An Indian doctor (centre left) wears a mask as a preventive measure against swine flu virus as he checks a patient at an emergency ward at a hospital in New Delhi. Image Credit: AP

New Delhi: With reports of nearly 500 cases of swine flu from across the country this season, doctors and experts say the viral disease sees an upswing during winter but there is no need to panic.

Closed and crowded spaces such as offices and air-conditioned homes aided the spread of the disease, say doctors.

According to doctors, though H1N1 flu cases peak during this season, infection can be avoided by taking simple precautions such as washing hands frequently, wearing masks and avoiding closed and crowded places.

Swine flu is a common occurrence in countries with extreme cold weather such as the United States and parts of Europe, said Randeep Guleria, head, Department of Pulomonary Medicine, All India Institute of Medical Sciences (AIIMS).

“The only difference is that while cases of swine flu peak in other parts of the world during winter, in India, there are two outbreaks -- one in winter and one in monsoon, specially in South India,” Guleria said.

According to the health ministry, the country has reported of 456 cases of swine flu till January-end. Rajasthan has seen the maximum number of cases at 246. The flu has claimed 91 lives so far.

Guleria said that contrary to popular perceptions, swine flu had nothing to do with pigs.

“The virus, when it was initially isolated in Mexico, was found similar to the flu strain found in swine and was thus named that,” he said, adding that it was better to call the virus ‘Pandemic H1N1 2009’.

He said enclosed spaces, such offices, and air-conditioned homes were ideal conditions for the spread of the infectious disease.

The World Health Organisation (WHO), while declaring the H1N1 Pandemic to be over in August 2010, also conveyed that the influenza virus now would take on the behaviour of seasonal flu and continue to circulate for some years to come. Hence, in the post-pandemic period, localised outbreaks of varying magnitude with significant level of H1N1 transmission are expected, said WHO.

On June 11, 2009, it raised a worldwide pandemic alert level to phase six for swine flu - the highest alert level. This alert level meant the swine flu had spread worldwide and there were cases of people with the virus in most countries. The pandemic level identifies the spread of the disease or virus and not necessarily the severity of the disease.

Swine flu spread very rapidly worldwide due to its high human-to-human transmission rate and due to the frequency of air travel.

In 2010, cases were confirmed in at least 171 countries and territories and the flu caused deaths in at least 139 cases, WHO said.

With the number of swine flu cases rising in India this season, doctors have asked people not to panic at the slightest flu symptoms. Most symptoms of swine flu are similar to common flu.