title: Descriptive clinical and epidemiological characteristics of influenza A H1N1 2009 virus infections in pigs in England.
abstract: Infection of pigs with influenza A H1N1 2009 virus (A(H1N1)pdm09) was first detected in England in November 2009 following global spread of the virus in the human population. This paper describes clinical and epidemiological findings in the first English pig farms in which A(H1N1)pdm09 influenza virus was detected. These farms showed differences in disease presentation, spread and duration of infection. The factors likely to influence these features are described and relate to whether pigs were housed or outdoors, the age of the pigs, inter-current disease and the management system of the unit. Infection could be mild or clinically inapparent in breeding pigs with more typical respiratory disease being identified later in their progeny. Mortality was low where disease was uncomplicated by environmental stresses or concurrent infections. Where deaths occurred in pigs infected with A(H1N1)pdm09 influenza, they were mainly due to other infections, including streptococcal disease due to Streptococcus suis infection. This paper demonstrates the ease with which A(H1N1)pdm09 virus was transmitted horizontally and maintained in a pig population.
authors.affiliation: Animal Health and Veterinary Laboratories Agency, Rougham Hill, Bury St Edmunds, Suffolk IP33 2RX, UK. susanna.williamson@ahvla.gsi.gov.uk
authors.forename: S M
authors.initials: SM
authors.lastname: Williamson
authors.forename: A W
authors.initials: AW
authors.lastname: Tucker
authors.forename: I S
authors.initials: IS
authors.lastname: McCrone
authors.forename: C A
authors.initials: CA
authors.lastname: Bidewell
authors.forename: N
authors.initials: N
authors.lastname: Brons
authors.forename: H
authors.initials: H
authors.lastname: Habernoll
authors.forename: S C
authors.initials: SC
authors.lastname: Essen
authors.forename: I H
authors.initials: IH
authors.lastname: Brown
authors.forename: J L N
authors.initials: JL
authors.lastname: Wood
mesh_terms: D000367:Age Factors; D000822:Animal Husbandry / Q000379:methods; D000818:Animals; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission; D008297:Male; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000473:pathology / Q000635:transmission / Q000662:veterinary*; D012307:Risk Factors; D012621:Seasons; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000473:pathology / Q000635:transmission; D015047:Zoonoses