Malaria – medical revision notes
In this article we will describe 10 medical revision notes about malaria.
Plasmodium malariae
Key Points
- Malaria is infection with Plasmodium species
- Malaria is prevalent in tropical and subtropical regions, particularly in sub-Saharan Africa, South Asia, and parts of Central and South America
- Symptoms and signs include fever (which may be periodic), chills, rigors, sweating, diarrhoea, abdominal pain, respiratory distress, confusion, seizures, haemolytic anemia, splenomegaly, and AKI/CKD
- Diagnosis is by seeing Plasmodium in a peripheral blood smear and by rapid diagnostic tests
- Malaria is treatable with antimalarial medication. The type of drug and duration of treatment depend on the species of Plasmodium causing the infection and the severity of disease.
A single mosquito bite is all it takes for someone to become infected.
1. Definition
Malaria is an infection caused by Plasmodium species, transmitted to humans through the bite of infected female Anopheles mosquitoes.
2. Epidemiology
- Malaria is prevalent in tropical and subtropical regions, particularly in sub-Saharan Africa, South Asia, and parts of Central and South America
- In 2020, an estimated 241 million people worldwide had malaria, resulting in about 627,000 deaths
- The majority of these deaths occurred in children under 5 years old in Africa
- Since 2000, global malaria-related deaths have decreased by approximately 60%. Some progress is being made.
3. Risk factors
- Infants and children under 5 years
- Pregnant women
- Travellers to endemic areas
- People living with HIV/AIDS.
4. Cause
Malaria is caused by Plasmodium parasites, transmitted to humans via the bites of infected Anopheles mosquitoes.
Types of Plasmodium
- P. falciparum (most deadly)
- P. vivax
- P. ovale
- P. malariae
- P. knowlesi
5. Symptoms
Common symptoms of malaria include:
- Fever, chills, headache, nausea, vomiting
- Muscle pain and fatigue.
Severe malaria: Typically caused by P. falciparum, severe malaria can lead to:
- Acute respiratory distress syndrome (ARDS) or pulmonary oedema
- Bleeding
- Coma or impaired consciousness
- Jaundice
- Recurrent seizures
- AKI
- Shock.
6. Diagnosis
Malaria diagnosis is confirmed by:
- Light microscopy of blood smears (thin and thick)
- Rapid diagnostic tests (RDTs)
Laboratory criteria for severe malaria include:
- Severe anaemia (Hb < 70 g/L)
- Disseminated intravascular coagulation (DIC)
- Haemoglobinuria
- Metabolic acidosis
- Parasite density > 5%
- Acute kidney injury (AKI).
7. Treatment
Malaria is treatable with antimalarial medications, with the choice of drug and treatment duration depending on the Plasmodium species and disease severity.
- Artemisinin-based combination therapies (ACTs) are standard for treating P. falciparum malaria.
- P. vivax and P. ovale infections require additional treatment to prevent relapse.
Drug resistance: Resistance to antimalarials such as chloroquine and sulfadoxine-pyrimethamine remains a challenge, particularly in P. falciparum infections. Ongoing efforts are in place to monitor and manage drug resistance.
8. Complications
- Cerebral malaria (responsible for 80% of malaria deaths, typically with P. falciparum infection)
- Severe malarial anaemia
- Acute kidney injury (AKI)
- Nephrotic syndrome (NS).
9. Prognosis
Malaria infections vary in duration and risk of relapse depending on the species:
- P. falciparum and P. ovale: Infection lasts 2-3 weeks, with relapse possible 6-18 months later
- P. vivax: Infection lasts 3-8 weeks, with relapses occurring months to up to 5 years later
- P. malariae: Infection can last 3-24 weeks, with relapse possible up to 20 years later.
10. Prevention
Preventive measures include:
- Insecticide-treated mosquito nets (ITNs)
- Indoor residual spraying (IRS) with insecticides
- Antimalarial prophylaxis for travellers and high-risk individuals.
Personal protective measures, such as wearing long sleeves and using insect repellents, are also important.
Vaccine development: The RTS,S/AS01 (Mosquirix) vaccine has been approved for use in children in high-risk areas of Africa, providing partial protection against P. falciparum malaria.
Other information
Global and economic impact
Malaria has a significant economic impact on endemic countries, affecting healthcare costs, productivity, and investment. In Africa, malaria is estimated to result in a $12 billion annual loss in GDP.
Africa bears the highest burden of malaria cases and deaths globally.
Summary
We have described 10 medical revision notes about malaria. We hope it has been helpful.
Other resources
Malaria (NHS England)
Malaria (NHS Scotland)
Review: Buck, 2023
