The age distribution and the infection rate of yaws in Jamaica

ABSTRACT

This report is based upon a study of 23,000 persons living in a yaws-infested, rural area in Jamaica B.W.I. The proportion of the population with yaws incseases rapidly to a level of 70 to 80 per cent at 15 to 20 years of age, after which their is a gradual decrease. Annual infection rates among previously uninfected persons rise sharply to a peak of 20 to 30 per cent at about 8 years of age, followed by a more gradual fall. There are few new infections occurring after 30 years of age. The proportion of the population with yaws falls short of the level expected on the basis of annual attack rates. This discrepancy increases most rapidly during the first decade, which is hard to explain on any basis other than that of a higher mortality in childhood among yaws sufferers than among those uninfected. A comparison of the sexes shows certain differences. (a) The level of infection is higher among males and its peak is reached earlier. (b) The annual infection rates for males are consistently higher and reach their peaks about a year later than the rates for females. (Summary)