DIAGNOSTIC-FINDINGS IN THE 1992 EPORNITIC OF NEUROTROPIC VELOGENIC NEWCASTLE-DISEASE IN DOUBLE-CRESTED CORMORANTS FROM THE UPPER MIDWESTERNUNITED-STATES
Cu. Meteyer et al., DIAGNOSTIC-FINDINGS IN THE 1992 EPORNITIC OF NEUROTROPIC VELOGENIC NEWCASTLE-DISEASE IN DOUBLE-CRESTED CORMORANTS FROM THE UPPER MIDWESTERNUNITED-STATES, Avian diseases, 41(1), 1997, pp. 171-180
Neurotropic velogenic Newcastle disease (NVND) occurred in juvenile do
uble-crested cormorants, Phalacrocorax auritus, simultaneously in nest
ing colonies in Minnesota, North Dakota, South Dakota, and Nebraska an
d in Lakes Michigan, Superior, Huron, and Ontario during the summer of
1932. Mortality as high as 80%-90% was estimated in some of the nesti
ng colonies. Clinical signs observed in 4- to -6wk-old cormorants incl
uded torticollis, tremors, ataxia, curled toes, and paresis or weaknes
s of legs, wings or both, which was sometimes unilateral. No significa
nt mortality or unusual clinical signs were seen in adult cormorants.
Necropsy of 88 cormorants yielded no consistent gross observations. Mi
croscopic lesions in the brain and spinal cord were consistently prese
nt in all cormorants from which Newcastle disease virus (NDV) was isol
ated. Characteristic brain lesions provided rapid identification of ne
w suspect sites of NVND. Lesions were also present in the heart, kidne
y, proventriculus, spleen, and pancreas bur were less consistent or no
nspecific. NDV was isolated at the National Wildlife Health Center fro
m 27 of 93 cormorants rested. Virus was most frequently isolated from
intestine or brain tissue of cormorants submitted within the first 4 w
k of the epornitic. Sera collected from cormorants with neurologic sig
ns were consistently positive for NDV antibody. The NDV isolate from c
ormorants was characterized as NVND virus at the National Veterinary S
ervices Laboratories, Ames, Iowa. The NVND virus was also identified a
s the cause of neurologic disease in a North Dakota turkey hock during
the summer of 1992. Although no virus was isolated from cormorants re
sted after the first month of submissions, brain and spinal cord lesio
ns characteristic of NVND were observed in cormorants from affected si
res for 2 mo, at which time nesting colonies dispersed and no more sub
missions were received. Risk to susceptible populations of both wild a
vian species and domestic poultry makes early recognition and confirma
tion of NVND in wild birds a priority.