Understanding Malaria: Causes, Symptoms, and Prevention

By Dr. Rajinder Kumar Singal in Internal Medicine

Oct 30 , 2023 | 5 min read

Malaria is named after the Italian term “mal’aria”, which means “bad air”, to represent the association of the disease with marshy areas. It is an endemic vector-borne parasitic disease caused by the protozoan parasites of the genus Plasmodium in tropical and subtropical regions worldwide. Plasmodium consists of over 200 species, infecting mammals, birds, and reptiles, and malaria parasites generally tend to be host-specific of the five Plasmodium species that cause malaria in humans; P. falciparum causes severe malaria.


Causes of Malaria

Malaria is primarily caused by Plasmodium parasites, including P. falciparum, P. vivax, P. malariae, and P. ovale. These parasites enter the bloodstream through mosquito bites and invade red blood cells, leading to the characteristic symptoms of the disease.

  • Malaria Parasite - Plasmodium parasites are single-celled organisms that undergo a complex life cycle involving both humans and mosquitoes. They multiply inside red blood cells, causing them to rupture and release more parasites, contributing to the cyclic nature of the disease.

  • Mosquito Vector - The Anopheles mosquito acts as the vector for malaria transmission. Female mosquitoes become infected when they feed on an infected human, allowing the parasites to develop within the mosquito. These infected mosquitoes can then transmit the parasites to other humans through their bites.


Understanding Malaria Transmission

Malaria transmission occurs when an infected Anopheles mosquito bites a human host. During the bite, the mosquito injects sporozoites (immature forms of the parasite) into the bloodstream. These sporozoites travel to the liver and multiply, eventually re-entering the bloodstream and infecting red blood cells.

Life cycle of the Malaria Parasite

The malaria parasite undergoes a complex life cycle involving asexual reproduction in humans and sexual reproduction in mosquitoes.

  • Transmission: An infected mosquito bites a human, injecting sporozoites.

  • Liver Stage: Sporozoites infect liver cells and multiply into merozoites.

  • Blood Stage: Merozoites enter red blood cells, replicate, and cause symptoms.

  • Sexual Stage: Some parasites become gametocytes.

  • Transmission to Mosquitoes: Mosquitoes ingest gametocytes during a blood meal.

  • Mosquito Stage: Gametocytes mature, fertilise, and become ookinetes.

  • Oocyst Stage: Oocysts produce sporozoites.

  • Salivary Gland Stage: Sporozoites reach the mosquito's salivary glands.

  • Transmission (Repeat): An infected mosquito bites a human, restarting the cycle.

Anopheles Mosquito and Its Role

Female Anopheles mosquitoes transmit malaria. After becoming infected by feeding on an infected human, the mosquito incubates the parasites in its salivary glands. Subsequent mosquito bites can then introduce the parasites into a new human host.


Common Symptoms of Malaria

Malaria symptoms vary but commonly include fever, chills, headaches, muscle pains, nausea, vomiting, fatigue, and weakness. These symptoms typically occur in cycles corresponding to the parasite's life cycle in red blood cells.

  • Fever and Chills - Fever and chills are hallmark symptoms of malaria and often coincide with the release of parasites from ruptured red blood cells.

  • Headaches and Muscle Pains - Headaches and muscle pains are common due to the immune response triggered by the presence of parasites in the bloodstream.

  • Nausea and Vomiting - Nausea and vomiting may result from the body's attempts to eliminate the infection or as a direct effect of the parasite's presence.

  • Fatigue and Weakness - Malaria can lead to significant fatigue and weakness as the parasites compromise the oxygen-carrying capacity of red blood cells.


Diagnosis of Malaria

Malaria diagnosis involves identifying the presence of Plasmodium parasites in the blood. This is commonly done through blood tests and rapid diagnostic tests (RDTs).

Blood Tests

Microscopic examination of stained blood smears allows skilled technicians to identify and differentiate Plasmodium species.

Rapid Diagnostic Tests (RDTs)

RDTs detect specific parasite antigens in the blood, providing quick results without the need for extensive laboratory equipment.


Different Types of Malaria

Malaria is caused by several Plasmodium species, each with distinct characteristics and geographical distributions.

  • Plasmodium falciparum P - falciparum is the most deadly species and is responsible for severe cases of malaria. It accounts for the majority of malaria-related deaths globally.

  • Plasmodium vivax P ;- vivax causes a recurring form of malaria due to its ability to remain dormant in the liver and reactivate later.

  • Plasmodium malariae P - malariae leads to a chronic form of malaria with less frequent but persistent symptoms.

  • Plasmodium ovale P - ovale also causes a recurring form of malaria and shares some similarities with P. vivax.


Malaria Complications

Malaria can lead to severe complications, particularly when caused by P. falciparum.

  • Severe Malaria - Severe malaria can cause organ dysfunction, neurological complications, and metabolic disturbances, often leading to death if not promptly treated.

  • Anemia - Malaria-related anaemia results from the destruction of red blood cells and impaired production of new ones.

  • Cerebral Malaria - Cerebral malaria involves severe neurological symptoms and can lead to coma or other cognitive impairments.


High-Risk Areas for Malaria

Malaria is prevalent in parts of Africa, Asia, and the Americas, where Anopheles mosquitoes thrive.


Malaria Prevention and Control

Preventing malaria involves a multi-faceted approach that includes the following methods-

  • Insecticide-Treated Bed Nets (ITNs) - ITNs create a physical barrier against mosquito bites and are treated with insecticides to repel or kill mosquitoes.

  • Indoor Residual Spraying (IRS) - IRS involves the application of insecticides to indoor surfaces to reduce mosquito populations.

  • Antimalarial Drugs - Various antimalarial drugs are available for both prevention and treatment, targeting different stages of the parasite's life cycle.


Malaria in Pregnancy and Children

Pregnant women and children are particularly vulnerable to malaria, requiring special attention and precautions.

Risks and Precautions

Malaria during pregnancy can lead to complications for both the mother and the fetus. Preventive measures, such as bed net use and antimalarial medication, are crucial.

Malaria remains a significant global health challenge, but advancements in research, prevention strategies, and treatment options are providing hope in the fight against this deadly disease. Understanding the intricacies of malaria transmission, symptoms, diagnosis, and prevention is vital for reducing its impact and ultimately eradicating it from affected regions.


Frequently Asked Questions

1. Can malaria be transmitted from person to person?

Malaria is not directly transmitted from person to person. It requires the intermediate step of mosquito transmission.

2. Can malaria be treated with antibiotics?

No, malaria is caused by parasites, not bacteria, so antibiotics are not effective. Antimalarial drugs are used for treatment.

3. Is malaria a life-threatening disease?

Yes, particularly when caused by P. falciparum, malaria can lead to severe complications if not treated promptly.

4. Can pregnant women safely travel to malaria-endemic areas?

Pregnant women are comparatively at a higher risk of severe malaria and related complications. Travel to endemic areas should be carefully considered, and preventive measures taken.

5. How can I protect myself from malaria while travelling?

Using insecticide-treated bed nets, wearing protective clothing, applying insect repellent, and taking antimalarial medication are essential precautions for travellers to endemic areas.