Parasitological study of long-dried fecal samples.

To rehydrate dried, ancient human fecal specimens an alkaline chelating solution (cold) was used. Identi fiable evidence of one animal parasite of man was found ? the eggs of Enterobius vermicularis. Rhabditoid nema todes in one specimen and mites in many probably in vaded the feces after deposition. If the nematodes were a maize parasite, they might have caused crop loss, if present in large enough numbers. The sedation of mites in specimens from different strata may provide evidence concerning their evolution in the Mesa Verde area. AMONG the remains of occupation at the L Wetherill M sa cliff dwellings were a num ber of human fecal specimens. Since evidences of many human parasites are found in man's feces, the possible value of a study of these re mains was immediately apparent. Anthropo logically, the intestinal animal parasites infect ing the group can give a measure of various habits that pertain to hygiene, living conditions, and foods. Biologically, it is of interest to know both the antiquity and earlier geographic distri bution of a group of organisms and to determine if there have been any changes. All the fecal specimens were, of course, in a dry state. The fact that they have remained recognizable suggests that they dried rapidly; otherwise they would have disintegrated in a short time. Fast drying would also have been favorable for the preservation of certain para sites and their products before autolysis and microorganisms could destroy them. Particu larly, it was expected that portions of intestinal worms, if present, might have survived in recog nizable form. Nematodes (roundworms) possess a cuticle which is highly resistant to biological and chemical activity, and this would still be recognizable even if the soft tissues had decom posed. This is true of all stages, egg to adult, and for different organisms any of the stages may appear in feces. Platyhelminths (flat worms) have fewer structures which would last as well, but there is some possibility of remains. The probability of finding recognizable remnants of protozoan parasites seemed much more re mote. Recognizable traces of trophozoites in the unprotected, motile forms would be most un likely; the cysts, although encased in a wall, 1 This is Contribution No. 29 of the Wetherill Mesa Archeological Project. would not be much more resistant to such severe treatment. The pressure and distortion of drying would probably have rendered such small objects unrecognizable. Severe drying of the specimens to the parch mentlike or stony objects found was thus a mixed blessing. In diagnostic laboratory prac tice, dried material is not considered suitable for analysis and is rejected. Since it was im possible to find material of better quality, it was necessary to find a method, or methods, suited to these special circumstances. Any technique to be used would have to rehydrate without severe chemical damage. Crushing the material, as a preliminary step, was also inadvisable, since large objects, such as worms, might easily be broken into unrecognizable fragments. Materials and Methods The fecal specimens were excavated by proj ect personnel at a number of sites, primarily at Long House and Mug House. Identification of the material as being of human origin was made by Olaus Murie and Douglas Osborne. On an empirical basis, denaturing of protein and precipitation of salts in drying, were the chief problems in reclaiming the material for study. Basic solutions with cation-sequestering properties were tried at various concentrations and temperatures. Glycerol and other penetrat ing and wetting agents, such as detergents, were also used initially. The final procedure evolved was quite simple. A large fragment of the speci men, 1 to 5 cm. in diameter, was detached with as little crushing as possible, weighed, and placed in a beaker. For each gram of feces, 20 ml. of rehydrating solution were added, and the beaker was then placed in the refrigerator for 24 to 72 hours. The beaker was swirled gently several times a day to aid penetration and dissolution of the specimen. The solution most used has been 2% (w/v) sodium hydroxide plus .5% (w/v) ethylenedinitrilo tetraacetic acid disodium salt (disodium EDTA). About 20 specimens were studied in detail with this technique. When the specimen had softened and mixed, a preliminary search for larger specimens was made with a hand lens; none was found. A sample of the sediment was then pipetted to a