Isolation of Borrelia puertoricensis from ticks collected in Merida, Yucatan, Mexico

Isolation of tick-borne relapsing fever (TBRF) spirochetes has proven to be a useful tool to understand their distribution by geographic areas where the tick vectors inhabit. However, their isolation and culture are not easy and in general an animal model is needed to achieve this task. Here, argasid ticks were collected from a neighborhood in Ciudad Caucel, Merida, Mexico, and Borrelia puertoricensis was isolated with an immunosuppressed mouse model. By using this model, a higher number of spirochetes were observed in blood samples, and these were successfully cultivated in Barbour-Stoenner-Kelly (BSK)-IIB media. Genomic analyses confirmed that the isolate to be B. puertoricensis. The present report shows that this spirochete is present in argasid ticks in Ciudad Caucel and presents a potential medical and veterinary health risk. Author SummaryRelapsing fever is a neglected disease caused by spirochetes bacteria of the Borrelia and genus that are different than those in the Lyme disease group. These bacteria are transmitted mostly by Ornithodoros (Alectorobious) soft ticks. In many countries, including Mexico, Ornithodoros species are understudied and often misidentified. In this report we obtained an isolate of Borrelia puertoricensis from ticks captured in a small park in the city of Merida, Yucatan. These results emphasize the need for fine-scale vector surveillance in neighborhoods to determine the abundance of Borrelia species, and to define their impact on humans and domestic and wild animals.