Improvement in the identification of intestinal parasites by a concentrated merthiolate-iodine-formaldehyde technique

To increase the sensitivity of the merthiolate-iodine formaldehyde (MIF) technique in detecting various stages of intestinal parasites in stool specimens, a concentration step was added before preserving the stool specimen with MIF solution. This step involved mixing the stool specimen in 10% formalin, filtering the mixture through a double-layered cotton filter, and removing most of the liquid content. This modification was evaluated in a large screening program. Its positive identification of 10 helminths and 2 protozoa was comparable to formalin-ethyl acetate (FEA) sedimentation and hookworm eggs were readily recognizable. Although the modified MIF technique requires an overnight drying procedure, only a few simple procedures are involved in the concentrating step. This technique is relatively simple and suitable for large-scale screening programs or epidemiologic studies.