Kasaragod: The College of Agriculture in Kasaragod's Padannakkad has been cordoned off after nine students on the campus tested positive for H1N1 and H3N2 fever, said District Health officials. The students had a cough and cold. "We conducted the test because around 30 students had fever with symptoms of the flu," said District Medical Officer Dr A V Ramdas.

Of the samples collected, nine people were infected with influenza type A fever, he said. The samples were tested at the National Institute of Virology in Alappuzha. One more child tested positive for H1N1 at a private lab in the district. All the students of the agriculture college with symptoms have been given special accommodation in the hostel, he said.

The flu has been identified as being caused by H1N1 and H3N3 viruses, spread through respiratory droplets, he said. The main symptoms of influenza type A fever are cold, cough, sore throat, headache, body pain, fatigue, and chills, accompanied by vomiting and diarrhoea, said officials.

Dr Ramdas recommended bringing back masks. "Use masks, especially when visiting hospitals," he said. "Cover your mouth and nose with a tissue when you cough or sneeze, and wash your hands with soap and water. Drink plenty of water and eat nutritious food."

The DMO urged pregnant women and seriously ill to be careful as the possibility of flu spreading was high.

What is H1N1 and H3N2
The H and N refer to the proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N). H1N1 has one type of hemagglutinin (H1) and one type of neuraminidase (N1). H3N2 has three types of hemagglutinin (H3) and two types of neuraminidase (N2).
These surface proteins help the virus infect cells and spread within the body.

H1N1 caused the 2009 swine flu pandemic. It was also responsible for the 1918 Spanish flu, one of the deadliest pandemics in history. H3N2 first appeared in 1968, causing the Hong Kong flu pandemic, which resulted in a significant number of deaths worldwide.

H1N1 and H3N2 circulate as part of seasonal flu strains, but the dominant strain can change each year. H3N2 is generally considered more severe during seasonal outbreaks, especially for older populations, while H1N1 can disproportionately affect younger people, said doctors.