Citizens' participation is key in checking the spread of the A/H1N1 swine flu virus responsible for 159 deaths in Mexico, an academic epidemiologist told Xinhua on Tuesday.

"Steps can be taken to overcome the epidemic only when citizens follow the information and instructions given by the federal government and the Mexico City mayor's office," said Robna Galaz, who earned her doctorate at the National Polytechnic Institute in Mexico.

Five days after the health authorities declared an epidemic outbreak, the number of cases tops 2,000 with 70 percent of them yet to be confirmed as the new swine flu strain.

Galaz said that official instructions to wear face masks, wash hands frequently, avoid large gatherings, and consult a physician early if in doubt, would not only protect the individual but also the family, community and all society.

Face masks quickly became visible in public transport, malls, streets and offices. She also praised the Mexican army for its Plan DN-III, deployed to the streets to distribute the masks.

People believe the government is delivering trustworthy information that calms the population, said Galaz.

"Mexico can fight this new virus as soon as it has more information," she said. "It currently incubates from two to five days and there is enough time to attack it."

She added that the nationwide suspension of classes from nursery to university starting on Monday was a precautionary measure to allow the other places of the country to detect new cases or outbreaks.