Actinomyces species are worldwide in distribution. The organisms are components of the endogenous oral and gastrointestinal tract flora. Actinomyces species are opportunistic pathogens, and disease results from penetrating (including human bite wounds) and nonpenetrating trauma. Infection is rare in infants and children. Overt, microbiologically confirmed, monomicrobial disease caused by Actinomyces species has become rare in the era of antimicrobial agents.

The incubation period varies from several days to several years.