India aims to eliminate malaria by 2030, but faces complex hurdles including asymptomatic carriers, remote geographies, dual-species infections, and evolving parasites and vectors.
About Malaria
- Malaria is a life-threatening disease caused by parasites and spread to humans through the bites of infected female Anopheles mosquitoes.
- It is common in tropical regions, but is preventable and treatable.
- Malaria does not spread from person to person, though it can also be transmitted through infected blood or contaminated needles.
- Five species of Plasmodium infect humans: P. falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi.
- If left untreated, especially in cases of P. falciparum, P. Vivax infection, it can lead to severe illness or even death within 24 hours.
- Symptoms: Fever, chills and headache, fatigue etc.
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Current Scenario
- Global Burden: In 2023, malaria infected nearly 294 million people and killed close to 6,00,000.
- Stagnation in Progress: Global advances have stalled due to parasite resistance to drugs and mosquitoes’ survival against insecticides.
- India’s Reduction: India reduced malaria cases by over 80% between 2015 and 2023.
- Persistent Pockets: Tribal districts like Lawngtlai (Mizoram) and Narayanpur (Chhattisgarh) still report high incidence—56 and 22 cases per 1,000 respectively.
- Species Challenge: India battles both Plasmodium falciparum and the relapse-prone Plasmodium vivax.
- Asymptomatic Carriers: Silent carriers and mixed infections, especially in Jharkhand (nearly 20% cases), complicate elimination.
Vaccine Development
First-Generation Vaccines
- RTS,S Vaccine (2021): Offered 55% protection initially; efficacy waned by 18 months, needing a fourth booster.
- R21/Matrix-M Vaccine (2023): Developed by Oxford & Serum Institute; Received WHO approval in 2023; shows up to 77% efficacy, requires fewer doses, and is produced affordably in India.
- Limitation: Both target only one stage of the parasite; reinfection and transmission remain possible.
Whole-Parasite and Blood-Stage Vaccines
- PfSPZ Vaccine: Uses radiation-weakened P. falciparum sporozoites delivered intravenously; showed up to 79% protection after third dose.
| RH5-based vaccines prevent Plasmodium from invading red blood cells and target the blood stage after symptoms. |
- PfSPZ-LARC2: A modified one-dose version being developed for use in outbreak zones and remote areas.
- PfRH5 Vaccine: Targets blood-stage RH5 protein, offering cross-strain protection; trials in UK, Gambia, and Burkina Faso showed promising results.
- A whole-parasite vaccine uses the entire malaria parasite (typically Plasmodium falciparum), either in a weakened, killed, or genetically modified form—to stimulate an immune response.
- Blood-stage vaccines target the red blood cell stage of the malaria parasite’s life cycle. Their goal is to reduce disease severity by preventing the parasite from multiplying in red blood cells.
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| Transmission-blocking vaccines aim to halt the spread of malaria by preventing mosquitoes from becoming carriers. |
Transmission-Blocking Vaccines (TBVs )
- (TBVs)Pfs230D1: Reduced malaria transmission by 78% in Mali by preventing parasite fertilization inside mosquito gut.
- India’s TBV Efforts:
- AdFalciVax (2025): India’s first dual-stage malaria vaccine, combining pre-erythrocytic (PfCSP) and transmission-blocking (Pfs230 and Pfs48/45) antigens.
- Performance: Triggered strong immune responses lasting 4+ months in mice; stable at room temperature for 9 months.
- Vivax-Focused TBVs:
- Reduced mosquito transmission of P. vivax by 96% in Thailand’s first-in-human trial; similar Indian candidate under research.
mRNA-Based Vaccines
- Encoded Pfs25 antigen in mRNA lipid nanoparticles; blocked transmission in mice with two doses and antibodies lasting six months
Vector Control Through Gene Drives
- CRISPR technology is being used to modify the doublesex gene in female mosquitoes, the primary carriers of malaria.
| Gene Drive is the use of gene-editing techniques to alter the law of inheritance to pass on a particular genetic trait from one generation to the next generation, faster than the normal rate. |
- When female mosquitoes inherit two altered copies of this gene, they develop male-like traits and lose the ability to bite or reproduce.
- This leading to the gene edit spreads through populations via gene drive,complete elimination of female mosquitoes within eight generations.
- In a landmark study, such a method eliminated entire Anopheles gambiae populations within a year, without any observed resistance.
- Ethical Concerns: Wild adaptation, ecological impact, and irreversible nature pose major questions.
- Gene Edits Without Eradication:
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- Edited single base in the FREP1 gene, in mosquitoes blocks parasite development while retaining fertility.
- Another strategy engineered infected mosquitoes to die sooner, creating a feedback loop that suppresses transmission.
Challenges with Malaria Vaccines
- Parasite Resistance: Plasmodium parasites are evolving resistance to drugs and adapting to control measures, reducing the efficacy of existing tools.
- Mosquito Adaptability: Mosquitoes are increasingly resistant to insecticides, making traditional vector control methods less effective.
- Asymptomatic Transmission: Adults and older children act as silent carriers even in low-incidence regions.
- Mixed Infections: States like Jharkhand report 20% mixed P. falciparum and P. vivax infections, complicating diagnosis and treatment strategies.
- Geographic Hurdles: Tribal and forested districts in Chhattisgarh, Jharkhand, and Northeast remain malaria strongholds with limited healthcare.
- Vivax Research Gaps: Early vivax model (P. cynomolgi) efforts stalled due to monkey access laws and limited foresight.
- mRNA Transition Barriers: While mRNA platforms offer flexibility, translating them into effective malaria vaccines has been complex and unpredictable.
- Ethical Concerns in Gene Editing: CRISPR-based gene drives that alter mosquito populations raise ecological, ethical, and regulatory concerns about irreversible environmental effects.
Way Forward
- Focused Local Action: Targeted efforts are needed in tribal belts of Chhattisgarh, Jharkhand, and Northeast India, where healthcare access is limited.
- Boosting Vaccine Pipelines: India must accelerate clinical trials and manufacturing of candidates like AdFalciVax through public-private partnerships and regulatory support.
- Global Collaboration: Global cooperation on funding, data-sharing, and trials can fast-track technologies like TBVs and whole-parasite vaccines.
- Smart Vector Control: Gene-editing strategies that shorten mosquito lifespan or block parasite development without ecological harm offer promising alternatives.
Indian Initiatives to Control Malaria
- National Framework for Malaria Elimination (2016–2030): Aligns with WHO’s Global Strategy; aims for zero indigenous malaria cases in India by 2030, with an internal target of elimination by 2027.
- National Strategic Plan for Malaria Elimination (2017–2022): Shifted focus from control to elimination, targeting malaria elimination in 571 of 678 districts by 2022.
- Malaria Elimination Research Alliance-India (MERA-India): ICMR-led initiative bringing together stakeholders to promote research and coordinated efforts in malaria elimination.
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