Studies on hemolytic streptococcal infection: 1). Outbreak of group C hemolytic streptococcal infection in Formosan squirrels

Abstract

Between mid-October to mid-November 1992, of 500 freely-ranging Formosan and striped squirrels kept at Garden Y in the suburbs of Kanagawa Prefecture, 414 (82.8%) suddenly died one after another by bleeding from the nasal and oral cavities after developing a mild facial swelling. Isolation of microbes including viruses were carried out from the Formosan squirrels that had suddenly died. Various organs from these animals were histologically examined. 1. In bacteriological tests, beta-hemolytic streptococcal strains were isolated in a pure culture from 5 (83.3%) of 6 Formosan squirrels that had died suddenly. By serological analysis, 14 isolated strains were serotyped as group C according to the classification of Lancefield. From their biochemical characteristics, these were identified as Streptococcus equi subsp. zooepidemicus. A drug sensitivity test revealed that ABPC, PCG, SBPC, CMX and CPZ are highly sensitive against the isolates. 2. In the virological test, the viral isolation was applied for three blind passages by primary cultured kidney cells of Formosan squirrels, but no evidence of CPE was obtained. 3. At autopsy, a pathological change was detected mainly in the lungs. Histopathological examinations revealed severe hypertrophic changes of the alveolar wall in the entire pulmonary lobe. Severe congestion, hemorrhagic pneumonia, neutrophils and macrophages infiltration were observed in the hypertrophic alveolar wall. In the other cases, thrombi were observed in the branches of the pulmonary artery. Other organs demonstrated no remarkable histopathological changes. 4. Streptococcal strains were not isolated from the pharynx in all of the employees working at this garden.