Deafness: malaria as a forgotten cause

Background: Ototoxicity from antimalarials is a well publicised cause of deafness and a great deal of time and resources are spent assessing it in relation to new drugs. The effect of the malaria parasite itself on hearing is, however, poorly documented and most evidence is anecdotal. This paper aims to collate existing evidence of this association. Methods: Two systematic literature searches were performed on Ovid Medline, first for 'malaria' and 'hearing loss' or 'hearing impairment' or 'deafness', and secondly for 'cerebral malaria' and 'neurologic' or 'neurological' or 'neurocognitive sequelae'. The articles were then individually studied for relevance. Results: Malaria has been implicated as a rare cause of hearing loss in various studies, but recommendations and hypotheses have not been taken seriously or investigated. Searches also returned numerous studies of neurological sequelae after cerebral malaria, a small proportion of which observed hearing impairments on follow-up. However, no attempt was made to distinguish between treatment and disease as the cause. A few antimalarial drug trials which assessed hearing before treatment found unexplained hearing loss which improved with elimination of the parasite. Conclusion: Evidence from this review suggests that the falciparum parasite is a potential cause of hearing loss. Malaria is a disease of such high prevalence that even if only a small proportion of survivors develop this impairment the effects on children's education could be detrimental. More attention should be focussed on investigating this association as the clinical and pathophysiological implications are potentially considerable.