Porcine circoviruses in wild boars in Nagano Prefecture, Japan.

We investigated the prevalence of porcine circovirus 2 (PCV2) and 3 (PCV3) in wild boars captured or found dead in Nagano Prefecture in 2020. Based on PCR testing, 21 of 254 (8.3%) wild boars were PCV2-positive and 43 of 256 (16.8%) wild boars were PCV3-positive, 5 of 253 (2.0%) wild boars were both PCV2-positive and PCV3-positive. The frequency of detecting PCV3 in wild boars was significantly higher in adults than in juveniles (P=0.014). The PCV2-positive wild boars were found in all districts except for the North Alps and Hokushin, while PCV3-positive wild boars were found in all districts except for Suwa. This is the first report of PCV2 and PCV3 detected in wild boars in Japan.