Istanbul, Jan 1 : The Turkish Medical Association has recently warned about the potential escalation of a flu epidemic across the country, urging the use of masks in public transportation. There are "unusual intensities" in emergency rooms at hospitals nationwide due to the flu epidemic, the medical group said on Sunday in a warning letter sent to the Health Ministry this week. "As long as the epidemic is not extinguished, the health of society and healthcare professionals is under threat" unless necessary measures are taken, the letter said. Each doctor at family centres sees at least 100 patients suffering from flu symptoms per day in Istanbul, according to the association. The association also urged the relevant authorities to distribute masks free of charge and promote the use of masks in public vehicles, Xinhua news agency reported. A Turkish health expert has also warned on Saturday that a flu epidemic is spreading across Turkey. "Especially in the last two weeks, we have frequently encountered upper respiratory tract infections. Almost all of them are caused by viruses," said Celalettin Kocaturk, a thoracic surgery specialist. "We most frequently encounter Influenza A, Influenza B, Parainfluenza, Rhinovirus, Covid-19, other types of coronaviruses, and Adenoviruses," he added. These viruses have the potential to cause death among older adults and those with additional diseases, according to Kocaturk. He urged people to wear masks indoors, observe hygiene rules, and avoid sending sick children to school until May, when the flu epidemic will ease with the onset of warm weather. /IANS