The H5N1 virus is a highly pathogenic strain of avian influenza virus, which primarily causes disease in birds, and in some cases pigs and cats.  In rare cases, the disease can also be spread to humans.The first documented cases of human infection with H5N1 virus occurred in Hong Kong in 1997, when the H5N1 strain caused severe respiratory disease in 18 humans, 6 of the sufferers died. 

The virus was subsequently brought under control and went undetected for several years, until it reemerged in Asia in 2003. Since then, the virus has been detected in many countries, causing disease and often death in millions of birds. More than 150 people have also died of the disease.Indonesia reported its first case of H5N1 infection in poultry in Pekalongan and Tangerang Regencies in August 2003, and the first human case In Indonesia occurred in July 2005 in Tangerang Regency. At present the H5N1 virus does not spread easily between birds and humans, or between humans and humans.

However, the continuous occurrence of H5N1 in birds and humans has raised the possibility that a new, fully-transmissible virus infecting humans could emerge, with the potential to start a worldwide pandemic.

The Government of Indonesia, the World Health Organization (WHO), the Food and Agriculture Organization (FAO), and other international and domestic partners are working together to control the H5N1 virus and prevent a human pandemic.

Clinical Symptoms in Humans
Early signs of bird flu are often similar to seasonal human influenza (cough, sore throat, high fever, headache, muscle ache, etc). The disease can progress into pneumonia where there might be shortness of breath, difficulty breathing and respiratory failure. If you think you have been exposed to bird flu and have influenza-like symptoms, seek medical advice as soon as possible. Source: WHO

 Clinical Symptoms in Birds
The clinical signs are very variable and are influenced by factorssuch as the virulence of the infecting virus, species affected, age,sex, concurrent diseases and environment.

In virulent (or highly pathogenic) AI of the type traditionallyassociated with fowl plague, the disease appears suddenly in a flockand many birds die either without premonitory signs or with minimalsigns of depression, inappetence (lack of Appetite), ruffled feathersand fever. Other birds show weakness and a staggering gait. Hens mayat first lay soft-shelled eggs, but soon stop laying. Sick birds oftensit or stand in a semi-comatose state with their heads touching theground. Combs and wattles are cyanotic (dark bluish) andoedematous,(accumulation of fluid) and may have petechial (pin size)haemorrhages at their tips. Profuse watery diarrhoea is frequentlypresent and birds are excessively thirsty. Respiration may belaboured. Haemorrhages may occur on unfeathered areas of skin. Themortality rate varies from 50 to 100%.

In broilers, the signs of disease are frequently less obvious withsevere depression, inappetence, and a marked increase in mortalitybeing the first abnormalities observed. Oedema of the face and neckand neurological signs such as torticollis (twisted neck) and ataxia(uncoordinated movement) may also be seen. The disease in turkeys issimilar to that seen in layers, but it lasts 2 or 3 days longer and isoccasionally accompanied by swollen sinuses. In domestic ducks andgeese the signs of depression, inappetence, and diarrhea are similarto those in layers, though frequently with swollen sinuses. Youngerbirds may exhibit neurological signs.

Do not touch sick or dead birds! Report sick or dead birds to theauthorities as soon as possible.

Source: FAO

For more information on the H5N1 virus and efforts on curbing the disease, please visit:
http://www.depkes.go.id
http://www.deptan.go.id
http://www.who.or.id
http://www.who.int
http://www.fao.org