The Epidemiology of Lyme Disease and Bartonellosis in Humans and Animals

The expansion of vector borne diseases in humans, a variety of mammalian hosts, and arthropod vectors draws attention to the need for enhanced diagnostic techniques for documenting infection in hosts, effective vector control, and treatment of individuals with associated diseases. Through improved diagnosis of vector-borne disease in both humans and animals, epidemiological studies to elucidate clinical associations or spatio-temporal relationships can be assessed.;Veterinarians, through the use of the C6 peptide in the SNAP DX test kit, may be able to evaluate the changing epidemiology of borreliosis through their canine population. We developed a survey to evaluate the practices and perceptions of veterinarians in North Carolina regarding borreliosis in dogs across different geographic regions of the state. We found that veterinarians' perception of the risk of borreliosis in North Carolina was consistent with recent scientific reports pertaining to geographic expansion of borreliosis in the state. Veterinarians should promote routine screening of dogs for Borrelia burgdorferi exposure as a simple, inexpensive form of surveillance in this transitional geographic region.;We next conducted two separate studies to evaluate Bartonella spp. bacteremia or presence of antibodies against B. henselae, B. koehlerae, or B. vinsonii subsp. berkhoffii in 296 patients examined by a rheumatologist and 192 patients with animal exposure (100%) and recent animal bites and scratches (88.0%). Among 296 patients examined by a rheumatologist, prevalence of antibodies (185 [62%]) and Bartonella spp. bacteremia (122 [41.1%]) was high. In the population exposed to animal bites and scratches, we documented Bartonella spp. seroreactivity or bacteremia in 49.5% (n=95) and 23.9% (n=46) of the patients, respectively. In both studies, serology, in conjunction with blood, serum, and BAPGM enrichment culture PCR, facilitated the diagnosis of Bartonella spp. bacteremia. Patients in both studies frequently reported symptoms including fatigue, sleeplessness, joint pain, and muscle pain. However, neither study can establish a causal link between Bartonella spp. infection and these symptoms in our populations. In our rheumatology population, B. henselae bacteremia was significantly associated with prior referral to a neurologist, most often for blurred vision, subcortical neurologic deficits, or numbness in the extremities, whereas B. koehlerae bacteremia was associated with examination by an infectious disease physician. The contribution of Bartonella spp. infection to these symptoms should be systematically investigated.;Due to low levels of bacteremia in nonreservoir-adapted hosts, which result in diagnostically low levels of circulating bacteria in the bloodstream at a given point in time, Bartonella detection at a single time point may result in false negatives. Therefore, we next sought to determine if the testing of specimens collected serially over a 1-week period significantly improved PCR documentation of Bartonella bacteremia in human patients compared to the testing of specimens from a single time point. Detection was improved when patients were tested three times within a one week period (OR = 3.4 [1.2-9.8]; p = 0.02). Obtaining three sequential blood samples during a one-week period should be considered as a diagnostic approach when bartonellosis is suspected.;Finally, based upon the established oncogenic properties of Bartonella, we hypothesized that Bartonella spp. can be molecularly detected in canine cutaneous histiocytoma (CCH) and can be localized within skin neoplasms using indirect immunofluorescence (IIF). There were no significant differences in the prevalence of Bartonella spp. between our CCH group and controls (p=0.63), and Bartonella was identified in only 2/4 (50.0%) CCH tissues using IIF. Bartonella spp. are unlikely to cause CCH. Though Bartonella can be visualized in CCH using IIF, cellular localization of Bartonella within the skin has reduced sensitivity due to low organism load, a limitation well-supported by previous attempts by our laboratory to localize the bacterium in various tissues and lesions.