J. Gilkerson et al., EPIDEMIOLOGIC INVESTIGATION OF EQUID HERPESVIRUS-4 (EHV-4) EXCRETION ASSESSED BY NASAL SWABS TAKEN FROM THOROUGHBRED FOALS, Veterinary microbiology, 39(3-4), 1994, pp. 275-283
Equid herpesvirus-4 (EHV-4) was detected in nasal swabs taken from foa
ls using a PCR based test and this information used to study the epide
miology of EHV-4 disease on three Australian Thoroughbred stud farms i
n NSW in 1992. There was a very high level of agreement (kappa value o
f 0.84) between the PCR results and virus isolation using cell culture
techniques. There was a strong seasonal distribution of EHV-4 sheddin
g. Twenty-five of 26 positive samples were collected in January and Ma
rch with the remaining positive sample collected in February. Foals wi
th clinical signs of upper respiratory tract infection per se were no
more likely to be shedders of EHV-4 (odds ratio [OR] 1.4, 95% confiden
ce limits [CL] 0.5-3.8). However, EHV-4 was more likely to be isolated
from foals exhibiting copious serous or mucopurulent nasal discharge
than those with no clinical signs (OR 4.6, 94% CL 1.1-19.0 and OR 2.5,
95% CL 0.8-8.0, respectively). The month of the year was more importa
nt than weaning or age as a risk factor for excretion of EHV-4. Male f
oals and those with a history of respiratory disease that had required
veterinary treatment were more likely to shed EHV-4.