Article

Outbreak of neurologic disease caused by equine herpesvirus-1 at a university equestrian center

University Equine Veterinary Services, Findlay, OH 45840, USA.
Journal of Veterinary Internal Medicine (Impact Factor: 2.22). 01/2007; 21(1):157-65. DOI: 10.1892/0891-6640(2007)21[157:OONDCB]2.0.CO;2
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ABSTRACT Equine herpesvirus type 1 (EHV-1) infection causes neurologic disease in horses. However, risk factors for the disease and long-term prognosis are poorly characterized.
There are identifiable risk factors for equine herpes-1 myeloencephalopathy.
The entire population of 135 horses housed within the equestrian facility.
A descriptive study investigated the clinical, serologic, virologic, and management aspects of an outbreak of EHV-1 myeloencephalopathy.
Out of 135 horses at the facility, 117 displayed signs of EHV-1 infection. Forty-six horses developed neurologic deficits characterized by symmetrical hind limb ataxia and weakness. Twelve horses that developed neurologic deficits became recumbent and did not survive. The development of severe neurologic deficits during the outbreak was associated with the presence of residual deficits at the 6-month examination. Within 1 year of the outbreak onset, all horses that survived had returned to an exercise level comparable to that experienced before the outbreak. Factors associated with the development of neurologic disease included age of > 5 years, location in the south or arena stall areas, and highest rectal temperature on day 3 or later of the febrile period.
Being > 5 years of age, having had a rectal temperature of > 103.5 degrees F, and highest rectal temperature occurring on or after the 3rd day of the febrile period were the factors most predictive of the development of neurologic disease and death. Data obtained during this outbreak substantiate previous findings relating to clinical aspects and diagnosis of EHV-1 myeloencephalopathy. The prophylactic and therapeutic use of acyclovir during this outbreak is described.

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    • "The body temperature was measured during sampling from clinically affected equines. Previous studies on naturally occurring outbreaks of EHM indicated that fever occurs days before the onset of neurological signs, but is often absent during the neurological disorders (Henninger et al., 2007). Gryspeerdt et al. (2011) also reported rapid occurrence of ataxia and paralysis immediately after the disappearance of fever. "
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    • "Nucleosidic antiviral drugs have been used to treat human herpesviral infections since the 1970s, and have been tested and applied for limited applications in veterinary species, including for HV infections (Rollinson et al., 1988; Wilkins et al., 2003; van der Meulen et al., 2006; Henninger et al., 2007). However, widespread clinical use of antiviral drugs is not common in veterinary medicine (Kahn et al., 2005). "
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    • "doi:10.1016/j.jevs.2011.12.006 Europe is of major concern to the equine veterinarians and equine industry, because the affected horses get paralyzed or other neurological symptoms are seen in them, resulting in deads [3] [7] [8]. Molecular analysis of open reading frame (ORF30) indicated that a single-nucleotide substitution of guanine (G) for adenine (A) at position 2254 in the viral DNA polymerase gene (encoded by ORF30) is found to be strongly associated with neurological disease in horses [4,5,9-13]. "
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