280 CHAPTER SEVEN As would be expected, the estimated number of trachoma blind cases, the prevalence rate per 1,000 population, and the prevalence rate per 1,000 trachoma cases, all increased with age. The number of trachoma blind cases increases from fewer than 3,000 for per- sons under age 30 to 6,155 cases for persons 50 year§ and older. Prevalence per 1,000 population increases from 0.3 blind per 1,000 persons under age 30 to 4.1 per 1,000 persons age 50 and older. Similarly, the prevalence rate per 1,000 trachoma cases increases from 4.6 for persons under age 30 to 46.7 for persons age 50 or older. One-half (50.1%) of the trachoma blind are age 50 or older. The distribution of trachoma blindness by ethnic group is shown in Table 7-32. Only the Chhetri, Magar, and Tharu groups had sufficient numbers of cases to be displayed separately. These three ethnic groups account for more than 85 percent of the trachoma blindness, 10,508 of the 12,275 estimated trachoma blind cases. Estimated prevalence rates per 1,000 population range from 1.8 for the Chhetri to 4.2 for the Tharu, while prevalence rates per 1,000 trachoma cases range from 15.2 for the Tharu to 27.7 for the Chhetri. The prevalence rates for other groups are much smaller than the rates for Nepal overall. It is widely believed that the Tharu community is the most heavily effected by trachoma and trachoma blindness. Therefore, it is surprising that while the Tharu have the highest prevalence rate per 1,000 population, the Chhetri group has more trachoma blindness (4,095 cases) and a higher prevalence rate per 1,000 trachoma cases. In summary, there are estimated to be 12,275 trachoma unilateral and bilateral blind in Nepal. Nearly three-quarters of these trachoma blind are female and half are age 50 or older. Four- fifths of the trachoma blindness is concentrated in the Far West region, and the Chhetri, Magar, and Tharu ethnic groups account for more than four- fifths of the trachoma blindness. 7.3.4 High-Intensity Trachoma The distribution of blindness due to trachoma, whether unilateral or bilateral, certainly reflects characteristics about the trachoma dis- ease process in Nepal. However, trachoma blindness prevalence is a measure of the final result of a history of repeated infections. It may not he related to the present distribution of active disease. For example, trachoma blindness prevalence was much higher in per- sons age 50 or older than in persons in the younger age groups, and yet, as noted in in Section 7.3.1, trachoma has a fairly uniform dis- tribution with respect to age. The complications such as trichiasis, entropion, and blindness are not only of interest for planning inter-
