Polman K, De Vlas S J, Van Lieshout L, Deelder A M, Gryseels B
Department of Parasitology, Leiden University Medical Centre, The Netherlands.
Parasitology. 2001 Feb;122(Pt 2):161-7. doi: 10.1017/s0031182001007193.
Regression analysis of the relationship of serum circulating anodic and cathodic antigens (CAA and CCA), as a possible direct measure of worm burden, and fecal egg counts allows the study of phenomena like density-dependent fecundity in human Schistosoma mansoni infections. For a reliable analysis, variations in egg count measurements as well as in circulating antigen levels have to be taken into account, and an accurate estimation of these variations (represented by parameter lambda in the so-called Deming regression) is of great importance. From a new, extensive data set of repeated measurements of fecal egg counts and CAA and CCA concentrations we determined the respective values for parameter lambda, and (re)analysed the relationship between circulating antigens and egg counts in 3 data sets from Burundi, Senegal and Zaire by Deming regression. For comparison, ordinary linear regression was performed as well, which considerably biased the regression lines for CCA, but not for CAA. The analyses resulted in a clearly non-proportional relationship between egg counts and CAA, and, to a lesser extent, CCA. Assuming that egg counts and antigen measurements directly reflect egg production and worm burdens, respectively, our findings reinforce the indication of density-dependent fecundity in schistosomiasis mansoni, as suggested by others.
血清循环阳极和阴极抗原（CAA和CCA）作为衡量虫负荷的一种可能的直接指标，与粪便虫卵计数之间关系的回归分析，有助于研究曼氏血吸虫感染中密度依赖性繁殖力等现象。为了进行可靠的分析，必须考虑虫卵计数测量以及循环抗原水平的变化，准确估计这些变化（在所谓的Deming回归中由参数λ表示）非常重要。我们从一个新的、广泛的粪便虫卵计数以及CAA和CCA浓度重复测量数据集确定了参数λ的各自值，并通过Deming回归对来自布隆迪、塞内加尔和扎伊尔的3个数据集中循环抗原与虫卵计数之间的关系进行了（重新）分析。为作比较，也进行了普通线性回归，这使得CCA的回归线出现了相当大的偏差，但CAA的回归线没有。分析结果显示，虫卵计数与CAA之间存在明显的非比例关系，与CCA之间的非比例关系程度稍小。假设虫卵计数和抗原测量分别直接反映产卵量和虫负荷，我们的研究结果强化了其他人所提出的曼氏血吸虫病中存在密度依赖性繁殖力的迹象。
