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MALARIA
Introduction
Malaria is a vector-borne parasitic disease caused by protozoa of the genus
Plasmodium and transmitted by the bite of infected female Anopheles mosquito.
The important species infecting humans are Plasmodium falciparum, P. vivax, P.
malariae, and P. ovale.
After entering the body, the parasite undergoes a complex life cycle involving liver (hepatic stage) and red blood cells (erythrocytic stage). The clinical manifestations are mainly due to destruction of RBCs and release of toxic substances. Malaria is a major public health problem in tropical countries like India. If
untreated, especially in P. falciparum infection, it can lead to severe
complications such as cerebral malaria, renal failure, severe anemia, and death.
Types Plasmodium falciparum Malaria This is the most virulent and fatal form of malaria. It infects RBCs of all ages, leading to high parasitemia. Infected RBCs become sticky and adhere to capillary walls (cytoadherence), causing blockage of microcirculation. This results in complications like cerebral malaria, acute kidney injury, pulmonary edema, and shock. Plasmodium vivax Malaria This is the most common type in India. It infects young RBCs and generally causes milder disease. However, it forms hypnozoites (dormant forms) in the liver, which can reactivate and cause relapses weeks or months later. Plasmodium malariae Malaria This type causes chronic, low-grade infection. It infects older RBCs and may persist for long periods. It is associated with nephrotic syndrome (kidney damage) in some cases. Plasmodium ovale Malaria
This is less common and similar to P. vivax. It also forms hypnozoites, leading to
relapses. The disease is usually mild. Signs and Symptoms
- Classical malarial paroxysm: o Cold stage โ chills and shivering o Hot stage โ high fever (39โ41ยฐC) o Sweating stage โ profuse sweating and fall in temperature
- Headache
- Undergo asexual multiplication (schizogony) forming merozoites
- Liver cells rupture โ merozoites released into blood
- Merozoites invade RBCs
- Inside RBCs โ develop into trophozoites and schizonts
- RBCs rupture โ release merozoites + toxins (hemozoin)
- This causes periodic fever and chills
- Repeated RBC destruction โ hemolytic anemia
- Activation of immune response โ cytokine release (TNF, IL-1)
- In P. falciparum: o RBCs become sticky โ sequestration in capillaries o Leads to microvascular obstruction and organ damage
- Results in: o Brain involvement โ cerebral malaria o Kidney involvement โ renal failure o Liver involvement โ jaundice Diagnosis Medical History and Clinical Examination Diagnosis begins with history of fever with chills, travel to endemic area, and mosquito exposure. Physical examination may reveal fever, pallor, and enlarged spleen. Microscopic Examination (Peripheral Blood Smear) Gold standard test.
o Thick smear: detects presence of parasite o Thin smear: identifies species and parasite load Rapid Diagnostic Tests (RDTs) Detect malarial antigens (HRP-2, pLDH). Useful for quick diagnosis, especially in remote areas. Complete Blood Count (CBC) Shows anemia, thrombocytopenia, and sometimes leukopenia. Other Investigations o Liver function tests โ detect jaundice o Kidney function tests โ detect renal failure o Blood glucose โ detect hypoglycemia Treatment
- Artemisinin-based Combination Therapy (ACT) Mechanism: Generates free radicals inside parasite, damaging proteins and membranes โ rapid parasite killing. Examples: o Artesunate + Sulfadoxine-Pyrimethamine o Artemether + Lumefantrine
- Chloroquine Mechanism: Inhibits heme polymerization in parasite food vacuole, causing accumulation of toxic heme โ parasite death.
Use: Sensitive P. vivax malaria
- Primaquine
o Uncomplicated malaria: โ ACT (Artemisinin-based combination therapy) o Vivax/ovale malaria: โ Chloroquine + Primaquine
- Severe Malaria Management o IV Artesunate immediately o Supportive care (fluids, oxygen, transfusion)
- Add Primaquine o For radical cure and relapse prevention
- Monitoring o Check parasite count o Monitor complications
- Prevention o Mosquito nets, repellents o Eliminate stagnant water o Prophylactic drugs (in high-risk areas)
