Which statement best describes serovars?

• A. Different from a species or subspecies
• B. Based on O and H antigens
• C. Relative prevalence varies by country
• D. All of the above

Answer: (D)

Serovars are distinct antigenic types within a single bacterial species. They are not separate species or subspecies, but variations that help us differentiate strains within the same species. Serotyping commonly uses surface antigens, especially the O (somatic) and H (flagellar) antigens, to distinguish these types because these features differ among strains. The prevalence of specific serovars also varies by country or region due to differences in food sources, animal reservoirs, and transmission patterns. Putting these points together, serovars are antigen-defined variants within a species, identifiable by O and H antigens, with geographic differences in which ones are more common.