European Surveillance Network for Influenza in Pigs 2
The European Surveillance Network for Influenza in Pigs (ESNIP) 2 will maintain and expand a surveillance network that was established during a previous EC concerted action (ESNIP, QLK2-CT-2000-01636). Three work packages (WP 1, 2, 3) aim at a better understanding of the epidemiology and evolution of swine influenza virus (SIV) in different European countries, through an organised surveillance programme together with antigenic/genetic characterisation using standardised methodology. These data will be used to improve the diagnosis of SIV by updating the reagents used in classical techniques (WP 4) and by the development of a rapid, molecular test for SIV detection (WP 5).
The virus bank and electronic database that were established during ESNIP will also be expanded with relevant SIV isolates and information (WP 6). Beyond this, we will be better able to define the public health risks of influenza in swine. This will be achieved by serological monitoring of swine for avian influenza viruses (WP 7) and by comparison of the influenza viruses that are currently circulating in swine, avian species and humans (WP 8). ESNIP 2 represents the only organised surveillance network for influenza in pigs and the first attempt to establish formal interactions with human and avian surveillance networks.
These initiatives and interactions are entirely consistent with improved pandemic preparedness and planning for human influenza. The consortium consists of 11 participants who are actively working with SIV. Eight participants are from seven different EU Member States, five of which have been actively involved in the ESNIP network whilst one participant is from Bulgaria, a candidate Member State (at the time of the project start date). Participation from third countries (Hong Kong, USA) will facilitate greater global interaction and worldwide understanding of the epidemiology of SIV. Comparisons of swine populations in Europe and in southern China, the classical epicentre for influenza, for the circulation of avian influenza viruses will prove invaluable and permit technology and knowledge exchange.[+] Read More
During the last decade, the epidemiology of swine influenza in Europe has become particularly complex. At least 3 SIV subtypes - H1N1, H3N2 and H1N2 - are currently circulating and new reassortant viruses between these subtypes have been occasionally detected. The heterogeneity in swine influenza has important implications for the diagnosis and control. Indeed, the strains used in serodiagnostic tests need to be matched to the current epidemic viruses, and inactivated SIV vaccines should contain all of the prevailing subtypes for a broad protection. Two significant difficulties, however, are that there is little surveillance for SIVs and that our understanding of the SI epidemiology is far from complete.
So far there have been rather limited attempts at detailed characterisation of SIVs. In addition, there has been confusion about the extent of antigenic evolution of these viruses, i.e. considerable antigenic drift of H1N1 and H3N2 SIVs was reported in some regions of Europe (de Jong et al. 1999, 2000), but not in others (Campitelli et al. 1997). One difficulty was a lack of standardised reagents and protocols for the subtyping and antigenic/genetic characterisation of SIV, which greatly contributed to discordant results between different laboratories.
Virus isolation followed by haemagglutination inhibition (HI) and neuraminidase inhibition (NI) with reference sera is the standard procedure for subtyping SIVs. The HI test is also most widely used for the serologic diagnosis and for serologic studies of SIV. The reagents used in such tests must be updated if relatively minor antigenic changes in the circulating SIVs should occur, and failure to do so may result in incorrect subtyping of SIVs and false seronegatives in the HI test. There is also a strong need for alternative, more rapid and simple tests for detection and subtyping of SIVs.
Finally, pigs are known to be susceptible to infection with both human and avian influenza viruses and there are concerns that avian influenza viruses or human-avian reassortants may transmit to humans via the pig. However, the true public health risk of the pig remains unknown, because there is no screening of pigs for influenza virus from other hosts.
The strategic objectives of the current Coordination Action are:
The research objectives can be grouped into six major tasks:
Technical and policy support:
In a broader context, this Coordination Action supports the EU animal health policy, because it will contribute to a high status of swine health throughout the EU. Indeed, SI is an economically important disease for the swine industry. Investigations in the Netherlands and Belgium have shown that SIV is involved in up to 50% of the acute respiratory disease outbreaks in fattening swine. In the UK, the financial loss resulting from reduced weight gain in fattening pigs due to SIV alone has been estimated at approximately 7 per pig, equivalent to a total loss in the UK per annum of 60 million.
The project will improve and facilitate the diagnosis of SI and the subtyping of SIVs. This is essential for a rational design of vaccination strategies on individual swine farms. In addition, we will obtain a clear picture of the SIV subtypes that are currently circulating in Europe and their antigenic characteristics in comparison with vaccine strains. This will indicate whether changes in the vaccine strain composition may be required. In this way the ESNIP 2 project will contribute to the welfare of swine and the profitability of swine farmers.
The objectives of the project are also in line with the OIE missions, namely:
Finally, our research will have an impact on food quality and safety. We will determine the prevalence of avian influenza viruses in swine in Europe, which will reveal whether there is a potential risk for pig meat to be contaminated with such potentially hazardous viruses.