Twenty years of Hendra virus: laboratory submission trends and risk factors for infection in horses.

Hendra virus (HeV) was first described in 1994 in an outbreak of acute and highly lethal disease in horses and humans in Australia. Equine cases continue to be diagnosed periodically, yet the predisposing factors for infection remain unclear. We undertook an analysis of equine submissions tested for HeV by the Queensland government veterinary reference laboratory over a 20-year period to identify and investigate any patterns. We found a marked increase in testing from July 2008, primarily reflecting a broadening of the HeV clinical case definition. Peaks in submissions for testing, and visitations to the Government HeV website, were associated with reported equine incidents. Significantly differing between-year HeV detection rates in north and south Queensland suggest a fundamental difference in risk exposure between the two regions. The statistical association between HeV detection and stockhorse type may suggest that husbandry is a more important risk determinant than breed per se. The detection of HeV in horses with neither neurological nor respiratory signs poses a risk management challenge for attending veterinarians and laboratory staff, reinforcing animal health authority recommendations that appropriate risk management strategies be employed for all sick horses, and by anyone handling sick horses or associated biological samples.

Detection and quantitation of gallid herpesvirus 1 in avian samples by 5' Taq nuclease assay utilizing Minor Groove Binder technology.

A 5' Taq nuclease assay utilizing Minor Groove Binder technology and targeting the thymidine kinase gene of gallid herpesvirus 1 (GaHV-1) was designed and optimized for use in diagnosing avian infectious laryngotracheitis. The assay was specific for GaHV-1 in that it did not react with other avian viral or bacterial pathogens. The detection limit was 1.0x10(-2) median tissue culture infectious dose per reaction or 90 target copies per reaction. Fifteen out of 41 diagnostic samples from sick birds reacted in the assay, five of which produced a typical alphaherpesvirus cytopathic effect (CPE) on chicken kidney (CK) cells. Sequencing, using amplicons generated by a polymerase chain reaction with primers flanking the 5' Taq nuclease amplicon, confirmed the presence of GaHV-1 in six samples (two producing alphaherpesvirus CPE on CK cells, three not producing alphaherpesvirus CPE, and one that was not inoculated onto CK cells). Tracheal swabs taken from 18 healthy broilers did not react in the assay. The ability of the assay to determine viral load in samples was demonstrated. Overall the assay is suitable for the rapid diagnosis of infectious laryngotracheitis.

Indigofera spicata (creeping indigo) poisoning of three ponies.

Three ponies continuously grazed a pasture containing an estimated 24% Indigofera spicata (wet weight basis) for 4-6 weeks in April and May 2004. They developed ataxia, paresis, depression, muscle fasciculations, dysphagia, ptyalism and halitosis. Two also developed corneal opacity. One pony recovered with supportive treatment, but the other two were euthanased and necropsied. Neuropathology was not present in either case, but both livers had periacinar and periportal lymphocytic infiltrations and hydropic degeneration of mid-zonal hepatocytes, with mild to moderate periacinar necrosis also evident in one. The I. spicata contained 2.66 mg 3-nitropropionic acid (3-NPA)/g dry matter and 1.5 mg indospicine/g dry matter. Indospicine, but not 3-NPA, was detected in serum from both of the euthanased ponies and indospicine was detected in heart, liver and muscle from the one pony in which this assay was performed. The clinical syndrome closely resembled 'Birdsville horse disease' caused by I. linnaei and was similar to that reported in horses poisoned by the closely related species I. hendecaphylla and to 3-NPA poisoning of other animals, including humans. 3-NPA is thought to cause this neurological syndrome. To our knowledge, this is the first authenticated report of I. spicata poisoning in grazing animals. We also report here the first published evidence that 3-NPA and indospicine exist in naturalised I. spicata in Australia and of the formation of indospicine residues in tissues of animals grazing paddocks infested with I. spicata.