EPIDEMIOLOGY OF SCHISTOSOMA HAEMATOBIUM AND S MANSONI INFECTIONS IN EGYPT-49 PROJECT AREA .4. MEASUREMENT OF INCIDENCE OF BILHARZIASIS

  • 1 January 1966
    • journal article
    • research article
    • Vol. 35  (3) , 331-+
Abstract
The measurement of incidence, or the rate at which people become positive, for S. haematobium and S. mansoni was carried out in 4 parts of the Egypt-49 project area near Alexandria. For S. haematobium, rates as high as 22.8%/year were found for children 0-6 years old in a rural area; in the same area, the incidence of S. mansoni was 8.5%/year. The true incidence is underestimated because many cases become negative spontaneously. This loss rate of S. haematobium cases Is 0.476/year for children 0-4 years old, and 0.049/year for those aged 5 and 6 years; for S. mansoni, the rates are 0.580 and 0.327, respectively. Despite the error, incidence is the most accurate and sensitive method of assessing the success of control operations, and is an important measurable parameter in epidemiology.