Leman: Porcine deltacoronavirus in the US
In February 2014, PDCoV emerged in breeding herds
30 June 2025
3 minute read
By: Porcine deltacoronavirus (PDCoV), an enveloped RNA virus, causes atrophic enteritis in neonatal piglets, which leads to diarrhea, malabsorption, dehydration, and death. In February 2014, PDCoV emerged in the United States (U.S.) as the country was still managing the recent emergence of another coronavirus, Porcine epidemic diarrhea virus (PEDV).
Studies at the time contributed to the understanding of the emergence of PDCoV but the current situation of the disease in the U.S. is largely unknown.
Mariana Kikuti, University of Minnesota and colleagues at UMN and Michigan State University characterized the PDCoV occurrence in the U.S. breeding herd population since its emergence. The results of the study were presented at the 2024 Leman Swine Conference.
Breeding herd data from the Morrison Swine Health Monitoring Project (MSHMP) between January 2015 and December 2023 were analyzed, representing approximately 60% of the US breeding herd. Production systems voluntarily report herds’ PDCoV outbreaks. Yearly cumulative incidence was calculated using the number of breeding herds reporting either PRRS, PEDV, or PDCoV statuses (sites that were sharing information for at least one of the main diseases monitored by MSHMP) as the denominator and reported cases as the numerator.
Throughout 2015–2023, the median number of sites monitored through MSHMP was 1166, ranging from 1062 in 2015 to 1187 in 2020. In total, 244 PDCoV outbreaks occurred in 186 sites from 22 production systems across 16 states. During the entire period, 140 herds reported one PDCoV outbreak, 36 herds reported PDCoV twice, 8 reported it three times, and 2 herds reported it four times.
For sites that experienced more than one PDCoV outbreak, the interval between outbreaks had a median of 2.11 years. Cases were more frequently reported during the fall and winter seasons. Most cases occurred in the South (69.9%) and the Midwest (24.7%), with the remaining cases located in the West (1.6%) and Northeast (0.5%). In 2017, a shift in the spatial distribution occurred with the majority of cases originating from the South. The yearly cumulative incidence ranged from 0.44% in 2017 to 4.28% in 2023.
The potential seasonality of PDCoV transmission in colder months has also been observed in other countries. Unfortunately, no standardized classification of PDCoV status has been proposed that would allow the estimation of disease prevalence through time. The absence of universally adopted standardized criteria for declaring a herd negative post-outbreak hampers the ability to understand an outbreak’s duration.
Laboratory submissions more frequently represent clinically relevant cases in which the probability of testing positive is higher than in the general population. Even though PDCoV occurs at a much lower frequency than other important swine diseases in the U.S., such as PRRS and PED, it is still very much present in the U.S. breeding herd as cases continue to be reported each year. In fact, PDCoV incidence has increased when compared to earlier years. These results show that PDCoV monitoring is still important, and control measures need to be strengthened to limit the spread and impact of the disease.
