Avian influenza continues circulating in Egypt

Researchers have determined that the continued circulation of avian influenza in Egyptian poultry is perpetuating human exposure to the illness and the resultant infections.

The study was reported in the U.S. Centers for Disease Control and Prevention’s journal Emerging Infectious Diseases and was written by scientists from the St. Jude Children’s Research Hospital in Memphis and the National Research Center in Giza, Egypt.

According to the study’s authors, the endemic nature of the virus has led to the development of substantial genetic diversity. To determine the full extent of the incidence and development of the H5N1 virus in Egypt, the authors conducted surveillance for one year.

Approximately 200-700 samples were collected every month from poultry in six administrative regions, as well as from a group of wild egrets found in greater urban Cairo.

The authors determined that H5N1 has most likely been established as the dominant influenza strain present in Egyptian poultry due to the lack of other subtypes found during the experiment. The lack of co-circulation of multiple virus subtypes reduces the chances that viral evolution will occur in Egypt through reassortment.

Chickens were responsible for the overwhelming number of positive samples taken during the experiment. Commercial chicken farms appear to be a major reservoir for the illness. The overall positivity rate of avian influenza in commercial farms exceeded seven percent.

Chicken farms frequently use commercially available influenza vaccines. The high positivity rates raise questions as to the effectiveness of such vaccines.

The study’s findings suggest that the H5N1 threat to humans in Egypt is much higher than previously reported, not just with rural poultry growers, but with people living in more urban areas as well. Specimens from live-bird markets and slaughterhouses in Cairo showed a positivity rate approaching six percent.

The scientists recommend closer surveillance of avian influenza in domestic poultry and an expansion into surveillance of wild and migratory birds.