Relapsing fever <em>Borrelia</em> in California: a pilot serological study

Abstract

BackgroundBorrelia spirochetes are tick-borne Gram-negative bacteria that cause disease in humans and animals. Although many studies have focused on Borrelia burgdorferi (Bb), the agent of Lyme disease, recent studies have examined the role of Relapsing Fever Borrelia (RFB) in human disease. In this pilot study, we have evaluated serological reactivity against Bb and RFB in patients residing in California.MethodsSerological testing for reactivity to Bb and RFB antigens was performed in 543 patients with suspected tick-borne illness using a Western blot technique. Further evaluation of a subset of 321 patients residing in California was obtained. Serum samples were tested for IgM and IgG antibodies reactive with Bb and RFB, and samples were classified by county of residence according to Bb reactivity alone, RFB reactivity alone, and dual reactivity against Bb and RFB. Seroreactivity was ranked in counties with the highest absolute number and the highest prevalence of positive samples.ResultsOf the 543 total serum samples, 32% were positive for Bb, 22% were positive for RFB, and 7% were positive for both Bb and RFB. Of the 321 serum samples from patients residing in California, 33% were positive for Bb, 27% were positive for RFB, and 11% were positive for both Bb and RFB. In the California cohort, the highest rates of positive serological testing for Bb were found in Santa Clara, Alameda, and Contra Costa counties, while the highest rates of positive serological testing for RFB were found in Santa Clara, Alameda, Marin, and San Francisco counties. The highest rates of dual reactivity against Bb and RFB were found in Contra Costa, Alameda, and San Francisco counties. Among the 24 counties with patients who were tested, Bb seropositivity alone was found in four counties, RFB seropositivity alone was found in two counties, and seropositivity for both Bb and RFB was found in 14 counties.ConclusionResults of this pilot study suggest that seroreactivity against Bb and RFB is widespread in California, and dual exposure to Bb and RFB may complicate the diagnosis of tick-borne disease. Greater awareness of RFB and broader screening for this tick-borne infection is warranted.

Lyme Disease: Diversity of Borrelia Species in California and Mexico Detected Using a Novel Immunoblot Assay

“…Although the ecology and epidemiology of RFB in Africa is well described [13], advances in molecular testing led to widespread identification of Borrelia spp. in human specimens, thus challenging prevailing thought regarding geographic distribution and prevalence of RFB infection [15]. For example, a recent study reported that approximately 23% of a cohort of 301 patients in Russia with confirmed Borrelia infection demonstrated positive molecular testing for B. miyamotoi [31].…”

“…The genetic diversity of Borrelia spirochetes, as well as the symptoms of infection that are as diverse as the organisms causing them, makes it challenging to diagnose Borrelia-associated disease [15,43]. It is important to recognize that classification is a human concept and the organisms encompassing the genus Borrelia fall within a continuous spectrum of organisms rather than into well-defined genetically distinct groups that are easily categorized.…”

“…The CDC case definition for LD is narrowly drawn and the laboratory criteria needed to qualify as a positive case are rigid [63]. Commercial serological tests are based on antigens of just one Bbss strain, B-31, and this test protocol is, therefore, not capable of detecting antibody reactivity to Borrelia species and strains that lack cross-reactivity with B-31-a limitation that excludes detection of many Borrelia pathogens [1,15,43].…”

“…RFB infection should be considered a major public health concern. Individuals infected with RFB can develop flu-like symptoms such as recurrent fevers, arthralgias, myalgias, headaches, and nausea, as well as more severe symptoms, such as central nervous system involvement [14,15]. Patients infected with certain RFB species such as B. miyamotoi are said to exhibit more significant symptoms than patients with Bbsl infection [14].…”

“…Diagnosis and reporting of LD cases is based on insensitive serological detection of Bbss infection, and it fails to take into account the genetic diversity of spirochetes capable of causing LD and LD-like illness [1,[20][21][22]. Although research into the diagnosis and treatment of RFB infection is limited in scope, a recent pilot study suggested that seroreactivity against both Bbsl and RFB could be widespread in California, thus complicating the diagnosis of LD in that state [15].…”