Comparison of Formol-Ether, Direct Smear and Nigrosine Methylene Blue for the Diagnosis of Human Intestinal Parasites

Abstract

In this study, we compared three methods of intestinal parasites diagnosis in order to come out with a simple, precise and affordable method. Intestinal parasitic infections are more prevalent in developing countries and their burden may even be more than that of bacterial infections. The Formol-ether concentration technique has been considered as a gold standard for the detection of most intestinal parasites; however, because of its low safety and hazardous impact, the need for a better and cheaper method is of paramount importance especially in this part of the globe. A total of 51 fecal samples were collected and each stool sample was examined by: Direct smear using saline and iodine preparation, Formol-ether concentration method and Nigrosine methylene blue concentration method. Of the 51 stool samples examined, 20(39.2%) were positive for parasitic infection. The sensitivity indicated that Nigrosine methylene blue has the highest percentage of 85%, followed by Formol ether with 75% and the Direct smear had the least with 65%. The sensitivity of the three methods indicated that Nigrosine methylene is good and is even better than the Formol-ether and should be preferred to the most celebrated Formol-ether and the conventional direct smear because even people with less technical expertise can use it more conveniently with good result.