Mansonella ozzardi in Haiti. III. A comparison of the sensitivity of four sampling methods in detecting infections.

A study to compare the sensitivity of four sampling methods in detecting Mansonella ozzardi among 133 inhabitants of Bayeux, Haiti, is reported. The Knott method proved the most sensitive with 40 microfilaria carriers detected. No additional infections were revealed by the other sampling methods. This was followed in order by 20 mm3 thick films of earlobe blood (34 cases), finger-prick blood (32 cases in the first sample), and skin biopsy (14 cases from paired samples). The combination of three finger-prick samples (60 mm3 of blood) detected 38 of 40 (95%) Knott-positive infections. The Knott method detected only one case not observed by at least one of the other three sampling methods. This sampling procedure did not detect more M. ozzardi in the 0-19-year age group than observed by the 20-mm3 finger prick method. Based on these results, a correction factor of 1.25 can be applied to our earlier Bayeux survey.