Audiological and haematological studies on the Todas of Nilgiris.

A detailed audiological study combined with certain haematological investigations which were never previously done was undertaken on Todas, a small vanishing tribe of Nilgiris, South India. Ten per cent of the Todas studied exhibited otosclerosis which, though lower than that of a previous study, is still a very high percentage when compared to the general population. The incidence of chronic suppurative otitis media in Todas is markedly low (1-6 per cent) and 13-3 per cent of Todas had sensorineural hearing loss. Evaluation of hearing thresholds at various frequencies in the different age groups did not show much variation from that of the general population. The incidence of presbyacusis is not found to be low as reported earlier. Blood pressure recordings did not show any age-related increase. The majority of Todas studied belonged to the blood group 'B' (63 per cent) and 16-6 per cent belonged to the 'AB' group, which is distinctly different from the distribution pattern seen in the general Indian population. There was no significant variation in the serum cholesterol level in Todas.