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हिन्दी — Read in HindiCommunicable diseases, animal health and One Health
Infectious diseases in people and animals: outbreaks, surveillance, India's disease programmes, and the One Health approach that joins human, animal and environmental health. Prelims has asked which disease the H1N1 virus is linked to and whether viruses spread only through vectors.
Foundation note: The diseases Prelims asks: pathogen, vector, programme
Outbreaks in people
An outbreak is a pathogen finding the conditions it needs: standing water for Leptospira, a sandfly season for Chandipura, four serotypes circulating together for severe dengue. What each subject below carries is the mechanism, the vector or reservoir, and who is at risk; the counts belong to the season.
Chandipura virus
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Chandipura virus is a rhabdovirus related to rabies, carried mainly by sandflies.
- It causes fever that can turn into acute encephalitis, inflammation of the brain, in children, killing within days.
- Outbreaks recur in summer in Gujarat, Maharashtra and Rajasthan.
- Testing animals beside people in an outbreak is One Health in practice.
What changed
26 Jul 2026BriefRajasthan stepped up surveillance after two girls from Dungarpur and Sirohi who died tested positive. The Hindu, 26 Jul 2026: Rajasthan on alert after deaths linked to Chandipura virus (opens in a new tab)
Leptospirosis
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Leptospirosis is a bacterial zoonosis caused by Leptospira from the urine of rodents and other animals.
- The bacteria survive in standing water and soil and enter through cuts or mucous membranes, so the disease peaks after monsoon floods among farmers, cleaners and construction workers.
- It does not pass from person to person.
- Treated early with antibiotics it is mild; diagnosed late it goes on to pulmonary haemorrhage and multi organ failure, which is what kills.
What changed
3 Aug 2026BriefIt killed 50 people in Kerala in July 2026, the State's deadliest communicable disease that month, and late diagnosis was named as the cause. The Hindu, 3 Aug 2026: Why is Kerala facing high leptospirosis mortality? | Explained (opens in a new tab)
Dengue serotypes in India
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Dengue has four serotypes, and where all four circulate together, a state called hyperendemicity, a person infected with two at once is more likely to develop severe dengue.
Ebola: the Bundibugyo strain
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The Bundibugyo strain is one of several species of Ebola, with a fatality rate of up to 40 per cent and no approved vaccine or treatment.
- The Zaire strain has an approved vaccine, Ervebo, built on the rVSV platform.
- Candidate vaccines against Bundibugyo reuse proven platforms: rVSV, and ChAdOx1, the platform of the Oxford AstraZeneca COVID 19 vaccine.
- Oxford and the Serum Institute of India are developing the ChAdOx1 Bundibugyo vaccine.
- Confirmation needs a strain specific polymerase chain reaction (PCR) test available in few laboratories.
- Rapid tests built for the Zaire species miss cases until viral load is very high, which delays diagnosis and isolation.
What changed
29 Jun 2026
- The outbreak in eastern Democratic Republic of the Congo, declared on 15 May, had the most confirmed cases in a first month of any African Ebola outbreak and spread to Uganda.
- WHO declared a Public Health Emergency of International Concern on 17 May under the International Health Regulations (2005).
- India had no confirmed case and launched Air Suvidha 2.0, a self declaration portal in which international arrivals give a 21 day travel history shared in real time with the Airport Health Officer, immigration and the Integrated Disease Surveillance Programme.
Mains: preparedness is strongest for crises seen repeatedly and weakest for novel ones, so it must become broader, not only deeper, with stable financing as global health funding falls.
The Hindu, 29 Jun 2026: U.S. starts vaccine effort for Ebola Bundibugyo as outbreak spreads (opens in a new tab) · The Hindu, 24 Jun 2026: Congo's Ebola outbreak has most cases in first month of any African outbreak, WHO says (opens in a new tab) · PIB, 25 Jun 2026: Ministry of Civil Aviation & DIAL Launch AIR SUVIDHA 2.0 Portal for Ebola Health Screening at Points of Entry (PoEs) in India (opens in a new tab) · The Hindu, 24 Jun 2026: France confirms Ebola virus in patient who worked in Congo (opens in a new tab) · The Indian Express, 26 Jun 2026: DRC Ebola outbreak: modelling study on risk of cross-border spread (opens in a new tab) · The Indian Express, 21 Jun 2026: The outbreak is outpacing us: Inside Congo's fight against rare Ebola strain (opens in a new tab) · The Hindu, 5 Jun 2026: What Bundibugyo Ebola vaccines and treatments are under development (opens in a new tab) · The Hindu, 2 Jun 2026: WHO says suspected Ebola cases drop to 116 after hundreds ruled out (opens in a new tab) · The Indian Express, 11 Jun 2026: From Hantavirus to Ebola, pandemic preparedness must become broader (opens in a new tab)
Surveillance and preparedness
India watches disease through three networks, district reporting, the virology laboratories and sentinel sites, and answers an outbreak under disaster law as well as health law. The gap the 2026 flu season showed is not in watching but in deciding when watching becomes acting.
Disease surveillance and biological disaster preparedness
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Disease surveillance is how India watches for outbreaks, through three networks; biological disaster preparedness is how it responds to an epidemic, a pandemic or a deliberate release.
- Influenza A subtypes are named for two surface proteins, haemagglutinin (H) and neuraminidase (N); H1N1 caused the 2009 pandemic and settled into the seasonal mix.
Testing
- Influenza like illness and severe acute respiratory infection (SARI) samples tested year round
- No alert thresholds
Coordination
- Split between ICMR, NCDC and the States
Treatment
- Under 10 per cent of admitted patients get antivirals
Watching
- The Integrated Disease Surveillance Programme collects weekly reports from every district.
- The Indian Council of Medical Research's Viral Research and Diagnostic Laboratory network has four regional sequencing hubs and wastewater surveillance.
- Sentinel sites watch named diseases, such as dengue.
- Surges are compared by incidence, new cases per population over a period, not by raw counts.
- What the system lacks is a trigger: it watches continuously without a rule for declaring that an outbreak has begun.
- The bodies that watch are not the bodies that act.
Responding
- A biological disaster, an epidemic, a pandemic or a deliberate release, is handled under the Disaster Management Act, 2005 as well as health law.
- The Health Ministry is the nodal ministry, and the NDMA's 2008 guidelines and the 2019 National Disaster Management Plan set out who does what.
- ICMR's virology laboratories and two mobile BSL 3 laboratories do the testing.
- NDRF teams are trained for chemical, biological, radiological and nuclear response.
What changed
3 Sep 2026
- Seasonal influenza surged across India with H1N1 reported from several cities; the season's vaccine matched the circulating strain but uptake was low.
- A column called the surge a test for the next pandemic and proposed an integrated command structure to replace the split between surveillance and response.
The Indian Express, 3 Sep 2026: India's current flu spike is a test for the next pandemic. Failure is not an option (opens in a new tab) · Frontline, 8 Sep 2026: Public health is political: Brian Wahl (opens in a new tab)
UPSC has asked
- Prelims 2015: the disease the H1N1 virus is linked to
- Prelims 2013: whether viruses spread only through biological vectors
Animals and One Health
Most new human infections come from animals, so One Health treats human, animal and environmental health as one problem; the zoonoses plan names the ten diseases that matter most, and lumpy skin disease shows what an animal epidemic costs.
Zoonoses action plan
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The National Action Plan for Prevention and Control of Zoonoses is built on the One Health approach and names ten priority zoonoses.
- The ten run from anthrax and brucellosis to Nipah, rabies and Zika.
- Each State is to write its own plan on the same lines.
What changed
6 Jul 2026New
- A draft National Action Plan for Prevention and Control of Zoonoses, built on the One Health approach, has been prepared, and States will write their own plans on the same lines.
- The ten priority zoonoses are anthrax, brucellosis, Kyasanur Forest Disease, Crimean-Congo haemorrhagic fever, Nipah, mpox, rabies, leptospirosis, scrub typhus and Zika.
Programmes and treaties
One national programme with an elimination date and one international agreement with an unfinished annex: what India does at home against hepatitis, and what the world has yet to agree on sharing pathogens and the vaccines made from them.
TB Mukt Bharat Abhiyaan
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The intensified 100 day TB Mukt Bharat Abhiyaan, a campaign against tuberculosis (TB), moves from waiting for patients to active case finding in villages, urban wards and congregate settings.
- It screens through Ayushman Arogya Shivirs, handheld X ray, Truenat and cartridge based nucleic acid amplification tests (CBNAAT).
- Nikshay Mitras give community support, and nutritional support is stressed to cut mortality.
What changed
19 Jun 2026BriefThe Health Minister reviewed the second phase of the campaign, due to end in the first week of July. In ten years TB incidence fell by about a quarter and deaths by more than a third, from 2014 to 2024. PIB, 19 Jun 2026: Union Health Minister Chairs High-Level Virtual Review Meeting of TB Mukt Bharat Abhiyan with all States and UTs; Calls for Push Towards a TB-Free India (opens in a new tab)
Also filed elsewhere
- Dengue vaccines: Qdenga, DengiAll and antibody dependent enhancement · on Vaccines and immunisation
Dengue has four serotypes, and antibodies from a first infection can help a different serotype enter cells in a second, which is antibody dependent enhancement and is why dengue vaccines are hard to design: vaccination raises type specific antibodies, which block one serotype, and cross reactive antibodies, which block all four only at high levels and can enhance a new infection into severe dengue once they wane.