The Indonesian veterinary authority sent an Immediate Notification dated 26 November to the World Organisation for Animal Health (OIE).

The report describes the discovery at the end of August 2009 of the H1N1 flu virus in 250,000 pigs on Bulan Island in Riau Islands province.

According to the report, outbreak investigation has been conducted by Disease Investigation Center, Region II, Bukittinggi. In total, 180 nasal swabs and serum samples were collected in pigs in the breeder, weaner and farrow/finishing units. Of these, 33 samples were positive for influenza A and divided on 11 pool samples, which were sent to the Indonesian Research Center for Veterinary Sciences and to the Australian Animal Health Laboratory for advanced tests. Six samples were positive for pandemic influenza A/H1N1.

The Ministry of Agriculture officially declared on 23 November 2009 that an outbreak of pandemic influenza A/H1N1 occurs in pigs.