Streptococcus equi subsp. zooepidemicus infections associated with guinea pigs

Streptococcus equi subsp. zooepidemicus is a known zoonotic pathogen. In this public health investigation conducted in Virginia, USA, in 2013, we identified a probable family cluster of S. zooepidemicus cases linked epidemiologically and genetically to infected guinea pigs. S. zooepidemicus infections should be considered in patients who have severe clinical illness and report guinea pig exposure. Streptococcus equi subsp. zooepidemicus is a facultative pathogen affecting animals and humans. Infections have occurred in horses, pigs, ruminants, guinea pigs, monkeys, cats, and dogs. Zoonotic transmission of S. zooepidemicus is rare and is usually associated with drinking unpasteurized milk or through contact with horses by persons who usually have underlying health conditions. Few if any human case-patients with S. zooepidemicus infection have documented guinea pig exposure even though S. zooepidemicus infections have been described in guinea pigs since 1907. This case report describes 1 probable and 1 confirmed human case of severe S. zooepidemicus infection and the laboratory methods used to link human and guinea pig isolates. S. zooepidemicus infection should be considered in patients who have purulent wounds or systemic symptoms of infection who have had known contact with guinea pigs or their environment. Likewise, patients whose specimen cultures reveal S. equi or further test results show S. zooepidemicus should be questioned about guinea pig exposure as well as exposure to other animals associated with this pathogen: horses, pigs, ruminants, monkeys, cats, and dogs.  Emerging Infectious Diseases  Original web page at Emerging Infectious Diseases