Health & Hype: On Sexually Transmitted Lyme disease
By Keith Berndtson, MD
This January, a research abstract on Lyme disease made the news. The abstract was one of dozens presented at the Western Regional Meeting of the Journal of Investigative Medicine in December 2013. (1)
The research focused on a simple question: could Lyme disease be sexually transmitted? Sexual transmission means that the same specific organism found in the index patient will be found in the monogamous intimate partner of the index case. There must be evidence that the partner could only have been sickened by the index case and that absence of a tick bite, ECM rash and antecedent flu-like illness is documented. The intimate partner must be known to have a negative Western blot before contact with the index case and the cases of both index and partner cases must meet published peer-reviewed criteria for a confirmed case of acute Lyme disease.
As a first step, using a study design that involved people rather than mice or other rodents, researchers attempted to culture living Lyme organisms (Borrelia burgdorferi) from the genital secretions of patients and from partners of people with a history of Lyme disease. Three subjects with a history of Lyme disease were enrolled in the study. They transferred vaginal secretions from the two women, and semen from the one man, into culture media known to encourage the growth of Lyme spirochetes.
The cultures grew intact, viable, motile spirochetes. DNA sub-typing confirmed that these organisms were indeed the feared Borrelia burgdorferi — the cause of Lyme disease. The answer to the first part of their research question was yes, it is possible to culture viable Lyme spirochetes from the genital secretions of women and men with a history of Lyme disease. The illness status of these three patients was not revealed to us, so we don’t know if they had Lyme disease at one time or if they still had Lyme disease when in this study.
One would think that presence of viable Lyme spirochetes in the three cases would mean the patients who hosted these organisms were still ill, but that vital bit of data is not presented.
Unfortunately, the next step, one necessary (but not sufficient) to show transmission of Lyme through intimate contact, was not done. We would want to see development of Lyme in the intimate contacts of the cases, followed by isolation of the exact same Lyme organism from the intimate partner as was found in the index case. The absence of prospective confirmation of illness in intimate cases ends all scientific discussion in this study about existence of transmission of Lyme through intimate contact alone.
Does this study show that intimate contact can spread Lyme disease? No. The data collected in the study don’t show us anything about transmission.
Let’s face it: transmission is the momentous, highly charged question. It will take many more steps, including replication of this preliminary study and a series of more advanced studies, to answer that one. Let us remember the work of Dr. Robert Koch, father of causation in microbiology, as his Postulates detail how to show proof of transmission.
Let’s look at a linked series of questions that might be asked using a rodent model of Lyme. What would happen if we injected some of those cultured spirochetes into mice? Would they survive? If so, could they find their way into the bellies of lab-reared sterile deer tick larvae? If that happened, would the spirochetes survive as the larval ticks morph into nymphs? And if by feeding on a fresh mouse, would those infected nymphs be able to transmit those spirochetes from the mid-gut of the nymphs into the mouse? If all that were so, would that mouse develop an infection with significant inflammatory disease caused by those spirochetes?
That gives you an idea of the preliminary work needed to answer the momentous question.
Yet an irresponsible press release led the media and then the public to believe that the transmission question had been answered. Worldwide news coverage falsely implied that a recent study had found that Lyme disease can be sexually transmitted. And it didn’t take long before Lyme sites on the Internet trumpeted sexual transmission of Lyme disease was confirmed.
The press release failed to make clear that the study had answered only a preliminary question with limited implications. The giant question that would likely change feelings about intimate contact for million of people with Lyme disease and their loved ones around the world remained unanswered.
The abstract's conclusion contains just one frightening sentence: “The culture of viable B. burgdorferi in genital secretions suggests that Lyme disease could be (emphasis added) transmitted by intimate person-to-person contact.” This statement is unfounded in science, and does not meet any acceptable research standard. Scientists are expected to clarify when their research study findings are preliminary and tell us that further study is indicated.
The press release, however, contained a quote from a study author that sensationalized their preliminary finding in a way that might leave those with a history of Lyme disease wondering if they could ever have intimate relations with a clear conscience. Here’s that quote: “There is always some risk of getting Lyme disease from the woods. But there may be a bigger risk of getting Lyme disease in the bedroom.”
That researcher, if challenged on those words, might understandably defend use of the term “may be, “just as the abstract used the term “could be.” Technically, neither the abstract nor the press release ever claimed that Lyme disease is sexually transmitted, yet left that possibility open.
While they could be congratulated for establishing a preliminary finding on the matter in three patients, they failed to include key caveats, such as:
1. No peer-reviewed studies in rodents or other mammals have ever found credible evidence to show that infectious Lyme spirochetes are sexually transmitted.
2. We don't know how inoculation from an infected tick would compare to passive transmission via intimate contact. But we’re sure that intimate contact would include no tick salivary proteins to protect sexually transmitted spirochetes from the immune system of their new host. For Borrelia species, the immune evasion advantages of tick salivary proteins are well documented. (2)
3. It is a law of microbiology that viability does not equal infectivity or virulence. If it’s possible to transmit viable Lyme spirochetes via intimate contact, perhaps spirochetes transmitted this way might only be able to cause infection in a host with a serious form of immune compromise.
4. If sexual transmission of Lyme disease were common, the prevalence of Lyme disease would be orders of magnitude higher than it already is, based on known transmission by blood-sucking arthropod vectors, yet the epidemiological data on Lyme disease do not support the idea of “sexually transmitted disease.”
As a result of the press release and the broad media coverage it generated, doctors must now allocate precious appointment time to addressing patients' fears about sexually transmitted Lyme disease.
The authors tossed a scary sound bite to the media, whose members took to it like a cougar to red meat: “Coming up after the break: Can you get Lyme disease in the bedroom? Stay tuned.”
We owe the media and the public an accurate rendering of the complexities of Lyme disease. We need top-notch research to answer the question regarding its potential transmission through intimate contact, and we need top-notch science communication skills to guide the public when such momentous implications are at stake.
Thanks to Patti Schmidt and Ritchie Shoemaker MD for comments and review of this manuscript.
- http://afmr.org/archives/2014/files/WRM-2014-Abstracts.pdf (scroll down to the bottom right of page 280 to read the abstract).
- Berndtson K. Review of evidence for immune evasion and persistent infection in Lyme disease. International Journal of General Medicine. 2013:6; 291-306. http://www.dovepress.com/review-of-evidence-for-immune-evasion-and-persistent-infection-in-lyme-peer-reviewed-article-IJGM
The first medically identified patient in a family or other group, with a particular condition, often an infection, which triggers a line of investigation.
Robert Koch established four criteria to identify the causative agent of a particular disease:
1. the microorganism or other pathogen must be present in all cases of the disease
2. the pathogen can be isolated from the diseased host and grown in pure culture
3. the pathogen from the pure culture must cause the disease when inoculated into a healthy, susceptible laboratory animal
4. the pathogen must be re-isolated from the new host and shown to be the same as the originally inoculated pathogen