Rapid diagnosis of equine influenza by the Directigen FLU-A enzyme immunoassay.

The study evaluates the efficiency of the Directigen FLU-A enzyme immunoassay in diagnosing equine influenza by detecting equine-2 influenza viruses present in the nasopharyngeal fluids of horses and ponies. It concludes that the test is rapid, simple, and could provide a convenient method for the rapid diagnosis and screening of horses for equine influenza infection.

Methodology

• The Directigen FLU-A enzyme immunoassay was tested on 125 swabs taken from horses and ponies. These swabs were collected from experimental infections and from different sources of natural infection in the USA and Hong Kong.
• The assay results were compared to the results of a standard virus culture in embryonated chicken eggs or Madin-Darby canine kidney cells. This was done to examine the degree of correlation and reliability of the immunoassay.
• The serology of the horses sampled was also considered in this comparison to provide further understanding of the detection capabilities of the immunoassay.

Findings

• The enzyme immunoassay showed high efficiency in identifying equine-2 influenza viruses with 83% sensitivity, 78% specificity, 70% positive predictive value, and 88% negative predictive value.
• When compared with haemagglutination, a technique used to measure the level of viruses in a sample, the test proved more sensitive in detecting low levels of virus in embryonated egg cultures.
• The test also demonstrated the ability to detect equine-1 influenza virus in culture, further indicating its detection capabilities.

Implications

• The study suggests the Directigen FLU-A enzyme immunoassay is a speedy, simple, and potentially convenient method for the rapid diagnosis and screening of horses for equine influenza infection.
• This can be particularly important in the early detection and management of the disease, allowing for appropriate response actions to be taken.