select search filters
briefings
roundups & rapid reactions
Fiona fox's blog
Chickens at a poultry farm in Norfolk are being culled after dead birds tested positive for the H7 strain of bird flu and the HPA has confirmed that a poultry worker at the site is suffering from conjunctivitis after contracting the H7 flu.
Dr John McCauley, Institute for Animal Health, said:
“The last time this strain of low pathogenic avian flu was seen in UK poultry was in 1979. Low pathogenic avian flu’s have the potential to become highly pathogenic, which is much more serious for birds. This outbreak in Norfolk is in the very early stages and it is therefore very likely that culling will effectively contain the infection before it can move into a highly pathogenic form.
“Infection of humans with H7 avian flu’s has happened before in Canada and Holland. Those people with symptoms had conjunctivitis like the Norfolk poultry worker. In Italy a large outbreak of H7 avian flu occurred in poultry but no people had symptoms. Most at risk are those handling and culling infected birds. Best practice for these individuals is to take anti-viral drugs in order that co-infection with H7N3 and a human form of flu cannot occur. However, the human flu season is very nearly over and there has been low incidence of flu in humans in the UK so far this year.”
Alan Hay, director of the Medical research Council’s World Influenza Centre, said:
“This is a suspected case of eye infection caused by an H7N3 virus. It’s not unusual. It’s similar to H7N3 which have been causing infections in birds since 2002 in Italy. There have been very few documented cases of human infection in that outbreak. These sporadic human infections do happen in the case of H7 when people are in very close contacts with birds. You have to keep this in context, people in close contact have to take sensible precautions such as wearing eye masks and gloves but this is not an infection that other people should be concerned about catching.”
Dr Wendy Barclay, Reader in Virology, University of Reading, said:
“Both H5N1 (Asian bird flu) and H7N3 (the strain found in Norfolk) are still several steps (mutations) away from being the sort of viruses that could transmit from person to person and cause a pandemic.”
Dr Azra Ghani, Reader In Infectious Disease Modelling, London School Of Hygiene And Tropical Medicine, said:
“H7N3 avian influenza is common in birds. Because it is of low pathogenicity, there is unlikely to be rapid spread amongst poultry. H7 in humans causes mild symptoms, conjunctivitis being the most common symptom.
“H7N3 has only been observed to transmit to humans who are in very close contact with infected birds. However, for the highly pathogenic H7N7 which circulated amongst poultry in the Netherlands in 2003, 86 people were infected, 3 of whom were not in direct contact (family members of poultry workers). Further family members of exposed poultry workers had serological evidence of infection (that is, probably acquired a mild non-symptomatic illness). 1 veterinary officer, who did not receive antiviral drugs, died from this disease.
“Whilst there is no immediate cause for concern, particularly given that this is a low pathogenic virus and of a different subtype, I would recommend that all exposed poultry workers and their household members are closely monitored and offered anti-viral drugs (oseltamivir) at the first presentation of symptoms.”
Dr Jim Robertson, National Institute of Biological Standards and Control, said:
“H7 is one of the 16 strains of bird flu. It is also one of the two strains that can be in the highly pathogenic form, but the good news is that the cases reported are low pathogenicity. This confirms the need for urgent culling of chickens to stamp out the virus, not only to prevent spread but also to stop the possibility of it mutating into the high pathogenic form.
“High pathogenic is a form that rapidly kills the chickens, whereas the low pathogenic is a much milder illness for the poultry.”
Professor Ian Jones, Director of Research, Reading University, said:
“There have been a number of cases of H7 influenza infecting humans in the past. In many cases these were so mild as not to be noticed by those infected although cases of conjunctivitis have been noted. Only one human death has been ascribed to H7 influenza, in the Netherlands in 2003, so while this is another form of bird flu it is not H5N1 and unless something very unexpected has happened to the virus it does not pose the same level of threat.”