Frequency distribution of lymphatic Filariasis microfilariae in human populations: Population processes and statistical estimation

P. K. Das, P. K. Rajagopalan, B. T. Grenfell, D. A.P. Bundy

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


This paper uses simple mathematical models and statistical estimation techniques to analyse the frequency distribution of microfilariae (mf) in blood samples from human populations which are endemic for lymphatic filariasis. The theoretical analysis examines the relationship between microfilarial burdens and the prevalence of adult (macrofilarial) worms in the human host population. The main finding is that a large proportion of observed mf-negatives may be ‘ true ‘ zeros, arising from the absence of macrofilarial infections or unmated adult worms, rather than being attributable to the blood sampling process. The corresponding mf distribution should then follow a Poisson mixture, arising from the sampling of mf positives, with an additional proportion of ‘true’ mf-zeros. This hypothesis is supported by analysis of observed Wuchereria bancrofti mf distributions from Southern India, Japan and Fiji, in which zero-truncated Poisson mixtures fit mf-positive counts more effectively than distributions including the observed zeros. The fits of two Poisson mixtures, the negative binomial and the Sichel distribution, are compared. The Sichel provides a slightly better empirical description of the mf density distribution; reasons for this improvement, and a discussion of the relative merits of the two distributions, are presented. The impact on observed mf distributions of increasing blood sampling volume and extraction efficiency are illustrated via a simple model, and directions for future work are identified.

Original languageEnglish (US)
Pages (from-to)417-427
Number of pages11
Issue number3
StatePublished - Dec 1990
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Infectious Diseases
  • Animal Science and Zoology
  • Parasitology


  • Wuchereria bancrofti
  • frequency distributions
  • lymphatic filariasis
  • microfilariae
  • truncated negative binomial


Dive into the research topics of 'Frequency distribution of lymphatic Filariasis microfilariae in human populations: Population processes and statistical estimation'. Together they form a unique fingerprint.

Cite this