Objective—To evaluate humoral immune responses
of emus vaccinated with commercially available
equine polyvalent or experimental monovalent eastern
equine encephalomyelitis (EEE) virus and western
equine encephalomyelitis (WEE) virus vaccines and to
determine whether vaccinated emus were protected
against challenge with EEE virus.
Procedure—Birds were randomly assigned to groups
(n = 5/group) and vaccinated with 1 of 2 commercially
available polyvalent equine vaccines, a monovalent
EEE virus vaccine, or a monovalent WEE virus vaccine
or were not vaccinated. Neutralizing antibody
responses against EEE and WEE viruses were examined
at regular intervals for up to 9 months. All emus
vaccinated with the equine vaccines and 2 unvaccinated
control birds were challenged with EEE virus.
An additional unvaccinated bird was housed with the
control birds to assess the possibility of contact transmission.
Results—All 4 vaccines induced detectable neutralizing
antibody titers, and all birds vaccinated with the
equine vaccines were fully protected against an otherwise
lethal dose of EEE virus. Unvaccinated challenged
birds developed viremia (> 109 plaque-forming
units/ml of blood) and shed virus in feces, oral secretions,
and regurgitated material. The unvaccinated
pen-mate became infected in the absence of mosquito
vectors, presumably as a result of direct virus
transmission between birds.
Conclusions and Clinical Relevance—Results indicate
that emus infected with EEE virus develop a hightiter
viremia and suggest that they may serve as
important virus reservoirs. Infected emus shed EEE
virus in secretions and excretions, making them a
direct hazard to pen-mates and attending humans.
Commercially available polyvalent equine vaccines
protect emus against EEE virus infection. (J Am Vet
Med Assoc 2001;218:1469–1473)