What is the window of infectivity for early childhood caries?

• A. First 2 years of life
• B. Birth to 6 months
• C. Between ages 4 and 6
• D. After age 7

Answer: (A)

The window of infectivity is the period when a child is most likely to acquire cariogenic bacteria from a caregiver, especially Streptococcus mutans, through saliva-sharing behaviors. In early childhood caries, transmission often occurs during the time when primary teeth are starting to erupt and the oral environment becomes conducive to colonization. That makes the first two years of life the critical period for acquiring these bacteria and establishing a cariogenic microflora, which is why this option is the correct one. Birth to 6 months is typically too early for meaningful transmission and tooth eruption; ages four to six or after seven are past the main window when initial colonization occurs.