Malaria Notes

Malaria

Global Impact (2022)

  • Approximately 249 million malaria cases worldwide.
  • Estimated 608,000 malaria deaths across 85 countries.
  • The WHO African Region is disproportionately affected:
    • 94% of global malaria cases (233 million).
    • 95% of global malaria deaths (580,000).

What is Malaria?

  • Malaria is an acute febrile illness.
  • It is caused by Plasmodium parasites.
  • Spread to humans through bites from infected female Anopheles mosquitoes.
  • Five Plasmodium species cause malaria in humans but P. falciparum and P. vivax are the most threatening.
  • P. falciparum is the deadliest and most prevalent in Africa.
  • P. vivax dominates in most countries outside sub-Saharan Africa.

Symptoms

  • Initial symptoms (fever, headache, chills) appear 10-15 days post-bite.
  • Symptoms can initially be mild and mistaken for other illnesses.
  • Untreated P. falciparum malaria can rapidly progress to severe illness and death within 24 hours.

Biological Risk Factors & Immunity

  • Risk varies based on acquired immunity.
  • Repeated malaria infections can lead to partial immunity, reducing the risk of severe disease.
  • Non-immune individuals (minimal or no prior exposure) face a high risk of severe illness and death.

High-Risk Populations (Biological Factors)

  • Non-immune migrants, mobile populations, and travelers
  • Pregnant women
  • Children under 5 years of age

Socio-Economic and Cultural Risk Factors

  • Poverty
  • Physical barriers
  • Social exclusion
  • Accessibility barriers
  • Literacy barriers
  • Human rights barriers
  • Gender barriers
  • Financial barriers
  • Cultural norms
  • Complex emergencies
  • Psycho-social barriers

Underserved Populations at Higher Risk

  • Refugees and internally displaced persons
  • Populations in remote areas facing geographical barriers to services
  • Women and children from poor settings
  • Indigenous populations
  • Prisoners
  • Undocumented workers
  • Ethnic minorities
  • Migrant workers

Prevention Strategies

  • Expanded access to prevention interventions has significantly reduced the global burden.
  • Key strategies include:
    • Effective vector control
    • Preventive antimalarial drugs

Vector Control

  • Vector control is critical for malaria control and elimination.
  • It prevents infection and reduces disease transmission.
  • Core interventions:
    • Insecticide-treated nets (ITNs)
    • Indoor residual spraying (IRS)
  • Emerging insecticide resistance among Anopheles mosquitoes threatens progress.

Preventive Chemotherapies

  • Use of medicines to prevent malaria infections and their consequences.
  • Includes:
    • Chemoprophylaxis
    • Intermittent preventive treatment of infants (IPTi)
    • Intermittent preventive treatment in pregnancy (IPTp)
    • Seasonal malaria chemoprevention (SMC)
    • Mass drug administration (MDA)

Malaria Vaccine

  • WHO recommends broad use of the approved malaria vaccine since October 2021.
  • Target population: children in regions with moderate to high P. falciparum transmission.
  • The vaccine significantly reduces malaria and deadly severe malaria in young children.

Case Management

  • Early diagnosis and treatment reduces disease, prevents deaths, and reduces transmission.
  • All suspected cases should be confirmed with parasite-based diagnostic testing:
    • Microscopy
    • Rapid diagnostic test (RDT)

Treatment

  • Artemisinin-based combination therapy (ACT) is the best available treatment, especially for P. falciparum.
  • The primary goal is rapid and complete elimination of Plasmodium parasites.
  • This prevents uncomplicated malaria from progressing to severe disease or death.

Antimalarial Drug Resistance

  • Emergence of resistance is a threat to global control efforts, particularly in Africa.
  • Resistance is the ability of a parasite strain to survive and/or multiply despite appropriate drug administration and absorption.

Factors Facilitating Drug Resistance

  • Parasite mutation rate
  • Overall parasite load
  • Strength of drug selection
  • Treatment compliance
  • Poor adherence to malaria treatment guidelines
  • Improper dosing
  • Poor pharmacokinetic properties
  • Fake drugs (leading to inadequate drug exposure)
  • Poor-quality antimalarials

Elimination

  • Malaria elimination: interruption of local transmission of a specified malaria parasite species in a defined geographical area.
  • Achieved through deliberate activities but requires continued measures to prevent re-establishment.
  • Countries with ≥3 consecutive years of zero indigenous cases can apply for WHO certification of malaria elimination.

Surveillance

  • Continuous and systematic collection, analysis, and interpretation of malaria-related data.
  • Used for planning, implementation, and evaluation of public health practice.

Global Targets (by 2030)

  • Reduce malaria case incidence by at least 90%.
  • Reduce malaria mortality rates by at least 90%.
  • Eliminate malaria in at least 35 countries.
  • Prevent resurgence of malaria in all malaria-free countries.

Global Technical Strategy for Malaria 2016-2030

  • Goals, milestones, and targets are outlined in this strategy.

Algorithm for Malaria

  • Test for malaria.
  • Treat with an ACT