The H5N1 avian influenza virus can survive for more than a month in bird droppings in cold weather and for nearly a week even in hot summer temperatures, the World Health Organization said on Friday.
When people become infected with bird flu, they get a high fever and pneumonia very quickly, according to an updated factsheet from the WHO...
The new factsheet incorporates the most recent findings on the avian flu virus, which WHO says is causing by far the worst outbreak among both birds and people ever recorded.
It has been found from South Korea, across Southeast Asia, into Turkey, Ukraine and Romania. It has infected 149 people and killed 80, according to the WHO figures, which do not include the most recent deaths and infections in Turkey. Bird droppings may be a significant source of its spread to both people and birds, the WHO said.
"For example, the highly pathogenic H5N1 virus can survive in bird feces for at least 35 days at low temperature (4 degrees C or 39 degrees F)," the WHO site reads.
"At a much higher temperature (37 degrees C or 98.6 degrees F), H5N1 viruses have been shown to survive, in fecal samples, for six days."
Poultry, especially those kept in small backyard flocks, are the main source of the virus.
"These birds usually roam freely as they scavenge for food and often mingle with wild birds or share water sources with them. Such situations create abundant opportunities for human exposure to the virus, especially when birds enter households or are brought into households during adverse weather, or when they share areas where children play or sleep," WHO says.
H5N1 has different qualities from seasonal flu, the WHO said.
"The incubation period for H5N1 avian influenza may be longer than that for normal seasonal influenza, which is around 2 to 3 days. Current data for H5N1 infection indicate an incubation period ranging from 2 to 8 days and possibly as long as 17 days," it said.
"Initial symptoms include a high fever, usually with a temperature higher than 38 degrees C (100.4 degrees F), and influenza-like symptoms. Diarrhea, vomiting, abdominal pain, chest pain, and bleeding from the nose and gums have also been reported as early symptoms in some patients."
And with H5N1 infection, all patients have developed pneumonia, and usually very early on the the illness, the WHO said.
"On present evidence, difficulty in breathing develops around five days following the first symptoms. Respiratory distress, a hoarse voice, and a crackling sound when inhaling are commonly seen."
There is bloody sputum, it said.
"Another common feature is multiorgan dysfunction, notably involving the kidney and heart," WHO said.
The WHO recommends using Tamiflu, Roche AG's flu drug known generically as oseltamivir, as soon as possible to treat bird flu.
WHO stresses that H5N1 remains mostly a disease of birds, with tens of millions infected in two years.
"For unknown reasons, most cases have occurred in rural and periurban households where small flocks of poultry are kept. Again for unknown reasons, very few cases have been detected in presumed high-risk groups, such as commercial poultry workers, workers at live poultry markets, cullers, veterinarians, and health staff caring for patients without adequate protective equipment," it adds.
"Also lacking is an explanation for the puzzling concentration of cases in previously healthy children and young adults." 
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