Sleigh A, Hoff R, Mott K, Barreto M, de Paiva T M, Pedrosa J de S, Sherlock I
Trans R Soc Trop Med Hyg. 1982;76(3):403-6. doi: 10.1016/0035-9203(82)90201-2.
We compare results of one Bell and one Kato-Katz examination performed on each of 315 stool specimens from residents in an area in north-eastern Brazil endemic for schistosomiasis mansoni. The prevalence of Schistosome infection detected by the Bell technique was 76% and by the Kato-Katz technique was 63%. 81% (44/54) of the infections missed by a Kato-Katz smear were light infections (one of 50 epg range by Bell examination). Over, all, 55% (44/80) of stools in this egg count range by the Bell technique were negative on a single Kato-Katz smear. This implies that five Kato-Katz smears per stool would ensure a 95% probability (0.55(5) X 100) of detecting such light infections. However, a single Kato-Katz smear detected eggs in 97% (124/128) of stools with a Bell count greater than 100 epg. For stools positive by both methods the egg counts per gram of stool were higher (p less than 0.001) by Kato-Katz examination. Geometric mean egg counts for the infected population were 199 epg by the Kato-Katz and 92 epg by the Bell methods. 64% (59 v. 36) more persons were classified as heavily infected (greater than 400 epg) by the Kato-Katz method than by the Bell method. The differing measurements of schistosome infection obtained with the Bell and Kato-Katz methods must be considered when comparing data on morbidity-infection relationships.
我们比较了对巴西东北部曼氏血吸虫病流行地区315名居民的粪便样本分别进行一次贝氏检验和一次加藤厚涂片法检验的结果。贝氏检验法检测到的血吸虫感染率为76%，加藤厚涂片法检测到的感染率为63%。加藤厚涂片法漏检的感染病例中，81%（44/54）为轻度感染（贝氏检验法每克粪便虫卵数在50个范围内）。总体而言，贝氏检验法检测到的每克粪便虫卵数在此范围内的粪便样本中，55%（44/80）的样本经单次加藤厚涂片法检测呈阴性。这意味着每份粪便样本进行5次加藤厚涂片法检测，可确保有95%的概率（0.55(5)×100）检测到此类轻度感染。然而，单次加藤厚涂片法在贝氏检验法每克粪便虫卵数大于100个的粪便样本中，检测到虫卵的概率为97%（124/128）。两种方法均呈阳性的粪便样本，加藤厚涂片法检测到的每克粪便虫卵数更高（p<0.001）。感染人群的几何平均虫卵数，加藤厚涂片法为每克粪便199个，贝氏检验法为每克粪便92个。加藤厚涂片法判定为重度感染（每克粪便虫卵数大于400个）的人数比贝氏检验法多64%（59比36）。在比较发病率与感染关系的数据时，必须考虑贝氏检验法和加藤厚涂片法检测血吸虫感染的不同结果。
