There are numerous issues with testing and diagnosis.
According to a recent review "a major obstacle is that only 30% of the patients report a history of tick bite and only 70–80% present with a primary erythema migrans, the pathognomonic (diagnostic) initial lesion. This lesion may go unrecognized, or be mistaken for an 'insect bite' or an 'allergic rash'. Mini-erythema migrans are less likely to be diagnosed". The situation is more complex in Scotland as in a recent study, "the low number of patients with EM (48%) was surprising and is much lower than that documented in other studies (69.1 to 89.3%)." and "only 61% of patients could recall having a tick bite".
Diagnostic tests are therefore relied on. However, these are unreliable. According to Lyme Disease Action (certified by the Information Standard run by NHS England), “there are no conclusive tests for Lyme disease currently in routine use in the UK that will accurately diagnose Lyme disease or distinguish active from past infection.”
According to Scottish doctors, "traditional two-tier (enzyme immunoassay [EIA] screening and Western blot confirmation) testing for the laboratory diagnosis of Lyme borreliosis (LB) is expensive, lacks sensitivity in the diagnosis of early LB, cannot distinguish between current and past infection and cannot be used as a marker for treatment response".
According to Trinity Biotech, one manufacturer of tests for borrelia, "patients in the early stage of disease and a portion of patients with late manifestations may not have detectable antibodies."
In a recent meta-analysis, it was found that "sensitivity of an individual test was as low as 7.4%. The mean sensitivity of all test kits with all samples was 59.5%, and ranged from 30.6% to 86.2%". In a related study, it was found that "using clinically representative LD test sensitivities, the two-tier test generated over 500 times more false-negative results than two-stage HIV testing."
In addition, immune response in European patients has been found to be undulatory and so test results can be negative during infection. Findings of a recent study "disprove that all patients with LNB develop positive serum Borrelia antibodies within 6 weeks after infection".
Doctors therefore need to be able to recognise a collection of symptoms of Lyme disease, many of which mimic other illnesses, with or without an erythema migrans rash and with or without positive serology.
Recent research on a Lyme antigen test which uses urine instead of blood and which does not depend on the presence of antibodies has shown great promise. A commercial Lyme antigen test, described as "a game changing tool for Lyme disease diagnosis", is now available in Europe but is not yet available to Scottish patients.
Scottish Testing was More Limited in the Past
The Scottish Lyme Reference Laboratory at Raigmore has put much effort into improving testing in Scotland. However, according to a recent Scottish paper, “initially, an in-house Western blot incorporating reference strain B. burgdorferi sensu stricto was used, followed by a local B. burgdorferi sensu stricto and B. afzelii antigen (50:50) mix in June 2007. ... There was a significant change in testing protocols in July 2012. The in-house Western blot was replaced with CE marked commercial assays (EU Lyme IgG Western blot, Trinity Biotech or Recomline Lyme IgG, Mikrogen)”.
Tests are not Available for all Species of Borrelia
The Chief Medical Officer (personal letter from November 2016) advised that, "in a study, 8% of ticks from 25 sites across Scotland were identified as being infected with B. valaisiana, however, the majority of genospecies were B. afzelii (48%) and B. garinii (36%)". It is not known how prevalent the more recently identified borrelia miyamotoi is but it has been identified to exist in Scotland.
The Chief Medical Officer also stated that "Raigmore Hospital ... carried out an internal audit by comparing five commercial and one in-house immunoblot method which identified the Mikrogen assay as the most effective and accurate immunoblot. This is the assay which is currently being used and can detect antibodies to B. burgdorferi sensu stricto, B. afzelii, B.garinii, B.speilmanii and B.bavariensis."
So, testing in Scotland was initially limited to only borrelia Burgdorferi and borrelia afzelii. Although the recent tests used includes borrelia garinii, current testing does not include borrelia valaisiana or borrelia miyamotoi. As borrelai valaisiana has a prevalance of 8% in ticks in Scotland, and the prevalence of borrelai miyamotoi is unknown, at least 8% of infections and possibly much higher could be missed.
Tests are not Available for all Tick-Borne Co-infections
The situation is complicated because ticks can transmit multiple infections, which many patients have. There are no tests which cover all species of bartonella, babesia, and other tick-borne co-infections. A recent study in cats showed multiple species of borrelia and babesia in attatched ticks.
Lyme Disease can be Misdiagnosed
Given the unreliability of testing and the undulatory nature of immune response, it is very easy for Lyme Disease to be misdiagnosed. The Lyme Disease Action charity provides a long list of differential diagnoses.
Lyme Disease has also been controversially linked as a potential cause for numerous diseases, including Alzheimer's Disease (AD), Motor Neuron Disease (also known as Amyotrophic Lateral Sclerosis), Multiple Sclerosis, and others.
A number of studies have shown that "Borrelia burgdorferi persists in the brain in chronic lyme neuroborreliosis and may be associated with Alzheimer disease." In another recent study, researchers duplicated previous findings that demonstrate "that the plaques, which are characteristically found in AD brains, reveal the presence of biofilms. These biofilms are undoubtedly made by the spirochetes present there; further, we have also found that the biofilms co-localize with the β amyloid that is a signature finding in the disease". A recent meta-analysis showed "a strongly positive association between bacterial infection and AD".
A recent paper is one of a number which link Amyotrophic Lateral Sclerosis to borrelia infection, reporting on "Lyme disease -induced polyradiculopathy mimicking amyotrophic lateral sclerosis."
It has been hypothesised that "Chronic Lyme borreliosis [is] at the root of multiple sclerosis – is a cure with antibiotics attainable?"
A recent article found "association between infectious burden and Parkinson's disease", including Borrelia burgdorferi amongst other infections. Subacute parkinsonism has recently been found as a complication of Lyme Disease.