Avian flu first 'jumped' the "species barrier" from birds to humans and caused an outbreak in Hong Kong in 1997. Humans may be infected via close contact with infected birds and by working in an environment that is heavily contaminated with HPAI viruses. You can catch the virus if an infected bird coughs or sneezes directly in your face or if you breathe in particles from the droppings (wind-borne dry dropping particles are a source). Infection has not been transmitted via handling or consumption of poultry products (meat and eggs)^[15]. Recent developments, however, point at instances of possible transmission of H5N1 viruses through consumption of uncooked duck blood. Therefore, uncooked poultry or poultry products, including blood, should not be consumed^.

Influenza viruses are RNA viruses, meaning they lack mechanisms for proofreading and repairing genetic errors. This makes them especially prone to mutation requiring us to reformulate vaccines every year.

Signs and symptoms:  Since H5N1 is an influenza virus, symptoms similar to those of the common flu, such as fever, malaise, cough, sore throat, and sore muscles, can develop in infected humans. However, in some cases, pneumonia and severe problems with the respiratory system can develop. Patients with H5N1 avian influenza have rarely had conjunctivitis, unlike human cases of the H7 virus. Persistent high fever is an useful symptom.
Diagnosis:  X-ray of the chest is useful in detecting early viral pneumonia.
Treatment:  Treatment for infection by the H5N1 strain is essentially similar to that employed for infections due to the other influenza viruses. Four Antivirals work against influenza. Amantadine and Rimantadine (which target M2, a proton channel found in the viral membrane) have minimal efficacy against H5N1. Both Tamiflu (marketed by Roche), known generically as oseltamivir, and Relenza, known generically as zanamivir (marketed by GlaxoSmithKline), work better. Tamiflu and Relenza, in a class known as neuraminidase inhibitors (which act on a protein conserved in all influenza A viruses), do not cure influenza infection but can reduce the severity of illness, by attacking the influenza virus and stopping it from spreading, if given within 48 hours after symptoms begin. They may also help prevent infection if given early
The expensive and not readily available Tamiflu (a full course of Tamiflu -10 pills over five days, costs USD 80 - 90) has become the brand of choice for governments and organizations in their preparations for a possible H5N1 pandemic. Amantadine and rimantadine are inexpensive and widely available. The current strain of H5N1 found in Northern China, Mongolia, Kazakhstan and Russia is not Amantadine resistant