Hendra knowledge: Horse owners could do better

Black Flying Fox (Pteropus alecto) at rest, in Brisbane, Queensland.
Black Flying Fox (Pteropus alecto) at rest, in Brisbane, Queensland. © James Niland

A worrying number of Australian horse owners who responded to an online survey indicated little or no knowledge of the deadly Hendra virus.

Researchers who carried out the survey, the findings of which were published on Friday in the open-access journal, PLoS ONE, described the finding as disconcerting.

The survey targeted horse owners in the states of Queensland and New South Wales, to assess their adoption of recommended risk management strategies and to identify any reasons that might discourage them from doing so.

There were 1431 respondents in the target states.

“Disconcertingly, a higher proportion of respondents indicated little or no knowledge of Hendra virus than indicated a high or very high knowledge,” the researchers said.

“This response intuitively suggests limited success of the current communication strategy based on state government and industry-provided information via internet, printed material and live forums.

“However, the response and this interpretation are at odds with the high proportion of horse owners who have seen their state’s Hendra virus guidelines/information pack for horse owners (nearly two-thirds), and who regarded the information as useful in minimising Hendra virus risk.

“A plausible interpretation of this anomaly is that horse owners are accessing the information, but are not actually being informed, perhaps because of the volume of material, the complexity of the epidemiology of Hendra virus infection, or the way the information is presented.

“Alternatively, it may suggest that horse-owner focus is narrow, and that they primarily seek details that are directly relevant to their specific situation.

“This latter interpretation is consistent with the generally high level of knowledge of the most common clinical signs associated with Hendra virus infection in horses.”

Hendra virus
Hendra virus

The researchers, Nina Kung, Amanda McLaughlin, Melanie Taylor, Barbara Moloney, Therese Wright, and Hume Field, said it was concerning that only one-third of respondents included veterinary advice in their top three information sources.

This suggested a missed opportunity for private veterinary practitioners to meet client needs, they said.

The ultimate challenge, they said, was to package and convey key information accordingly for the different horse-industry sectors.

Hendra virus, first described in 1994, is a bat-borne virus which is able to infect horses. The virus is able to be passed from infected horses to humans, with seven recorded cases. Four have proved fatal.

Infection in horses is believed to be via oral or nasal contact with the body fluids of infected fruit bats.

All human cases are attributed to direct contact with the body fluids of infected horses, meaning strategies for managing human exposure risk focus on avoiding direct and unprotected contact with sick horses.

Self-rated horse-owner knowledge of Hendra virus was generally limited, the researchers found, with only 13% rating their level of knowledge as high or very high. A further 53% rated their knowledge as moderate.

The level of knowledge varied significantly between states and industry sectors.

Nearly two-thirds of all respondents had seen a Hendra virus information pack for horse owners, with a significantly greater proportion of Queensland respondents having done so.

Similarly, a significantly greater proportion of Queensland respondents felt the information was useful to them in reducing Hendra virus infection.

“Ten percent of respondents gave additional written comments, with the most frequent comments being that the information was impractical and not in layman’s terms, the risk-mitigation strategies were expensive to implement, and that more focus should be on flying-fox control,” the researchers said. These respondents were predominantly from the recreational, equestrian, and agistment/breeding sectors.

Awareness of the main clinical signs of Hendra infection in horses was generally good, they said, and nearly half of all respondents had spoken with their veterinarian about how to limit the risk.

Just over a quarter of all respondents thought it was very likely or extremely likely that a Hendra virus case could occur in their area, with a significantly greater proportion of Queensland respondents thinking so.

A further 29% of all respondents believed the chance of a Hendra virus case occurring locally was moderately likely, while 38% believed such a scenario was a little likely or not at all likely.

Nearly two-thirds of respondents were very concerned or extremely concerned that their horse could become infected if there was a local Hendra virus case, with a significantly greater proportion of New South Wales respondents indicating so.

“Similarly, almost half of all respondents were very concerned or extremely concerned that they personally might be infected if there was a local equine case, again with a significantly greater proportion of New South Wales respondents indicating so.”

Thirty-six percent of respondents observed their horse sometimes or often ate leaves off trees or shrubs in the paddock. Three percent had seen flying-foxes come to the horse feed or water points sometimes, frequently or every night.

Just over a third of all respondents indicated they would consider Hendra virus if their horse seemed generally unwell.

The researchers said Hendra virus infection was a topical and contentious issue with horse owners, veterinarians and para-veterinary professions in Australia because of its cryptic bat origin, its typically fatal outcome, and its zoonotic potential.

They noted there had been 80 confirmed or possible equine cases and seven human cases recorded in the 18 years since the first detected case.

“While the likelihood of infection is low, the consequences of infection can be dire given the high case fatality rate.

“Media reporting generated by the latter tends to skew horse owner perception of risk, so it is not surprising that respondents from postcodes with a previous Hendra virus case have an elevated perception of likelihood of a case in their area.”

“Another challenging aspect of communicating Hendra virus risk is the frequent confusion by horse owners about the infectivity of a case horse.” People tended to equate the the virus’s ability to cause serious disease with high infectivity, they said. However, the virus was not highly infectious.

“Clearly, the subject of risk communication and perception requires additional and targeted effort.

“This situation is underlined by the alarming finding that only about one-third of respondents would consider Hendra virus if their horse was unwell, and paradoxically by almost half the respondents who were very concerned or extremely concerned that they personally might be infected if there was a local equine case.

“Several Hendra virus infection risk mitigation strategies for horses have been promoted by the relevant state government departments, including removing feed and water points from under trees, placing feed and water points under roofed structures, night stabling, and excluding horses from access to flowering and fruiting trees in the paddock.

“This survey found that 3% and 20% of respondents respectively had feed and water points near or under trees, and that half said it would be easy or very easy to move feed and water points away from trees.

“Some respondents commented that they placed water troughs under trees to reduce evaporation, especially when trees were the only shade in the paddock. While 13% and 15% of respondents respectively had placed feed bins and water points under a roofed structure, two thirds indicated it would be difficult, very difficult or impossible to move feed and water containers under solid cover.”

They found that effective risk mitigation actions can be readily implemented by a substantial proportion of respondents, with removal of feed bins and water points from near or underneath trees being the easiest.

“These actions have been proposed for several years, particularly in the Queensland Hendra virus Information for Horse Owners on-line brochure, yet it would seem that either a substantial number of horse owners remain unaware of them, or are aware of them but have not implemented them.

“These drivers require better understanding, and potentially more efficient or targeted communication.

“However, notwithstanding this unrealised potential for feasible risk reduction, many respondents commented that the recommended risk management strategies were impractical in their circumstances, were onerous, or were prohibitively expensive.”

The researchers concluded: “We found inconsistent awareness and/or adoption of available knowledge by horse owners, suggesting the need for review of current communication strategies.

“We also found enduring confusion in relation to Hendra virus risk perception, with both over-and under-estimation of true risk.

“Finally, we found considerable lag in the uptake of recommended risk minimisation strategies by horse owners, notwithstanding their apparent ready implementation.

“In contrast to this however, we identified frustration and potential alienation by horse owners who found the recommended strategies not feasible.”

Kung N, McLaughlin A, Taylor M, Moloney B, Wright T, et al. (2013) Hendra Virus and Horse Owners – Risk Perception and Management. PLoS ONE 8(11): e80897. doi:10.1371/journal.pone.0080897

The full study can be read here



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