JALISCO, Mexico – Animal health officials in Mexico ramped up efforts to contain an outbreak of H7N3 avian influenza after more infected birds were discovered.

Eight million more chickens have been slaughtered and another 66 million have been vaccinated in an effort to contain the outbreak, according to chron.com. Vaccines were imported from Pakistan, and Mexico's agriculture officials said they developed a seed-based vaccine to be delivered to laboratories in preparations to make more than 80 million doses.

The virus was first uncovered in Mexico’s western state of Jalisco on June 20. Mexico’s government issued a national animal health emergency on July 2. Jalisco produces 11 percent of the country’s poultry meat and 50 percent of its eggs, according to Reuters.