CDC Publishes Report on Infection Risk of H5 Avian Influenza

On July 24, 2015, the Center for Disease Control (CDC) published a report on the risk of human infection posed by exposure to birds with Highly Pathogenic Avian Influenza (HPAI) H5 viruses.

Human infection with avian influenza, although rare, has occurred. The most prominent strains that have occurred in humans are the HPAI strain H5N1 and the low pathogenic avian influenza strain H7N9. H5N1 has been detected in humans in several countries, while H7N9 has occurred mostly within China. When infection occurs, the disease is considered to be severe for these strains. The strains the CDC studied in the report are new strains of the virus found in the United States.

The study focused on exposure during the time-frame of December 2014 to March 2015, where a total of 60 outbreaks of HPAI H5 viruses occurred across 13 states. During this time, a total of 164 people were exposed to infected birds. Of these 164 people 5 developed acute respiratory infections within 10 days of exposure, but HPAI H5 viruses were not detected in any individual. The CDC believes this suggests “the risk of virus transmission to humans appears to be low…” but individuals should remain vigilant when responding to an outbreak.

The severity of infection of these US strains of HPAI is currently unknown, but the CDC states that the strains should be considered to cause potentially severe or fatal illnesses until proven otherwise. The CDC urges individuals to avoid unprotected contact with infected birds, and those exposed to infected birds should be tested for infection in the event that respiratory symptoms develop.

Written by Tyler R. Etter- Research Assistant
August 5, 2015