This tactile feedback is related to a difference in tis-sue density as one goes from the parenchyma to the vessels or from the parenchyma to the collecting sys-tem, and also to the selectivity of the CUSA to spare tissue of high collagen content.
1 In the least developed countries, the overall illiteracy rate is 49 percent. 2  52 percent of all non-literates live in India and China. 3  Africa as a continent has a literacy rate of less than 60 percent. 4  In Sub-Saharan Africa since 1980, primary school enrollment has declined, going from 58 percent to 50 percent.
Data from Africa are very scarce. A study in a Nigerian student population found a 26.1% prevalence, based on the Rome II criteria. A study among outpatients in the same country, based on the same criteria, reported a prevalence of 33%.