Malaria

Introduction

Malaria is a life-threatening mosquito-borne disease caused by Plasmodium parasites. Infected Anopheles mosquitoes transmit the parasite to humans through bites, mainly in tropical and subtropical regions.

After infection, parasites multiply in the liver then invade red blood cells, causing cyclical fevers, chills, and anaemia. Without prompt treatment, some species—especially Plasmodium falciparum—can cause severe organ failure and death.

Malaria remains a major global health burden, though prevention with bed nets, insect repellents, and prophylactic medicines has reduced deaths. Travellers to endemic areas and residents alike need awareness of symptoms and urgent treatment access.

This page covers how malaria develops, symptoms including severe disease, diagnosis, treatment, prevention, and when to seek emergency care.

Overview

Five Plasmodium species commonly infect humans: P. falciparum (most dangerous), P. vivax, P. ovale, P. malariae, and P. knowlesi in parts of Southeast Asia. Incubation is typically 7–30 days but may be longer with some species or partial immunity.

Classic malaria presents with periodic fever, chills, sweats, headache, and body aches. Severe malaria involves impaired consciousness, respiratory distress, anaemia, jaundice, kidney failure, or abnormal bleeding and requires hospital care.

Diagnosis is confirmed by blood smear or rapid antigen test. Artemisinin-based combination therapy (ACT) is first-line for uncomplicated falciparum malaria in most settings. Drug resistance patterns vary by region.

• Mosquito-borne infection with Plasmodium parasites
• P. falciparum causes the most severe and fatal cases
• Endemic in much of sub-Saharan Africa, South Asia, and elsewhere
• Classic triad: fever, chills, sweats in cyclical pattern
• Severe malaria is a medical emergency with organ dysfunction
• Diagnosed by blood smear, rapid test, or PCR
• Treated with antimalarial drugs matched to species and region
• Preventable with nets, repellents, and chemoprophylaxis when travelling

What happens in the body

Mosquito injects sporozoites that travel to the liver and multiply silently during the hepatic phase. Merozoites then enter the bloodstream, invading red blood cells where they reproduce, rupture cells, and trigger fever cycles.

Immune responses and parasite load cause anaemia, splenic enlargement, and—in severe falciparum malaria—microvascular obstruction, cerebral malaria, pulmonary oedema, and metabolic acidosis from high parasite burden.

• Sporozoites infect liver cells before blood-stage parasites emerge
• Red blood cell rupture releases toxins triggering fever cycles
• P. falciparum can sequester in microvasculature causing organ ischaemia
• Anaemia and splenic clearance result from haemolysis and immune response

Signs and symptoms

Symptoms vary by species, immunity, and severity. Common features include:

• High fever occurring in episodes with chills and sweats
• Headache and generalised body aches
• Fatigue and weakness
• Nausea, vomiting, and diarrhoea in some cases
• Muscle and joint pain
• Enlarged spleen on examination (splenomegaly)
• Mild jaundice with significant haemolysis
• Anaemia causing pallor and breathlessness
• In children: irritability, poor feeding, and rapid progression to severe disease
• Cough in some P. vivax or severe malaria presentations
• Confusion or drowsiness in cerebral malaria
• Dark urine from haemoglobinuria (“blackwater fever” in severe cases)
• Prostration— inability to sit or stand without support in severe malaria

Causes and risk factors

Malaria transmission requires parasite, vector, and human host interaction:

• Bite of female Anopheles mosquito carrying Plasmodium
• Travel to or residence in endemic regions without prevention
• P. falciparum, P. vivax, P. ovale, P. malariae, or P. knowlesi infection
• Blood transfusion or shared needles (rare but documented)
• Congenital transmission from infected mother (uncommon)
• Relapse from liver hypnozoites in P. vivax and P. ovale
• Seasonal and geographic variation in mosquito breeding
• Lack of bed nets, indoor spraying, or prophylaxis in at-risk groups
• Delayed treatment allowing progression to severe malaria

Diagnosis and evaluation

Prompt laboratory confirmation guides species-specific treatment:

• Travel and exposure history in endemic area within past year
• Thick and thin blood smears for parasite identification and quantification
• Rapid diagnostic test (RDT) for field or clinic screening
• PCR for species confirmation and low-parasitaemia cases
• Repeat smears if initial test negative but suspicion remains high
• Full blood count showing anaemia and thrombocytopenia
• Liver and kidney function tests in moderate to severe illness
• Glucose monitoring—hypoglycaemia common in severe falciparum malaria
• Differentiation from dengue, typhoid, influenza, and other fevers

Treatment and management

Treatment depends on species, severity, age, pregnancy status, and local resistance:

• Artemisinin-based combination therapy (ACT) for uncomplicated falciparum malaria
• Chloroquine where P. vivax remains sensitive (regional guidance varies)
• Primaquine or tafenoquine for P. vivax/ovale liver hypnozoites to prevent relapse
• Intravenous artesunate for severe malaria—hospital emergency care
• Supportive care: fluids, blood transfusion, anticonvulsants, dialysis as needed
• Monitor for hypoglycaemia, acidosis, and respiratory distress in severe cases
• Avoid single-artemisinin monotherapy to reduce resistance development
• Pregnancy-specific regimens—avoid certain drugs in first trimester per guidelines
• Follow national and WHO treatment protocols for local resistance patterns
• Complete full course even if fever resolves quickly

Prevention, self-care, and lifestyle

Not every condition is fully preventable, but the steps below may lower risk or recurrence:

• Insecticide-treated bed nets in endemic households
• Indoor residual spraying and mosquito control programmes
• DEET or picaridin repellents and protective clothing outdoors at dusk
• Chemoprophylaxis for travellers to endemic areas per guidelines
• Prompt diagnosis and treatment to reduce community transmission
• Screening blood donations in endemic regions
• Eliminate standing water breeding sites near homes
• Community education on fever after travel to malaria zones

Possible complications

Delay, missed care, or unsafe self-medication can raise the chance of complications in some cases:

• Cerebral malaria with coma and neurological sequelae
• Severe anaemia requiring transfusion
• Acute kidney injury and metabolic acidosis
• Acute respiratory distress syndrome (ARDS)
• Hypoglycaemia, especially in children and pregnant women
• Death if severe malaria untreated—particularly P. falciparum
• Relapse months later with P. vivax or P. ovale without hypnozoite therapy
• Chronic anaemia and splenic complications in repeated infections

When to see a doctor or seek emergency care

Seek prompt medical advice or emergency care if any of the following apply—it is safer not to wait and see:

• Any fever after travel to a malaria-endemic region—urgent same-day evaluation
• Confusion, drowsiness, or inability to wake—emergency care
• Difficulty breathing, severe anaemia, or persistent vomiting
• Jaundice with high fever suggesting severe haemolysis
• Seizures or repeated convulsions in a child with fever
• Signs of shock—cold extremities, weak pulse, low blood pressure
• Pregnancy with fever in endemic area—immediate obstetric and infectious disease care
• Failure to improve 48 hours after starting antimalarial treatment

Living with the condition

After recovery, complete all prescribed antimalarials and any primaquine course for vivax/ovale to prevent relapse. Keep follow-up blood tests if advised.

If you live in or repeatedly visit endemic areas, use consistent prevention and seek care early for any fever—delay increases risk of severe disease.

Frequently asked questions

Can malaria be cured?

Yes, with prompt appropriate antimalarial drugs. Severe cases need hospital care but can recover fully with timely treatment.

How soon do symptoms appear?

Usually 7–30 days after bite, depending on species. Some vivax/ovale relapses occur months later from liver stages.

Is malaria contagious person to person?

Not through casual contact. It spreads via mosquito bites or rarely blood transfusion.

Do I need prophylaxis when travelling?

If visiting endemic regions, consult a travel clinic for recommended preventive medicines and mosquito precautions.

What is severe malaria?

Malaria with organ dysfunction—altered consciousness, respiratory distress, severe anaemia, jaundice, or shock. It is a medical emergency.

Can I get malaria more than once?

Yes. Infection does not guarantee lasting immunity. Repeat episodes are common in endemic areas.

Important caution

Malaria kills when diagnosis or treatment is delayed—especially falciparum malaria.

Any fever after travel to an endemic region warrants urgent malaria testing the same day.

Prevention with nets, repellents, and prophylaxis saves lives; early treatment cures most cases.