Cyclosporiasis with Dr. Derek Larson

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Hello, I'm Commander Ann Long, and welcome to another episode

of the GSAP podcast. In this episode, I'll be interviewing

Dr. Derek Larson, a Navy infectious disease physician and

current program director of the Infectious Disease Fellowship at

Navy Medicine Readiness and Training Command San Diego, Dr.

Larson attended medical school at Lake Erie College of

Osteopathic Medicine at Seton Hill, and completed his

residency in internal medicine at Naval Medical Center

Portsmouth. He then went on to complete his infectious disease

fellowship at NMRTC San Diego in 2018. His previous duty stations

include Fort Belvoir Community Hospital in Virginia and First

Medical Battalion at Camp Pendleton, California. He has

traveled to multiple countries, practicing in Honduras, Ghana,

Haiti, and Djibouti. Today, we'll be talking about the

recent cyclospora outbreak and what military emergency

physicians need to know about recognizing and managing the

disease. Thanks for listening. Hi, everybody. Welcome to this

episode of the GSA ASEP podcast. I'm Dr. Ann Long, your host, and

today I have Dr. Derek Larson. Welcome to the podcast.

Oh, thanks for having me. All

right. So today's topic is the lovely Cyclospora, which has

been a lot in the news recently. For our first question, for the

ER physician who hasn't thought about cyclospora since probably

med school or residency, what is it, and why are we talking about

it right now?

Yeah, yeah. So why are we talking about it right now? And

it's funny. I was thinking about this last night and trying to

prepare for this. And actually, last time I was doing an

interview about this, it was also about diarrhea. So

personally, it's very on brand for me, I guess. But the yeah,

cyclospor itself is an interesting little prozoan

parasite that seems to have made the news a bunch recently, and

it's kind of it shows up every year. But this year has been

fairly remarkable, and so yeah, I think it's really nice that

the the podcast is picking it up because when we send out these

news alerts from public health authorities, right, the whole

purpose is to remind ourselves of things that that wouldn't

normally part of our diagnostic or or management algorithms. So

yeah, I think it's a really good idea you guys covered this.

Yeah, yeah, for sure. So, what's happening right now with the

current cyclospora outbreaks, and then you know what what is

unusual about this year's? The

interesting thing is that obviously, if I give numbers,

they continue to evolve. But currently, we're sitting at just

under about 17,000 cases statewide. About 900 of them

have been hospitalized, and and currently we're only sitting at

two deaths. So, so that's I guess at least a favorable

ratio. Although zero would of course be better. When when we

look at this current outbreak, we're we're sitting at about

11,000 just from that single source that everybody has been

seeing in the news, and the rest of them have come from a couple

of other sources. But when when you look at how this sets it

apart, I think last year we had about 1,800 cases statewide, or

not statewide, countrywide, and and the last peak we had was

about 2019, which was just shy of 5,000 proven cases. So,

sitting at 18,000 now, and and that number is still going to

change because last I checked with the CDC, there was still

about 11,000 under investigation, so I don't know

which way those are going to go. But yeah, the numbers are still

going to change a bit.

It's definitely a lot more than those previous years. Moving on

to how these patients would come into the ER, what should trigger

an ER doc to think that this might be cyclospora instead of

like the normal viral gastroenteritis.

Yeah, that's a that's a tough one. I was trying to shift my my

mentality away from being an ID doc to being you know lines of

the ED. It's a little easier after they've seen three or four

people before they get to me.

Yeah, but yeah,

the overlap is is significant, and the the closest thing that I

think we. We're used to thinking about would be another protozoan

of Giardia, where you know if they're presenting like we

normally think of that with kind of the more abdominal pain,

lower intestinal symptoms, bloating, flatulence, copious,

watery diarrhea, that moves a little bit more into the the

cyclospora world. Although the overlap with VGE is is

definitely there because they can show up a couple of days

after an exposure, they can show up a couple of weeks after an

exposure. Some of the VGEs have a you know four to five day

incubation period. Sapa virus, astroviruses. So yeah, that that

world is definitely gray, and and not everybody comes in

saying right. I think I was exposed to lettuce that was part

of this outbreak. I know. I

mean, I can't even really remember what I ate this

morning, so you know, it's it's difficult for people sometimes.

Yeah, yeah, and and you know, if any of my fellows are listening,

or anybody gets a tricky board question where they mention like

cilantro or raspberries-that's like your board style question.

But like you're saying, people people see other people every

day and are exposed that way, and people tend to eat multiple

times a day. So it's really hard to parse down a particular

exposure that that would really send off the radars here. But

yeah, again, kind of that Giardia esque presentation would

start moving me in in that category.

So that kind of goes through a little bit of like the

cyclospora presentation. So I'll move on to the next question,

which is how important is the duration of diarrhea, and what

point does gastroenteritis become? This may need a little

bit more evaluation.

You know, classically, the cyclosporine is going to last

for weeks, if not a couple of months, if untreated in your

even immunocompetent patients. So certainly, if someone is is

showing up after you know a week or two, when most of BGEs or

even bacterial gastroenteritises would have passed, and now

you're starting to get into that world again. Of is it Giardia or

is it like a non-infectious? Is it IBDs? Is it IBS? Is it things

over in GI world for the more kind of subacute to chronic? I

would start to add that into the differential, especially in in

what we call cyclospora season, which I don't know if everybody

celebrates, but it's it's between May and August

typically, unless there's a big outbreak like this.

Say we've worked up the patients, or you know now

they're kind of more into their illness. Who tends to be sick

enough to require hospitalization? And then, is

there any special treatment for any immunocompromised people,

you know, thankfully the the average human doesn't tend to

get sick enough from this to warrant hospitalization. Now,

some could be quite miserable with that that copious and

especially urgent diarrhea. They're they're certainly not

happy, but usually able to keep up with the fluids because

there's not as much of a nausea and vomiting component to it is

is some of the other GI bugs, but folks who who really are

kind of behind on the cellular immunity side of things because

it's a it is an intracellular pathogen. So you think about

advanced HIV into AIDS territory. You think about your

transplant patients, either solid organ or bone marrow, or

someone on an immunosuppressive in that realm, maybe moving into

the realm where they're going to be at risk for higher disease. I

do have to give a shout out to to modern antiretrovirals.

You'll see a lot of the old studies about HIV patients, but

you know, with the modern therapy, they're actually not as

immunocompromised, assuming they're on the therapy, as they

were back when they did the studies with cyclosporin HIV in

the '90s and the '80s, so that that data needs a little bit of

a critical review. But yeah, overall, still about 5% of

symptomatic folks are are hospitalized. There's probably,

depending on the cohort, you know, up to 40% are

asymptomatic. So not everybody even gets disease. Thankfully, a

lot of people will eventually clear it, but I'm not. I'm not

expecting to see too many inpatients with it.

That's pretty reassuring. When should ER docs actually order

stool testing? And does the traditional ONP exam reliably

detect cyclospora?

Another very complex question, and I'm sure a lot of the

different society guidelines are, of course, going to vary on

this. And there's a lot of nuance to these conversations.

But I group it into two things, right? If someone's getting

hospitalized, running all the tests to see kind of what we're

what we're treating there, because obviously you're going

to treat protozoans different from Shigella and Entech, and

either norovirus or even community-acquired C diff or

antibiotic-associated C diff, right? If they're that sick, I

think running the the tests on them is very fair. And then if

there's an ongoing outbreak in the community and you need it

for public health purposes, or they think they have an

exposure, someone in the house, someone in the school, someone

at work, someone in the. Same unit has something that they

want to know about. That seems very reasonable. I do think in

the the modern era of PCR, we're we're over testing a little bit,

but I think we may chat about that later.

Yes, little preview there. Thanks. Yeah, yeah,

no problem. I did try to study for this a little bit. And the

the traditional OMPs to answer that question very directly are

not going to detect this. They will detect a plethora of the

different little parasites that'll sit there. But this one

requires a modified acid fast stain, which at least based on

our where we practice, our commercial sendout lab runs

something called the Cyclospora smears. So it's a little easier

to find, but it does have to be added in addition to the ONP,

and some sites will probably vary on that. Yeah,

can you see Giardia on a normal ONP? Okay.

Yeah, you should be able to see that.

We mentioned treatment a little bit, so from an antimicrobial

stewardship standpoint, which patients with diarrhea should

not receive empiric antibiotics.

I also do sit on a couple of ASP committees, as one would

imagine. So this is a question near and dear to my heart.

Yes,

right. The the vast majority of of non ambulatory and not

traveling patients mostly just need supportive care, even if

they have E. coli or or some other bacteria that was produced

stateside or caught stateside, and since the vast majority of

diarrheal illnesses over here are caused by viruses, then

yeah, the antibiotics don't do anything productive for them,

and and of course can lead to more diarrhea later or other

side effects, or the C diff, which would definitely be a

bounce back to the ER on that one. But yeah, I think that's

the the majority of the answer there.

And then, what is the first line therapy for cyclosporiosis? And

then, how quickly should we expect these patients to improve

once they've started it?

So the first line is is going to be your time out there from

sulfametoxazole, and probably continuing that between seven

and 10 days, I didn't see any definitive, you know, answer as

to whether we measure duration of therapy by the the standard

calendar seven days or the number of fingers we have of 10

days. But but that's the the best data we have right now for

immunocompetent people. And yeah, a really important part of

that question there is that how quickly should they improve?

Because this is not a quick recovery. This is not, you know,

let us know in a couple of days if you're not better. This this

recovery can be protracted over days to weeks, and also has a

pretty high chance of relapsing, even with appropriate treatment.

So you ask about special populations, folks with AIDS.

There's recommendations to continue them on Monday,

Wednesday, Friday. Trimulfa, and they might already hit that

wicket depending on what their CD4 count is, just for you know

toxoplasmosis and other prophylaxis there PCP. But if if

you can't use trimsulfa for some reason, either right earlier,

late stage pregnancy, severe g6 PD, some sulfa allergy that we

don't want to trial, then the nitozoxanide for a week is

actually the next go-to, and that that should be safe in all

of those populations. And I think many pharmacies carry it

on. There's not a huge stock of it typically in a lot of

pharmacies that I'm aware of.

I was going to say I can't say I've ever prescribed that.

It's not the most common, but I think most of the big hospitals

will will keep one around or readily available within about a

day or so to be able to pull it in. If you start getting into

the alternatives, there's just a lot of drugs that don't work for

it that we may start to move into this category. Like

ciprofloxacin definitely has inferior outcomes. Azithromycin

won't work for this. Metronidazole won't work for

this, so that's why it's kind of important to start piecing out

from the other things that we might, you know, accidentally

treat it with if if it was going to be susceptible. But doesn't

tend to fall into NAO's algorithms very cleanly,

right? Yeah, like those are all like the kind of typical first

line treatments for like traveler's diarrhea or like

yeah, empiric treatment. It's definitely good to know, like

that. It's a very specific therapy. So let's shift gears to

military standpoint. So let's say this was a sailor or marine

who is returning from deployment to CENTCOM or like Africom. How

does the differential change?

Yeah, I would say it would move your your pathogenic E. coli's

way up the list. You know we've seen in the the Treaty one and

two studies, which were done by military personnel. That's

really what afflicts most of our travelers into these areas, and

even into the Indo-Pacific or PACOM. I guess now it is.

Anytime you're getting traveling, you know you got a

lot of exposure to the other viruses. So I would move the E.

coli's way up, the noroviruses, Astroviruses, Sappos way up as

well, and in that case, you'd use the Empiric azithromycin is

now the the first go to for traveler's diarrhea. Since we're

seeing so much ciprofloxacin resistance worldwide, we've

moved away from the from that as empiric. And then I would be

certainly remiss in my job if I didn't mention that malaria can

actually present as kind of a diarrheal predominant disease.

Wow, it's not the most

common, but if someone's presenting with fever and

diarrhea after being in a malaria endemic area, I don't

think any ID doc is going to fault anybody for throwing a

thick and thin smear on for someone traveling. That's one

thing I

learned from Trop Med. It's always think about malaria.

Yeah. If underway or deployed, and you know, say we don't have

access to the GIPCR or you know any other advanced testing, what

would be the recommendation for evaluation and management?

Now this one gets really tough. I was trying to come up with my

own little algorithm for for going back and forth on this,

and you know we see so many different GI things occur in in

our forward and deployed folks, and whether or not it's

developing IBS or IBD or dietary intolerances, or they get an

acute diarrhea and then they have any of those things,

piecing that out without the diagnostics, I think, would be

very tough, and and like we talked about before, there's you

know the bacter or the trimethoprim sulfamethoxazole

doesn't really fall into any regular treatment algorithms.

You might get lucky with a cipro for something that's persistent,

but if I was if I was forward and I had questions about this,

thankfully, it's rare. But I'd probably reach out to the local

pref med unit to see if they can test because they often have the

GI PCRs or some other advanced antigen testing that they can

send back and provide a little bit more testing than some of

our forward MTFs could.

If every military ER doc listening changed one

thing about how they evaluate diarrheal illness after this

episode. What would you want that to be?

It's funny. I came up with my answer and then I went back

almost on it because that's the easiest way to diagnose

cyclospora. But I do have to say it. I I would decrease the

amount of of multiplex stool PCR testing for someone in the

outpatient setting, I think many of your listeners have given the

call, and I've received the call often in bit of a conundrum.

Right, the patient was moderately ill, but good enough

to go home, and then some target pops up on this very these very

nice panels that can detect almost anything, and they're

very sensitive but not very specific because they catch a

lot of colonizers, and then everybody's kind of stuck in the

the what do you do with it? They're they're better, but

they've got this result, and is it E. coli or something else?

And I don't think oftentimes in that situation it actually

improves clinical outcomes, or it might even just cause more

patient anxiety, knowing you know they've got E. coli, right?

That's a that's kind of a buzzword for patients, and they

tend to be fairly costly, from my ID and public health minded

self. If we're doing other things like the ONPs, we're

doing cultures. We then can do more testing on the back end,

and we can send it to public health and figure out exactly

what's going on. But the PCR testing is is kind of a dead end

for most of these things, right? We get that one answer. We don't

have antimicrobial resistance. We don't know if it was a true

pathogen, and now we kind of have to work ourselves backwards

to actually take care of the patient. But of course, if

they're getting admitted or we need a cyclosporine answer very

quickly, I'm not saying they're not appropriate at all. But the

question is, would I change that a little bit? I'd change that a

little bit.

Your little ID doc wish list over there. Well, Dr. Derek

Larson, thank you so much for joining us today. And hopefully,

the next time we talk, it won't have to be about explosive

diarrhea.

We'll see how it goes, but I'll be here if you need it.

Thank you so much.

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