Scientist advises school project investigating disease cause

By Communications staff, Washington State University
 
 
 
After an unusual disease outbreak at a western Washington fair resulted in cattle deaths and losses exceeding $20,000, students at nearby Sumner High School conducted a study to find out why.
 
 

Hong Li
(Photo by
Peggy Greb,
USDA-ARS)
Their work, supervised in part by Hong Li, a microbiologist with WSU veterinary microbiology and pathology, is reported in the spring newsletter from WSU Veterinary Medicine Extension.
 

The fall 2008 outbreak of malignant catarrhal fever (MCF) was in cattle infected by the sheep virus ovine herpesvirus 2 (OvHV-2). The students sought to determine whether fair-related stress increased shedding of OvHV-2 in adolescent lambs.

 
 

Cattle movement studied
in spread of salmonella

A recent study by WSU researchers highlights the role of animal movement in the transmission of a multidrug-resistant (MDR) salmonella strain within herds. It is reported in the spring newsletter f
rom WSU Veterinary Medicine Extension.

WSU scientists who authored the study include Tom Besser, John Gay, Lawrence Fox, Margaret Davis, Rowland Cobbold, Russell McClanahan and Dale Hancock.

Over 15-21 months, 59 commercial dairy farms were sampled seven times to determine the role of animal movement, including off-farm rearing of heifers, in the interherd transmission of the salmonella.

Findings showed that off-farm heifer raising, including contract heifer raising where the animals mingle with cattle from other farms, was significantly associated with introduction of new MDR salmonella strains. The study also showed that introduction of the new strains was not associated with housing heifers and cows in the same close-up pens, a common hospital-maternity pen, or the number of purchased cattle.

The study was reported in the Journal of Dairy Science.

During 2009, blood and nasal secretion samples were taken from lambs at fairs across Washington. The OvHV-2 in these lambs was compared with previous data describing the frequency and intensity of shedding under normal (non-fair) conditions.
 

Fair lambs demonstrated higher shedding frequency than lambs at normal conditions – about one shedding episode per 9.8 days compared to one per 52.8 days. However, the intensity – or levels of viral DNA in nasal secretions – was no different between lambs at fairs and those in their home barns.

So the students determined that fair-related stress conditions increase shedding of OvHV-2 in adolescent lambs, thus increasing risk of virus transmission.
 
They suggested biosecurity protocols at livestock exhibitions could be improved by separating lambs and species susceptible to MCF, such as cattle.