Background
Avian influenza viruses are members of the Influenzavirus genus and the Orthomyxoviridae virus family. Avian influenza is also sometimes referred to as Fowl Pest or Fowl Plague. In late 2003 and into 2004, outbreaks of Avian Influenza A (H5N1) occurred in 8 countries in Asia. More than 100 million birds succumbed to the disease or were destroyed to prevent further spread of the disease.

During the period between December 30, 2003 and March 17, 2004, human cases of the disease (12 in Thailand and 23 in Vietnam) were reported. These cases resulted in 23 deaths. By the end of February 2004, no further cases of human illness were reported and no conclusive evidence of sustained human to human transmission were uncovered.

Recent Developments
In June 2004, new outbreaks of Avian Influenza H5N1 were reported in several countries in Asia (www.cdc.gov/flu/avian/outbreaks/asia.htm). These new outbreaks in poultry were followed by a few new human cases of H5N1 in Vietnam and Thailand. A case of human H5N1 infection was reported in Cambodia on February 2, 2005. A suspected case of human to human transmission was reported from Thailand in September 2004. There have now been 55 human cases of H5N1 resulting in 42 deaths since this strain emerged in late 2003.

Susceptible Species
All birds are believed to be susceptible to this infection; however, some species are more susceptible. Migratory water fowl appear to be the natural reservoir for avian influenza. The disease can range from a mild disease to a rapidly fatal disease. Avian influenza viruses can mutate from mild to highly pathogenic viruses with mortality approaching 90%.

Disease Transmission
Control of avian influenza outbreaks involves quarantining of infected farms and destruction of infected or potentially exposed flocks. The disease spreads through direct contact between birds and also from farm to farm by physical means such as contaminated equipment, vehicles, cages, clothing and other articles moving between farms. The virus can also be carried from farm to farm by rodents, flies or other species moving between farms. Droppings from wild birds can also move the virus considerable distances within a short period of time. For the highly pathogenic form, a single gram of contaminated manure can contain enough virus to infect up to one million birds.

The virus can survive for long periods of time in the environment. Avian influenza has shown to persist in feces for more than a month at 4° C. At room temperature, the virus can remain infective for 7-10 days. The virus is inactivated at a temperature of 56° C for 3 hours and 60° C for 30 minutes.

Symptoms in Birds
The period of incubation in birds is usually 3-5 days. A high fever (110-112° F) develops rapidly, and the birds become lethargic with a loss of appetite. The comb and wattle of chickens display whitish necrotic areas of skin, a mucoid nasal discharge develops and edema of the head and neck is often observed. Death can occur within a few hours after the symptoms appear.

Human Cases of Avian Influenza
While avian influenza viruses do not normally infect species other than birds and swine, the first documented infection in humans occurred in Hong Kong in 1997 with 18 humans affected and six deaths. Human symptoms include, fever, sore throat and cough. In fatal cases, severe respiratory distress and viral pneumonia were exhibited.

We are now seeing a reoccurrence of the disease and a few human cases in Asia. These new outbreaks of the H5N1 strain have caused concern over the spread in poultry throughout Asia and appear to be able to jump the species barrier causing a severe disease in humans with a potential for high mortality rates.

Disinfectants
Influenza virus belongs to the family Orthomyxoviridae which are lipid-enveloped RNA viruses. These viruses are not as resistant to disinfection as non-enveloped viruses such as Norovirus, Poliovirus and Hepatitis A virus. Products which carry label claims again influenza viruses or have documented efficacy against this genus of virus should provide some measure of activity against the Avian influenza virus type H5N1.

Ecolab Virucidal Agents Disclaimer: In the United States, claims against a specific infectious agent must appear on the product label. Currently, no US products carry a claim against Avian Influenza type H5NI.

Product Recommendations
In February 2003 an outbreak of highly pathogenic avian influenza occurred in the Netherlands. During this outbreak Ecolab responded with cleaning and disinfection recommendations to help prevent the spread of this disease. The products associated with these recommendations may be specific to Europe, however alternative products available in other parts of the world are provided for reference. For specific product recommendations consult your local Ecolab representative.

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