Alphaherpesvirus Outbreak Associated with Mortality in a Group of Grevy’s Zebra (Equus grevyi) Housed in a Mixed-Species Exhibit: Diagnosis, Management and Surveillance
Abstract
A herd of seven captive-born Grevy’s zebras (Equus grevyi) experienced a sudden outbreak of nasal discharge and sneezing. Clinical signs were severe and acute in three animals and included lethargy and anorexia. These animals were kept in separate stalls. A 16-mo-old zebra died within 48 h of the onset of clinical signs. Three additional animals then developed mild nasal discharge but no lethargy and one remained clinically asymptomatic.
Treatment of the remaining severely affected zebras (adult and 2-mo-old females) included valacyclovir (40 mg/kg p.o., t.i.d.), meloxicam (0.6 mg/kg p.o./i.m.) and cefquinome (2.5 mg/kg i.m. every 48 h). The adult female improved rapidly and clinical signs resolved within 48 h of treatment; however, valacyclovir compliance was poor in the young female and rapid deterioration and death occurred within 48 h. The mildly affected animals were not treated and recovered spontaneously.
Common findings at necropsy included severe fibrinonecrotic interstitial pneumonia that in one case was associated with vascular thrombosis. Herpesvirus was detected on both individuals (lung, nasal swab) by nested PCR. Sequencing of the amplicons revealed a novel sequence with 99.5% similarity with previously published equine herpesvirus-1 (EHV-1) and equine herpesvirus-9 (EHV-9) sequences.1-5
The zebras share housing facilities with other species, including white rhinoceros, giraffe, and several antelope species. None of these individuals showed clinical signs; however, nasal swabs and blood samples for PCR were collected. All were negative for herpesvirus except for the springboks, which were positive for springbok herpesvirus 1.
This report illustrates the risk of herpesvirus outbreak in zebras. The source of the infection remains unclear and investigation is ongoing.
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