Malaria

Malaria is a parasitic disease caused by plasmodium that enters the human bloodstream by a mosquito bite. Plasmodium has different species, based on which different types of malaria are identified. Malaria is endemic in temperate regions of the world.

Malaria is caused by a parasite called plasmodium transmitted by the bite of the female anopheles mosquito. Different species of plasmodium are:

• P. Vivax
• P. Falciparum
• P. Malaria
• P. Ovale
• P. Knowles

The different morphology of their cells identifies the different types.

Types of malaria are classified according to the kind of plasmodium causing it. Different types are:

• Falciparum malaria
• P. vivax malaria
• P. malariae malaria
• P. ovale malaria
• P. knowlesi malaria

Amongst them, malaria caused by P. falciparum is the most severe form. It is resistant to traditional antimalarial therapy, and if left untreated, it can cause death. It can affect RBCs of all ages, whereas P. vivax and ovale only affect RBCs of the young generation.

Malarial parasites are transmitted into the blood of humans by mosquito bites. After entering the bloodstream, they travel to liver cells and remain there for a few weeks. After maturation in the liver cells, they enter the bloodstream again and attack red blood cells. Further development takes place inside red blood cells. After they have fully developed, they cause red blood cells to rupture, resulting in fever and other clinical symptoms. The cycle is repeated, and the parasite grows inside the human body exponentially.

Other forms of transmission include blood transfusion and maternal to fetal information.

The risk factors for malaria are:

• Travel to endemic areas
• Intensity and type of malaria infection
• Use of precautions such as bed nets, anti-mosquito liquids, etc.
• Host immunity

According to WHO, malaria is responsible for around 1-3 million deaths per year, most of which occur in Africa in children caused by falciparum malaria. Co-infection with malaria and HIV is also a problem in these countries. Young children are at an increased risk of death due to malaria.

The incubation period for malaria is a few weeks after the infection. The common symptoms are:

• Fever with chills and sweats- classic outbreak of malaria is shaking chills that last for up to 1 hour, followed by a high-grade fever followed by excessive sweating, causing the body temperature to drop to normal. Some patients do not exhibit this paroxysm.
• Cough
• Fatigue
• Malaise
• Generalized muscle and joint pains
• Jaundice
• Diarrhea and vomiting

Complications due to falciparum malaria include:

• Cerebral malaria
• Pulmonary edema
• Rapidly developing anemia
• Renal problems
• Microvascular damage due to vascular obstruction
• Blackwater fever is the passage of dark-colored urine containing blood due to the breakdown of blood cells and vascular damage caused by the parasite.
• Lactic acidosis
• Bleeding that can be life-threatening

• Thick and thin blood smears are used for malaria diagnosis. Thick films indicate the presence of infection, whereas thin films are analyzed to determine the type of species.
• Rapid diagnostic tests are also used for malaria diagnosis when thick and thin films can not be prepared and analyzed.
• PCR testing can also be used.
• Complete blood count with findings of anemia, thrombocytopenia, increased retic count, and atypical lymphocytosis.
• Increased LDH levels.
• Increased liver function tests and abnormal renal function tests are seen when the liver and kidneys are also involved
• Lumbar puncture is done when there is suspicion of cerebral malaria.

Differential diagnoses for malaria include:

• Viral Illnesses
• Bacteremia
• Enteric Fever
• Hodgkin’s Lymphoma
• Cholera
• Food Poisoning
• Hepatitis
• Heatstroke
• Dengue Fever
• Viral Pneumonia
• Sinusitis
• Yellow Fever

• Patients with uncomplicated malaria are treated outdoors, and blood smears are obtained daily to monitor their response to the treatment.
• Supportive treatment is given for most symptoms. Adequate hydration, electrolyte replacement, and pain management are recommended.
• IV antimalarials such as IV quinine is given to treat the complicated and severe cases of malaria.
• Acute malaria with no complications is treated by oral antimalarials used in combination forms, such as artemether and coartem, proguanil HCl and quinine. 
• For drug-resistant P. falciparum that does not respond to conventional antimalarials, multi-drug therapy is used.
• Vaccination against malaria was first introduced in 2015; it is still under research and has been piloted in a few parts of the world with promising results.

Most forms of malaria are benign and carry a good prognosis. They are highly responsive to antimalarial therapy, and outcomes improve within 48 hours of initiation of treatment. The mortality rate associated with falciparum infection is the highest. But if adequate treatment is started timely, the prognosis for even this form of malaria is also good.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on May 25, 2023.

References

Malaria (who.int)

https://www.who.int/news-room/fact-sheets/detail/malaria

Microorganisms | Free Full-Text | Malaria: The Past and the Present (mdpi.com)

https://www.mdpi.com/2076-2607/7/6/179