What are the risk factors of Haemophilus influenzae type b (Hib) meningitis?

Updated: Jul 09, 2018
  • Author: Prateek Lohia, MD, MHA; Chief Editor: Niranjan N Singh, MBBS, MD, DM, FAHS, FAANEM  more...
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Answer

An individual’s risk for Hib meningitis depends not only on that person’s vaccination history but also on the degree to which the entire population has been vaccinated. This suggests that herd immunity has an effect on the prevalence of particular meningogenic bacterial strains. Vaccination appears to reduce the prevalence of carriage of Hib within the general population, presumably including colonization and carriage by household contacts.

Day care attendance appears to enhance risk in children younger than 2 years. That risk enhancement is greatest in the first month of day care attendance.

A twin sibling is at greater risk for the development of Hib meningitis than are other siblings of an index case, risk that may be due to proximity in combination with the fact that a twin is in exactly the same vulnerable age bracket for Hib meningitis risk, whereas other siblings are likely to fall outside that most vulnerable age group.

Some evidence suggests that crowded urban living, especially as experienced by children of comparatively low socioeconomic status, may enhance risk for invasive Hib disease, although these observations have not carefully excluded potential confounding variables. Some of the potential confounding variables include the possibility of genetically enhanced risk, possibly among blacks or especially American Indians/Eskimos.

These studies, in turn, have not excluded the possible contribution of crowding, low socioeconomic status, or other variables (eg, dietary factors, alcohol consumption) in explaining the higher risk discerned in these more or less genetically homogeneous populations.


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