Here's a fun case for us this week from my technical specialist, Emily Fernholz. The following objects were seen on a Giemsa-stained thick film from a patient with recent travel to the Western United States. Diagnosis? What additional testing would you recommend?
9 comments:
Relapsing Fever spirochetes--Borrelia sp.
Relapsing fever Borrelia, depending where in the Western United States will depend on the likely species, but B. hermsii is the most widespread versus B. parkeri, which is more constrained to the further southwest states.
I wonder if there is more history to this. Did the hiker sleep in a back-country cabin? It is unlikely to have been contracted during the hike itself due to the nature of how Ornithodorus feeds.
Nice pictures!
Tickborne Relapsing Fever - Possibly Borrelia hermsii carried by soft ticks. Spirochetes are more commonly seen in blood films with this species than with Borrelia burgdorferi.
Every time I hope being the first respondent, it turns out some folks already gave me the blessing of their answer. For sure when we perform a Giemsa blood smear exam, we may be lucky to find something other than a parasite, it may be bacterial or fungal. Such is our fortune as this case gives us a chance to see Borrelia spirochete as we may not see it in the South Eastern United States.
Unlike the other hard tick borne vectors, this is a soft tick or louse transmission.
Thank you Dr. Pritt for this reminder. We don’t see much of this in Florida.
Florida Fan
As far as further testing I would probably look at dark field microscopy and maybe a Lyme disease serological test just because I’m interested in what it would show.
Lyme serology will be predictably positive on the ELISA/CIA screen and +/- on the immunoblot if the patient has relapsing fever Borrelia infection. Lyme serology is not recommended in this clinical scenario, as the Lyme Borrelia are rarely found in fluids (blood, CSF, synovial fluid) and tend to be more tissue tropic than the RFB counterparts (bite site, synovium lining tissue, tissue within the CNS). We offer PCR from blood for relapsing fever and it is a great tool. If you see it in a blood smear it will be easily detected by PCR. The serology will just put you down a rabbit hole and a false assumption of Lyme could be the result. Lyme PCR from blood is only ~20% sensitive as well.
For clinical purposes, serology may not be recommended, but for curiosity's sake, I find it interesting.
Another nice fact to know is that -in contrast to malaria- the number of bacteria in the blood are highest on a peak of fever in case of RFB! So if the first thick BF of a suspected case turns out to be negative, it’s worthwhile making sure to have a sample on a fever peak in this case.
Not sure what it is, but a thin film couldn't hurt?
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