Do patients with recurrent episodes of campylobacteriosis differ from those with a single disease event?

Laboratory-confirmed cases of campylobacteriosis reported in the province of Quebec, Canada, through ongoing surveillance between 1996 and 2006 were analyzed. The risk of having a recurrent episode of campylobacteriosis was described using life table estimates. Logistic regression was used to assess if gender, age and patient residential location were associated with an increased risk of recurrence.Compared to the baseline risk, the risk for a recurrent disease event was higher for a period of four years and followed a decreasing trend. This increased risk of a recurrent event was similar across gender, but higher for people from rural areas and lower for children under four years of age.These results may suggest the absence of durable immunity or clinical resilience following a first episode of campylobacteriosis and periodical re-exposure, at least among cases reported through the surveillance system.In Canada, infection by Campylobacter spp. is the leading cause of bacterial gastro-enteritis, with an average of 39 cases per 100,000 people reported annually over the last decade [1]. However, given the mild clinical expression of most Campylobacter infections, this reflects an underestimation of the true burden in the population, as only a fraction of people affected consult their physician and have stool samples submitted for culture [2].In Canada as in many other countries, human campylobacteriosis is a reportable disease. Regional public health authorities are notified of confirmed cases and selected information is then gathered into surveillance databases. These databases can then be used in epidemiological investigations as sources of information for evaluating individual or environmental risk factors [3,4]. It was recently proposed that acquired immunity to the infection could bias results from risk factor analysis by reducing the risk of developing the disease in areas of high exposure [5].Following an infection with Campylobacter, most people develop a humo