An evaluation of sampling methods within communities and the validity of parasitological examination techniques in the field
Brinkmann, U.K.; Powollik, W.; Werler, C.; Traoré, M.
Tropical Medicine and Parasitology Official Organ of Deutsche Tropenmedizinische Gesellschaft and of Deutsche Gesellschaft für Technische Zusammenarbeit 39(2): 162-166
1988
ISSN/ISBN: 0177-2392 PMID: 3140358 Document Number: 318076
In the Mali National Schistosomiasis Control Programme, screening samples from villages gave infection rates within 5% of those determined by screening all inhabitants. Sample age distributions were similar to those obtained by including all inhabitants but ages given by respondents were accurate only to within 5 years. The sensitivity and specificity of identification of eggs from urine samples was directly correlated with degree of experience. The pairs of figures (sensitivity and specificity) were 97.3% and 79.4%, and 91.1% and 99.3% for senior technicians in general and intense infections (>20% prevalence) respectively. For a district health centre laboratory technician the corresponding figures were 83.0% and 45.5%, and 76.5% and 97.9%. Sampling techniques using small samples were thus assessed grossly inaccurately in the field.