IN-DEPTH: INFECTIOUS DISEASE OUTBREAK MANAGEMENT


SAHO may be aware of other similar incidents and thus potential exposure risks may be identified through this initial discussion between the equine practitioner and the SAHO. A list of contact infor- mation for the State Veterinarian is available at http://www.usaha.org/Portals/6/StateAnimalHealth Officials.pdf or at http://equinediseasecc.org/ veterinarians.aspx. Detection of a regulated reportable equine disease


results in the SAHO assessment of disease risks and determination of appropriate disease control mea- sures to implement, such as quarantine, movement controls, and biosecurity measures. The regulatory response depends upon the disease agent detected and the epidemiologic investigation findings. De- pending on the disease, a regulatory action, such as quarantine, may be instituted for a suspect case, but oftentimes regulatory action is not taken until a confirmatory diagnosis is made. However, it is im- portant to note that reporting of a disease situation does not necessarily dictate a regulatory response, given that the SAHO investigation of the situation may deem control measures unnecessary and thus the report of a monitored condition or disease may require no SAHO action. For highly infectious and highly contagious diseases, expansive quarantines and movement restrictions may be essential to quickly and effectively control disease. Humane euthanasia may be the only option for protecting the equine population if and when a disease cannot be controlled. For the more common equine regula- tory diseases, such as EIA, EP, equine viral arteri- tis, and CEM, there are federal guidance documents or recommendations for handling suspect and posi- tive cases. Unfortunately, there are no federal equine domestic control program regulations and very limited federal disease control standards, which can lead to inconsistent handling of equine regulated diseases across the United States.


4. Examples of Responses to Reportable Disease Incidents in California


EHM


In February 2012, there were two2 confirmed EHM incidents in California. One incident involved a 350-horse boarding facility and one incident in- volved a 500 horse polo facility. Upon notifica- tion, the SAHO visited each site and in consultation with the private practitioner performed a risk as- sessment to determine appropriate quarantine pa- rameters and biosecurity measures. Biosecurity risks identified by the SAHO at the boarding facility included lack of isolation facilities, numerous daily visitors (14 trainers, eight onsite farriers, an onsite veterinary practice, and an onsite training facility), sharing of equipment, communal water and carrot bins, frequent commingling of horses, lack of horse inventory monitoring (i.e., no records of horse movements), frequent movement of horses on and off the premises, and nonexistent


biosecurity measures. Based on the numerous movements at the facility and the commingling of horses, the entire premises was quarantined and recommended biosecurity measures were imple- mented. Due to slow implementation of biosecurity and failure to immediately implement adequate iso- lation, febrile EHV-1 cases and horses with nasal discharge cases continued to be diagnosed and the quarantine was prolonged to 34 days at this facility. At the polo facility, the private practitioner was presented with a horse displaying acute onset of neurologic signs, specifically severe hind limb ataxia, urinary bladder atony and eventual recum- bency with inability to rise. The neurologic horse was immediately removed from the population and isolated and subsequently euthanized. Upon labo- ratory confirmation of EHM, the SAHO was con- tacted. Biosecurity risks identified at the polo facility included riders’ sharing of horses and shar- ing of equipment between horses. Minimal but some biosecurity measures were in place on the polo grounds. Based on the extensive commingling of horses and sharing of equipment between horses, the entire premises was quarantined and a re- stricted training and exercise plan was implemented to eliminate commingling of horses on the operation. The polo facility was very prompt in isolating and removing the sick horse within 12 hours of initial detection of disease as well as implementing neces- sary enhanced biosecurity measures. They were also prompt in the cleaning and disinfecting of the index horse’s stall area. No additional cases were detected on the premises and quarantine was effec- tively released in 21 days from the time it was ini- tiated. Subsequently, the facility implemented an EHV-1 control plan. This same facility experienced anEHMcase in 2016; theEHMcase was euthanized within 3 hours of clinical onset of neurological signs. Based on lessons learned from the 2012 incident, the operation had implemented routine biosecurity and disease control measures to minimize disease risk on the premises. The 2016 risk assessment dem- onstrated a marked reduction in risk of potential disease spread, thus the resulting quarantine was restricted to one stabling area containing 70 exposed horses allowing for business continuity on the other parts of the premises. The prompt detection and the routine implementation of biosecurity enabled the facility to quickly eliminate the source of infec- tion and prevent disease spread. The quarantine was released 14 days after the removal of the clinical case given that no additional clinical cases were detected and the likelihood of exposure of horses on the operation to EHV-1 based on routine biosecurity that was in place was minimal. In general, SAHOs take action to prevent spread


of EHV-1 off of the affected operation but SAHOs may have a limited role in assisting the operation in reducing spread of the virus at the premises level. Thus, the private practitioner’s role would be to assist their client with implementation of appropri-


AAEP PROCEEDINGS  Vol. 62  2016 337


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