THE EFFICACY OF A GIARDIA-LAMBLIA VACCINE IN KITTENS

Twenty kittens were vaccinated with a Giardia lamblia vaccine prepared on a commercial scale on day 0 and boosted on day 21 (group 1); while 10 kittens received only saline (group 2). These kittens were challen ged on day 35 with 10(6) Giardia lamblia trophozoites by a surgical in traduodenal injection. Three control kittens were not vaccinated and n ot challenged (group 3). Following challenge, Giardia vaccinated kitte ns had significantly fewer days in which abnormal stools were observed and reduced food intake occurred compared to saline injected animals. The rate of weight gain between group 1 and group 2 animals was not d ifferent in the prechallenge period (day 0 to day 35), but vaccinated animals had a significantly higher weight gain in the postchallenge pe riod (P < 0.05). On day 56, all vaccinated animals were not passing cy sts in their feces, while 40% of saline injected kittens had Giardia c ysts in their feces. In vaccinated kittens, cysts were never demonstra ted in 45% of the animals, while cysts were detected in 90% of the sal ine injected kittens. Viability of the cysts in vaccinated kittens was 38% while the cysts viability in saline injected kittens was 99%. On postmortem examination, trophozoites could be detected in 5% of vaccin ated kittens and 60% of saline injected kittens. Vaccination produced an elevated Giardia specific serum IgG and IgA response prior to chall enge and throughout the postinfection period. The Giardia infection in the saline injected group did not induce an elevated specific serum r esponse. Giardia vaccination of kittens provides protection in kittens from an experimental challenge by reducing or eliminating intestinal trophozoites and fecal cyst excretion.