Monthly Archives: October 2016

Influenza virus infection in pigs is a major farming problem, causing considerable economic loss and posing a zoonotic threat. In addition the pig is an excellent model for understanding immunity to influenza viruses as this is a natural host pathogen system. Experimentally, influenza virus is delivered to pigs intra-nasally, by intra-tracheal instillation or by aerosol, but there is little data comparing the outcome of different methods. We evaluated the shedding pattern, cytokine responses in nasal swabs and immune responses following delivery of low or high dose swine influenza pdmH1N1 virus to the respiratory tract of pigs intra-nasally or by aerosol and compared them to those induced in naturally infected contact pigs. Our data shows that natural infection by contact induces remarkably high innate and adaptive immune response, although the animals were exposed to a very low virus dose. In contacts, the kinetics of virus shedding were slow and prolonged and more similar to the low dose directly infected animals. In contrast the cytokine profile in nasal swabs, antibody and cellular immune responses of contacts more closely resemble immune responses in high dose directly inoculated animals. Consideration of these differences is important for studies of disease pathogenesis and assessment of vaccine protective efficacy. Hemmink JD, Morgan SB, Aramouni M, Everett H, Salguero Canini L, Porter E, Chase-Topping M, Beck K, Loughlin RM, Carr BV, Brown IH, Bailey M, Woolhouse M, Brookes SM, Charleston B, Tchilian E; Distinct Immune Responses and Virus Shedding in Pigs following Aerosol, Intra-Nasal and Contact Infection with Pandemic Swine Influenza A Virus, A(H1N1)09; Vet Res. 2016 Oct 20;47(1):103. PMID: 27765064 DOI: 10.1186/s13567-016-0390-5

Oral treatment with antimicrobials is widely used in pig production for the control of gastrointestinal infections. Lawsonia intracellularis (LI) causes enteritis in pigs older than six weeks of age and is commonly treated with antimicrobials. The objective of this study was to evaluate the efficacy of three oral dosage regimens (5, 10 and 20mg/kg body weight) of oxytetracycline (OTC) in drinking water over a five-day period on diarrhoea, faecal shedding of LI and average daily weight gain (ADG). A randomised clinical trial was carried out in four Danish pig herds. In total, 539 animals from 37 batches of nursery pigs were included in the study. The dosage regimens were randomly allocated to each batch and initiated at presence of assumed LI-related diarrhoea. In general, all OTC doses used for the treatment of LI infection resulted in reduced diarrhoea and LI shedding after treatment. Treatment with a low dose of 5mg/kg OTC per kg body weight, however, tended to cause more watery faeces and resulted in higher odds of pigs shedding LI above detection level when compared to medium and high doses (with odds ratios of 5.5 and 8.4, respectively). No association was found between the dose of OTC and the ADG. In conclusion, a dose of 5mg OTC per kg body weight was adequate for reducing the high-level LI shedding associated with enteropathy, but a dose of 10mg OTC per kg body weight was necessary to obtain a maximum reduction in LI shedding. Larsen I, Hjulsager CK, Holm A, Olsen JE, Nielsen SS, Nielsen JP; A Randomised Clinical Trial on the Efficacy of Oxytetracycline Dose through Water Medication of Nursery Pigs on Diarrhoea, Faecal Shedding of Lawsonia Intracellularis and Average Daily Weight Gain; Prev Vet Med. 2016 Jan 1;123:52-9. doi: 10.1016/j.prevetmed.2015.12.004. Epub 2015 Dec 14.