Das P K, Manoharan A, Srividya A, Grenfell B T, Bundy D A, Vanamail P
Vector Control Research Centre, Medical Complex, Indira Nagar, Pondicherry, India.
Parasitology. 1990 Dec;101 Pt 3:429-34. doi: 10.1017/s0031182000060625.
This paper examines the effects of host age and sex on the frequency distribution of Wuchereria bancrofti infections in the human host. Microfilarial counts from a large data base on the epidemiology of bancroftian filariasis in Pondicherry, South India are analysed. Frequency distributions of microfilarial counts divided by age are successfully described by zero-truncated negative binomial distributions, fitted by maximum likelihood. Parameter estimates from the fits indicate a significant trend of decreasing overdispersion with age in the distributions above age 10; this pattern provides indirect evidence for the operation of density-dependent constraints on microfilarial intensity. The analysis also provides estimates of the proportion of mf-positive individuals who are identified as negative due to sampling errors (around 5% of the total negatives). This allows the construction of corrected mf age-prevalence curves, which indicate that the observed prevalence may underestimate the true figures by between 25% and 100%. The age distribution of mf-negative individuals in the population is discussed in terms of current hypotheses about the interaction between disease and infection.
本文研究了宿主年龄和性别对班氏吴策线虫在人类宿主体内感染频率分布的影响。分析了来自印度南部本地治里班氏丝虫病流行病学大型数据库的微丝蚴计数。按年龄划分的微丝蚴计数频率分布通过零截断负二项分布成功描述，并采用最大似然法拟合。拟合得到的参数估计表明，10岁以上人群中微丝蚴计数分布的过度离散随年龄呈显著下降趋势；这种模式为微丝蚴强度的密度依赖性限制作用提供了间接证据。该分析还估计了因抽样误差而被判定为阴性的微丝蚴阳性个体的比例（约占总阴性个体的5%）。这使得能够构建校正后的微丝蚴年龄流行率曲线，表明观察到的流行率可能低估了真实数字的25%至100%。本文根据当前关于疾病与感染相互作用的假说，讨论了人群中微丝蚴阴性个体的年龄分布情况。
