The epidemiology of travel-associated shigellosis--regional risks, seasonality and serogroups.
OBJECTIVE
To give a detailed risk estimate of contracting travel-associated shigellosis in various regions of the world.


METHODS
Data on notifications of travel-associated shigellosis in Sweden 1997-2003 were compared with information on recent travel abroad from a comprehensive database based on telephone interviews with more than 160,000 Swedish travellers.


RESULTS
From the national notification database 2678 patients with travel-associated shigellosis were retrieved. The highest risk of being notified with shigellosis was seen in returning travellers from India and neighbouring countries (318/100,000 travellers), East Africa (219/100,000), West Africa (120/100,000), and North Africa (76/100,000). Data on serogroup was available for 2529 isolates. Shigella sonnei was the most common serogroup (67%), followed by Shigella flexneri (26%), Shigella boydii (5%), and Shigella dysenteriae (3%). A higher risk was seen in children below the age of six, compared to older children and adults and in women compared to men. A distinct seasonal pattern was noted with the highest risk of shigellosis in July-October and the lowest in May.


CONCLUSIONS
Denominator based data on reported travel-associated infections are well suited to give risk estimates per region of infection, that could be used to target high-risk groups for pre-travel advice.
Ekdahl
Karl
K
Department of Epidemiology, Swedish Institute for Infectious Disease Control (SMI), Stockholm, Sweden. karl.ekdahl@smi.ki.se
Andersson
Yvonne
Y
D000293:Adolescent; D000328:Adult; D000349:Africa; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004405:Dysentery, Bacillary / Q000453:epidemiology* / Q000382:microbiology; D005060:Europe; D005260:Female; D006801:Humans; D007194:India; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012621:Seasons; D012703:Serotyping; D012760:Shigella / Q000145:classification* / Q000302:isolation & purification; D013548:Sweden / Q000453:epidemiology; D014195:Travel