What are the racial predilections 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

Conflicting data and conclusions have been reported regarding the influence of race on susceptibility to Hib meningitis. To some extent, these conflicts derive from the artificiality of the demographic construct termed race and the lack of available scientific measures of the genetic contribution, giving rise to the superficially expressed characteristics upon which a racial assignment is based. These studies are further compromised by adverse socioeconomic factors that may be associated with race. However, the available data do suggest certain correlations.

Several studies have found a significantly higher rate of disease among blacks than many other nonwhites. According to some authorities, the risk that Hispanics have for Hib meningitis falls into an intermediate level between the higher risk that some studies have reported for blacks and the lower risk that some have reported for whites.

Data suggest even higher risk for Native Americans than for black populations. One prevaccination-era study from Washington State showed that annual case rates per 100,000 children were 2.2 in whites, 3.4 in blacks, and 13.5 in Native Americans.

Among American Eskimos younger than 5 years, an incidence of 409 meningitis cases per 100,000 per year was documented in 1981. [17] However, more recent study documents that the annual incidence of meningitis among all North American Arctic residents has decreased to 0.6 per 100000 cases annually. [18]

Other high-risk populations include Australian Aboriginals, Canadian Keewatins, and the Apaches and Navajos of the American Southwest. The overall risk for Hib meningitis in unimmunized individuals from these kindreds range from 35-530 cases per 100,000 annually in children younger than 5 years, with mean risk of 418 cases per 100,000 annually.

Some studies reporting race-related predilection have found that enhanced risk is defined not only by race but also by age. Some data suggest that enhanced risk in blacks is found only in children older than 1 year but not in children younger than 1 year.

On the other hand, some studies have found no racial predilection for Hib meningitis. Some authorities think that racial incidence studies are confounded by other risk factors (including socioeconomic factors such as poverty, crowding, poor healthcare, and poor nutrition) and that this may account for perceived race-related determination of risk.

For example, urban crowding may enhance the risk for Hib infection, and therefore the population risk for Hib meningitis, and may even enhance the risk for serious consequences of Hib infection. This has been demonstrated for whites living in urban as compared to rural environments in Minnesota; however, this enhanced risk was found to be true only for nonmeningitic invasive Hib disease. Some studies have suggested that low socioeconomic status may also increase the risk of contracting invasive Hib disease.


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