Method for concentration of parasites from small amounts of feces

Abstract

A total of 258 formalinized stool specimens received in our clinical laboratory were examined for parasites by direct smears and by the standard Formalin-ethyl acetate (FEAc) concentration method. Microconcentration (MC), a miniaturization of the FEAc method, was compared with the standard method for efficiency of parasite recovery. MC employed 0.25 to 0.50 ml of formalinized stools, 0.5 ml of Formalin, and 0.25 ml of ethyl acetate; the washing steps were omitted, whereas the rest of the procedure remained the same as the FEAc method. A total of 36 (13.9%) specimens were positive for parasites; of these, 23 (63.9%) were negative on direct examination. In 14 of these 23 specimens, the FEAc and MC methods were equivalent in detecting parasites. MC failed to detect parasites in eight specimens that were positive by FEAc and detected a parasite in one specimen that was negative by FEAc. Of 14 specimens positive by both concentration methods, FEAc detected additional parasite species in 2 specimens and MC did so in 1 specimen. The reduced sensitivity of parasite concentration evident in the MC we believe to be exclusively due to the drastically reduced sample size. We propose MC as an alternative to the FEAc concentration method when only small amounts of feces can be obtained.

Prevalence of intestinal parasites among HIV patients at the Yaoundé Central Hospital, Cameroon

“…First, a direct wet mount in physiological saline and iodine, was examined under a light microscope for ova, cyst and parasite detection. Second, samples were concentrated using a formol-ether and Kato-Katz technique [ 13 ]. Fecal smears were then stained following the ZiehlNeelsen modified technique for the detection oocysts [ 14 ].…”

Wild Animals in Captivity: An Analysis of Parasite Biodiversity and Transmission among Animals at Two Zoological Institutions with Different Typologies

“…Once in the laboratory, a macroscopic analysis of each sample was made, searching for the presence of parasitic structures. Faecal concentrates (following the formalin–ethyl acetate stool concentration technique) [ 21 ] were made, and the sediments were examined on temporary slides stained with Lugol’s iodine. Morphological features were measured and photographed with Olympus DP20 or Olympus DP23 cameras on an Olympus BX51 microscope (Olympus, Tokyo, Japan).…”

State-of-the-Art Techniques for Diagnosis of Medical Parasites and Arthropods

“…It has been used for parasitological diagnosis for several hundred years ( Figure 1 ) [ 12 ]. Direct wet smear, concentration, staining, and scotch tape techniques are used to detect ova and parasite ( Table 1 ) [ 13 , 14 , 15 , 16 , 17 ]. For malaria diagnoses, microscopic examination of Giemsa-stained thick and thin blood films is a standard practice, even though several approaches have emerged, such as dipstick antigen detection and polymerase chain reaction (PCR).…”