Cumulative incidence of PED and PDCoV in Canada is decreasing according to data coming from the industry for the year 2014, 2015 and 2016.
PED showed a cyclical pattern when looking at the number of farms infected. However, PDCoV showed a more erratic pattern with no clear trends.
Industry driven disease control programs provide useful information to understand temporal evolution and disease patterns.
The primary goal of this study was to estimate herd-level incidence and prevalence measures for PEDV and PDCoV in swine herds in Ontario (Canada) between January 2014 and December 2016, based on industry data (Ontario Swine Health Advisory Board (OSHAB) Disease Control Program (DCP)).
The full paper was published in the Transboundary and Emerging Diseases journal.
Herd-level incidence risk and rate of two novel porcine coronaviruses (PEDV and PDCoV) in Ontario swine herds between 2014 and 2016, and estimated prevalence of positive cases at the end of each year based on data provided in the Ontario Swine Health Advisory Board (OSHAB) Disease Control Program (DCP) database (average number of herds for 2014–2016 = 1093).
PED showed a cyclical pattern over the three years of the study while PDCoV showed a more erratic pattern. Incidence decreased over time between 2014 and 2016 in both, PED and PDCoV.
Influenza is endemic and seasonal in piglets from sow farms in the Midwest with higher infections in winter and spring.
Influenza seasonality was partially explained by outdoor air absolute humidity and temperature trends.
Influenza genetic diversity was high and co-circulation of more than one genetically distinct virus was common.
To study influenza levels over time and its seasonality, monthly testing data of piglets at weaning from 34 sow farms during ~5 years were analyzed.
There were 28% of positive submissions with a median influenza herd-level prevalence of 28%. Genetic diversity was significant with 10 genetically distinct clades of contemporary US swine influenza viruses as shown below. Furthermore, 21% of farms had 3 genetically distinct viruses circulating over time; 18% had 2, 41% had 1 and 20% had no isolates available.
In summary, influenza herd-level prevalence in Midwestern sow farms had a seasonal pattern with higher levels in winter and spring. This is important to better allocate influenza control strategies such as vaccination in sow farms. Influenza seasonality was partially explained by outdoor air absolute humidity and temperature although other factors such as immunity and new introductions may play a role in the observed seasonality.
Read the full story at https://www.frontiersin.org/articles/10.3389/fvets.2017.00167/full.
Seasonal patterns can be seen in different cohorts located in different regions.
A comparison from a prevalence standpoint between the cohort of farms belonging to the 13 systems participating at the start of the MSHMP (CS) and the cohort of farms from systems that joined the program later (CL), was performed with the objective of assessing whether the patterns between cohorts compare.
As seen in Figure 1–CS, there was a clear shift towards more use of MLV over LVI for sow herd stability purposes. The proportion of farms using LVI in the CS versus the CL is 5% and 10%, respectively. When assessing the proportion of farms in each AASV PRRS category (Holtkamp et al., 2011) both groups are comparable (Table 1). Also the temporal pattern of infection can be seen in both cohorts as described by Tousignant et al (2014).
In summary, both cohorts of farms (CS versus CL) yield similar results which continue to highlight the robustness of the program and the representativeness of the systems contributing to this program.
The Torremorell lab is continuing to explore swine influenza epidemiology in this recent publication from Dr. Fabian Chamba Pardo in Frontiers in Veterinary Science. After showing that multiple genome constellations of similar and distinct influenza viruses co-circulate in pigs, the group is now presenting new data about influenza herd-level prevalence in the Midwest, and how it is influenced by seasons. Click on the banner below to read the entire research article.
60 sow farms from a single Midwestern production system were enrolled in this study. Between one and seven oral fluid samples were collected at each farm weekly and meteorological data (air temperature and relative humidity) was compiled from stations located from the farms.
28% of submissions had at least one influenza positive result. All farms tested positive at least once during study period. Herd-level prevalence ranged from 7% to 57% as show in the figure above. Prevalence was low in summer, rose during fall, and peaked twice in both early winter (December) and late spring (May). August was the month with the lowest prevalence. Influenza herd-level prevalence was higher when both mean outdoor air temperature and air humidity were lower.
The most common clades identified were H1 delta 1, H1 gamma 1, and clusters H3 IV A and H3 IV B. Furthermore, 21% of the farms had 3 different influenza genetic clades circulating during the study period and 18% had 2.
Influenza is a costly disease for pig producers and understanding its epidemiology is critical to control it. In this study, we aimed to estimate the herd-level prevalence and seasonality of influenza in breed-to-wean pig farms, evaluate the correlation between influenza herd-level prevalence and meteorological conditions, and characterize influenza genetic diversity over time. A cohort of 34 breed-to-wean farms with monthly influenza status obtained over a 5-year period in piglets prior to wean was selected. A farm was considered positive in a given month if at least one oral fluid tested influenza positive by reverse transcriptase polymerase chain reaction. Influenza seasonality was assessed combining autoregressive integrated moving average (ARIMA) models with trigonometric functions as covariates. Meteorological conditions were gathered from local land-based weather stations, monthly aggregated and correlated with influenza herd-level prevalence. Influenza herd-level prevalence had a median of 28% with a range from 7 to 57% and followed a cyclical pattern with levels increasing during fall, peaking in both early winter (December) and late spring (May), and decreasing in summer. Influenza herd-level prevalence was correlated with mean outdoor air absolute humidity (AH) and temperature. Influenza genetic diversity was substantial over time with influenza isolates belonging to 10 distinct clades from which H1 delta 1 and H1 gamma 1 were the most common. Twenty-one percent of farms had three different clades co-circulating over time, 18% of farms had two clades, and 41% of farms had one clade. In summary, our study showed that influenza had a cyclical pattern explained in part by air AH and temperature changes over time, and highlighted the importance of active surveillance to identify high-risk periods when strategic control measures for influenza could be implemented.