vaccines (Ivins, 1988), suggesting that cellular immunity as well as humoral immunity is important for protection against anthrax infection.

Animal Studies

As noted earlier in this chapter, adverse health outcomes in animals after injection may result from the toxic effects of the injected substances or from stimulation of the immune system. Injection of the live spore vaccine can cause infection. Injection of protective antigen vaccines can result in adverse effects associated with administration of the exotoxins.

Live attenuated spore vaccines. Studies in veterinary use. Many of the studies using the live spore vaccine have involved large-scale vaccination of animals of economic importance. Avirulent, nonencapsulated strains of B. anthracis, including the Sterne live spore vaccine, have been used for vaccination. In general, these studies have relied on anecdotal reports from farmers and veterinarians to measure the incidence of reactions of livestock (primarily horses, cows, calves, sheep, lambs, and goats) to the vaccination. In some cases, data on the number of animals vaccinated and the number of deaths from anthrax have been collected by survey or from veterinarian reports.

In most cases, the primary focus has been on evaluating the efficacy of the vaccine, rather than on monitoring adverse effects; therefore, many studies of veterinary use of the live spore vaccine have not commented on adverse effects associated with vaccination (Sterne et al., 1942; Kaufmann et al., 1973; Salmon and Ferrier, 1992).

The primary health outcomes in animal studies are edema at the site of injection, a febrile response, or death. The extent of the edema ranged from no reaction, to mild irritation, to lameness in some animals. Edema is due to elaboration of the edema toxin or to an allergic response to a previously administered vaccine. An early study by Sterne (1939) used a retrospective questionnaire to solicit complaints regarding the effectiveness and adverse effects of vaccinating sheep and cattle with live spore vaccines. With a limited response to the questionnaire, the majority of reports for cattle indicated that no reactions occurred. However, some cattle experienced lameness and transient decreases in milk yield. Some animals showed severe swelling at the site of injection and one death occurred. Kolksov and Mikhailov (1959) described either insignificant or mild reactions in the majority of 650,000 animals that were vaccinated. Some horses and cattle had swelling at the injection site measuring 12–40 cm2 and lasting 3 to 4 days, along with a slight temperature rise. Of the 650,000 animals (including cattle, horses, oxen, sheep, and goats) 20 animals were reported as dying from unspecified causes. In another study of the Sterne live spore vaccine, it was noted that three of the 34,000 cattle, horses, mules, hogs, and sheep receiving the vaccine experienced instances of excessive swelling (Lindley, 1963). Increased temperature of the animals, lasting for days, has been observed in other studies (Kolksov and Mikhailov, 1959; Kolosov and Borisovich, 1968;



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