title: Frequency distribution of Wuchereria bancrofti microfilariae in human populations and its relationships with age and sex.
abstract: 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.
authors.affiliation: Vector Control Research Centre, Medical Complex, Indira Nagar, Pondicherry, India.
authors.forename: P K
authors.initials: PK
authors.lastname: Das
authors.forename: A
authors.initials: A
authors.lastname: Manoharan
authors.forename: A
authors.initials: A
authors.lastname: Srividya
authors.forename: B T
authors.initials: BT
authors.lastname: Grenfell
authors.forename: D A
authors.initials: DA
authors.lastname: Bundy
authors.forename: P
authors.initials: P
authors.lastname: Vanamail
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000818:Animals; D016010:Binomial Distribution; D002648:Child; D002675:Child, Preschool; D004605:Elephantiasis, Filarial / Q000453:epidemiology* / Q000469:parasitology; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D007223:Infant; D008297:Male; D008842:Microfilariae / Q000254:growth & development; D008875:Middle Aged; D015995:Prevalence; D012737:Sex Factors; D014958:Wuchereria bancrofti / Q000254:growth & development*