Cryptosporidiosis

Many studies evaluate the timeliness and accuracy of outbreak detection algorithms used in syndromic surveillance. Of greater interest, however, is defining the outcome associated with improved detection. In case of a waterborne cryptosporidiosis outbreak, public health interventions are aimed exclusively at preventing new infections, and not at medical treatment of infected individuals. The effectiveness of these interventions in reducing morbidity and mortality will depend on their timeliness, the level of compliance, and the duration of exposure to pathogen. In this work, we use simulation modeling to examine several scenarios of issuing a boil-water advisory (BWA) as a response to outbreak detection through syndromic surveillance, and quantify the possible benefits of earlier interventions.

Objective

To quantitatively assess the benefit of issuing a boil-water advisory for preventing morbidity and mortality from a waterborne outbreak of cryptosporidiosis.

Cryptosporidiosis is a gastrointestinal illness due to a protozoan parasite that is highly contagious, and resistant to multiple disinfectants. Utah experienced a large, community-wide outbreak of cryptosporidiosis between June and December of 2007. During this time period, the Utah Department of Health received reports of 1,902 laboratory confirmed cryptosporidiosis cases across the state.2 Nearly 40% of these cases occurred in Salt Lake County (SL County), Utah. In past years, SL County averaged fewer than five cases annually; however, the incidence rate in the county for this entire outbreak was 125.9 per 100,000 person–years.

Objective

The objective of this study was to investigate if prospectively applied space-time surveillance could have detected significant, emerging clusters as cryptosporidiosis, cases were reported to the Salt Lake Valley Health Department during the 2007 outbreak.