Malaria has been known to occur since centuries. Even the Vedic literature Atarva Veda and Chakra Samhita talk about Malaria. Since independence we have launched various programs and strategies to fight against the disease. Inspite of all these WHO estimates that India accounts for 75% of all malaria cases in South East Asia. About 95% population resides in malaria endemic area.
How does Malaria Cause Infection?
During the rainy seasons the puddles and pools of dirty water become the breeding grounds for the females Antelopes Mosquitoes which is responsible for malaria. P. falciparum (more severe disease), P. ovale and P. Malariae are the common malaria causing organisms.
Human infection begins when sporozoites in the salivary gland of female Anopheles mosquito inoculated into the human host by an insect bite. These parasites reach the human liver within 30 minutes of inoculation where each divides into 30,000mesozoites. These rupture the liver cells and enter the blood stream to infect the red blood cells and cause their rapture. Also these mesozoites differentiate into male and female gametocytes that are ingested by female anopheles mosquito for further in transmission by undergoing various stages to form sperozoites. These sperozoites rest in salivary glands of mosquito for repeated cycles.
Rupture of red blood cells occurs periodically i.e. every 72 hours for P. malariae (quartarn malaria) and every 48 hours for other malaria species (i.e. tertian malaria). Fever greater than 40oC is lethal to shizonts, so life cycle tends to be synchronized over course of infection, leading to periodic rather than continuous fever. Rupture of red blood cells and sequestration of red blood cells in enlarged liver and spleen causes anaemia. Iron stores are depleted as haemoglobin from lysed RBC’s is lost in urine.
Effects of Malaria:
Occlusion of vasculature can result in renal failure and cerebral malaria (only in P. falciparum infection), partial resistance to malaria occurs in sickle cell trait and in absence of duffy antigen. Fever, chills and headaches are hall mark of malarial infection. The stage of acute chills can last for 6 hours after which symptoms disappear and excessive fatigue occurs. The degree of parasetemia (>2%) correlates with severity of infection.
How is Malaria Diagnosed?
Diagnosis since ages is by Giemsa stained thick and thin smears of fresh fingerprick blood. Even through thin smear is easier to read, thick smear is 10 to 40 times more sensitive and can detect as few as 50 parasites/ µl. Dectatable parasitemia may lag behind aches, fevers and child by 2 days so if malaria is suspected, thick and thin smears should be done every 8 to 12 hours on at least 3 occasions, the collection of which should not be tied to fever spikes. Rapid blood test using dipstick or test strip with monoclonal antibodies are also available.
Pregnant Women and Malaria:
Pregnant women have increased risk of malarial infection, the difference is most marked in the first pregnancy(incidence of parasitemia 66% in 1st and 29% in 2nd and 20.9% in subsequent pregnancies). This is so because pregnant females seem to be more attractive to females anopheles mosquito and sequestration 3% and placental parasitemia 70%).
Although the major adverse effect of malaria in pregnancy on mother is anaemia, risk of developing severe and complicated malaria is three times higher in pregnancy and that of developing hypoglycaemia is seven times more likely. Studies have demonstrated an increased incidence of intrauterine growth restriction when parasitemia is found in antenatal period and increased incidence of premature with cord blood parasitemia (probably reflecting active infection).
Management of Malaria in pre-pregnancy and antenatal period of Pregnancy:
- Avoidance of travel to endemic areas.
- If at all travelling to endemic area chemoprophylaxis is a must and needs to begin 2 weeks before and 4 weeks after leaving the endemic area.
- Advice patient to use pyrethroid containing insect spray and permethrin impregnated bed-nets with liberal use of DEET insect spray topically to reduce frequency of mosquito.
- Chloroquine is safe and an effective chemoprophylactic and a therapeutic drug for susceptible strain of Plasmodium.
- Quinine, mefloquine and clindamyan are also appropriate and safe in pregnancy.
After therapy maintain vigilance for IUGR and preterm labour.