WEST NILE VIRUS VACCINE, BIRD REACTION - CANADA
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Date:  3 Jul 2003
From: Chris Dutton <cdutton@torontozoo.ca>


2 comments / questions on West Nile virus vaccinations:

1. At the Toronto Zoo, we have a group of 18 green-naped lorikeets, 
and each was vaccinated for West Nile virus 3 times in 2002 (1 ml 
Fort Dodge WNV vaccine IM) with no apparent problems. However, when 
we boosted them with a similar single dose this year, we lost 4 
birds. The deaths occurred on days 2, 3, 10 and 10 after vaccination. 
2 birds were found dead, while 2 others were found lethargic and 
dyspneic, and died despite supportive care. Blood samples from the 
latter 2 birds showed marked anemia and markedly elevated granulocyte 
counts.

On necropsy, there were no significant gross lesions. Histologically, 
there were very few red cells, and massive erythrophagocytosis, 
primarily in the liver. In the first 2 birds the phagocytized 
erythrocytes were whole or barely broken down, while in the last 2 
birds there were more typical red inclusions and pigment formation. 
Bacterial culture from all 4 birds revealed no significant pathogens, 
and a PCR viral/chlamydial panel on blood was negative.

It all looks like some form of autoimmune hemolytic anemia, possibly 
induced by the vaccination.

2. We also have a group of Loggerhead shrikes, and each was 
vaccinated for West Nile virus 3 times this spring (0.5 ml Fort Dodge 
WNV vaccine IM). Subsequently, we have had little evidence of 
breeding this year (as compared to excellent breeding in the previous 
2 years). Obviously, there are many possible causes for this, but 
concern has arisen that the vaccination may have been responsible.

Anyhow, we just wanted to raise awareness regarding these issues, and 
wondered whether anyone else has had similar experiences.

--
Dr. Christopher Dutton, Veterinarian
Dr. Mads Bertelsen, Veterinary Resident
Toronto Zoo
361A Old Finch Avenue
Scarborough, Ontario
M1B 5K7
Phone: 416-392-5976
Fax: 416-392-4979
<cdutton@torontozoo.ca>

[Currently the only vaccine against West Nile Virus is manufactured 
by Fort Dodge and is approved for use in equines. Use in other 
species is extra-label. For this reason, there are no research data 
to help answer the questions or shed light on any of the observations 
noted here.

Since the vaccine is being used in an extra-label fashion, what basis 
was there for vaccinating the birds 3 times? There has been some 
serology work done by some veterinarians in zoos and possibly with 
the American Association of Zoo Veterinarians.  At the time of this 
posting, we were still awaiting responses from some veterinarians 
involved in this serology effort.- Mod.TG]
..................tg/pg/lm

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