June 24 (Bloomberg) -- Indonesia reported its first swine flu infections, two days after it was listed by the Singapore health ministry among countries known to have exported cases to the city-state.

An Indonesian pilot who had traveled to Australia and Hong Kong before falling ill is recovering in Jakarta, and a British woman who arrived from Australia is hospitalized in Bali, Health Minister Siti Fadilah Supari said today. Tests on relatives of the pilot were negative for the new H1N1 virus, she said.

Health officials worry that transmission of the virus in Indonesia, Southeast Asia’s most-populous nation, would increase the chances that the bug combines with the H5N1 bird flu strain that’s lethal in three of every five reported cases. Indonesia accounts for a third of the 433 fatal bird flu cases reported to the World Health Organization worldwide.

“What we fear is if H1N1 combines with H5N1,” Supari told reporters in Jakarta. “The combined virus may have the ease of spread, like H1N1 has, with the increased virulence of H5N1.”

The bug may have been circulating in Indonesia if infected travelers from the nation carried it into Singapore. People carrying the virus typically take two to seven days to develop a fever, cough and other symptoms.

“So far, there are no local cases,” Supari said, adding that visitors from Australia to Bali, a popular holiday destination, will be screened more carefully for the virus. “I am, frankly, concerned about visitors from Australia. We will add special measures for this.”

Exported Cases

Indonesia, which neighbors Singapore, is among 15 places where the virus has spread in the community or which are known to have exported cases, Singapore’s health ministry said. Others include Hong Kong, Australia and Thailand, it said.

More than 52,000 cases have been reported by at least 90 countries, the WHO said on June 22. The Geneva-based agency is watching for signs the disease is worsening as the germ circulates globally, creating opportunities for its genes to mutate or combine with those of other viruses. The WHO on June 11 declared that swine flu had triggered the first influenza pandemic since 1968.

In Singapore, students and staff who have visited affected countries since June 22 are required to take a seven-day leave of absence from school, the nation’s Ministry of Education said in a statement yesterday. Those who are unwell while in school and have traveled recently to affected countries will be isolated and taken by ambulance for medical treatment, the ministry said.

To contact the reporters on this story: Jason Gale in Singapore at j.gale@bloomberg.net; Naila Firdausi in Jakarta at nfirdausi@bloomberg.net.

Last Updated: June 24, 2009 05:45 EDT