It took a World Health Organisation pandemic warning for India to begin screening passengers arriving from affected countries.
Screenings began in Delhi after 9 pm. Mumbai, Kolkata, Hyderabad, Chennai, Kochi, Goa, Jaipur and Hyderabad would follow.
The H1N1 virus has killed 159 people and infected over 2,000 in Mexico. It has travelled to the US, Canada, New Zealand, Israel, Britain, Spain and Germany. The first swine flu death outside Mexico occurred in the US on Wednesday.