Epidemiology and Infection

Incidence and clinical symptoms of Aeromonas-associated travellers' diarrhoea in Tokyo

a1 Tama Branch Laboratory, Tokyo Metropolitan Research Laboratory of Public Health, 3-16-25, Shibazaki-cho, Tachikawa, Tokyo 190, Japan
a2 Department of Microbiology, Tokyo Metropolitan Research Laboratory of Public Health, Tokyo, Japan
a3 Division of Clinical Pathology, Department of Medical Science, Nonthaburi, Thailand
a4 School of Health Science, Kyorin University, Tokyo, Japan


In a survey examining the causes of travellers' diarrhoea treated in Tokyo between July 1986 and December 1995, Aeromonas species were isolated from 1265 (5·5%) of 23215 travellers returning from developing countries. Aeromonas species were the fourth most frequent enteropathogen isolated, following enterotoxigenic E. coli (8·5%), Salmonella spp. (7·6%) and Plesiomonas shigelloides (5·6%). Aeromonas species were found in 1191 (5·6%) of 21257 patients with diarrhoea and in 74 (3·8%) of 1958 healthy individuals without diarrhoea. Mixed infection was observed in 512 (40·5%) cases. No significant difference in the prevalence of Aeromonas by year, season, age distributions, or sex was observed, but a slight difference was noted depending on the country where the travellers visited. Of the 1265 Aeromonas isolates, 893 strains (70·6%) were A. veronii biovar sobria, 330 (26·1%) were A. hydrophila, and 42 (3·3%) were A. caviae. The clinical symptoms of patients from whom Aeromonas species was isolated as the only potential enteric pathogen were almost similar, which were watery diarrhoea (about 60%), abdominal cramps (43%), fever (around 15%), and nausea or vomiting (13%). Although the severity of illness was milder than that of enterotoxigenic E. coli alone, these data suggest that Aeromonas species are important enteric pathogens in travellers' diarrhoea.

(Accepted April 10 1997)