Travel-related shigellosis in Quebec, Canada: an analysis of risk factors

Travel-related shigellosis is not well documented in Canada although it is frequently acquired abroad and can cause severe disease.

To describe the epidemiology of travel-related cases of shigellosis for Quebec (Canada) and to identify high-risk groups of travelers.

We performed a random sampling of 335 shigellosis cases (from a total of 760 cases) reported in the provincial database of reportable diseases from January 1, 2004, to December 31, 2007. Each case was analyzed according to information available in the epidemiology questionnaire. Total number of trips by region from Statistics Canada was used as denominator to estimate the risk according to region of travel.

Annually, between 43 and 54% of the shigellosis cases were reported in travelers, 45% of whom were aged between 20 and 44 years. Children under 11 years accounted for nearly 16% of cases, but represent only 4% of travelers. Most cases in travelers were serogroups Shigella sonnei (50%) or Shigella flexneri (45%). Almost 31% of cases were reported between January and March. The majority (64%) were acquired in Central America, Mexico, or the Caribbean. However, the Indian subcontinent, Africa, and South America had the highest ratio of number of cases per number of trips. Tourists represented 76% of the cases; 62% of them had traveled for <2 weeks. At least 15% of cases among travelers were hospitalized.

In Quebec, travel-related cases of shigellosis represent a large burden of total cases. Short-term travelers are at risk, as well as young children. The majority of cases occur in the winter months, corresponding to the peak of travel to "sunshine destinations." Continuous efforts should be made to encourage all travelers to seek pre-travel care, and to inform primary care practitioners of health risks faced by their patients abroad, even for those going to resorts.