Amebiasis in the New Orleans Population as Revealed by Autopsy Examination of Accident Cases

View More View Less
  • Department of Tropical Medicine, Tulane University, New Orleans, Louisiana

Conclusions and Summary

In a series of 202 post-mortem examinations conducted on accident cases in New Orleans within four hours after death, thirteen infections of Endamoeba histolytica (6.44 per cent) were demonstrated by the recovery of the organism within the bowel. In five of these cases the ameba was found in scrapings of lesions in the bowel wall. In two additional cases the organism was identified from mucus removed from the surface of lesions or nearby. In four more cases E. histolytica was recovered from feces or mucus throughout extensive lengths of the large intestine, and in each of two instances only a single cyst was diagnosed. Thus, in five of the thirteen individuals positive for E. histolytica, and possibly in two more, there was concrete evidence of tissue invasion; in four cases large numbers of amebae were found without direct proof of associated lesions; and in each of two additional cases the discovery of a single cyst in hematoxylinstained fecal films of intestinal feces suggested minimal infection without evidence of tissue invasion or possibly in one case transit of the cyst through the digestive tract without excystation. There was no evidence of a relationship between the racial size of the amebae and their ability to invade the intestinal wall.

The highest percentage of positive diagnoses was made on iodine-stained fresh wet preparations filmed from feces and mucus taken at representative levels of the bowel. However, hematoxylin films of intestinal feces were responsible for three positive diagnoses which would otherwise have been missed. Fresh wet films prepared from feces and mucus in the lumen and superficial scrapings of the mucosa at different levels of the bowel constitute a reliable, rapid technic for recovery and diagnosis of E. histolytica in post-mortem examinations made within four hours after death. Moreover, this method provides a more accurate diagnosis than routine gross inspection of the bowel wall for lesions supplemented by sections of fixed material.

The intestinal lesions demonstrated in this series were confined exclusively to the mucosa, and consisted of three varieties, (1) minute pinpoint lesions, (2) shallow craters, and (3) rather extensive, superficial erosive processes. In each of these types of tissue involvement amebae were demonstrated and in no instance was there evidence of leukocytic infiltration suggesting secondary invasion by bacteria, or of fibrous repair processes. No amebiasis of the liver was discovered in any of the members of this series. Although previous investigators have studied the pathology in so-called “symptomless carriers” of Endamoeba histolytica, they have invariably reported appreciable involvement of the bowel wall with “typical amebic ulceration.” The amebic processes demonstrated in this series constitute much milder, less advanced pathology and suggest a better balance between host tissue and the parasite. As in early experimental amebic lesions in the dog, so in this series there is a preponderance of lesions in the cecum-appendix area.

In addition to Endamoeba histolytica the following intestinal parasites were identified in the present series: E. coli, 6.44 per cent; Endolimax nana, 9.4 per cent; Iodamoeba bütschlii, 1.0 per cent; Dientamoeba fragilis, 0.5 per cent; Giardia lamblia, 4.5 per cent; Trichomonas hominis, 1.0 per cent; flagellate sp. inq., 0.5 per cent; Necator americanus, 1.9 per cent; Ascaris lumbricoides, 1.5 per cent; Trichocephalus trichiurus, 1.9 per cent; Enterobius vermicularis, 0.5 per cent, and Strongyloides stercoralis, 0.5 per cent. Forty-two members of the series were positive for one or more parasites, giving a parasite index of 0.36 for the entire group of 202 and an index of 1.74 for the infected individuals.