Prevalence and risk factors for swine influenza virus infection in the English pig population

Abstract

Infection of pigs with influenza viruses is a cause of considerable economic loss for pig farmers as well as a potential human health concern - as evidenced by the identification of genetic material derived from swine-adapted influenza viruses in an novel strain of H1N1 influenza virus in 2009. A study was conducted investigating the prevalence of influenza virus infection in a selection of 143 English pig herds between April 2008 and April 2009, which found evidence of recent virus circulation in over half of these herds (n=75). Farms which were sampled in the Summer months were found to have lower odds of recent virus circulation, as were farms containing pigs kept in straw yards. Additionally, farms containing pigs kept indoors and farms containing high numbers of finisher pigs per water space were found to have higher odds of recent virus circulation. It is hoped that further studies will expand on these findings, and may allow targeting of surveillance for influenza viruses in the English pig population.

Swine influenza: clinical, serological, pathological, and virological cross‐sectional studies in nine farms in Argentina

“…These results are similar to those of a recent study in Spain using an ELISA test where antibodies against IAV were detected in 93·9% of the farms evaluated . In England, a national study detected antibodies to IAV in 52% of the farms analyzed . Both studies informed a within‐herd seroprevalence that ranged from 4 to 100% .…”

A Universal Influenza Vaccine Can Lead to Disease Exacerbation or Viral Control Depending on Delivery Strategies

“…We thus added 500 µg CpG to VC and uncomplexed SA–AG in half of the immunized pigs. The animals were from a conventional breeding unit and thus had significant levels of preexisting Ab against NP and HA2 at the time of vaccination, in line with the fact that a large fraction of the pig population is immune to influenza (34) (Figures 3A–C). All vaccine regimens significantly increased the anti-NP and anti-HA2 IgG levels measured at 55 dpv relatively to d0 ( p  < 0.02 and 0.05, respectively, paired bilateral t -test), but not the anti-M2e levels (Figures 3A–C).…”

Increased risk of A(H1N1)pdm09 influenza infection in UK pig industry workers compared to a general population cohort

“…Pig veterinarians were recruited at November 2009 and May 2010 meetings of the Pig Veterinary Society, a species specialist group of the British Veterinary Association. Pig farm workers were recruited from 17 farms in September–December 2010 from a large group of farrow‐to‐finish pig farms that participated in a related study of SIV infection in English pigs 3. Farms came from two main clusters in North Yorkshire and East Anglia, both regions with higher densities of the pig population 34.…”

“…To examine the association between SIV infection among pig farm workers and SIV infection among the pigs they worked with, blood specimens were obtained from a sample of pigs on their farms as part of the aforementioned SIV infection study 3. Blood specimens were taken from pigs during the same season as the pig farm workers (autumn 2010).…”

“…Observations over the past 40–50 years have documented subtypes of viruses A(H1N1), A(H1N2) and A(H3N2) circulating in pigs worldwide and strain variations between Europe, North America and Asia have been noted 2. In the UK, A(H1N2) was the most commonly observed swine subtype in a large pig serosurvey conducted between 2008–2009 3. Between 1998 and 2009, an avian‐like H1N1 strain most commonly and an H1N2 strain were regularly detected in UK pigs 4, 5.…”