PATTERNS OF INFECTION, INCIDENCE AND REINFECTION WITH SCHISTOSOMA-MANSONI IN NILE DELTA GOVERNORATE - KAFR-EL-SHEIKH

Two annual follow-up measures of incidence, reinfection after treatmen t and reuersion rates were estimated in a large prospective study of S chistosoma mansoni located in the northern Nile Delta of Kafr El Sheik h, Rates were estimated in a cohort established from a probability sam ple of the entire rural area of Kafr El Sheikh, Infection was determin ed by the examination of two Kato stool slides, The weighted first and second annual ovrerall incidence rates were 20.4%, SE +/- 1.4 and 15. 9%, SE +/- 1.4, respectively, Geometric mean egg counts in incident ca ses were 35.6 epg, SE +/- 1.2 and 31.0, SE +/- 1.6 in the first and se cond follow-ups, Incidence was strongly associated with first round pr evalence (r(2) = 0.34). Reinfection rates were higher: 33.4%, SE +/- 3 .1 and 31.0%, SE +/- 2.1. Reinfection was associated with incidence (r (2) = 0.32), Reversion rates were highest in children 0 to 4 years old (61.2%, SE +/- 18.1 and 78.5%, SE +/- 7.0, respectively) and increase d from the first to second follow-up: 37.2%, SE +/- 3.4 and 47.0%, SE +/- 3.7, respectively. Patterns of these rates by village community, a ge and sex are also given over both follow-up examinations and compari son with limited data on rates of S. mansoni infection from previous s tudies, suggests a stable pattern of transmission over time in the Nil e Delta.