It begins with just a telephone call. Unusual deaths in a flock of backyard chickens or ducks may prompt a call to the state veterinarian’s office, launching a statewide system of “bird flu” testing centered at the Washington Animal Disease Diagnostic Laboratory (WADDL), in the WSU College of Veterinary Medicine.
WSU is a founding member of the National Animal Health Laboratory Network (NAHLN) — a network of 49 regional laboratories responsible for the surveillance of and response to exotic disease outbreaks affecting livestock in the U.S. As such, it was among the first labs in the nation to begin intense testing for the avian influenza virus last summer.
High risk area
Millions of birds migrate from Asia and Russia along the Pacific Flyway — a route stretching along the west coast from Alaska to Mexico. Consequently, the Pacific Northwest ranks as a high-risk area for entry of the deadly, highly pathogenic H5N1 strain of avian influenza that originated in Hong Kong in 1996. The virus is responsible for the deaths of at least 154 people and the destruction of millions of domestic fowl in Asia, Africa and the Middle East. There is fear it could combine with a human influenza virus, potentially becoming a pandemic.
“We have tested more than 7,000 birds since last August,” said Terry McElwain, executive director of the WADDL. “And we have had lots of positive results, but they are all of the low pathogenic type of virus — the type that is endemic to wild bird populations and seldom causes disease.”
Hoping to keep it that way, a statewide team of reserve corps veterinarians, fish and game officials and state field veterinarians stands armed with swab kits, ready to roll at a moment’s notice. Should an “incident” — or die-off — occur, the closest officials are summoned to the site. They carefully take swab samples from the birds and pack them into coolers for transport to either the WADDL Avian Health and Food Safety Laboratory in Puyallup or the main laboratory in Pullman.
Biosafety hot zone
Dan Bradway, associate in molecular diagnostics and laboratory manager in the WADDL, receives the samples in his Biosafety Level 3 (BSL-3) laboratory, where the virus can be safely inactivated before it is analyzed in the less restricted BSL-2 lab.
Each biosafety level has its own set of safety regulations, Bradway said. In a BSL-3 laboratory, lab coats, gloves, safety glasses — even pencils — must be autoclaved and discarded. There is also a shower for technicians to pass through before re-entering the BSL-2 laboratory.
In both of these labs, airflow is unidirectional to help prevent microorganisms from escaping — air first enters the BSL-2 lab, then the BSL-3 lab and finally passes through a HEPA filter before leaving the building. In addition, all of the hoods that technicians work under have airflow protectors — a curtain of air — that stops microbes from getting in or out.
Once the virus has been inactivated and the samples meticulously documented in the computer system, Bradway and his crew run an RNA screening test, called real-time PCR, to look for the signature matrix gene that shows up in all types of influenza A viruses, including avian influenza.
In most cases, the results are benign, but in the event of a positive identification, Bradway follows up with a second test to determine if it may be a strain of a potentially dangerous H5 or H7 virus. A positive H5 or H7 is immediately shipped to the National Veterinary Services Laboratory in Ames, Iowa, for verification.
Incident command system
According to Paul Kohrs, assistant state veterinarian, if a true positive for a highly pathogenic strain of the virus is ever confirmed, a national alert would go out and federal and state veterinarians would take charge.
The affected premises — sale yard, fairground or backyard coop — would be quarantined and a federal incident command system would be activated. A “hot zone” would be established and every bird within five miles of the discovery would be swabbed and sampled. A secondary surveillance zone would be set up outside that area with slightly less intense testing.
For Bradway and the others at WADDL, a high path positive would mean an overwhelming demand for PCR tests. But they are prepared, with new high-throughput machines that allow them to test about 1,000 samples per day.
“Our lab would be running 24/7,” said Bradway. “We are ready in case it happens but, of course, we hope it never does.”
