The Possibility We Can’t Ignore
Lyme disease is already a mess of controversy, but there’s one question that hasn’t gotten nearly enough attention: Could it be sexually transmitted?
For years, we’ve been told that Borrelia burgdorferi, the bacteria behind Lyme disease, is spread only through tick bites. But there’s a big problem with that assumption—over half of Lyme patients in my practice don’t recall a tick bite or even tick exposure. And if you talk to enough patients, you start to see a pattern: entire couples or families dealing with chronic Lyme symptoms, even when only one person ever remembers getting a tick bite.
So, if Lyme is purely a tickborne illness, how do we explain that?
The truth is, we don’t have all the answers. But there’s enough evidence to warrant serious investigation into sexual transmission—and if you or your partner is struggling to recover despite treatment, it might be time to consider testing both of you.
Why the Suspicion?
There are a few reasons researchers have questioned whether Lyme disease could be passed through intimate contact:
- Lyme bacteria are spirochetes – the same shape as Treponema pallidum, the bacteria that causes syphilis (which is sexually transmitted).
- Borrelia burgdorferi has been detected in semen and vaginal secretions of Lyme patients in some studies.
- Several animal studies suggest it may be possible, though results vary between species.
- Too many patients don’t recall a tick bite, yet test positive for Lyme disease—and some are in areas where Lyme-carrying ticks are supposedly rare.
What Does the Research Say?
The evidence isn’t conclusive, but it’s enough to raise serious questions:
- Animal Studies: Some research shows that infected male mice can pass Lyme bacteria to female mice during intercourse, and a study with dogs found Borrelia in semen. However, other studies in rats and hamsters didn’t show the same results.
- Human Studies: Some small studies have found Borrelia in the genital secretions of Lyme patients, but detecting bacteria doesn’t automatically mean it can spread that way. However, one study found Borrelia in both partners of a couple, despite only one having a known tick bite.
- The Epidemiological Gap: Many Lyme patients—especially in non-endemic areas—have no recollection of a tick bite. If it’s not from ticks, what’s the explanation?
Why This Matters for Patients
The big takeaway here is that sexual transmission may be playing a role in Lyme disease persistence and reinfection, and we don’t have enough research to say for sure one way or the other. If you’re not improving on treatment, your partner should be tested, too.
Consider this: If Lyme bacteria can live in genital secretions, untreated partners could be a source of reinfection, much like we see with other bacterial infections. Infections like H. pylori (which causes stomach ulcers) and even Chlamydia often require both partners to be treated to prevent reinfection. Why would Lyme be any different?
We Need Urgent Human Research
The potential for Lyme to be sexually transmitted isn’t just an academic question—it’s a public health issue. If this is happening, even in a subset of cases, it could completely change how we diagnose, treat, and prevent Lyme disease.
At the very least, we need:
- Larger studies on couples where only one partner has a known tick bite.
- Better testing on bodily fluids to determine if live bacteria can be transmitted this way.
- Investigation into why so many patients don’t remember a tick bite and whether sexual contact could explain those cases.
What Should You Do Now?
While the debate rages on, here’s what you can do:
✔️ If you have Lyme and aren’t improving, consider testing your partner.
✔️ If your partner has symptoms, don’t assume it’s something else.
✔️ Support research efforts to answer this question once and for all.
For now, tick prevention is still the main focus—but if science continues to uncover new routes of transmission, the Lyme conversation could be about to change in a big way.