Post Reply - A new pandemic

Twenty-two years ago this month the world's attentions were focused on a different avian flu virus - HPAI H7N7 - which was spreading rapidly through hundreds of poultry farms in the Netherlands, infecting scores of farmers, and which killed a local veterinarian. 

While the subtype (H7), and the livestock (poultry), were different, this outbreak has some similarities to the cattle/poultry HPAI H5N1 outbreak we've been following for more than a year in the United States. 

In both cases, hundreds of farms were affected, and roughly the same number of people (U.S. 77, Netherlands 83) were confirmed as infected, with conjunctivitis being the major symptom reported. A handful of more serious infections (and 1 death) were reported in each country.

Of course, there are differences.  In the Netherlands, through rapid culling, the outbreak was quashed after a little more than 2 months, while the outbreak in the United States continues after more than a year.  

And in the Netherlands, a concerted effort was made to test as many people as possible for antibodies to the H7N7 virus, in order to better understand its spread.  An analysis (by the RIVM), found the spread of the virus to be much greater than originally reported. 

It is estimated that at least one thousand persons were infected with avian flu during the outbreak in the Netherlands in 2003. One-third of the poultry farmers whose holdings were cleared reported stress reactions, fatigue, and depression.

The extensive spread of the virus to humans underscores the importance of measures to prevent poultry-to-human transmission among people handling infected poultry. The possible uncertainty, stress, and anxiety associated with avian flu control demand specific health care attention. A total of 453 people reported symptoms, predominantly conjunctivitis.

Antibodies were found in 59% of family members of infected poultry workers. Of the 500 tested persons who had handled infected poultry, about 50% showed an antibody response.

An outbreak of highly pathogenic avian influenza A virus subtype H7N7 began in poultry farms in the Netherlands in 2003. Virus infection was detected by RT-PCR in 86 poultry workers and three household contacts of PCR-positive poultry workers, mainly associated with conjunctivitis.

(SNIP)

In conclusion, our study suggests that human-to-human transmission of HPAI A/H7N7 can occur within household contacts in the absence of contact with infected poultry.

Even if we discount the possibility of human-to-human transmission, the scope of the 2003 outbreak was at least 10 times greater than initially reported. Which, based on previous estimates of outbreaks of novel flu, is likely a low-ball number. 

All of which brings us to a preprint (awaiting peer review) of a rapid review of the epidemiological parameters (R0, pathogenicity, serial interval, etc.) of H5N1 based on current data and previously published studies.