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Naturally acquired immunity to Haemophilus influenzae type B in healthy Cuban children

Gilda Toraño Peraza1, Ibis Hernández Vadell, María Eugenia Toledo Romaní

  • 1National Reference Center for Haemophilus, Instituto de Medicina Tropical Pedro Kouri, Havana, Cuba. gilda@ipk.sld.cu

Memorias Do Instituto Oswaldo Cruz
|January 18, 2005
PubMed

Insights

In Cuba, nearly all healthy 4-5 year olds showed immunity to Haemophilus influenzae type b (Hib). This study found natural active immunity to Hib develops early, with very low nasopharyngeal carriage rates.

Area of Science:

  • Immunology
  • Pediatrics
  • Microbiology

Background:

  • The Haemophilus influenzae type b (Hib) vaccine was introduced in Cuba in 1999.
  • Children too old for the initial vaccination cohort were assessed for Hib immunity.

Purpose of the Study:

  • To evaluate the prevalence of antibodies against Hib in healthy Cuban children aged 4-5 years.
  • To estimate the prevalence of Hib nasopharyngeal carriage in this age group.

Main Methods:

  • Serum samples from 974 healthy children (aged 4-5) were analyzed for IgG antibody concentrations against Hib capsular polysaccharide.
  • Nasopharyngeal cultures were performed to determine Hib carriage rates.

Main Results:

  • A high prevalence of Hib immunity was observed, with 99.7% of children having antibody concentrations above 1 microg/ml.
  • Hib nasopharyngeal carriage was very low, confirmed in only one child (0.1%) after serotyping.

Conclusions:

  • Natural active immunity to Haemophilus influenzae type b is acquired at an early age in the Cuban population.
  • The findings suggest successful development of herd immunity or natural acquisition of immunity in young children.

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