Distribution of Borrelia burgdorferi, the causative agent of Lyme Disease in ticks across Texas

Abstract

The goal of this study is to determine where the Lyme disease (LD) causative agent is prevalent in Texas. According to the CDC, LD is the most prevalent arthropod borne disease in the US with 33,097 cases reported last year. In 2009 the case definition of LD was revised and nowadays the CDC differentiates in between confirmed and probable cases for this disease. Taking this into account, since 2009 Texas is the only state in the US in which the ratio of probable versus confirmed cases is repetitively 2:1. This can be attributed to many different causes, from doctors’ disregard for the disease and not testing for it or to the presence of genetically distinct Borrelia spp. and/or Ixodes scapularis vectors in Southern U.S. LD is transmitted by the bite of an infected Ixodes ticks. There are approximately 18 recognized genospecies of Borrelia that are present in ticks and make up the B. burgdorferi sensu lato complex. Only one of them has been shown to cause disease in humans in the U.S., B. burgdorferi sensu stricto, while B. garinii and B. afzelii have been proven to cause Lyme borreliosis in Europe. In addition B. spielmani, B. bissettii, B. valsiana and B. lusitane are currently under study in Europe to determine their implication in Lyme borreliosis (54). We have 3 collected ticks, the vectors of LD, from 23 counties in Texas and tested them for the presence of the bacteria pathogen, Borrelia burgdorferi sensu lato, by PCR utilizing different genetic markers (7, 27, 56, 58, 60) in order to determine what B. burgdorferi strains are circulating in Texas and how they are distributed across the state.