Kolkata sees spike in monsoon viruses as temperature fluctuates
Times of India | 27 June 2026
Kolkata: Temperature fluctuations triggered by rains since last Thursday have unleashed the first spate of monsoon viruses. Hundreds across Kolkata have been laid low with fever, severe cough and body ache since last week. With maximum temperature plunging sharply from 35.5°C last Thursday to 29°C on Friday, the conditions started turning ideal for viruses to multiply and spread, said physicians who said most are suffering from a bout of Influenza A and B, other than respiratory syncytial virus (RSV) that affects the lungs.
Minimum temperature, too, fell to 24.6°C on Wednesday, while the maximum clocked to 30.8°C. “This temperature fluctuation makes it difficult for the body to adjust. When the environmental temperature drops suddenly, the human body can struggle to adapt quickly, which in turn can make you more vulnerable to certain viral infections. The body relies on a stable internal temperature (around 37°C or 98.6°F). When external temperatures plummet unexpectedly, the body has to work overtime to preserve heat,” said Abhijit Aich Bhaumik, senior consultant, BP Poddar Hospital.
Charnock Hospital has received several H1N1 or Influenza A patients, along with those suffering from para-influenza and breathing distress since Friday. “The sudden mercury fluctuations have made it very difficult for those with lung ailments and the rest as well. The system turns vulnerable when the ambient temperature changes sharply. Over the last few days, we have received multiple patients with viral infections or lung ailment flare-ups triggered by temperature changes,” said Charnock Hospital pulmonology head Soumya Sengupta.
He warned that since monsoon rains are predicted to happen in clusters, punctuated by extended dry and warm periods, the fluctuations will keep happening repeatedly, making a significant number of people vulnerable to seasonal illnesses.
A sudden mercury drop acts as an acute physical stressor, catching the homeostatic mechanisms off guard and temporarily draining energy that would otherwise be used to maintain robust immune surveillance, said experts.
Manipal Hospitals have been receiving a steady stream of respiratory infection patients for the last three weeks, said head of pulmonology Debraj Jash. “There has been very little drop in the number of respiratory patients even during the summer. Previously, influenza and respiratory viruses struck at the season changes but they have turned more persistent now. We are now treating scores of influenza, rhinovirus, streptococcus pneumonae and Haemophilus influenzae patients,” said Jash.
Doctors pointed to a combination of environmental shifts and human behaviour that create a “perfect storm” for pathogens the moment the rains hit. “Rapid fluctuations stress the body, making it harder to adapt quickly. This sudden environmental shift can temporarily lower the immune system’s frontline defences, making individuals much more vulnerable to catching a virus,” said RN Tagore Hospital intensivist Sauren Panja.
Research shows that a drop in nasal cavity temperature of even just 5°C can significantly reduce the efficacy of the immune response inside the nose, leaving the doorway wide open for viruses to replicate.
Many respiratory viruses actually prefer cold, dry air. In lower temperatures, the outer lipid envelope of a virus hardens into a gel-like coating, which protects the virus and allows it to survive longer in the air or on surfaces, making it easier to transmit.
DISEASE WATCH
The transition from extreme summer heat to cooler, rainy weather causes sudden temperature drops
Doctors note that these rapid fluctuations stress the body, making it harder to adapt quickly
This sudden environmental shift can temporarily lower the immune system’s frontline defences, making individuals much more vulnerable to catching a virus
Viruses and bacteria thrive in warm, damp conditions
The surge in atmospheric humidity during early monsoon provides an ideal environment for airborne viruses (like influenza) to survive longer in the air and transmit rapidly from person to person, especially in crowded, poorly ventilated areas like public transits or offices
A sudden drop in temperature absolutely makes the body more vulnerable to respiratory viruses (like the common cold, rhinovirus, and influenza).