Hantavirus is that odd infection that can make a simple fever a medical emergency, says Delhi NCR pulmonologist

Hantavirus is the infection nobody talks about until someone gets sick from it. It's rare, which makes people ignore it. It's deadly, which makes people wish they hadn't. And it arrives looking so ordinary that by the time you realize something's seriously wrong, the virus has already started doing damage to your lungs.

"When fever and body ache starts most people are worried about dengue, swine flu or Covid. Hantavirus is a rare but potentially deadly infection that can quietly damage the lungs within days and very few people have heard of it," Dr. Pradeep Bajad, Senior Consultant Pulmonologist and Sleep Medicine specialist at Amrita Hospital in Faridabad told TOI Health.

The virus doesn't come from another person. You won't catch hantavirus from someone coughing on you or shaking your hand. That's part of why it flies under the radar. We're conditioned to worry about person-to-person transmission.
But hantavirus doesn't work that way. According to Dr. Bajad, "Hantavirus is primarily spread by infected rodents, particularly rats and mice. The virus is found in their urine, saliva and faeces. Humans are usually infected by inhaling contaminated particles in the air during sweeping of dusty storerooms, cleaning of enclosed spaces, warehouses, farms or old buildings that may have been inhabited by rodents."
So you're cleaning out a storage room. You're sweeping dust in a warehouse. You're dealing with accumulated grime in a place that's been closed for a while. The dust you're stirring up contains particles from rodent droppings infected with hantavirus. You breathe it in. And nobody even knows you've been exposed until you get sick.

Here's what makes hantavirus so insidious: it doesn't announce itself. The early symptoms are generic enough that you could have almost any viral illness.
"Most patients have an initial presentation of fever, fatigue, headache, muscle pain, chills, nausea, vomiting or abdominal discomfort," Dr. Bajad explains. "In many cases people think it's seasonal flu or food poisioning."
You think you've got a stomach bug. You think you've caught something going around. You rest. You hydrate. You wait for it to pass. And for the first few days, it seems like a normal illness. Your fever comes and goes. You feel weak, but not dangerously so. Nothing about these symptoms screams emergency.

This is where it becomes a crisis. "They may develop severe shortness of breath, chest tightness, dry cough, rapid heart rate and decreasing oxygen levels. Fluid starts to leak into the air sacs of the lungs, and breathing becomes more and more difficult. Some get so sick so fast they need to be in ICU and on a ventilator in a few hours."
The most severe form of hantavirus is called Hantavirus Pulmonary Syndrome, or HPS. Research has shown that studies published in journals like The Lancet and Clinical Microbiology Reviews have documented how hantavirus infections can trigger a severe inflammatory response in the lungs and blood vessels. The death rate for HPS in severe cases is around 35 to 40 percent, according to information from the US Centers for Disease Control and Prevention.

"The biggest problem with hantavirus is not the infection itself, but the false sense of normalcy in the first few days," Dr. Bajad says. "In lung medicine, sometimes those lost days can be the difference between recovery and crisis."
Think about that. The actual illness isn't the biggest problem. The problem is that you don't know you're in danger. You're at home, feeling gradually worse, thinking you'll bounce back like you always do. Meanwhile, your lungs are flooding with fluid and your oxygen levels are dropping and by the time you realize this is serious, you're already in critical condition.
"Basic measures such as controlling rodent infestation, safe disposal of rodent waste, covering food, improving ventilation in closed rooms and wearing gloves and masks while cleaning dusty areas can sharply reduce the risk of exposure," says the doctor.