Although our study material was represented by fecal preparations from more than 1,400 Egyptians, the number of species of protozoa found was not greater than observed in our previous studies involving far smaller samples of the population. Larger population samples, however, more strongly emphasize that the relationship between type of locality and presence of intestinal protozoans, and that between locality and prevalence of helminths, must be considered separately. Their establishment is dependent upon different means of transmission. Undoubtedly many of the protozoa are passed from person to person by contaminated hands and by food contaminated by hands and/or flies. Many of the peoples in this part of the world are unhygienic in their habits and one heavily contaminated hand thrust into a bowl which serves the entire family provides an effective vector of protozoan cysts and, in some instances, probably trophozoites. These modes of transfer are not greatly influenced by the unusually dry habitats in which many of the Egyptian peoples live. This conclusion is supported by the high incidence of intestinal protozoa in the semi-desert and desert communities.
Entamoeba coli is the most common intestinal protozoan among the Egyptian peoples and the total incidence of the large and small races of E. histolytica is much greater than that listed for other parts of the world. Perhaps the majority of the population would have been found harboring both species had a series of specimens from each person been examined. Balantidium coli was not detected in our studies and Isospora hominis occurred in only two persons.
This study of materials from a wide range of community types demonstrates the relationship between parasitism by some of the helminths and the habitat in which these peoples live. This was to be expected since successful establishment of infection involves intermediate hosts and favorable conditions for proper maturation of the helminth eggs outside the human body.
The present study lists 19 helminths, several species of which, (e.g., Opisthorchis, Haplorchis, Dicrocoelium and Fasciola of the Trematoda, and the cestode, Diphyllobothrium) are not considered parasites ordinarily found among the Egyptian peoples. Ascaris is the most common helminth and hookworm (Ancylostoma) apparently is much
The authors are indebted to Abdel Aziz Salah and Said Kassim Mohamed of NAMRU-3, Cairo, Egypt for assistance in collection of study specimens and to Dean E. Armstrong, HM1, USN for assistance in examination of materials.