COMPARISON OF CLINICAL OBSERVATIONS ON PATIENTS INFECTED WITH ENTAMOEBA HISTOLYTICA WITH SEROLOGICAL TITRES OF THEIR SERA AND VIRULENCE OF THEIR AMOEBAE TO RATS

A combined clinical and laboratory study was made of 40 patients infected with Entamoeba histolytica. Each patient was examined clinically, serum was examined for haemagglutinating and complement-fixing antibodies, and E. histolytica was isolated in vitro and its virulence to rats determined. The patients were divided into 2 groups, those with significant clinical symptoms (7 patients) and those without recognizable symptoms due to E. histolytica (33 patients). All 7 patients with symptoms were positive serologically, and the amoebae were virulent to rats. In the group of 33 patients, 21 were serologically very low or negative, while the remaining 12 showed high or moderate titres. The virulence of E. histolytica to rats from this group was generally low. A survey of the complete data from the whole series shows a correlation between high virulence to rats and high serological titre, and between low virulence to rats and low serological titre. The exceptions to this generalization and the rheoretical implications are discussed. © 1968 Royal Society of Tropical Medicine and Hygiene.