Avian pox is a disease caused by Avipoxvirus spp. that is known
to produce self-limiting, proliferative epithelial lesions in over 275
bird species from 70 families. Although generally benign, this emerging
disease can sometimes provoke significant outbreaks of mortality. In
rallids, there is a single serological record of Avipoxvirus. In this study, we report on field evidence for two avian pox-like outbreaks in Eurasian coots, Fulica atra.
In Utterslev Mose, Denmark, 17 birds were found in the winter and early
spring of 2006 with putative signs of pox-like lesions on the frontal
shield and bill. Similar lesions were detected in a population of c. 30
Eurasian coots from a small wetland in eastern Spain in the winter of
2018. Birds with active lesions were detected up to 73 days after first
finding, and percentage of birds with lesions also increased in this
period (from 9.1% to 69.6%), then declined. Lesions of individual birds
were observed to heal in 2 weeks. Three young coots exhibited severe
lesions that hampered breathing. In other 17 wetlands from the same
region, pox-like lesions were detected in 8 out of 843 Eurasian coots
from three localities (maximum prevalence: 18.8%) and 1 of 8 Crested
coots, Fulica cristata, in one locality. Reports from European
birdwatchers describing coots with abnormal frontal shields suggest that
some of these birds likely suffered also from avian pox. This disease,
unnoticed thus far, could be geographically widespread, thus its
potential population impact should not be underestimated, especially in
Crested coots.