bird flu 'fatal to humans', page-4

How serious is avian influenza virus in poultry?

Highly pathogenic influenza virus results in high mortality in poultry flocks and the detection of highly pathogenic influenza virus causes an emergency response that usually includes killing and disposal of infected chickens and tight quarantines until it is established that the disease agent has been eliminated.

Mildly pathogenic influenza virus results in a milder disease although there may be severe disease under some conditions such as the presence of secondary bacterial infection.

Avian influenza is reportable to the Board of Animal Health in Minnesota.

Minnesota has a cooperative avian influenza control plan in place that includes education, monitoring, reporting, and a responsible response.

Flocks are routinely monitored for evidence of influenza infection. Serological tests are conducted at the University of Minnesota Poultry Testing Laboratory in Willmar.

How is avian influenza spread in poultry flocks?

Virus is excreted from the eyes, nose and mouth and in the droppings of infected birds.

Within a flock the virus may be spread from bird to bird by aerosol droplets or shared drinking water.

Transmission from flock to flock is usually by people (contaminated footwear and clothing) and equipment involved in production, live-haul or live bird marketing.

What is the public health significance of avian influenza?

Prior to 1997 there were only three known instances of avian influenza viruses being implicated in human infection. In 1959, 1979 and 1996 evidence of influenza virus was detected in humans and in each case an H7N7 was involved.

In 1997 in Hong Kong highly pathogenic H5N1 avian influenza was detected in 18 humans, 6 of whom died.

In 1999 mildly pathogenic H9N2 influenza viruses were isolated from 7 people in Hong Kong and mainland China. None died.

More recently workers in Netherlands involved in killing chickens infected with highly pathogenic influenza became infected with H7N7 and one died.

Now highly pathogenic H5N1 is circulating in poultry in several countries in the Far East and humans are being infected after coming in contact with infected poultry.

In the United States, there was one person in Virginia with an antibody titer to H7 after the 2002 H7N2 outbreak in Virginia poultry. In 2003 someone in New York became ill and the illness was confirmed by CDC to be due to H7N2 in April of 2004.

In 2004 a high path H7N3 caused mild infection in humans in British Columbia.