Sunday, May 21, 2006
H5N1 strain of bird flu could be spread through water and sewage (WHO)
In a report entitled Review of latest available evidence on risks to human health through potential transmission of avian influenza (H5N1) through water and sewage, Who (The World Health Organization), suggests that the h5n1 strain of the bird flu virus could spread through water and sewage.
Routes of entry into water
Wild waterfowl are considered the natural reservoir of all influenza A viruses. Most infected birds exhibit no symptoms, even when they are excreting large quantities of infectious virus. These asymptomatic birds act as “silent” reservoirs of the virus, perpetuating its transmission to other birds.
Infected waterfowl carry avian influenza viruses in their gastrointestinal tract, where the viruses replicate. Birds infected with avian influenza virus shed large quantities of virus in their faeces as well as in their saliva and nasal secretions. Shedding occurs in the first two weeks of infection .
The period of avian influenza infectivity in faeces and secretions depends on pH and temperature conditions, but generally four weeks after
infection, avian influenza virus can no longer be detected . Ducks infected with the H5N1 virus have been found to shed the virus at high titres from the trachea as well as from the cloacae, with peak levels of virus shedding after three days.