title: Occurrence of swine influenza virus infection in swine with porcine respiratory disease complex.
abstract: We studied the occurrence of swine influenza virus (SIV) infection in piglets with respiratory symptoms resembling porcine respiratory disease complex (PRDC). A total of 106 samples including nasal swab and lung suspension from sick piglets were collected from 30 farms of medium size in the central and eastern parts of Thailand from August 2006 to February 2007. Samples were inoculated onto Mardin-Darby Canine Kidney (MDCK) cells and SIV infection was confirmed by immunofluorescent assay (IFA) and reverse transcriptase polymerase chain reaction (RT-PCR) specific for M gene. Of 106 samples, 3 pigs from 3 different farms were found to be SIV positive on all assays. The positive samples were further identified by RT-PCR as H3N2 subtype using specific primers for hemagglutinin (HA) and neuraminidase (NA) genes. SIV infection was found in 2.8% of swine suffering from respiratory distress suggesting SIV may not be the major pathogen for PRDC in the central and eastern Thailand. SIV was present in 3 of 30 farms (10%) indicating the prevalence of SIV in these regions is considerable. Since pigs are vulnerable to infection from both human and avian influenza viruses and interspecies transmission between humans and swine occurs sporadically, it is essential to continue surveillance and monitoring of SIV infection in the swine population.
authors.affiliation: Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Kasetsart University, Bangkok, Thailand.
authors.forename: Chatsirin
authors.initials: C
authors.lastname: Nakharuthai
authors.forename: Alongkot
authors.initials: A
authors.lastname: Boonsoongnern
authors.forename: Pariwat
authors.initials: P
authors.lastname: Poolperm
authors.forename: Worawidh
authors.initials: W
authors.lastname: Wajjwalku
authors.forename: Kitcha
authors.initials: K
authors.lastname: Urairong
authors.forename: Wilairat
authors.initials: W
authors.lastname: Chumsing
authors.forename: Preeda
authors.initials: P
authors.lastname: Lertwitcharasarakul
authors.forename: Porntippa
authors.initials: P
authors.lastname: Lekcharoensuk
mesh_terms: D000818:Animals; D002460:Cell Line; D017931:DNA Primers; D004285:Dogs; D005455:Fluorescent Antibody Technique; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics / Q000302:isolation & purification; D009980:Influenza A virus / Q000235:genetics / Q000302:isolation & purification*; D009976:Orthomyxoviridae Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology* / Q000821:virology; D013785:Thailand / Q000453:epidemiology
chemical_list: D017931:DNA Primers