they reproduce and produce merozoites. Merozoites infect RBCs and produce new infective merozoites which develop into immature gametocytes. Gametocytes are taken up from blood when mosquito bite human and mature in gut. Gametocytes after various steps again develop into Sporozoites and move to salivary glands of mosquitos, ready to infect a new host. Rarely, malaria can also be spread through blood transfusions and needle sharing.
Signs and Symptoms of Malaria
Symptoms of malaria develop 8-25 days after infection. Initial signs of disease resemble other illness such as sepsis, viral disease and gastroenteritis. Earlier manifestations include fever, headache, shivering, vomiting, and jaundice, and joint pain, hemoglobin in urine, convulsions and retinal damage. The classic sign of malaria is called paroxysm which is cyclical occurrence of sudden coldness followed by shivering and then fever and sweating. Paroxysm can reoccur every 36-48 hours or continuously in infection caused by P. falciparum. Fever cycle reoccur every two days in P. vivax and P. ovale infections and every three days for P. malariae. Malaria affecting brain can result in abnormal posturing, seizures, conjugate gate palsy and involuntary eye movement.