The Zoonoses Expert Council advises the government to be alert to bird flu (HPAI) in pigs. If HPAI viruses and swine influenza viruses were to mix in pigs, this could also be risky for humans. That is why a policy script for HPAI in pigs has recently been published. To date, no HPAI has been identified in pigs in the Netherlands.
The HPAI policy script for pigs contains guidelines and procedures that must be followed in the event of an outbreak of bird flu in pigs. The aim of the measures is to reduce the risk of the HPAI virus spreading and the emergence of a new virus. The script also provides an explanation of the measures. The policy script was drawn up in response to advice from the Zoonoses Expert Council, which considers vigilance against HPAI in pigs necessary.
Risk of virus mixing
Pigs are a potential mixing vessel for several influenza viruses. This means that pigs can be simultaneously infected with a swine influenza virus, a human influenza virus and/or an avian influenza virus. These viruses can then mix to form a new variant, possibly leading to the development of a new zoonosis. The risk of mixing mainly occurs on farms with both pigs and poultry. Pig farms with outdoor access, in the vicinity of poultry farms or in areas with many water birds also pose a risk.
The risk of mixing appears to be low at the moment, says Belgian professor of virology Kristien van Reeth. On the site of Vilt, the Flemish information center for agriculture and horticulture, she says: “Research has shown that pigs are particularly difficult to infect with the bird flu virus H5N1. There is a very large species barrier for that virus to jump to the pig.”
But the virology professor also points out the potential of flu viruses to mutate. After a mutation, the bird flu virus may be able to enter pigs. The situation may then arise where a bird flu virus and a swine flu virus mix. Van Reeth: “The risk for this remains very low, but the consequences could be major.”
Suspicion or contamination
Alertness to HPAI in pigs is necessary, even though this has not yet been demonstrated in the Netherlands. That is why a positive laboratory result must be reported to the NVWA, according to the HPAI policy manual in pigs. After a report, the NVWA may decide to conduct further investigation. After this, five scenarios can arise, with associated actions. These scenarios have been elaborated in the policy script. Little is known about suspicion based on clinical symptoms. Research shows that infection with a bird flu virus causes few symptoms in pigs.
Possible measures in the event of an outbreak
The Minister of Agriculture, Nature and Food Quality can impose various (national) measures based on national regulations, according to the policy script. Measures that the minister can take include:
- standstill (length of standstill depends on the situation)
- culling of contaminated establishments with pigs
- preventive culling of high-risk establishments with pigs
- hygiene measures and transport restriction measures
- establishing regions with different measures per region
- visitor regulations
- shielding and/or building obligation
- ban on events
- vaccination of animals
- breeding ban
These measures may also apply to hobby farms, petting zoos, zoos, laboratories or research institutions.
Source: Groen Kennisnet
