TABLE 1.

Summarization of case criteria for vaccinated and control horses after intrathecal WNV challenge

Vaccine group	No. of horses with criteriona
	Clinical signs	Fevere	Deathf	Virus isolation	Histopathic lesions
WN-FV	0/6	0/6	0/6	0/6	1/6h
CP-WN	1/5b	1/5	0/5	0/5	1/5h
K-WN	4/6c	1/6	0/6	0/6	3/6h
Controls	6/6d	3/6	6/6	6/6	6/6g

^aResults are shown as number of horses with criterion/total number of horses.

^bMild signs in several neurological categories (mentation, paresis, fasciculations, and ataxia) were noted for 1 day.

^cMild to moderate signs in at least one of the following categories were noted for 1 to 2 days: mentation, paresis, fasciculations, and ataxia.

^dModerate or severe signs in at least one of the following categories were noted for at least 2 days: mentation, paresis, fasciculations, and ataxia.

^eFever was indicated by a body temperature of ≥39.2°C (102.5°F).

^fDeath due to development of WNV disease severe enough to require euthanasia for humane reasons.

^gEncephalitic horses in the control group had moderate or severe encephalitis on histopathology.

^hMild inflammatory histopathologic changes were seen in neural tissues of vaccinated horses.