Sensorineural deafness in Tanzanian children--is ototoxicity a significant cause? A pilot study

9 years experience working in Tanzania revealed a surprisingly large population of profoundly deaf children. The object was to identify the cause.

200 children between the ages of 5-12 with significant sensorineural hearing loss were identified in Stone town, Zanzibar. These were aged and neighbourhood matched with 218 normal hearing children. A parental questionnaire administered by health workers from the Zanzibar Outreach Programme was used to interview parents of the matched group of deaf and normal hearing children. Outcome measures included the genetic history especially first cousin marriage (common in Zanzibar), rubella, head injury, fever admission, and drug treatment of fever. The limitations were lack of hospital records and it was a retrospective study. The results were analysed from Excel spreadsheets.

36% of the deaf group had an infant fever admission history compared with 4% of the normal hearing group. Nearly all had i.m. quinine and/or gentamicin. The genetic history was equal in both groups, and rubella was rare. Most fevers were assumed to be malaria or pneumonia which are unlikely causes of deafness on their own.

Ototoxic drugs given to sick infants with "fever", without weight recording or gentamicin level monitoring, was the probable cause of a third of all severe/profound deafened Zanzibarian children. The Ministry of Health and Social Welfare in Zanzibar have reacted by issuing posters to all health facilities advising hearing testing in all children three months after discharge following "fever" admission. This is a pilot study and the apparent findings need to be confirmed by a well designed prospective study as soon as possible.