Avian Influenza – Public Health Issue
Transmission of avian influenza viruses to people remains relatively uncommon and in most cases occurs as a result of handling infected poultry or other birds or their feces. Fecal material can contaminate dust, soil, water, feed, equipment and clothing and feathers. Transmission to people only occurs with certain subtypes of avian influenza.
As of February 2007, 270 laboratory-confirmed human cases have been reported in ten countries resulting in 164 deaths. Most infected humans regularly handle poultry and, currently, there is no evidence of sustained human-to-human transmission of H5N1. Indonesia is a current HPAI H5N1 hotspot with 63 laboratory-confirmed deaths (81 cases); however, based on population, the human fatality rate for avian influenza is about 1 in 3.5 million people in this country (in comparison, the fatality rate for motor vehicle accidents in Hawaii is about 1 in 10,000).
Symptoms of avian flu in people range from mild conjunctivitis to typical flu-like illness which can lead to acute respiratory illness that can be fatal. Infection with A/H5N1 has been characterized by sudden onset with cough and high fever.
There is currently no vaccine for the treatment of AI in people, though one is being developed. Most avian flu viruses are sensitive to antiviral drugs such as Oseltamivir (Tamiflu) or Zanamivir (Relenza). Antiviral agents may be used for either the treatment or prevention of avian flu in people.
Avian influenza has two significant implications for human health:
- The severity of illness that may follow infection with avian flu virus; and
- The potential for adaptation of an avian influenza virus into a strain that both causes severe disease in humans and spreads easily from person to person causing an influenza pandemic.
- Health experts are concerned that the spread of A/H5N1 increases the opportunity for people to become infected concurrently with human and avian flu viruses. If this happens, the person could act as a ‘mixing vessel’, enabling genetic re-assortment of the virus to occur and a novel influenza virus strain to emerge.
- Public health control measures during an outbreak of HPAI in poultry should be designed to protect people against infection and reduce the risk of genetic reassortment of the virus. Advice on the use of routine vaccination of poultry workers and veterinarians with seasonal human flu vaccine during a confirmed outbreak of avian flu as a protection against the possibility of re-assortment with human flu virus should be sought.
- Antiviral therapy, as appropriate, to protect against the development of avian flu should be given to those who may be exposed to infectious birds or secretions or excretions from infected birds. People at greatest risk include those involved in euthanasia, disposal, and cleaning/disinfecting activities.
Further more information regarding human health issues may be found at the following websites:
The Centers for Disease Control and Prevention (CDC): http://www.cdc.gov/
Official U.S. Government website: http://www.pandemicflu.gov/
Hawaii Department of Health: http://www.hawaii.gov/doh/