Malaria

Malaria is a mosquito-borne infectious disease caused by single-celled microorganisms of the Plasmodium group, primarily transmitted to humans through the bites of infected female Anopheles mosquitoes.

The disease predominantly affects tropical and subtropical regions around the equator, including sub-Saharan Africa, Asia, and Latin America.

Signs and Symptoms

The main symptoms of malaria include fever, chills, headache, vomiting, and fatigue. In severe cases, it can result in jaundice, seizures, coma, or death.

Symptoms typically begin 10-15 days after being bitten by an infected mosquito. Severe malaria, often caused by P. falciparum, can exhibit neurological symptoms such as abnormal posturing, seizures, or coma.

Diagnosis

Malaria is diagnosed through the microscopic examination of blood films or antigen-based rapid diagnostic tests (RDT). Microscopy is the gold standard, involving Giemsa-stained blood films to detect parasites. RDTs are used where microscopy is unavailable, detecting parasite proteins in a fingerstick blood sample.

Complications

Severe malaria can lead to respiratory distress, kidney failure, cerebral malaria, and haemoglobin in the urine. Pregnant women are at higher risk of complications like stillbirths, infant mortality, and low birth weight. Coinfection with HIV increases mortality rates.

Prevention

Preventive measures include the use of mosquito nets, insect repellents, and indoor residual spraying of insecticides. Two malaria vaccines, RTS,S and R21, are endorsed by the World Health Organisation (WHO) for children. Preventive medications are also available for travellers and at-risk populations.

Treatment

Malaria treatment depends on the type and severity of the disease. Uncomplicated malaria can be treated with oral medications, primarily artemisinin-based combination therapies (ACTs). Severe malaria requires intravenous antimalarial drugs, with artemisinin derivatives like artesunate being the preferred treatment over quinine. Supportive measures are also essential in managing severe cases, including monitoring for complications like seizures and respiratory distress.

Epidemiology

In 2021, there were an estimated 247 million cases of malaria, resulting in 619,000 deaths, with children under five being the most affected group. Sub-Saharan Africa accounts for approximately 95% of malaria cases and deaths. The global incidence and mortality rates have declined in recent years due to preventive measures, but challenges like drug resistance and climate change continue to pose significant hurdles.

History

Malaria has been known since ancient times, with references found in historical texts. The first effective treatment, quinine, was derived from the bark of the cinchona tree. The discovery of the malaria parasite in the late 19th century and the identification of mosquitoes as vectors marked significant milestones. Today, efforts continue towards malaria eradication, with a focus on preventive measures, treatment advancements, and research into vaccines and novel therapies.

---

Self-assessment MCQs (single best answer)

What is the primary method of malaria transmission?

Which region is most affected by malaria?

What is the gold standard for diagnosing malaria?

What is one of the severe complications of malaria in pregnant women?

Which vaccine is endorsed by the WHO for preventing malaria in children?

What is the preferred treatment for severe malaria?

Who received the Nobel Prize for Physiology or Medicine in 1902 for work on malaria?

What is the estimated number of malaria cases in 2021?

What is a common symptom of malaria?

What historical treatment was derived from the bark of the cinchona tree?