Spread of Haemophilus influenzae type b.
D000367:Age Factors; D002353:Carrier State / Q000382:microbiology; D002675:Child, Preschool; D006192:Haemophilus Infections / Q000635:transmission*; D006193:Haemophilus influenzae / Q000472:pathogenicity; D006801:Humans; D007223:Infant; D014774:Virulence