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Outbreak of Haemophilus influenzae type b meningitis in a day care center
I Andersson von Rosen1, L Gotherfors, S Schmeisser
1Department of Clinical Immunology, University of Göteborg, Sweden.
Insights
Haemophilus influenzae type b (Hib) meningitis outbreaks in day care centers were investigated. Carriage of Hib and nontypable H. influenzae (HiNT) differed between centers, suggesting HiNT may offer protection against Hib infection.
Area of Science:
- Microbiology
- Epidemiology
- Public Health
Background:
- Haemophilus influenzae type b (Hib) meningitis poses a significant public health risk, particularly in congregate settings like day care centers.
- Understanding the dynamics of nasopharyngeal carriage is crucial for controlling the spread of Hib and other H. influenzae strains.
Purpose of the Study:
- To investigate nasopharyngeal carriage of H. influenzae in children attending two Swedish day care centers following Hib meningitis cases in one center.
- To differentiate disease-associated Hib clones from carried strains using molecular markers.
- To explore potential inverse relationships between nontypable H. influenzae (HiNT) carriage and Hib infection.
Main Methods:
- Multilocus enzyme electrophoresis was employed to identify and characterize H. influenzae isolates.
- Nasopharyngeal swabs were collected from children in two day care centers: one with Hib meningitis cases and a control center without cases.
- Carriage frequencies and the composition of H. influenzae flora were compared between the two centers.
Main Results:
- The three Hib meningitis cases were caused by the same H. influenzae clone (ET14), which was also found in healthy carriers.
- Day care Center I, with meningitis cases, showed a lower overall H. influenzae carriage rate (28%) compared to the control center (57%).
- A higher frequency and greater sharing of nontypable H. influenzae (HiNT) were observed in the center without Hib disease, suggesting a potential protective role.
Conclusions:
- Accurate identification of disease-causing H. influenzae isolates is essential for assessing transmission risks.
- The findings suggest a possible inverse relationship between carriage of HiNT and susceptibility to Hib infection.
- Day care center attendees can harbor various H. influenzae strains, highlighting the need for epidemiological surveillance.
Abstract:
Three cases of Haemophilus influenzae type b (Hib) meningitis in a Swedish day care center prompted the investigation of the nasopharyngeal carriage in attendees of that day care center (I), and among children in another day center (II) in the same city, but without meningitis cases. Because the evaluation of the spread of Haemophilus influenzae (Hi) isolates through a population, such as children in day care centers, requires stable identification markers for the bacteria, this study used multilocus enzyme electrophoresis to separate Hib carried by day care attendees from the disease-associated Hib clone. The three meningitis episodes were caused by the same clone of Hib (ET14). This and other Hib clones occurred in the healthy carriers. The frequency of H. influenzae carriage and composition of the H. influenzae flora differed between the two day care centers. Center I with the meningitis cases had a lower overall frequency of H. influenzae carriage, 11 of 40 (28%) compared with both the control day care center (57%) and previous studies. The main difference between the two day care centers was in the nontypable H. influenzae (HiNT) flora. The frequency of HiNT was higher in the center without Hib disease, and there was a higher degree of sharing of HiNT isolates among the children in Center II. This raised the question of an inverse relationship between carriage of HiNT and Hib infection. The results emphasized the importance of accurate identification of the disease isolate in order to estimate the risk of acquisition and dissemination to secondary cases.