Herd-level prevalence and incidence of porcine epidemic diarrhoea virus (PEDV) and porcine deltacoronavirus (PDCoV) in swine herds in Ontario, Canada

Abstract

Porcine epidemic diarrhoea virus (PEDV) and porcine deltacoronavirus (PDCoV) were first identified in Canada in 2014. Surveillance efforts have been instrumental in controlling both diseases. In this study, we provide an overview of surveillance components for the two diseases in Ontario (Canada), as well as PEDV and PDCoV incidence and prevalence measures. Swine herds located in the Province of Ontario, of any type, whose owners agreed to participate in a voluntary industry-led disease control programme (DCP) and with associated diagnostic or epidemiological information about the two swine coronaviruses, were eligible to be included for calculation of disease frequency at the provincial level. PEDV and PDCoV data stored in the industry DCP database were imported into the R statistical software and analysed to produce weekly frequency of incidence counts and prevalence counts, in addition to yearly herd-level incidence risk and prevalence between 2014 and 2016. The yearly herd-level incidence risk of PEDV, based on industry data, was 13.5%, 3.0% and 1.4% (95% CI: 11.1-16.2, 2.0-4.2, 0.8-2.3), while the yearly herd-level incidence risk of PDCoV was 1.1%, 0.3%, and 0.1% (95% CI: 0.5-2.2, 0.1-0.9, 0.0-0.5), for 2014, 2015 and 2016, respectively. Herd-level prevalence estimates for PEDV in the last week of 2014, 2015 and 2016 were 4.4%, 2.3% and 1.4%, respectively (95% CI: 3.1-6.0, 1.5-3.3, 0.8-2.2), while herd-level prevalence estimates for PDCoV in the last week of 2014, 2015 and 2016 were 0.5%, 0.2% and 0.2%, respectively (95% CI: 0.1-1.2, 0.0-0.6, 0.0-0.6). Collectively, our results point to low and decreasing incidence risk and prevalence for PEDV and PDCoV in Ontario, making both diseases possible candidates for disease elimination at the provincial level.

Significant inhibition of re-emerged and emerging swine enteric coronavirus in vitro using the multiple shRNA expression vector

“…Successful RNAi on the inhibition of PEDV replication has been demonstrated by synthetic siRNA and plasmid-transcribed shRNA targeting M gene (Shen et al, 2015). However, recent epidemiological studies revealed that the presence of multiple virus strains simultaneously circulated in many endemic areas including PEDV, SADS-CoV, and PDCoV (Ajayi et al, 2018;Fig. 3.…”

“…Similar to other SECoVs, such as transmissible gastroenteritis virus (TGEV), these re-emerged and emerging SECoV diseases are age-dependent with high morbidity and mortality in neonatal pigs. Mixed infections of PEDV, SADS-CoV, and PDCoV are presented in swine herds, which mostly are double infections or successive infections (Ajayi et al, 2018;Niederwerder and Hesse, 2018;Trudeau et al, 2017;Zhou et al, 2018b). Currently, vaccination is the primary measure for prevention of PEDV.…”

Forecasting herd-level porcine epidemic diarrhea (PED) frequency trends in Ontario (Canada)

“…This in itself is not surprising since the biggest risk factor for the number of new cases of a communicable disease is the prevalence of infection (Krämer et al, 2010). Nonetheless, prevalence and other measures of disease frequency for newly emerging diseases are often changing rapidly, as was the case for this disease (Ajayi et al, 2018), and are frequently not known with reasonable certainty. Therefore, building surveillance systems which are capable of providing up-to-date prevalence estimates for PED and similar production diseases in the source population would be valuable for making predictions about short-term disease frequency trends.…”

“…The program is known as the Ontario Area Regional Control and Elimination (ARC&E) project. Detailed explanation of variables representing herd-level PEDV infection status is provided elsewhere (Ajayi et al, 2018). Briefly, (i) confirmed positive premises had to have at least one RT-PCR positive test for the PED virus, (ii) presumed positive premises did not have diagnostic testing conducted but housed animals that were moved from known positive sites (e.g.…”

“…The PED database allowed for tracing the PED status of individual herds in discrete locations, from time of initial infection until time of declaration of freedom from PEDV infection based on established criteria. As such, it was successfully utilized to obtain PED incidence and prevalence estimates for the province (Ajayi et al, 2018). With limited surveillance and disease control resources, accurate predictions for PED trends would be invaluable in allocating such resources, and fortunately, the PED database provides data which can be used for predictive purposes.…”