Some people still think of China as the country of cheap gadgets such as LED lights, while they think of the US and Europe as the shining example of scientific and technological innovation and quality. But make no mistake, China has started taking a great leap forward years ago. For instance, some Chinese research labs have more DNA sequencers than the whole of Europe together. And more importantly: China is progressively developing its own direction, unhindered by commercial interests and outdated wisdom of “authorities”, that increasingly restrict the advancement of science – and especially health care – in our part of the world.
Lyme disease is a growing problem in China as well. After Chinese researchers applied themselves to the criteria for interpreting the Lyme Western Blot (1) a number of years ago, they now seem to anticipate a bigger step forward. The fact that Lyme serology does not suffice, is openly admitted in China, and consequently, they develop something better instead of pretending that everything is alright, like we do … Over there, PCR has been used in Lyme research for years, but Lyme is predominantly a problem in the “outlying areas”, far away from the big cities, where there are often no modern laboratories with the latest equipment to provide fast and reliable diagnostics. For that reason, the Chinese CDC has explored a new PCR technique for Lyme diagnostics that requires a minimal amount of equipment (and is thus profitable for even the smallest labs), is very easy to use and even delivers the results within an hour (2). This so-called LAMP-PCR does not standardly use DNA sequencing confirmation, like some of the latest Borrelia PCR tests, but it does not necessarily have to, when the test has been thoroughly validated beforehand and you know that it does not produce false positives.
The new LAMP-PCR was compared to serology (IFA + Western Blot, similar to the two-step protocol that we also use) and to a standard nested-PCR test for Borrelia. They reviewed whether the PCR tests were able to detect the most important Borrelia species – the same as ours – and whether a number of well-known co-infections produced false positives. People who went to a rural clinic – tick bites are a common problem in the countryside – with symptoms that may indicate Lyme were tested using both serology and PCR. All positive results in the PCR tests were sequenced to ensure that there were no false positives. Of the 118 possible Lyme cases, 24 were confirmed using serology. Of those 24 seropositive cases, 9 were also detected using the PCR tests, but PCR additionally found 12 infections in patients who were serologically negative. We have seen similar results in other studies for both early and late Lyme, for example in the publications of Sin Hang Lee (3,4). Of the cases that were serologically positive, only a portion showed up positive using PCR (sequencing), but the PCR test also found a number of cases that were serologically negative and would therefore ordinarily have been diagnosed incorrectly. Since PCR + sequencing is continually involved, the standard statement from medical microbiologists and the CDC that “PCR results are false positive” is untenable here and it must be serology that is incorrect.
The ‘simple’ LAMP PCR and nested PCR by no means always yield the same result. This disparity can partly be explained because the two PCR tests employ different targets and perhaps in practice, the sensitivity of both tests could be too low to detect all cases. Opposers of PCR sometimes argue that PCR ‘is much too insensitive’ for general use. You could look at this study as confirmation of this statement, because only 9 of the 24 seropositive cases were PCR positive (sensitivity 38%, if you assume serology is the absolute standard). But what about those PCR positive and seronegative cases? In some cases, these will be very early infections, for which the antibody tests are not yet sensitive enough. But if PCR is indeed ‘much too insensitive’, the 118 possible cases must include more undetected Borrelia infections (serology false negative) than the 12 that popped up. Another interesting question: could it be that some patients who are serologically positive and PCR negative are no longer infected and the antibodies are merely a belated response to the former infection? If we continue to use indirect tests such as serology we will never find out …
The Chinese researchers see this test as a preliminary addition to serology. The low costs and speedy diagnosis make it an attractive approach. More extensive use and a detailed comparison to serology would probably yield a lot of knowledge to benefit both diagnostic techniques. Unfortunately, we fear that this type of enlightenment would not be appreciated in the West and that the IDSA, CDC and their many international supporters would continue to do their utmost to keep us in the dark regarding Lyme diagnostics.
(1) A Study of the Technique of Western Blot for Diagnosis of Lyme Disease caused by Borrelia afzelii in China
(2) Combination of Loop-Mediated Isothermal Ampliﬁcation Assay and Nested PCR for Detection of Borrelia burgdorferi sensu lato in Human Serum Samples. *
(3) DNA sequencing diagnosis of off-season spirochetemia with low bacterial density in Borrelia burgdorferi and Borrelia miyamotoi infections
(4) Detection of borreliae in archived sera from patients with clinically suspect Lyme disease.
* Note: this is not a full peer-reviewed scientific publication, but a ‘Letter to the Editor’. The description of the research is relatively scant and many details concerning the method and obtained results cannot be assessed. Nonetheless, this probably won’t be last we hear of it.
Published June 2, 2015
Aangepast: 15 maart 2016