Quantitative interpretation of coprocultures in a population infected with Oesophagostomum bifurcum.

Coproculture is used in northern Togo and Ghana in the research on Oesophagostomum bifurcum, a common parasite of man in these regions. Prior to a follow-up study to investigate patterns of reinfection in Oesophagostomum and hookworm, it was attempted to evaluate the relevance of counting larvae for the assessment of the intensity of infection at the population level. Of 102 samples, one egg count (Kato-smear) and three coprocultures were carried out. Frequency distributions of counts of larvae of Oesophagostomum and of hookworm isolated in three coprocultures, showed log-normality. There was a highly significant correlation between egg counts and the combined number of Oesophagostomum and hookworm larvae (Spearman rank correlation test, r = 0.74, p < 0.01). It is concluded that the mean larval counts of three coprocultures can be interpreted quantitatively, as normally done for egg counts. A quantitative classification of larval counts is proposed.