A 4-month-old child quarantined at Yokota Air Base after arriving Friday with its mother from the States does not have the virus that causes swine flu, officials said.

Japan’s Ministry of Foreign Affairs was notified testing for the H1N1 flu strain proved negative, a ministry spokesman said.

Japan’s National Institute of Infectious Diseases tested the infant, which had a fever during a health screening of passengers arriving on the Patriot Express from Seattle on Friday morning.

The infant’s mother and 13 passengers who were sitting near the child on the military chartered flight were found not to be infected and were to be released Sunday, the ministry spokesman said.

The spokesman also said the infant’s condition has improved.

U.S. Forces Japan officials told the ministry it will continue to require screening of passengers arriving from the States to U.S. bases in Japan, just as Japan is doing at international airports to prevent swine flu from entering the country, the spokesman said.

A USFJ official said the command had nothing to add to the ministry’s report.

Stars and Stripes reporter Bryce S. Dubee contributed to this report.