One of the difficult problems of amebiasis lies in the differences observed in symptomatology in the presence of infection with Endamoeba histolytica. It is difficult to explain the increasing tendency to dysentery and hepatic abscess in hotter climates. The same patient for unaccountable reasons may be subject to alternating diarrhea or dysentery, and constipation. Maintenance of host-parasite balance is often difficult to attain and maintain. Response to treatment shows great variability. Amebiasis clinically is a protean disease.
Various explanations have been attempted for this situation. It has been assumed that certain climatic factors influence the the host or the parasite in an unknown way. Brumpt has suggested that quadri-nucleated cysts may be divided on the basis of animal pathogenicity into three species, which he designates E. dysenteriae, E. hartmanni and E. dispar. He believes that the first of these predominate in warm climates and the latter two in cool climates.