Evaluation of the modified Baermann's method in the laboratory diagnosis of Strongyloides stercoralis

This study compares the modified Baermann's method with the formol-ether concentration and the direct/saline techniques in the diagnosis of Strongyloides stercoralis larvae in stool specimens. This study was conducted at Wonji-Shewa Sugar Estate located at about 110 kms. south east of Addis Abeba. Of the 718 randomly selected and examined stool specimens, 125 were found positive for Strongyloides stercoralis. Of these 98% were recovered by the modified Baermann's method, 23% by the formol-ether, and 22% by the direct saline techniques. The rate of recovery by the modified Baermann's method was significantly different (p less than 0.001) compared with those of the direct and the formol-ether concentration techniques. There was no difference (p greater than 0.1) between the direct saline and the formol-ether methods. The modified Baermann's method accounted for over 60% of the total positive findings. Furthermore, the sensitivity of the method excelled the other two techniques by four fold. Thus, the modified Baermann's method by the Merck and Sharp Dohme Company is effective, cheap and simple to use and hence recommended for routine use and epidemiological surveys.