Lyme and associated tick-borne diseases: global challenges in the context of a public health threat
Lyme disease, caused by Borrelia burgdorferi and transmitted by ticks, was initially considered a recent, rare and regional occurrence. We now have evidence that very similar bacteria infected humans in Europe during the ice age (Keller et al., 2012). Evidence-based data are scarce therefore many aspects of the disease remain controversial (Auwaerter et al., 2011; Lee and Vielmeyer, 2011; Perronne, 2012), but in 2013 the Centers for Disease Control and Prevention (CDC) revised their annual estimates from 30,000 cases to 300,000 cases in the USA alone. Having dramatically increased their numbers, the CDC are now calling Lyme disease “a tremendous public health problem in the United States” (CDC, 2011).
The lack of a gold standard for diagnosis makes producing accurate statistics difficult. Some pathogenic strains belonging to the B. burgdorferi sensu lato complex have a worldwide distribution, yet they are rarely considered or tested for (Varela et al., 2004; Lopes de Carvalho et al., 2009; Rudenko et al., 2009; Stanek and Reiter, 2011; Branda and Rosenberg, 2013; Clark et al., 2013; Lee et al., 2014; Margos et al., 2014). Borrelia miyamotoi, for instance, phylogenetically close to relapsing fever borreliae, is now recognized as a cause of Lyme-like disease and relapsing fever in Asia, Europe and North America. It usually does not cross react with B. burgdorferi tests (Branda and Rosenberg, 2013; Lee et al., 2014). A novel isolate of Borrelia has been isolated by PCR in a post-treatment serum from a patient with neurologic Lyme disease (Lee et al., 2014).
These recent historical, geographical and microbial data should prompt the medical community to realize that cases of persisting post tick-bite syndromes are probably due to multiple pathogens and that these occult infections will require a new approach if not an actual paradigm shift.