05.09.2014

Puzelli et al (2014) Emerg Inf Dis

On August 14, 2013, infection caused by a highly pathogenic avian influenza A(H7N7) virus was initially detected on a layer farm in Ostellato, Ferrara Province, Italy, representing the start of an epizootic that affected another 5 poultry farms in Ferrara and Bologna Provinces (Emilia-Romagna Region) during the next 3 weeks. Nearly 1 million chickens on the 6 farms were culled. All workers (≈200) who participated in depopulating infected premises applied strict infection prevention procedures and were monitored for symptoms. Among the workers, infection with highly pathogenic A(H7N7) avian influenza virus was confirmed for 3 who had conjunctivitis but no respiratory symptoms. Genetic analyses revealed that the viruses from the humans were closely related to those from chickens on affected farms. The researchers provide further evidence of H7 subtype–specific ocular tropism. The molecular findings suggest direct transmission of the virus from chickens to humans; the lack of known host adaptation markers does not support human-to-human transmission. The presence of 2 mutations in neuraminidase from the specimen of patient 3, which contained the highest viral load, might suggest a correlation with the efficiency of infection and replication in the conjunctiva. Indeed, specific neuraminidase mutations have been observed in H7N7 viruses from the Netherlands and have been associated with enhanced replication.