Malaria — Diagnosis, Species & Indian Treatment Guidelines

Malaria is transmitted by the bite of infected female Anopheles mosquito. Five species infect humans: P. falciparum (most severe), P. vivax (most common in India), P. ovale, P. malariae, P. knowlesi (zoonotic in SE Asia). India contributes approximately 2% of global malaria cases, with 80%+ of cases in tribal/rural areas of Odisha, Chhattisgarh, Jharkhand, Meghalaya, Mizoram. Cases peak during monsoon and post-monsoon.

Clinical features: Fever with chills and rigors, headache, body aches, nausea, vomiting, splenomegaly. Classical tertian (every 48 hr) or quartan (every 72 hr) fever pattern is the exception, not the rule. Severe malaria presents with cerebral malaria (impaired consciousness, seizures), severe anaemia, ARDS, AKI, hypoglycaemia, jaundice, haemoglobinuria (blackwater fever).

• Microscopy (gold standard): Thick and thin peripheral smear stained with Giemsa or JSB stain. Thick smear for sensitivity (detects low parasitaemia), thin smear for species identification and parasite count. Reports: species (vivax, falciparum, mixed), parasite density (parasites/µL — > 100,000 = severe).
• RDT (Rapid Diagnostic Test): Immunochromatographic test detecting parasite antigen. Two types: HRP-2 (P. falciparum specific, persists for weeks after treatment), LDH (species-specific, clears with treatment). Use bivalent RDTs that detect both species.
• CBNAAT: PCR-based, highly sensitive — useful for low parasitaemia and mixed infections. Not routinely used at peripheral level.

Every fever case in endemic area should be tested for malaria before treatment — 'Test-Target-Treat' strategy. Presumptive treatment without testing is no longer recommended due to drug resistance and over-treatment.

Chloroquine-sensitive areas (most of India):

• Chloroquine: 25 mg/kg total over 3 days — Day 1: 10 mg/kg, Day 2: 10 mg/kg, Day 3: 5 mg/kg (adult dose: 600 mg + 600 mg + 300 mg base)
• Primaquine: 0.25 mg/kg OD x 14 days (radical cure — kills hypnozoites in liver). G6PD deficiency check recommended before primaquine.

Chloroquine-resistant areas (Northeastern states): ACT-AL (Artemether-Lumefantrine) — same as for falciparum.

Primaquine contraindications: pregnancy, lactation, infants < 6 months, G6PD deficiency, severe illness. Always do G6PD testing before starting primaquine if available.

Uncomplicated P. falciparum: Artemisinin-based Combination Therapy (ACT) — 3 days:

• ACT-AS+SP (Artesunate + Sulfadoxine-Pyrimethamine): Artesunate 4 mg/kg OD x 3 days + SP 25 mg/kg (sulfadoxine) + 1.25 mg/kg (pyrimethamine) single dose on Day 1
• ACT-AL (Artemether + Lumefantrine): Artemether 80 mg + Lumefantrine 480 mg BD x 3 days (5 days for NE states)
• ACT-AS+AQ (Artesunate + Amodiaquine): Artesunate 4 mg/kg + Amodiaquine 10 mg/kg OD x 3 days

Primaquine: Single dose 0.75 mg/kg on Day 1 (gametocytocidal — prevents transmission to mosquitoes). Not for pregnant women, infants, G6PD deficiency.

Pregnancy (1st trimester): Quinine 10 mg/kg TID x 7 days. Avoid ACT in 1st trimester due to theoretical embryotoxicity (limited safety data).

Pregnancy (2nd-3rd trimester): ACT-AL or Quinine + Clindamycin. ACT is safe after 1st trimester.

Mixed infection (vivax + falciparum): Treat as falciparum (ACT) + full course of Primaquine 14 days for vivax radical cure.

Diagnostic criteria for severe malaria:

• Cerebral malaria: Impaired consciousness, seizures, abnormal posturing
• Severe anaemia (Hb < 5 g/dL in adults, < 7 in children)
• ARDS (acute respiratory distress syndrome)
• AKI (urine output < 0.5 ml/kg/hr, creatinine > 3 mg/dL)
• Hypoglycaemia (blood glucose < 40 mg/dL)
• Acidosis (pH < 7.25, bicarbonate < 15)
• Hyperparasitaemia (> 2% or > 100,000/µL)
• Haemoglobinuria (blackwater fever)
• Hyperbilirubinaemia (> 3 mg/dL), DIC, shock

Treatment:

• IV Artesunate: 2.4 mg/kg IV/IM at 0, 12, 24 hours, then daily until oral therapy tolerated. Switch to oral ACT when patient can take orally. Reduces mortality by 35% vs IV Quinine (SEAQUAMAT trial).
• IV Quinine: 20 mg/kg loading over 4 hours, then 10 mg/kg TID. Monitor ECG (QT prolongation), blood glucose (hypoglycaemia).
• Supportive care: ICU admission, fluid balance, blood transfusion for severe anaemia, dialysis for AKI, mechanical ventilation for ARDS, anticonvulsants for seizures, dextrose for hypoglycaemia.
• Exchange transfusion: Consider for parasitaemia > 10% with severe manifestations (controversial).

Malaria remains endemic in large parts of India, and every MBBS doctor will encounter cases. For UPSC CMS aspirants, ACT regimens, primaquine indications/contraindications, severe malaria criteria, and IV Artesunate are highly testable topics.