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Epidemiological update: Highly pathogenic influenza A(H7N7) in poultry and transmission to three human poultry workers in Emilia-Romagna, Italy, September 2013

19 Sep 2013

Summary of the situation
On 14 August 2013 highly pathogenic avian influenza (HPAI) was detected in poultry in Ostellato, Ferrara province, Emilia-Romagna, Italy. Influenza subtype A(H7N7) was confirmed. Protection and surveillance zones have been established in accordance with European Council Directive 2005/94. Monitoring of avian influenza, epidemiological and virological investigations are being carried out by regional authorities. Despite the establishment of the protection and surveillance zones, several subsequent outbreaks have been reported in this region: on 21st August in Mordano, Bologna, in a farm with commercial layer hens, on 23rd August in a farm with commercial layer hens in Mordan, Bologna and on 27th August in Portomaggiore, Ferrara, in a commercial turkey farm. On 4th and 5th September there were two other A(H7N7) confirmed outbreaks, one in a farm in Mordano, Bologna and another in a backyard flock in Bondeno, Ferrara.
All affected holdings have been cleaned and disinfected. Up to one million poultry has been culled in order to contain this outbreak. The protection zones remain valid until 21 days after the last action in an affected farm.
Emilia-Romagna region and locations of the poultry outbreaks with avian influenza A(H7N7)
 
 
Map from Google Maps
 

Human infections due to avian influenza - zoonotic transmission

Since A(H7N7) has been known to spread from poultry to humans with outcomes varying from mild conjunctivitis to death, active surveillance has been established. All people living in the affected farms as well as exposed workers and their cohabiting contacts with direct contact to sick animals are under surveillance up to 10 days after the last exposure. Up to 70 regular poultry workers and family contacts as well as up to 300 workers involved in culling operations have already been monitored. The people under surveillance have been contacted on a daily basis and interviewed about symptoms and general health.

As of 10th September 2013, three humans have identified with conjunctivitis due to A(H7N7). The infected men were between the ages of 46-51 years and had been working in an affected farm or participated in the culling. After the eye swabs were found to be positive, the workers were isolated at home. The cases with conjunctivitis recovered after 5-6 days without complications. One case had chills and muscle aches in addition to conjunctivitis.

A serological study screening exposed workers, cases and the family members of human cases is being planned to determine the number of seroconversions in those exposed. These results will provide valuable information about the frequency of avian-to-human transmission of A(H7N7)and the potential risk factors for being infected with A(H7N7)in people who have close contact to infected poultry in outbreak situations.

Other reports from zoonotic transmission
A limited number of human cases associated with HPAI outbreaks in poultry have been reported since 1959 (the date of first recognition). In the past, there have been reports of single cases of people infected from their domestic poultry which mixed with wild birds.[1, 2] Since 2000 there have been increasing and larger outbreaks of HPAI in poultry reported in the EU. The reason for this is unclear. Very large outbreaks have occurred in densely populated commercial bird populations such as in Italy in 1999 (type A/H7N1), the Netherlands, Belgium and Germany in 2003 (type A/H7N7) and Canada in 2004 (H7N3)[3]. An outbreak of highly pathogenic A/H7N7 avian influenza in birds, which began in the Netherlands in February 2003, caused the death of one veterinarian (from an acute respiratory illness). It also caused some mild illness (mostly eye infections) in 88 poultry workers and members of their families [4-7].

Serologic studies performed in Northern Italy between December 2008 and June 2010 compared 188 Italian poultry workers exposed during low and high H5 and H7 avian influenza virus and 379 non-exposed controls. A total of 6 of 188 (3.2%) poultry workers were H7-seropositive and none of the controls was positive [8].

Assessment

ECDC concludes that the risk of the current A(H7N7) avian influenza found in Italy being transmitted to the general population is low. Persons at risk are mainly people in direct contact/handling diseased chickens or their carcasses e.g. farmers, veterinarians and those labourers involved in the culling. Those groups are being actively monitored by the local health authorities. Human-to-human infections need to be monitored very closely to prevent further spread. The ECDC recommendation of pre- or post-expositional prophylaxis using antiviral treatment for people at risk need to be considered as this has been shown to decrease the risk of transmission of A(H7N7)[9, 10].
 
Outbreaks of HPAI can severely affect farms where it is found. Control of HPAI requires excellent surveillance (for both birds and humans) and stringent control measures. European sanitation protocols need to be followed and active surveillance systems have to be installed where HPAI affected farms are reported.
 
ECDC staff involved in this epidemiological update:
Cornelia Adlhoch, Elizabeth Bancroft, Eeva Broberg, Andrew Amato-Gauci
 

1. Wong, S.S. and K.Y. Yuen, Avian influenza virus infections in humans. Chest, 2006. 129(1): p. 156-68.
2. Malik Peiris, J.S., Avian influenza viruses in humans. Rev Sci Tech, 2009. 28(1): p. 161-73.
3. ECDC. Annual epidemiological report Reporting on 2010 surveillance data and 2011 epidemic intelligence data. SURVEILLANCE REPORT 2012; Available from: http://www.ecdc.europa.eu/en/publications/publications/annual-epidemiological-report-2012.pdf.
4. Bos, M.E., et al., High probability of avian influenza virus (H7N7) transmission from poultry to humans active in disease control on infected farms. J Infect Dis, 2010. 201(9): p. 1390-6.
5. Koopmans, M., et al., Transmission of H7N7 avian influenza A virus to human beings during a large outbreak in commercial poultry farms in the Netherlands. Lancet, 2004. 363(9409): p. 587-93.
6. Fouchier, R.A., et al., Avian influenza A virus (H7N7) associated with human conjunctivitis and a fatal case of acute respiratory distress syndrome. Proc Natl Acad Sci U S A, 2004. 101(5): p. 1356-61.
7. ECDC. AVIAN INFLUENZA PORTFOLIO Collected risk assessments, technical guidance to public health authorities and advice to the general public Stockholm, June 2006. Technical Report 2006; Available from: http://ecdc.europa.eu/en/publications/publications/0606_ter_avian_influenza_portafolio.pdf.
8. Di Trani, L., et al., Serosurvey against H5 and H7 avian influenza viruses in Italian poultry workers. Avian Dis, 2012. 56(4 Suppl): p. 1068-71.
9. te Beest, D.E., et al., Effectiveness of personal protective equipment and oseltamivir prophylaxis during avian influenza A (H7N7) epidemic, the Netherlands, 2003. Emerg Infect Dis, 2010. 16(10): p. 1562-8.
10. ECDC. The Public Health Risk from Highly Pathogenic Avian Influenza Viruses Emerging in Europe with Specific Reference to type A/H5N1 Version June 1st 2006. ECDC Scientific Advice 2006; Available from: http://www.ecdc.europa.eu/en/healthtopics/documents/1991_060601_public_health_risk_hpai.pdf.
 
 

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