The age distribution and the infection rate of yaws in Jamaica

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)

The control of yaws by an intensive treatment method

A description of the territory in Jamaica in which yaws has been under control for three years is followed by a brief account of preliminary studies. The intensive treatment method used in control is explained and results obtained are discussed. (Summary)

The relationship of certain environmental factors to the distribution of yaws in Jamaica

A study of the history of yaws in Jamaica reveals that the disease, while it may have been present before the advent of African negroes, was repeatedly introduced by slaves, and has tended to become localized in certain parts of the island. The present distribution has been determined by inspection trips, by actual survey of 48 widely separated areas, and by questionnaire returns from 611 schools situated in every part of Jamaica. The results of the surveys and questionnaire are tabulated and will be found to agree very closely where a direct comparison is possible. The present distribution, plotted on a map, is seen to be essentially the same as it was 20 and 40 years ago, as estimated from records of the Island Medical Department. The possible relationship between certain environmental factors and this distribution is considered. These factors are rainfall, geological formation, altitude, the sanitary status of the population, urban and rural localities, and the presence of a certain insect, namely, Hippelates pallipes. A discussion considers the possible influencing effects of environment upon distribution. (Summary)