New Bird Flu Study Reveals: Avian Bacterium More Dangerous Than Initially Believed

BORDETELLA HINZII, AVIANS - USA
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A ProMED-mail post

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International Society for Infectious Diseases


Date: 18 Jun 2009
Source: United States Department of Agriculture [edited]



Avian Bacterium More Dangerous Than Initially Believed
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_Bordetella hinzii_ just may be the Eddie Haskell of avian bacteria.
Like the notoriously sneaky character from the iconic 1950s
television show "Leave It to Beaver," _B. hinzii_ has been causing
trouble and dodging the blame. Until recently, _B. hinzii_ was
believed to be nonpathogenic in poultry. But Agricultural Research
Service (ARS) scientists have shown that the bacterium caused severe
disease in turkeys that was attributed to another Bordetella species.

_B. avium_ is a pathogenic bacterium that causes upper respiratory
disease in poultry and wild birds. It is very similar to _B. hinzii_,
and the 2 species are difficult to distinguish without using highly
specific, DNA-based tests.

Scientists at the ARS National Animal Disease Center (NADC) in Ames,
Iowa, used these tests to examine several Bordetella isolates,
including some that had caused 100 percent morbidity in turkey
poults. Although the isolates had been labeled as _B. avium_, the
scientists found that they were actually _B. hinzii_, flouting
conventional wisdom that the bacterium could not cause disease in
poultry.

_B. hinzii_ has been found in poultry with respiratory disease, but
was believed to be nonpathogenic because previous attempts to cause
disease in chickens and turkeys with the bacterium have failed.

To test the bacterium's pathogenicity, NADC microbiologist Karen
Register and veterinary medical officer Robert Kunkle selected 6
genetically distinct strains of _B. hinzii_ and attempted to infect
turkeys with them. Of those strains, 4 were able to grow and persist
in the trachea and also caused clinical disease. The strains varied
in severity, although none demonstrated 100 percent morbidity.

This study showed for the 1st time that some strains of _B. hinzii_
can cause disease in turkeys. The results of the study were published
in the March 2009 issue of Avian Diseases. In a related study with
chickens, no birds developed clinical disease, suggesting that the
pathogenicity of _B. hinzii_ does not extend to chickens.

Now, NADC scientists are examining how the disease-causing strains of
the bacterium differ. They are also working to identify virulence
factors that influence disease development in turkey poults.

ARS is the U.S. Department of Agriculture's principal intramural
scientific research agency.

[Byline: Laura McGinnis]

--
Communicated by:
ProMED-mail Rapporteur Susan Baekeland

[The researchers at ARS are very energetic and dedicated scientists.
While their work is excellent, it is likely that other avian
researchers across the globe will be looking to repeat the study. -
Mod.TG]

....................tg/ejp/lm

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