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Communicable diseases, animal health and One Health
Infectious disease in people and animals and the surveillance that catches it: outbreaks, zoonoses, neglected tropical diseases, livestock disease, and the international rules for pandemics. Prelims has asked which disease the H1N1 virus is linked to and whether viruses spread only through vectors.
UPSC has asked
- Prelims 2013: whether viruses spread only through biological vectors
All 11 subjects shown; the 5 that changed from 16 to 31 July 2026 are marked.Show only these
Chandipura virus
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A sandfly bite in a village in Gujarat or Rajasthan can end in brain inflammation, and it is children who are affected. What is still unsettled is how the virus actually reaches them, which is why the investigation is running through animals as well as insects.
- Chandipura virus is spread mainly by sandflies, and causes a fever that can progress to acute encephalitis syndrome, brain inflammation.
- It falls mostly on children.
- At least 22 children had died in Gujarat and Rajasthan by 6 August 2026.
- Mosquitoes, ticks and mites are being tested alongside the sandfly as vectors.
- Cattle, buffaloes and goats are being tested as reservoir hosts, so the National Centre for Disease Control (NCDC), ICMR and the Department of Animal Husbandry went in as one team.
- Testing animals beside people is One Health in practice, the approach that also ties crowded, antibiotic dosed livestock farming to antimicrobial resistance and to the spillover of pathogens.
What changed
6 Aug 2026
The Hindu, 6 Aug 2026: Chandipura virus outbreak in Gujarat and Rajasthan (opens in a new tab)
26 Jul 2026Updatealso in news
- Rajasthan stepped up surveillance after two girls from Dungarpur and Sirohi who died tested positive. The virus is carried by sandflies and mainly affects children under 15, causing acute encephalitis.
Background reading: PIB, 5 Aug 2026: Chandipura virus outbreak: national response team deployed (opens in a new tab)
Leptospirosis
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- zoonotic
- Spreading from animals to humans; a disease that does so is a zoonosis.
Kerala's monsoon leaves standing water that rodents have been in, and a bacterium in it enters through a cut on a bare foot. It is a zoonotic infection, carried from animals rather than from other people, and what kills is usually how late it is recognised.
- Leptospirosis is caused by the bacterium Leptospira, and does not pass from person to person.
- It is picked up from water or soil contaminated by infected animals, through cuts or mucous membranes.
- Heavy monsoon rain, floods and humidity help Leptospira survive, and rodents living near homes are its reservoir.
- Farmers, cleaners and construction workers are the most exposed.
- It killed 50 people in Kerala in July 2026, which made it the State's deadliest communicable disease.
- Late diagnosis is what carries the infection on to pulmonary haemorrhage and multi-organ failure.
What changed
Influenza A (H1N1)
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Subtypes of influenza A are named for two proteins on the virus surface, haemagglutinin (H) and neuraminidase (N). H1N1 is the pairing that caused the 2009 pandemic, and it did not go away afterwards but settled into the seasonal mix.
- By 3 September 2026 seasonal influenza had surged across India, with H1N1 reported from several cities.
- This season's vaccine matched the circulating H1N1 strain, but uptake is low.
What changed
UPSC has asked
- Prelims 2015: the disease the H1N1 virus is linked to
See also: Influenza surveillance
Influenza surveillance
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- Incidence
- New cases in a population over a set period, which allows fair comparison between places of different size.
The surge was the first real test of the surveillance India built after COVID-19. What it exposed is a system that watches continuously without ever having to declare that anything has begun.
- An integrated command structure was proposed to replace that split.
- Surges are compared fairly by incidence rather than by raw case counts.
- Wastewater surveillance can give early warning of a novel pathogen.
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
What changed
3 Sep 2026
21 Jul 2026Update
- The Viral Research and Diagnostic Laboratory network has grown to 163 laboratories, with four regional sequencing hubs and wastewater surveillance for early detection.
- Dengue is tracked through 887 sentinel hospitals and 27 apex laboratories, and a programme for leptospirosis strengthens surveillance and early antibiotic treatment.
PIB, 21 Jul 2026: Coordination mechanisms between Central and State health authorities during public health emergencies have been strengthened and tested through simulation exercises and mock drills (opens in a new tab) · PIB, 28 Jul 2026: Focused Interventions for Dengue, Malaria, Diarrhoea and Leptospirosis Supported by PPCL, STOP Diarrhoea Campaign and Flood Preparedness Measures (opens in a new tab)
Background reading: Frontline, 8 Sep 2026: Public health is political: Brian Wahl (opens in a new tab)
See also: Influenza A (H1N1)
Biological disaster preparedness
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- Biological disaster
- A disaster caused by living organisms or their toxins: an epidemic, a pandemic, or a deliberate release of a pathogen.
- National Disaster Management Plan
- The country's plan under the Disaster Management Act, 2005, setting out who does what in prevention, mitigation, response and recovery.
- BSL-3
- A Biosafety Level 3 laboratory, built to handle dangerous airborne pathogens.
A biological disaster is handled under disaster management law rather than as a health emergency alone, which puts several agencies into the same response. In August 2026 the Health Ministry set out how India prepares for one, and what it listed was the pieces already in place since before the pandemic rather than one new plan.
- The Ministry of Health and Family Welfare is the nodal ministry for a biological disaster.
- The National Disaster Management Authority (NDMA) issued Guidelines on Management of Biological Disasters in 2008.
- The National Disaster Management Plan of 2019 sits alongside them.
- ICMR runs over 150 Virus Research and Diagnostic Laboratories and two mobile BSL-3 laboratories.
- National Disaster Response Force (NDRF) teams are trained for chemical, biological, radiological and nuclear (CBRN) response.
- PM-ABHIM, the Pradhan Mantri Ayushman Bharat Health Infrastructure Mission, builds capacity against emerging diseases.
What changed
Lumpy skin disease
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- Lumpy skin disease
- A viral disease of cattle and buffaloes that causes fever and hard nodules in the skin.
- Ring vaccination
- Vaccinating every susceptible animal in a ring around an outbreak, building a barrier of immunity that stops the disease spreading outward.
Lumpy skin disease reached India's cattle in 2019 and has not left, so the work against it is surveillance and vaccination rather than a declared end to it. Because an insect carries it from animal to animal, control has to work on the vector as much as on the sick animal.
- India's first cases were recorded in West Bengal and Odisha in 2019.
- The Department of Animal Husbandry and Dairying reported that cases have come sporadically since July 2026, mainly in unvaccinated animals.
- It has strengthened surveillance, vaccination and disease control in response.
Pathogen
- A virus of the genus Capripoxvirus
- Same group as sheeppox and goatpox
Spread
- Biting flies
- Mosquitoes
- Ticks
Effects
- Generally low mortality
- Does not infect humans
Control
- Ring vaccination
- Movement control and vector control
- Isolation of sick animals
- Quarantine of new animals
What changed
8 Sep 2026
8 Sep 2026
- Lumpi-ProVacInd, the indigenous vaccine, was developed jointly by the Indian Council of Agricultural Research's National Research Centre on Equines, Hisar.
- More than 36 crore cattle had been vaccinated or revaccinated by 8 September 2026.
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.
What changed
29 Jul 2026New subject
- A two year study by the Indian Council of Medical Research network analysed 6,889 confirmed samples from 25 States and Union Territories. Eight reported all four serotypes circulating together, a state called hyperendemicity, with DENV-2 predominant.
- About 7 per cent of patients carried two or more serotypes at once and were more likely to develop severe dengue.
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, from anthrax and brucellosis to Nipah, rabies and Zika, with each State to write its own plan on the same lines.
What changed
6 Jul 2026New subject
- 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.
Pandemic Agreement: pathogen access and benefit sharing
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The Pathogen Access and Benefit Sharing system links the sharing of pathogens with pandemic potential to the sharing of the vaccines, tests and treatments made from them, and is the annex left unfinished when the WHO Pandemic Agreement was adopted in May 2025.
What changed
9 Jul 2026New subject
- Member states of the World Health Organization began a seventh round of talks on the Pathogen Access and Benefit Sharing system, the annex left unfinished when the Pandemic Agreement was adopted in May 2025.
- The system links the sharing of pathogens with pandemic potential to the sharing of vaccines, tests and treatments made from them, and is the main dispute between wealthy and developing countries.
- The talks opened during an Ebola outbreak in the Democratic Republic of the Congo that had spread into Uganda.
Amoebic meningoencephalitis
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Amoebic meningoencephalitis is a rare and usually fatal brain infection caused by free living amoebae in warm fresh water that enter through the nose, reported in Kerala among people who bathe in ponds.
What changed
29 Jul 2026New subjectalso in news
- Kasaragod in Kerala reported a further case in a person who had bathed in a pond. The infection is caused by free living amoebae in warm fresh water that enter through the nose.
The Hindu, 29 Jul 2026