TAIPEI (Taiwan News) — Taiwan continues to struggle with containing the H5N1 avian flu as a farm in Changhua County culled its livestock of hens on Friday (March 22).

The owner of the egg farm in Changhua’s Erlin Township reported to authorities on Monday (March 18) that several hens died for unknown reasons. After Animal Disease Control Center officials sent samples from the farm for testing, it was confirmed on Wednesday (March 20) that they were infected with H5N1, reported CNA.

On Friday, 19,788 hens were culled at the farm to stop the outbreak from spreading. The news follows outbreaks in southern Taiwan at farms in Pingtung and Tainan in February.

The Animal Disease Control Center of Changhua County released a statement saying that recent temperature fluctuations may reduce immunity among some bird populations. This time of the year also sees many birds species flying south to north on their annual migration, which may also spread harmful pathogens like H5N1 from wild birds to livestock.