Detection of Borrelia burgdorferi infected Ixodes scapularis (Acari: Ixodidae) associated with local Lyme disease transmission in Nebraska, USA, 2021

In August 2021, the Nebraska Department of Health and Human Services was notified by a local public health department of a cluster of two Lyme disease cases in patients with local exposure to wooded areas in a county located in their jurisdiction. Epidemiological investigations revealed that the two patients had similar symptom onset dates and had likely exposure to ticks at wooded sites located directly adjacent to one another. Two environmental investigations were completed in October 2021 and consisted of tick surveys at the patients' reported sites of tick exposure. 12 ticks were collected across the two surveys and identified the black-legged tick (Ixodes scapularis). During subsequent testing of the collected ticks, spirochete bacteria were isolated, cultured and confirmed as Borrelia burgdorferi sensu stricto by PCR. In total, 7 of 12 (58.3%) I. scapularis ticks tested positive for B. burgdorferi s.s. The results of this study document the fourth known established population of I. scapularis in Nebraska and confirms the first detection of B. burgdorferi s.s. in field collected ticks from Nebraska. The epidemiological and environmental investigation data provide the first evidence for local Lyme disease transmission occurring within Nebraska. These findings highlight the need for continued surveillance of I. scapularis and its associated pathogens in Nebraska to further characterize human risk and monitor emergence into other areas of the state.