Giardiasis, 2004

During 2004, 1,398 cases of Giardia infection (28.0 per 100,000 population) were reported. This represents a 64% increase from the 851 cases reported in 2003 and is greater than the median number of cases reported annually from 1996 through 2003 (median, 1,066 cases; range, 851 to 1,556). Of the total number of Giardia cases for 2004, 811 (58%) represented positive tests during routine screenings of recent immigrants and refugees.

The median age for all case-patients reported in 2004 was 10 years (range, 5 months to 89 years). The median age among non-immigrant cases was 33 years (range, 5 months to 89 years). As in previous years, cases were clustered among children less than 5 years of age (20%); only 19% of cases were over 50 years of age. Overall, 6% of case-patients were hospitalized; 16% of case-patients over 50 years of age were hospitalized. There were no outbreaks of giardiasis in Minnesota in 2004.

MDH began systematically interviewing cases of giardiasis in January 2002 to better characterize the illness and evaluate potential risk factors for infection. In 2004, 67% of the nonimmigrant cases were interviewed. The symptoms most commonly reported by case-patients included diarrhea (94%), gas or bloating (74%), abdominal pain (72%), weight loss (66%) and nausea (61%); less commonly reported symptoms included fatigue (41%), vomiting (37%), and fever (28%). The median duration of diarrhea was 17 days (range, 1 to 660 days).

Case-patients were interviewed about potential exposures during the 14 days prior to their illness onset. Thirty-seven percent of interviewed case-patients reported traveling prior to their onset. Among travelers, 30% reported travel outside the United States. Eleven percent of case-patients reported camping or hiking prior to onset, and 29% reported swimming or entering water. Forty-one percent of adult case-patients reported having children in their households; 48% of those case-patients had children in diapers. Twenty-eight percent of adults reported changing a diaper prior to onset. Among pediatric cases, 30% of interviewed parents reported that their child had contact with a childcare setting prior to and/or during illness.

• For up to date information see>> Giardiasis (Giardia)
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2004