Epidemilogy of aeromonas and plesiomonas diarrhoea

Abstract

Aeromonas spp. and Plesiomonas shigelloides can be commonly isolated from stools of patients with diarrhoea in developing countries though much less commonly from such patients in developed countries. ■ These bacteria are also common environmental water bacteria suggesting that persons who drink unpurified water will be ingesting these bacteria frequently. This paper reviews the studies which have attempted to determine if these agents are causes of diarrhoea. Although in some cases it seems likely that Aeromonas or Plesiomonas is the likely cause of the illness, it seems equally clear that these organisms can also be isolated from a great many people from whom these are not the causative agent. At present there is no clear case definition for the illness caused by either of these agents, and the lack of an adequate case definition inhibits epidemiological studies in determining the extent of the problem in a given geographical area. For both bacteria, specific virulence factors are being sought which would differentiate enteropathogenic from non-enteropathogenic bacterial isolates. Several such virulence factors are being proposed and will need to be validated in epidemiological studies. Because of suggestions from previous epidemiological studies, it is suggested that studies of Aeromonas should especially focus on persistent diarrhoea and that studies of P. shigelloides should focus on cases of mild dysentery.