Healthy Line: Malaria Disease Control and Prevention

Malaria: Causes, Symptoms, Treatment, and Prevention

Introduction

Malaria is a parasitic disease, which is life threatening and spreads through the bite of the infected female Anopheles mosquitoes. It has been one of the biggest threats to the health of the world, especially those of the tropical and subtropical countries. The World Health Organization (WHO) estimates that 247 million cases of malaria were reported globally in 2021 and caused 619,000 deaths, most of which involved the young children under five years of age in sub-Saharan Africa.

The article has taken a critical look at malaria, its causes, mode of transmission, its symptoms, diagnosis, and treatment, the preventive measures, and international campaigns against the malaria disease.

 

1. What Causes Malaria?

The protozoan parasites of the genus Plasmodium are responsible in causing malaria. Humans are known to be infected by five:

1.     Plasmodium falciparum - This is the most lethal species which causes most deaths due to malaria.

2.     Plasmodium vivax -The most prevalent species outside Africa and it is known to cause relapses as a result of the dormant liver forms (Hypnozoites).

3.     Plasmodium ovals - Just like P. vivax, it is able to lie in the liver and lead to relapses.

4.     Plasmodium malaria - results in milder malaria but may remain in the bloodstream many years.

5.     Plasmodium Knowles - A zoonotic malaria parasite that majorly occurs in Southeast Asia and that can inflict serious infections in humans.

 

Lifecycle of the Malaria Parasite

Malaria parasite has a complicated life cycle in which it uses two hosts, humans and mosquitoes.

A. Transmission to Humans (Through Mosquito Bite)

1.     Infected Bite by Mosquito: The Anopheles mosquito transmits the disease by piercing its mouth into the blood of a person and injecting sporozoites (the infectious form of the parasite) into the bloodstream.

2.     Liver Stage (Exo-erythrocytic Phase): Sporozoites move to the liver, enter cells (hepatocytes) in the liver and reproduce to form thousands of merozoites.

3.     Blood Stage (Erythrocytic Phase): The merozoites get released to the bloodstream infecting red blood cells (RBCs). Within RBCs, they reproduce and burst the cells releasing additional parasites, which produce cycles of fevers.

B. Transmission Back to Mosquitoes

Parasites vary and some become sexually differentiated (gametocytes). When these gametocytes are ingested by another mosquito when it bites an infected individual, it is colonized in the gut of the mosquito and becomes sporozoites, thus completing the cycle.

 

2. Symptoms of Malaria

The symptoms of malaria are usually displayed between 7 to 30 days after infection but may be slower in other situations (particularly in cases of P. vivax and P. ovals). The extent of severity is dependent on the species of the parasites and the immunity of the patient.

Common Symptoms

·        High fever (cyclic, sometimes, with the chills and perspiration)

·        Headache

·        Pain in the muscles and joints

·        Fatigue

·        Vomiting and nausea

·        Diarrhea

 

Severe Malaria (Mostly Caused by P. falciparum)

Severe malaria is a health emergency and may result to:

·        Seizures, coma and neurological damage (cerebral malaria)

·        Fatal anemia (caused by the destruction of RBC)

·        ARDS Acute respiratory distress syndrome (ARDS)

·        Kidney failure

·        Low blood sugar -Hypoglycemia

·        Multi-organ failure

 

Relapsing Malaria (P. vivax and P. Ovalle)

These organisms may lie dormant in the liver (hypnozoites) and may reactivate weeks or months later producing relapses.

 

3. Diagnosis of Malaria

It is important to diagnose the condition early to facilitate treatment. Diagnostic tools are:

A. Microscopic Examination (Gold Standard)

·        Blood smears are prepared by thick and thin smear, stained and are analyzed under the microscope to observe parasites.

·        Aids in establishing the species and the body-parasite burdens.

B. Rapid Diagnostic Tests (RDTs)

·        Determine blood presence of malaria antigens (e.g. Plasmodium lactate dehydrogenase, histidine-rich protein-2).

·        Apply to distant sites with little laboratory resources.

C. Molecular Testing (PCR)

·        Very sensitive, to identify species and low-level infections.

D. Serology Tests

·        Find antibodies, are only helpful in epidemiological studies and not in acute diagnosis.

 

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4. Treatment of Malaria

The treatment is based on the parasite, severity and location of drug-resistant patterns.

A. Uncomplicated Malaria

·        P. falciparum:

o   First-line treatments are Artemisinin-based Combination Therapies (ACTs) (e.g. artemether-lumefantrine).

·        P. vivax, P. Ovalle, P. malariae:

o   Chloroquine (resistance free) + Primaquine (to destroy liver hypnozoites and prevent relapse).

o   In the regions where chloroquine resistance is observed, ACTs are applied.

B. Severe Malaria

·        The use of intravenous (IV) artesunate is the most preferred.

·        Alternate: IV quinine or quinidine.

·        Supporting care (fluids, blood transfusion, anticonvulsants in case of necessity).

C. Antimalarial Drug Resistance

·        Resistance of P. falciparum to chloroquine and sulfadoxine-pyrimethamine is very common.

·        The developing artemisinin resistance in Southeast Asia (e.g. Cambodia, Thailand).

 

5. Prevention and Control of Malaria

Malaria prevention includes the use of vector control, chemoprophylaxis and vaccination.

A. Vector Control

1.     Insecticide-Treated Nets (ITNs): Reduce a rate of mosquito bites during sleep.

2.     Indoor Residual Spraying (IRS): Spraying of insecticides on the walls kills the mosquitoes.

3.     Environmental Management: Removing stagnant water (mosquitoes breeding places).

B. Chemoprophylaxis (Preventive Medications)

·        Atovaquone-proguanil (Malarone)

·        Doxycycline

·        Mefloquine

·        Chloroquine (in non-resistant regions)

C. Malaria Vaccines

·        RTS,S/AS01 (Mosquirix): It is the first malaria vaccine approved by WHO, and it prevents severe malaria in children.

·        R21/Matrix-M: A vaccine that seems to be promising and is under consideration.

D. Personal Protection Measures

·        Long-sleeved clothes.

·        DEET, picaridin mosquito repellents.

·        Using bed nets to sleep.

 

6. Global Efforts to Eliminate Malaria

There are a number of efforts that are trying to prevent the malaria cases and deaths:

·        WHO Global Malaria Programme: Policy and guidelines.

·        Roll Back Malaria (RBM) Partnership: Organizes the world actions.

·        The Global Fund: Provides funds to the malaria programs in the affected countries.

·        President Malaria Initiative (PMI): American-led malaria war.

 

Challenges in Malaria Elimination

·        Resistance to drugs and insecticides.

·        Poor health systems among endemic nations.

·        The spreading of mosquitoes as a result of climate change.

·        The malaria program funding deficits.

 

Conclusion

Malaria is a significant public health problem especially in tropical areas. Although much has been done towards prevention of cases and deaths as well as control of the vectors, effective treatment and vaccines, roadblocks such as drug resistance and funding have continued to be experienced.

Funding of malaria research, health infrastructure and community education has to be continued in order to eliminate malaria worldwide. The combination of preventive action, early diagnosis and effective treatment gives the world an opportunity to move towards malaria-free future.

 

References

·        Malaria Reports of World Health Organization (WHO)

·        Centers of Disease Control and Prevention (CDC)

·        The Lancet Infectious Diseases

·        National Institutes of Health (NIH)