H1N1: A Veterinary Perspective

The following article was written by Victor Del Rio Vilas, DVM, MBA, MSc, PhD, for the Global Outreach Committee's blog series on the Novel A (H1N1) influenza virus.

To date, four incidents of pandemic H1N1 2009 virus in domestic species have been reported worldwide (OIE). The first incident was reported in Canada and affected pigs. Pigs were also reported from Argentina and Australia. The fourth incident, in Chile, affected two commercial breeding turkey farms. This last incident in turkeys is the first report of birds being infected with the pandemic H1N1 2009 virus. This finding is at odds with previous evidence that showed that poultry (chickens) were refractory to infection (Lange et al., 2009). In all four cases there was some evidence that personnel working or visiting the premises showed some flu-like illness. In the Australian incident, pandemic H1N1 2009 virus was isolated from staff.

UK’s Government position, referring to disease in pigs, is one of collaboration with the industry. To date, UK’s animal authorities consider novel influenza in pigs an industry’s problem and so the industry should lead. UK’s authorities have supported the industry and provided advice in the production of a code of practice against influenza viruses (not only pandemic H1N1 2009). Other approaches have been developed elsewhere (e.g. the development of contingency plans for novel influenza in swine herds in the Netherlands). With regard to poultry, the British Veterinary Association (2009) has issued warnings to poultry keepers to prevent staff with flu-like illness from working with poultry.

There appears to be a consensus that infection in swine herds would not constitute a significant source of infection to humans, compared to human to human transmission, in a situation of widespread infection of the human population. However, there is uncertainty as to what it would be the impact of pandemic H1N1 2009 incidents in animal populations once the peak of the epidemic in humans has passed. At the tail of the epidemic in humans, if H1N1 does not become a recurrent event as it is the case of regular flu, the relevance of animal transmission to humans, and the surveillance value of reverse zoonosis incidents might increase. This would resemble the situation at the start of the epidemic when the first case reported in Canada in pigs had some value in the detection of human infection hidden to the regular Public Health surveillance systems.

The importance of pandemic H1N1 2009, from a veterinary perspective, goes beyond its Public Health impact. Following UK’s four reasons for Government intervention (welfare impact, Public Health impact, wider society impact and trade impact), novel influenza in any domestic species could result, as it has happened already, in trade restrictions. So far, infection in animals has shown mild disease presentations, in swine and birds, with rapid recovery. On this basis, the impact on the welfare appears to be reduced. Finally, the impact on the wider society, at the peak of the epidemic in humans, is likely to be, in comparison to the potential disruption caused by the human form, insignificant. This assessment may or course change in the future if the epidemic in humans recedes.

Surveillance of potential pandemic H1N1 2009 incidents in Great Britain relies on submissions of suspect cases by farmers. The number of submissions in 2009 remains steady. This is a positive result that challenges initial fears of a drop in the number of submissions by farmers due to potential retail pressures.

OIE (2009)
Lange E., Kalthoff D., Blohm U., Teifke J.P., Breithaupt A., Maresch C., Starick E., Fereidouni S., Hoffmann B., Mettnleiter T.C., Beer C., Vahlenkamp T.W. (2009). Pathogenesis and transmission of the novel swine-origin influenza virus A/H1N1 after experimental infection of pigs. Journal of General Virology 90, 2119-2123.

About the Author:
Victor J Del Rio Vilas, DVM, MBA, MSc, PhD
UK
*The views expressed above are solely those of the author.