Hearing impairment after childhood bacterial meningitis dependent on etiology in Luanda, Angola.

OBJECTIVE

Childhood bacterial meningitis (BM) damages hearing, but the potential of different agents to cause impairment in developing countries is poorly understood. We compared the extent of hearing impairment in BM caused by Haemophilus influenzae type b (Hib), Streptococcus pneumoniae or Neisseria meningitidis among children aged 2 months to 13 years in Luanda, Angola.

METHODS

Hearing of 685 ears of 351 (78%) survivors among 723 enrolled patients was tested by brainstem-evoked response audiometry on day 7 of hospitalization. The causative agent was sought by cerebrospinal fluid culture, PCR or the latex-agglutination test.

RESULTS

Altogether, 45 (12%) of the survivors were deaf (threshold >80 dB), and 20 (6%) had a threshold of 80 dB. The incidence of any kind of hearing loss, with ≥60 dB, was 34% with Hib, 30% with S. pneumoniae, 19% with N. meningitidis and 33% with other bacteria. Examining all ears combined and using the ≥60 dB threshold, the agents showed dissimilar harm (P=0.005), Hib being the most frequent and N. meningitidis the most infrequent cause. Compared to other agents, S. pneumoniae more often caused deafness (P=0.025) and hearing impairment at ≥60 dB (P=0.017) in infants, whereas this level of hearing loss in older survivors was most commonly caused by Hib (P=0.031).

CONCLUSIONS

BM among children in Angola is often followed by hearing impairment, but the risk depends on the agent. S. pneumoniae is a major problem among infants, whereas Hib is mainly a risk beyond 12 months. N. meningitidis impairs hearing less frequently.