However, this risk is less than the risk due to a natural infection resulting in chickenpox.

Just how effective these procedures are in increasing the incidence of natural infection is unknown.

Vaccines simulate a natural infection and its associated immune response, but do not cause the disease.

Their effectiveness depends on ability to replicated and elicits a response similar to natural infection.

Domestic ruminants are also susceptible to natural infection with F. magna.

In natural infections, animals typically receive a large dose of bacteria during exposure.

Such immunizations aim to trigger an immune response more rapidly and with less harm than natural infection.

Subsequent natural infections have since been reported.

In the United States, the last outbreak due to natural infection occurred in 1979.

For the period of 1777 to 1781, 89% of inoculated animals survived, compared to a 29% survival rate after natural infection.