Since 2000, case reporting and the geographic range of Lyme disease have steadily increased in the U.S., with the number of reported cases rising from 17,730 cases in 2000 to 29,513 in 2017. Ninety percent of these cases have been reported in Northeastern states such as New York, Connecticut, New Jersey, Pennsylvania, Massachusetts, Maryland, Rhode Island, and Wisconsin. However, the number of ‘high incidence’ states (states having an annual mean of at least ten confirmed cases per 100,000 people) has risen from nine to 16 during the 2000-2017 period.
This spread to other states has been attributed to the range expansion of the main tick vector, Ixodes scapularis. Although maps showing habitat suitability and expansion of the vector exist, no predictive risk maps show the possible spread of Lyme disease reporting in the U.S.
RTI, in collaboration with Columbia University, built a model to capture the factors that have driven the spatio-temporal spread of Lyme disease in the U.S. from 2000 to 2017 and created a map showing the risk of case reporting. Donal Bisanzio, Senior Epidemiologist at RTI, shares more about this model and how it can guide Lyme disease surveillance efforts.