Investigators from the Centers for Disease Control and Prevention (CDC) have reported a unique cluster of five cases of ocular syphilis linked to an unknown bacterial strain and potential systemic complications.
Let’s start with syphilis.
A sexually transmitted infection (STI), syphilis infections are currently at a 30-year high in the United States—with numbers skyrocketing tenfold since 2012 alone and 75% since 2017, according to the CDC.
If left untreated, the STI can cause ocular syphilis as well as otosyphilis and neurosyphilis, potentially, due to Treponema pallidum (a spirochete bacterium), which may infect different organs and systems including the eye, inner ear, or central nervous system.
And ocular syphilis entails… ?
Typically pain in the eyes, vision changes, and possibly blindness.
It’s also a rare disease, occuring in just 1% (usually) of syphilis infections for cases that are:
- Late stage
- In those aged 65+ years
- In immunocompromised patients such as human immunodeficiency virus (HIV)-positive or Hepatitis C
- Illicit drug use such as methamphetamines, heroin, or other synthetic drugs
Now this situation.
In its latest Morbidity and Mortality Weekly Report, the CDC detailed the identification of a cluster of five ocular syphilis cases among women in southwest Michigan during March to July 2022.
The connection: all women had the same male sexual partner.
Yikes. So how was this investigated?
State public health officials took action by:
- Launching a case investigation
- Notifying the female partners
- Referring patients to a public health clinic for:
- Diagnosis and treatment
- Hospital care
- Sample collection
Tell me more about these women.
All diagnosed with early syphilis, the women were:
- Between 40 and 60 years of age (mean = 49)
- Non-Hispanic White race
- HIV negative
- Hospitalized with intravenous (IV) penicillin
And their symptoms?
- Patient #1
- Referred following a reactive treponemal antibody test result
- Reported blurred vision, fear of blindness
- Patient #2
- Identified following hospital admission for neurosyphilis; identified by ophthalmologist noting cranial nerve abnormalities
- Reported headache, mild hearing loss, worsening blurry vision and double vision
- Patient #3
- Referred following reactive syphilis test
- Exhibited full body rash and peeling skin on palms of hands; reported floaters and photophobia
- Identified as having cranial nerve abnormalities
- Patient #4
- Identified following referral for worsening vision.
- Patient #5
- Identified following ophthalmology clinic evaluation for visual floaters, seeing flashing lights, and worsening vision after cataract surgery 3 months prior.
- Received reactive treponemal test result
- Admitted to hospital for neurosyphilis and ocular syphilis
See here for additional details.
Any other cases identified?
A sixth patient was identified in April 2022 who was later determined to be unrelated to the five cases due to no sexual link.
And this male partner?
The CDC reported that the man was diagnosed with early latent syphilis, never developed ocular syphilis, and did not report any visual or hearing impairment. He was treated with an IV penicillin following diagnosis.
Additionally—and this is important—syphilis molecular typing wasn’t possible due to a lack of genetic material in limited specimens.
Gotcha. Now talk about this bacterial strain.
While the CDC reported that this strain of T. pallidum may be associated with an increased risk for systemic manifestations of syphilis, the aforementioned “lack of genetic material” prevented molecular typing to more accurately determine this specificity of the specimen.
Translation: the strain will remain unidentified due to not enough material for testing.
So what happened after these cases were identified?
The agency reported that “no additional transmission was identified after the common male partner’s treatment” and that no other “ocular syphilis patients with sexual linkages to others who also developed ocular syphilis” have been identified in Michigan since this investigation.
Why?
The bacterial strain may have stopped circulating after all patients were treated, the CDC suggested.
However, “without cluster-specific or wider geographic T pallidum molecular typing surveillance,” that hypothesis can’t be confirmed.
Gotcha. So what preventative measures can be taken for the future?
When diagnosing ocular syphilis (plus otosyphilis and neurosyphilis), the agency recommended disease surveillance + intervention, early diagnosis, and treatment can prevent systemic complications like vision loss as well as proactive ophthalmic evaluation for syphilis patients with ocular complaints.