EN COMPARISON BETWEEN THE STANDARD OPG TECHNIQUE AND ITS MODIFICATIONS

Abstract

Gastrointestinal parasites are infections established in the gastrointestinal tract and can be caused by parasites such as helminths and coccidia. The diagnosis of these parasites can be performed in several ways and techniques, the best known, practical, and fast being the technique popularly known as the OPG method, which determines the number of parasite eggs per gram of feces to calculate the parasite load of the animal. The OPG, despite being the most used technique, presents a lot of variability in the results and several modifications have been described to improve the efficiency of the technique. Therefore, the objective of this work was to compare modifications of the techniques that result in the number of OPG to determine if any of the modifications equate to the result of the standard technique. For its development, a pool of samples of animals of the sheep species, naturally infected by helminths, was collected; the samples were processed by four modifications of the standard technique, known as the “Modified Gordon and Whitlock Method”, using the McMaster chamber, in order to try to estimate the parasite load of the animals. For each technique, five repetitions were performed using the same homogenized fecal sample, in all repetitions and in all techniques. We concluded that the standard technique proved to be the most efficient and viable technique, since its results differed statistically from the other techniques, even if some modifications produced a smaller amount of residue or required a smaller amount of sample.