Highly Pathogenic Avian Influenza Virus HPAI H7N7 - 2003 Epidemic in Europe
How the Virus Spread from Poultry to People and Pigs
Veterinarian Dies in Livestock Influenza Epidemic
On April 19, 2003, the Dutch Health Ministry reported that a 57-year-old male veterinarian had died as result of Avian Influenza (AI) infection. The vet developed pneumonia two days after working with AI-infected poultry and died soon afterwards in hospital. He had apparently not been taking anti-viral medication (see below).
There was concern that this human mortality case might indicate a shift of the virus genome towards increased virulence for people, but a Dutch health ministry spokesman told Reuters new agency "We now know there's no mutation of the virus, we know for sure that the vet died of the original bird flu. It's very good to know that".
History of the 2003 Epidemic
In less than two months, an epidemic of highly pathogenic avian influenza (also known as AI and classical fowl plague) due to an influenza A virus subtype H7N7 (HPAI H7N7) has devastated the Dutch poultry industry and spread to Belgium. The epidemic began on March 1st 2003 near Barneveld in poultry which had first developed symptoms on February 28th. Most of the initial outbreaks were in free-range poultry farms. Three turkey farms in Dinteloord, near Roosendaal, in the province of Brabant were early hosts for the virus.
Spread to Pigs
On April 16th 2003, the Dutch Agriculture Minister, Cees Veerman, reported that the virus had spread to swine. Antibodies to the new virus were found in swine on five farms in the Gelderland Valley which also had infected poultry. There is no evidence, however that the virus can spread from pig to pig. Also, none of the seropositive pigs have shown any clinical signs. However, all transportation of pigs in the Gelderland Valley Limburg and parts of North Brabant has been banned as a precautionary measure. In Belgium and the Netherlands, movement of pigs had already been banned from known infected farms.
The seropositive pigs appeared to have recovered from infection - no live virus was found.
An Agriculture Ministry spokesman is quoted as saying that the danger that new viruses created inside pigs could jump to humans is "not hypothetical".
Restrictions on general pig movements in the control zones of the country have now been lifted because investigations indicate that there is little risk of transmission by pigs.
Precautions against human infection
People undertaking slaughter of infected chickens, pigs and turkeys have been vaccinated against human influenza virus and are also receiving antiviral drug treatment. The aim is not only to to protect them against infection by the bird influenza virus, but also to avoid a new and more virulent virus being formed from mixing (reassortment) of human and avian influenza viruses in someone with co-infection of viruses.