The affected farms are found in the areas of Ban Nahay, Hatxaifong and Ban Phao, Hatxaifong, both in the capital of Vientiane. In the first case, since 21 June 2010, the animal health staff of the farm reported to the animal health officer of Vientiane Capital that some sows aborted and some pigs were sick. The farmer has given antibiotics to sick animals and some of them have become healthy but some still showed clinical signs. Eventually, the animal health staff of the farm submitted samples to the National Animal Health Centre for testing. On the second affected farm, a pig showing clinical signs was reported to the animal health officer in Vientiane Capital on 16 June 2010. Most of pregnant pigs aborted and some grower pigs showed coughing and died. The animal health officer treated them with antibiotics and some of the sick pigs recovered. Two severely affected pigs were submitted to the National Animal Health Centre for necropsy and samples were tested positive using real-time PCR.
The introduction of new live animals into the farm and low biosecurity of the farm are the likely source of the occurrence of the disease.