Many Kolkatans are down with low-grade fever, sore throat and body ache.
Doctors said the change in weather — warm conditions during the day and cool weather from late evening till early morning — is one of the factors driving the outbreak of the viral fever.
Children, too, are suffering from the symptoms.
Good cough etiquette, and respiratory and hand hygiene can help prevent the spread of the infection. Wearing masks will help, too, as respiratory viruses spread through droplets emitted during coughing and sneezing, doctors said.
The elderly and those with other illnesses such as chronic obstructive pulmonary disorder, chronic kidney disease, cardiac ailments and asthma should be extra careful, said a doctor.
“The symptoms include low-grade fever, runny nose, sore throat, ache in arms and headache. Some people are not running a temperature but are complaining of a feverish feeling,” said Chandramouli Bhattacharya, an infectious disease specialist at Peerless Hospital.
Bhattacharya said the illness is self-limiting and most people are being cured of the infection in three or four days. In some cases, the symptoms are persisting for a longer duration.
A man in his 40s had a mild fever and severe cough on Wednesday. The severity of the cough decreased by Sunday but he was still very weak. A Behala resident said his 5-year-old daughter missed school once last week as she had a runny nose and bouts of cough.
Amitabha Saha, head of critical care medicine at AMRI Hospitals Mukundapur, said fever and associated symptoms were caused by temperature fluctuations during this time of the year. “Virus activities increase with fluctuating temperatures. This kind of viral fever happens as winter approaches and again when winter recedes and temperatures start rising,” he said.
On October 29, the mercury dipped to 19.6 degrees Celsius. But the slide was short-lived. In the first week of November, the minimum temperature rose to around 23 degrees.
The past couple of days have seen a slide and on Sunday, the Celsius dipped below 19 degrees.
Amitabha Saha, the head of critical care medicine at AMRI Hospitals, said people with such symptoms always cover their nose and mouth while coughing and sneezing in public places.
“Wearing masks can prevent the spread of this viral infection,” he said.
Doctors are also asking patients with such symptoms to get tested for dengue, a cautionary step prompted by a large number of dengue infections being reported daily from across Kolkata and its surrounding areas.
Over 6,000 dengue infections have been reported from Kolkata so far this year and the rate of infection is still very high, said doctors.
Saha said about 30 per cent of all fever patients turning up at his clinic were still testing positive for dengue, and about40 per cent were suffering from seasonal viral infections.
Prabhas Prasun Giri, a doctor at the Institute of Child Health in Park Circus, said he was advising a dengue test for all children turning up at his clinic with fever.
“The seasonal viral infection is mostly limited to the upper respiratory tract, but in some children it is spreading to the lower respiratory tract as well, and creating breathing difficulties,” he said.