DH Interview | India does not face Hantavirus threat for now but needs stronger surveillance: Dr Ishwar Gilada

Dr Gilada breaks down the science, risks and preparedness surrounding the outbreak.

Years after the world battled the COVID-19 pandemic, another virus has begun making headlines: Hantavirus, a little-known but dangerous infection linked to rodents.

While fears and misinformation spread rapidly online, Mumbai-based infectious diseases expert Dr Ishwar Gilada believes awareness, not alarm, is the need of the hour.

In this interview, Dr Gilada, President-Emeritus of the AIDS Society of India and Governing Council member, International AIDS Society, breaks down the science, risks and preparedness surrounding the outbreak.

“While India is not facing an immediate hantavirus outbreak threat, these underlying risk factors emphasise the need for stronger surveillance, improved sanitation and rodent control, and greater clinician awareness — particularly during monsoon and post-flood periods when exposure risks tend to rise,” Dr Gilada tells DH’s Mrityunjay Bose.

What exactly is Hantavirus, and how does it spread?

Hantavirus is a zoonotic, or animal-borne, viral infection in which rodents – rats and mice – act as the natural reservoir. Humans are usually infected after exposure to rodent urine, saliva, or droppings, particularly in enclosed or poorly ventilated environments. Transmission most commonly occurs while cleaning rodent-infested areas such as warehouses, storerooms, garages, ships, cabins, and burrows of rodents where contaminated dust particles can become airborne and inhaled. Infection may also occur through contaminated food, touching contaminated surfaces and then the face, or occasionally through rodent bites. Unlike respiratory viruses such as COVID-19, hantavirus does not spread easily through casual human interaction. Human-to-human transmission is extremely rare and has mainly been documented with the Andes strain in parts of Argentina and Chile, where prolonged close contact among household members or intimate partners was involved.

What are the early symptoms and danger signs people should recognize?

Hantavirus infection often begins like a common viral fever, making early diagnosis difficult. Symptoms may develop anywhere between one and eight weeks after exposure to rodent-contaminated environments.

What are the early symptoms and warning signs?

Early symptoms commonly include: sudden fever and chills, severe muscle pain, especially in the back and thighs, headache and extreme fatigue, nausea, vomiting, or abdominal discomfort, dry cough. Warning signs requiring urgent medical attention include increasing breathlessness or rapid breathing, chest tightness, falling oxygen levels, low blood pressure or shock, reduced urine output or kidney dysfunction.

Can you elaborate on the strains?

Some strains, such as Andes and Sin Nombre viruses, can cause Hantavirus Pulmonary Syndrome (HPS), a severe respiratory illness leading to fluid accumulation in the lungs. Other strains, including Hantaan, Dobrava, and Seoul viruses, may cause Hemorrhagic Fever with Renal Syndrome (HFRS), which primarily affects the kidneys and may produce bleeding complications. A recent history of rodent exposure or cleaning dusty enclosed spaces is often an important clinical clue. For the Andes virus, the estimated period when a person may be contagious is 1–2 days before symptoms begin through the first 5–7 days of illness (the fever/prodromal phase), so the total potentially contagious window is around 6–9 days overall.

Is India equipped to detect and manage Hantavirus infections?

India’s infectious disease surveillance system has improved substantially after the COVID-19 pandemic through institutions such as the Indian Council of Medical Research (ICMR), the National Institute of Virology (NIV), Pune, and the nationwide Viral Research and Diagnostic Laboratory (VRDL) network. Major tertiary hospitals and advanced reference laboratories are capable of identifying hantavirus infections when there is sufficient clinical suspicion. However, routine testing remains limited across most healthcare settings. One challenge is that hantavirus symptoms can closely resemble dengue, influenza, leptospirosis, scrub typhus, or severe viral pneumonia, increasing the possibility of underdiagnosis.

Should India be concerned about the infected Indian passengers linked to the cruise outbreak?

At present, these appear to be isolated imported infections rather than evidence of a wider public-health threat to India. The concern mainly arises because the outbreak involves the Andes strain, known for limited human-to-human transmission. Nevertheless, hantavirus remains predominantly a rodent-borne infection, and widespread community transmission is not expected under normal circumstances.

Dr Ishwar Gilada.

Could climate change, flooding, and urbanisation increase India’s future risk?

Climate change, flooding, overcrowding, poor sanitation, rapid urbanisation, and ecological disruption can all increase the risk of zoonotic infections, including the rodent-borne hantavirus. Floods and heavy rainfall often force rodents into human settlements, while garbage accumulation, slums, warehouses, and poorly planned urban growth create ideal conditions for rodent breeding and human exposure. These conditions increase the likelihood of contact with contaminated urine or droppings.

How vulnerable is India to future hantavirus outbreaks?

India does possess environmental and social conditions that could increase vulnerability to sporadic rodent-borne infections. India’s most recent major plague epidemic occurred in 1994, beginning in Beed district of Maharashtra with bubonic plague cases and later spreading as pneumonic plague in Surat, was fundamentally a rodent-borne disease outbreak caused by the bacterium Yersinia pestis. Large rodent populations, overcrowded settlements, poor waste disposal systems, monsoon-related sanitation challenges, and frequent flooding may contribute to increased exposure risk.

Are there any similarities with other diseases?

Another concern is that hantavirus infections can mimic more common illnesses such as dengue, influenza, leptospirosis, or severe viral pneumonia, leading to delayed recognition. While India is not facing an immediate hantavirus outbreak threat, these underlying risk factors emphasise the need for stronger surveillance, improved sanitation and rodent control, and greater clinician awareness — particularly during monsoon and post-flood periods when exposure risks tend to rise.