A LIVE ORAL HYBRID VACCINE AGAINST NATURALLY OCCURRING SHIGELLOSIS OF MACACA MULATTA.
Final rept. Jun 68-Nov 69,
SCHOOL OF AEROSPACE MEDICINE BROOKS AFB TEX
Pagination or Media Count:
Protection studies were conducted in Macaca mulatta monkeys using a live oral vaccine prepared from an Escherichia coli-Shigella flexneri 4b hybrid. A total of 162 Macaca mulatta were used in three experiments. In the first, any effect of the vaccine was minimized by the transfer of the hybrid strain to some of the control animals as a result of housing the two groups in contiguous cages and administration of an inexplainably low initial dose. In the second, the incidence of naturally occurring shigellosis in the controls was so low as to render impossible any significant reduction of cases in the vaccinated half of the group. In the third experiment, with 79 vaccinated monkeys and an equal number of controls, cases occurring 5 or more days after the second vaccine dose revealed a difference which, statistically, was highly significant P .01. The carrier rate in the vaccinated group, however, was also significantly less than that of the controls P .01, despite randomization. Further studies are needed to determine whether or not the vaccine actually confers protection, or if carrier rates influence the number of naturally occurring cases. Author