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Haemophilus influenzae type b disease. Incidence in a day-care center
Insights
Day-care outbreaks of Haemophilus influenzae type b (Hib) disease highlight its contagiousness in infants. Hib polysaccharide vaccine showed a poor antibody response in young children, indicating limited effectiveness.
Area of Science:
- Pediatrics
- Infectious Diseases
- Immunology
Background:
- Haemophilus influenzae type b (Hib) disease poses a significant risk in congregate settings like day-care centers.
- Previous prophylaxis and vaccination strategies may have limitations in preventing Hib transmission and invasive disease.
Purpose of the Study:
- To investigate an outbreak of Haemophilus influenzae type b disease in a day-care setting.
- To evaluate the effectiveness of ampicillin trihydrate prophylaxis and Hib polysaccharide vaccine in a susceptible infant population.
Main Methods:
- Conducted a 14-month surveillance study in a day-care center.
- Monitored disease incidence, nasopharyngeal carriage rates, and implemented ampicillin trihydrate prophylaxis.
- Administered Haemophilus influenzae type b polysaccharide vaccine and assessed antibody responses.
Main Results:
- Seven of 48 infants developed Hib disease; 58% were nasopharyngeal carriers.
- Ampicillin trihydrate prophylaxis did not reduce the carrier rate.
- Only 26% of vaccinated infants showed an adequate antibody response to the Hib polysaccharide vaccine; one vaccinated infant developed meningitis.
Conclusions:
- Haemophilus influenzae type b is highly contagious in closed populations of young, susceptible infants.
- The Hib polysaccharide vaccine demonstrated suboptimal immunogenicity in this cohort.
- Outbreaks underscore the need for effective prevention strategies in high-risk pediatric populations.
Abstract:
Haemophilus influenzae type b (HIB) disease was observed during a 14-month period in seven of 48 infants attending a day-care center. Surveillance studies showed that 28 (58%) infants had positive nasopharyngeal cultures for HIB; four infants were colonized with HIB for nine to 12 months. Ampicillin trihydrate prophylaxis failed to reduce the HIB carrier rate. Haemophilus influenzae type b polysaccharide vaccine was administered to 34 of the children. Sera obtained prior to immunization showed detectable antibody in all infants. Only nine (26%) infants had twofold or greater rises in serum HIB antibody titers after vaccination. Antibody response was independent of age, preimmunization antibody concentration, and HIB carrier status. In one infant, HIB meningitis developed four months after she received polysaccharide vaccine. This outbreak emphasizes that HIB is highly contagious in closed populations of young, susceptible infants.