Amid a change in season and a decline in temperatures, the number of people suffering from flu-like illnesses has started surging in major hospitals across the country.

Doctors attending patients say they expect a further surge in influenza cases as winter progresses.

“Cases of flu and fever have started to rise in our hospital,” said Dr Yuba Nidhi Basaula, director at the Sukraraj Tropical and Infectious Disease Hospital. “Along with a rise in the cases of fever and flu, demand for flu shots has also spiked of late.”

Every year, during season changes and winter, thousands of people from across the country get infected with influenza viruses, which become more active in the cold season.

The National Public Health Laboratory, which carries out regular influenza surveillance, said cases of influenza started to rise from September. The laboratory’s own data shows that the positivity rate of the influenza virus is around 16 percent. However, combined data, which includes figures from provincial public health laboratories and other influenza surveillance sites show over a 35 percent positivity rate.

“Influenza cases surge twice a year, in February-March and in October-Novermber,” said Dr Ranjan Raj Bhatta, director at the laboratory. “One should not worry too much about the rise in influenza cases, as this happens on a regular basis, not only in our country but also elsewhere.”

Doctors however, say that elderly people, small children and those having underlying health conditions—heart disease, renal problems, cancer, diabetes, among others—are vulnerable to getting severe.

“Those with underlying health conditions who can afford the influenza vaccine should get inoculated on time,” said Dr Sher Bahadur Pun, a virologist and the chief of Clinical Research Unit at Sukraraj Hospital. “We don’t know who will get infected and develop severe symptoms, so it’s better to take precaution early.”

Seasonal influenza caused by regular viruses—A(H1N1), A (H3), influenza B (victoria) and some others, whose lineages have not been subtyped yet—are responsible for the current surge.

Doctors say seasonal influenza is also highly contagious. It mainly affects the lungs and quickly spreads in communities. They warn that if seasonal influenza is left untreated, it can cause pneumonia, which can be fatal.

Pneumonia, an infection of the lungs caused by various types of bacteria, viruses and fungi, is the leading cause of death among children under five in Nepal. It kills more children annually than malaria, tuberculosis and HIV combined. According to the World Health Organisation, pneumonia accounts for 15 percent of under-five mortality.

Doctors say pneumonia caused by bacteria is deadlier than that caused by viruses, and children under five and people above 65 years of age are highly vulnerable to the disease.

Its symptoms include fever, cough, body aches, and in some cases, vomiting and diarrhoea.

Thousands of people across the country contract pneumonia every year. Back in 2018, the average cost of hospitalisation for pneumonia was Rs13,250, nearly half the average monthly household expenditure in Nepal, according to a study by Pneumo Nepal, whose report was published in 2020.

The study—which was carried out at Patan Hospital, Kanti Children's Hospital, Mission Hospital in Palpa, Bheri Hospital in Nepalgunj, and BP Koirala Institute of Health Sciences—showed that unexpected medical costs often push families into poverty.

“We recommend comorbid children to administer with updated influenza vaccines, which protects them from getting severe,” said Dr Srijana Shrestha, professor of pediatric at Patan Academy of Health Sciences. “Parents of small children must take precautions to protect their wards from cold and flu.”

Experts say early diagnosis is crucial for preventing infection and complications. Patients recover quicker if treated promptly. However, the severity of the disease and deaths increase if seasonal influenza cases are not diagnosed on time.

Public health measures—mask-wearing, handwashing, avoiding crowds, and maintaining social distancing—can reduce infection, doctors say.