Antimicrobial resistance and emerging diseases

The first principle

A microbe population is never uniform, and an antibiotic acts as a filter that kills the susceptible cells and leaves any resistant ones to multiply. Antimicrobial resistance (AMR) is therefore evolution by natural selection happening in weeks, and every dose, needed or not, applies that pressure. The same logic explains emerging diseases: pathogens constantly cross from animals to people, and the ones that spread are those that meet crowded, mobile, poorly protected human populations, so both problems are managed by limiting the opportunities rather than by any single drug.

The core

How resistance arises and spreads

• Mutation and selection. Some bacteria can divide every twenty minutes or so in good conditions, so a rare mutation that blunts a drug appears often in a large population, and the drug then removes its competitors.
• Horizontal gene transfer. Bacteria also swap genes directly, most often on plasmids, small circles of DNA passed from cell to cell, so a resistance gene can jump between species. The gene for New Delhi metallo beta lactamase (NDM-1), named after the city where the first patient had been treated, spread across continents within a few years this way.
• Four mechanisms. A resistant bacterium may make an enzyme that destroys the drug, as beta lactamases and carbapenemases do; pump the drug out; change the target the drug binds to; or shelter inside a biofilm, a slimy community stuck to a surface such as a catheter.
• Why Gram negative bacteria are hardest. Their extra outer membrane keeps many drugs out, and carbapenem resistant Klebsiella pneumoniae, Escherichia coli and Acinetobacter baumannii now cause infections in intensive care units that have few remaining treatments.
• The drivers in India. Antibiotics are bought without prescription, taken for viral fevers they cannot cure, stopped early, used to promote growth in poultry and fish, and released in factory effluent, while poor sanitation spreads resistant strains.
• Antibiotics act on bacteria, not viruses. Antivirals, antifungals and antimalarials face their own resistance, which is why the wider term is antimicrobial resistance.

Emerging and re emerging diseases

• Zoonoses. Most new human infections come from animals: Nipah from fruit bats in Kerala, Kyasanur Forest disease from ticks in the Western Ghats, and avian influenza from birds. Forest clearing and dense livestock farming bring people and pathogens together.
• Vector borne diseases depend on the carrier: the night biting Anopheles mosquito carries malaria, so bed nets and indoor spraying work; the day biting Aedes carries dengue, chikungunya and Zika and breeds in clean stored water, so removing that water works; the Culex mosquito carries Japanese encephalitis and lymphatic filariasis; and the sandfly carries kala azar.
• Key measures. The basic reproduction number (R₀) is the number of people one case infects in a fully susceptible population, so a disease spreads when it is above one. Incidence counts new cases in a period; prevalence counts all existing cases.
• Eradication and elimination. Eradication means the pathogen is gone worldwide, achieved only for smallpox in humans in 1980, while elimination means transmission or cases are below a set threshold in one country or region.

Dimensions

• Health. The GRAM study published in The Lancet in September 2024 estimated that bacterial AMR directly caused about 1.14 million deaths in 2021 and was associated with about 4.71 million, and projected about 39 million direct deaths between 2025 and 2050 if nothing changes. Surgery, chemotherapy and transplants all depend on antibiotics that work.
• Economic. Resistant infections mean longer stays and costlier drugs, mostly paid out of pocket, while a new antibiotic is kept in reserve and so earns little, which is why most large firms have left the field.
• Environmental and agricultural. Effluent from antibiotic factories and growth promoters in poultry and fish select resistance that reaches people through water and food.
• Global. Microbes cross borders, so AMR is governed through the World Health Organization (WHO) and its One Health partners for food, animal health and the environment.

In practice

India's response to AMR

• Rules on sale. Schedule H1 of the Drugs Rules, notified in 2013, requires a prescription and a sale register for many antibiotics; the Red Line campaign of 2016 marks their packs with a red vertical line; and in 2019 the government banned colistin, a last resort drug, for use in food producing animals and feed.
• Plans. The National Action Plan on AMR (2017 to 2021) set six strategic priorities across ministries, and Kerala made the first State plan in 2018. Its successor, the National Action Plan on AMR 2.0 for 2025 to 2029, was launched in November 2025 with actions for each ministry.
• Surveillance. The Indian Council of Medical Research (ICMR) runs an AMR surveillance network of hospital laboratories.
• New drugs. Nafithromycin, developed by Wockhardt for community acquired bacterial pneumonia with support from the Biotechnology Industry Research Assistance Council (BIRAC), was launched in November 2024 as an antibiotic developed in India.
• Global targets. WHO's AWaRe system sorts antibiotics into Access, Watch and Reserve groups, and the United Nations General Assembly political declaration of September 2024 set a goal of cutting deaths associated with AMR by 10 per cent by 2030 and of making Access antibiotics at least 70 per cent of human use.

Disease elimination: what India has achieved and promised

• Achieved. India was certified polio free in 2014, eliminated maternal and neonatal tetanus in 2015, was declared free of yaws in 2016, and WHO validated the elimination of trachoma as a public health problem in October 2024. Leprosy was eliminated as a public health problem at the national level in 2005, though new cases still occur.
• Tuberculosis. India set itself the goal of ending tuberculosis by 2025, five years ahead of the global 2030 target, and did not meet it; WHO's Global Tuberculosis Report 2025 nevertheless showed incidence falling from 237 per lakh in 2015 to 187 per lakh in 2024, a 21 per cent decline, about twice the global pace.
• Kala azar. By the end of 2023 every endemic block in India reported fewer than one case per 10,000 people, the elimination threshold, and WHO validates elimination only after the threshold has been held for three consecutive years.
• Targets. Malaria: zero indigenous cases by 2027 and elimination by 2030 under the National Framework for Malaria Elimination (2016), after India left WHO's High Burden to High Impact group in 2024; lymphatic filariasis: elimination by 2027; measles and rubella: elimination targeted for 2026 under a campaign launched in April 2025; rabies: zero human deaths from dog bites by 2030.
• One Health. The National One Health Mission, approved by the Prime Minister's Science, Technology and Innovation Advisory Council (PM-STIAC), joins more than a dozen ministries in common surveillance of human, animal and environmental health, anchored by the National Institute of One Health at Nagpur.
• Global rules. Amendments to the International Health Regulations, adopted in 2024, entered into force in September 2025 and created a new alert level of pandemic emergency above a public health emergency of international concern; the WHO Pandemic Agreement, adopted in May 2025, cannot be signed until an annex on sharing pathogens and their benefits is agreed, and talks on it were extended in 2026. Managing a pandemic as a disaster belongs to the Disaster Management note on biological disasters.

Issues and way forward

• Over the counter sale. Rules exist but are weakly enforced at chemists, so electronic prescriptions linked to sales and stricter State drug controllers are needed.
• Thin surveillance. Most district hospitals lack microbiology laboratories, so resistance data come mainly from city hospitals, and district laboratories would fill the gap.
• Few new drugs. Since antibiotics earn little, governments can pay for availability rather than volume through subscription models, alongside public research funding.
• Effluent. Discharge limits for antibiotic residues from factories should be finalised and enforced.
• Infection prevention. Clean water, sanitation, hospital hygiene and vaccination prevent infections, which makes them the cheapest AMR policy.
• Elimination needs the last mile. Targets are missed less for lack of drugs than for missed cases, so active case finding, nutrition support and community health workers matter as much as medicine.

Common confusions

• Who becomes resistant. Resistance belongs to the bacterium, not the patient; the microbes a person carries become resistant.
• Elimination and eradication. Elimination is reduction below a threshold in one place, while eradication is permanent removal worldwide.
• Epidemic, pandemic and endemic. An epidemic is a rise in cases above the expected level in an area, a pandemic is an epidemic across many countries and continents, and an endemic disease is constantly present at a steady level.
• A public health emergency of international concern and a pandemic emergency. The first is WHO's long standing alert for a serious international event, while the pandemic emergency, created in 2025, is a higher level for an event that is or may become a pandemic.
• Watch and Reserve antibiotics. Watch drugs are in common use but select resistance easily and should be limited, while Reserve drugs are last resorts kept for confirmed multidrug resistant infections.

For the exam

• Keyword bank: natural selection, horizontal gene transfer, plasmid, carbapenem resistance, AWaRe classification, antibiotic stewardship, Schedule H1, Red Line campaign, colistin ban, National Action Plan on AMR, One Health, zoonosis, elimination and eradication, International Health Regulations, Pandemic Agreement.
• Previous year questions: Practise the previous year questions on this topic →
• Use in an answer:
  • Introduction with data: The GRAM study in The Lancet (2024) estimated that bacterial AMR directly caused about 1.14 million deaths in 2021 and could cause about 39 million between 2025 and 2050.
  • Introduction with a source: The United Nations General Assembly political declaration of 2024 committed countries to cut deaths associated with AMR by 10 per cent by 2030 and to make Access antibiotics 70 per cent of human use.
  • Conclusion: Resistance is a tragedy of the commons, since every needless dose spends a shared resource, so regulation of sale, sanitation and surveillance must do what no new drug can do alone.
  • Conclusion: India's elimination record, from polio to trachoma, shows that targets are met when the health system reaches the last case, which is the test the tuberculosis and malaria goals now face.