Serologic Evidence of H1 Swine Influenza Virus Infection in Swine Farm Residents and Employees

• Main Authors: Christopher W. Olsen, Lynnette Brammer, Bernard C. Easterday, Nancy Arden, Ermias D. Belay, Inger Baker, Nancy J. Cox
• Format: Article
• Language: English
• Published: Centers for Disease Control and Prevention 2002-08-01
• Series: Emerging Infectious Diseases
• Subjects: H1; hemagglutination-inhibition; influenza; seroprevalence; swine; United States
• Online Access: https://wwwnc.cdc.gov/eid/article/8/8/01-0474_article
• ISSN: 1080-6040; 1080-6059

We evaluated seropositivity to swine and human H1 influenza viruses in 74 swine farm owners, employees, their family members, and veterinarians in rural south-central Wisconsin, compared with 114 urban Milwaukee, Wisconsin, residents. The number of swine farm participants with positive serum hemagglutination-inhibition (HI) antibody titers >40 to swine influenza viruses (17/74) was significantly higher (p<0.001) than the number of seropositive urban control samples (1/114). The geometric mean serum HI antibody titers to swine influenza viruses were also significantly higher (p<0.001) among the farm participants. Swine virus seropositivity was significantly (p<0.05) associated with being a farm owner or a farm family member, living on a farm, or entering the swine barn >4 days/week. Because pigs can play a role in generating genetically novel influenza viruses, swine farmers may represent an important sentinel population to evaluate the emergence of new pandemic influenza viruses.