31 July 2006
In the August 2006 issue of Emerging Infectious Diseases Yingst, Saad, and Felt from the Naval Medical Research Unit (NAMRU-3) in Cairo, Egypt reported finding domestic cats with fatal H5N1 avian flu infection in February 2006 in the Erbil governate of Kurdish northern Iraq. The infection of the cats occurred near the time of the outbreak of H5N1 in northern Iraq (Sulymaniyeh and Erbil Governates).
The authors reported that the cats had the more recent “clade 2” H5N1 virus, unlike earlier infections of tigers and leopards in Thailand with the “clade 1” H5N1 viruses. Specifically, this clade 2 virus is very similar to the H5N1 clade 2 viruses found at Qinghai Lake in the western China in the spring of 2005 associated with the deaths of several thousand migratory birds. In addition, the authors reported the unusual finding of severe hemorrhagic pancreatitis in the two cats that underwent necropsy. Their brief report can be found online on the CDC website at www.cdc.gov/eid.
The outbreak study was performed after the government of Iraq requested a World Health Organization (WHO) investigation. The NAMRU-3 team also participated in the H5N1 avian flu investigation in Azerbaijan, using the innovative PCR diagnostic equipment that had been adapted by them for use in the field, thereby shortening the time required to make the diagnosis of H5N1 by avoiding the need to transport specimens to a distant reference laboratory.
In the Iraq study of domestic cats, the H5N1 virus was found in the large intestine, pancreas, and lungs of both cats, and in the feces of the one cat in which it was looked for. The route of infection of the cats was not proven, but might have occurred by consumption of H5N1-infected chickens or geese given that such species were also found to be infected with H5N1 at the same time as the cats. No evidence of cat-to-cat transmission was established, as likely occurred between tigers in a zoo in Thailand (Emerg Infect Dis (EID) 2005; 5:699-701).
Clade 2 H5N1 infections, antigenically distinct from the clade 1 H5N1 viruses that appeared in 2003-2004 in Vietnam and Thailand, are now found in multiple nations inside and outside Asia. These clade 2 viruses have recently lead to the announcement that WHO is providing clade 2 H5N1 viruses for candidate vaccine development, in addition to the earlier clade 1 H5N1 viruses. A color map of the early geographical distinction between clade 1 and clade 2 H5N1 viruses in Asia can be found in the paper published by the WHO Global Influenza Program Surveillance Network in October 2005 in this same journal (Emerging Infectious Diseases (EID) volume 11: pages 1515-1521.
Director, Center for Biologic Counterterrorism and Emerging Diseases,
EROne Institutes, Washington Hospital Center Dept. of Emergency Medicine
Adjunct Professor, Department of Microbiology and Immunology
Georgetown University School of Medicine, Washington, DC
Website: www.BePast.org e-mail:Daniel.r.Lucey@Medstar.net