The effect of age and sex on incidence of kala-azar.

Of 89 persons suspected to be suffering from kala-azar, the parasite could be demonstrated in 54 of them by smear and culture examination of the bone marrow aspirates. In the pre-pubertal age group (4-12 years), incidence of kala-azar in both the sexes was practically the same (P greater than 0.05). However, in the reproductive age-group (males 13-60 years, females 12-45 years), there were significantly less cases in females than males (P less than 0.05). This protection could be due to the presence of female sex hormones. The incidence of kala azar in females was 83.3 per cent in pre-pubertal age group, while in the reproductive age group, it was 35.5 per cent. The difference is statistically highly significant (P less than 0.01).