Future physician Sophie Samson, Dr. Kristen Bastug, and Dr. Beth Thielen discuss a case of a 7 year old girl who presented with new onset seizure, headache, and fever in Minnesota.
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Febrile is produced with support from the Infectious Diseases Society of America (IDSA)
Hi everyone, welcome to Febrile, a cultured podcast about
Sara Dong:all things infectious disease.
Sara Dong:We use consult questions to dive into ID clinical reasoning, diagnostics,
Sara Dong:and antimicrobial management.
Sara Dong:I'm Sara Dong, your host and a MedPeds ID doc.
Sara Dong:First, I did just want to announce some wonderful news.
Sara Dong:Febrile is now partnering with IDSA, who will be helping to produce
Sara Dong:and expand the podcast platform.
Sara Dong:So, super excited to continue to share ID knowledge with you and
Sara Dong:excitement about the field of ID.
Sara Dong:So I, of course, would love to just add a plug that I would always love
Sara Dong:to hear from you, especially if you want to join an episode of Febrile.
Sara Dong:Febrile really likes to highlight trainees and junior faculty in particular.
Sara Dong:So if you would like to come on as a representative for your fellowship
Sara Dong:program, or as an individual, I would love to welcome you to the show
Sara Dong:for an episode, just let me know.
Sara Dong:All right.
Sara Dong:So today we have a great multi level learner team from
Sara Dong:the University of Minnesota.
Sara Dong:Let's meet them.
Sara Dong:First up, we have Sophie Samson.
Sara Dong:Sophie is currently a third year medical student at the University
Sara Dong:of Minnesota Medical School.
Sara Dong:She plans to train in pediatrics and has a particular interest
Sara Dong:in pediatric ID and neurology.
Sophie Samson:Hi, my name is Sophie, and I'm happy to be here.
Sara Dong:Next, we have Dr.
Sara Dong:Kristen Bastug.
Sara Dong:Kristen is a pediatric ID fellow from the University of Minnesota.
Sara Dong:She is interested in the intersection of ID, global child health, climate
Sara Dong:change, and environmental health.
Kristen Bastug:Hi, this is Kristen.
Kristen Bastug:Excited to be doing this.
Sara Dong:And last but not least, we have Dr.
Sara Dong:Beth Thielen.
Sara Dong:Beth is an adult and pediatric ID physician scientist at
Sara Dong:the University of Minnesota.
Sara Dong:She was previously on episode number 19, Finding a Needle in a Haystack from 2021.
Sara Dong:She currently leads a lab that is particularly interested in understanding
Sara Dong:the factors that influence the severity of respiratory viral infections.
Sara Dong:In addition to that, she has clinical interest in the care of immunocompromised
Sara Dong:patients, travel and tropical medicine, and clinical immunology.
Beth Thielen:Hi, this is Beth.
Beth Thielen:Happy to be back.
Sara Dong:All right.
Sara Dong:And as everyone's favorite cultured podcast, we would love
Sara Dong:to hear a little piece of culture that brings you happiness.
Sophie Samson:Well, I am a pretty avid reader.
Sophie Samson:So one of my favorite books in the past year is called Cloud Cuckoo Land.
Sophie Samson:And it is, um, set in multiple different centuries with a cast of characters and
Sophie Samson:they're all intertwined in some way.
Sophie Samson:And it's kind of a, a book that's an ode to book lovers in
Sophie Samson:a way, so I really enjoyed that.
Sara Dong:I love that.
Sara Dong:So someone mentioned that on Febrile before and I bought it and it's
Sara Dong:actually sitting like right off camera as my like next selection to read.
Sara Dong:I love it.
Beth Thielen:I think I heard about it from one of the
Beth Thielen:Curbsiders podcasts, actually.
Sara Dong:Yeah, it's good.
Sara Dong:It means multiple people liked it.
Sara Dong:Just another endorsement.
Kristen Bastug:Well, that's great.
Kristen Bastug:Um, I like to read as well, but I actually saw a really cool Netflix show recently.
Kristen Bastug:Life on our planet.
Kristen Bastug:Um, so it's a documentary style film with some CGI graphics.
Kristen Bastug:Um, actually Morgan Freeman narrates it, but they go through some of the
Kristen Bastug:really interesting geologic changes of our planet and then the ecosystem
Kristen Bastug:changes that were part of it.
Kristen Bastug:But I just really loved seeing the reimagined like graphic
Kristen Bastug:representation of these weird animals that like hadn't quite evolved yet.
Kristen Bastug:Um, I thought it was a lot of fun.
Sara Dong:Very cool.
Beth Thielen:Well, one of my culture moments is that during the pandemic,
Beth Thielen:I took up a new hobby, which was learning to play the accordion.
Beth Thielen:Just a little bit of a realization of a lifelong dream.
Beth Thielen:And I play in an accordion group, and we had an opportunity for our group
Beth Thielen:to travel together to eastern Italy to a small town called Castelfidardo,
Beth Thielen:which is home of both the Guinness Book of World Records world largest
Beth Thielen:accordion, which I was able to play, um, and we were able to tour an accordion
Beth Thielen:factory, which is a kind of ground zero for the manufacturer of accordions.
Beth Thielen:And so, uh, that is, that is the, my, my piece of culture for today.
Sara Dong:That is amazing.
Sara Dong:I love it so much.
Sara Dong:Awesome.
Sara Dong:Well, I will hand it over to Sophie to get us started.
Sophie Samson:Yeah.
Sophie Samson:So I will start by telling you all a little bit about our patient..
Sophie Samson:So, our patient is a seven year old girl who presented to the ED a few days before
Sophie Samson:with an acute onset seizure, headache, fever, and largely intact cognition.
Sophie Samson:On the morning of admission, she experienced a right
Sophie Samson:sided temporal headache.
Sophie Samson:She then developed abdominal pain with one episode of emesis.
Sophie Samson:She laid down and was found drooling and chewing with the right side of her mouth.
Sophie Samson:Her eyes were open, but not focused, and she developed left sided, circular
Sophie Samson:arm movements with associated urinary incontinence and tongue biting.
Sophie Samson:She was not interactive, and the episode lasted about one hour, terminating
Sophie Samson:with benzodiazepine given by EMS.
Sophie Samson:In the ED, she had a low grade fever to 104 degrees Fahrenheit, and initial
Sophie Samson:workup showed mild leukocytosis, elevated absolute neutrophil count, normal CMP
Sophie Samson:except for elevated phosphorus, and inflammatory markers within normal limits.
Sophie Samson:Infectious workup included a group A strep PCR, and a respiratory viral
Sophie Samson:panel, which were both negative.
Sophie Samson:Kristen, if you got a call based on this information, what are you
Sophie Samson:thinking about at this point in terms of differential diagnosis, and what are
Sophie Samson:you thinking about doing for management?
Kristen Bastug:Yeah, thanks Sophie.
Kristen Bastug:Um, so at this point, I think we need to keep our differential
Kristen Bastug:pretty broad and consider first any etiologies that could be emergent.
Kristen Bastug:When I hear her presentation, the symptoms of headache, emesis, and
Kristen Bastug:focal seizure like activity raise my concern that there could be an
Kristen Bastug:intracranial process occurring.
Kristen Bastug:An intracranial hemorrhage could present this way, so I think we
Kristen Bastug:need to consider some head imaging to rule out an acute bleed.
Kristen Bastug:Her low grade fever and leukocytosis in the context of a seizure could
Kristen Bastug:be due to the seizure itself.
Kristen Bastug:However, I also want to consider infectious etiologies that could
Kristen Bastug:have triggered the seizure.
Kristen Bastug:At 7 years old, she is older than I would expect for someone having a febrile
Kristen Bastug:seizure, so I would like to obtain some additional diagnostic studies
Kristen Bastug:to help us investigate the etiology.
Kristen Bastug:I would recommend a lumbar puncture so that we can obtain the cerebrospinal
Kristen Bastug:fluid studies in order to evaluate further for an infectious cause.
Kristen Bastug:I would send meningitis and encephalitis PCR panel in addition to the standard
Kristen Bastug:cell count, glucose, protein, and aerobic culture on the CSF fluid.
Kristen Bastug:The meningitis encephalitis panel doesn't test for all pathogens, but
Kristen Bastug:it can test for several pathogens that are on my differential.
Kristen Bastug:These would include Streptococcus pneumoniae and Herpes Simplex Virus.
Kristen Bastug:Listeria and E.
Kristen Bastug:coli are less common at her age of seven, but are still possible.
Kristen Bastug:I would also consider Staphylococcus aureus, and if she is unvaccinated,
Kristen Bastug:then Haemophilus influenzae would be a higher possibility.
Kristen Bastug:Enterovirus is another one that comes to my mind, particularly in the summertime.
Beth Thielen:Thanks, Kristen.
Beth Thielen:That's a great, uh, kind of, discussion of your thought process.
Beth Thielen:Um, I did also wanna highlight that since we're discussing the possibility of both
Beth Thielen:head imaging and an LP in a patient whom we're, uh, ruling out bacterial meningitis
Beth Thielen:that we should, uh, think, you know, think about some of the literature around this.
Beth Thielen:And specifically I wanted to bring up a, uh, a, that the topic of CT and, and
Beth Thielen:lumbar puncture was recently discussed in the Choosing Wisely campaign, uh,
Beth Thielen:as something that we do for no reason.
Beth Thielen:And, uh, importantly I think they make this dis-, we make this distinction
Beth Thielen:between patients at high risk and at low risk for abnormal imaging.
Beth Thielen:And both the IDSA and ESCMID guidelines for bacterial meningitis do include
Beth Thielen:new seizures as a high risk feature.
Beth Thielen:So this is a patient definitely we'd be considering as high risk.
Sophie Samson:So with what we know at this time, would you recommend
Sophie Samson:empiric antibiotic treatment?
Kristen Bastug:I think that in order to help me answer that, it would be
Kristen Bastug:really helpful to have a, an updated understanding of her neurologic status.
Kristen Bastug:Because in a patient who's minimally responsive, I would have a lower
Kristen Bastug:threshold to start antibiotics and even acyclovir as soon as possible.
Kristen Bastug:If her symptoms have resolved and she is stable, then I think it's reasonable
Kristen Bastug:to first obtain the lumbar puncture promptly and then start the empiric
Kristen Bastug:antibiotic therapy with, um, I would choose ceftriaxone and vancomycin for her.
Kristen Bastug:Given that the meningitis encephalitis panel will result fairly quickly,
Kristen Bastug:typically within a few hours, if her clinical status is stable,
Kristen Bastug:then I would not start empiric acyclovir at this time for her.
Kristen Bastug:Finally, when considering the differential diagnosis for a seizure, we should
Kristen Bastug:also be thinking about alternative causes in case the patient doesn't
Kristen Bastug:respond to treatment as we expect.
Kristen Bastug:A focal seizure could be caused by a focal brain lesion, such as a brain tumor, which
Kristen Bastug:is another reason I favor pursuing head imaging as part of the initial workup.
Kristen Bastug:Other possibilities that are less likely at this time include autoimmune
Kristen Bastug:etiologies, such as acute disseminated encephalomyelitis, toxic substance
Kristen Bastug:ingestion, or a traumatic injury.
Sophie Samson:A lumbar puncture was performed due to persistent headache
Sophie Samson:that migrated to the back of her head and neck and was notable for CSF neutrophil
Sophie Samson:predominant pleocytosis, 42 nucleated cells with the normal range being
Sophie Samson:between 0 to 5 cells per microliter, and normal glucose and protein levels,
Sophie Samson:and a meningitis encephalitis panel, and aerobic CSF cultures that are in process.
Sophie Samson:MRI was performed later that day and revealed multiple
Sophie Samson:bilateral T2 hyperintensities.
Sophie Samson:MRA showed no vascular lesions.
Sophie Samson:After the initial LP was performed, she was started on ceftriaxone, 100 mg
Sophie Samson:per kg per day, divided every 12 hours.
Sophie Samson:She had a clinical seizure captured on EEG lasting 90 seconds, and she was
Sophie Samson:subsequently started on levetiracetam.
Sophie Samson:She then spiked two discrete high fevers up to 104.
Sophie Samson:2 degrees Fahrenheit, prompting a formal pediatric infectious disease consultation.
Sophie Samson:Cultures are negative to date after 48 hours in the hospital.
Sophie Samson:Kristen, as the ID fellow on the team with this new information, how
Sophie Samson:does this change your differential?
Kristen Bastug:Yeah, I'm glad we got the lumbar puncture because those results will
Kristen Bastug:really help us adjust our differential.
Kristen Bastug:So, her normal CSF glucose, normal protein, and mild to moderately elevated
Kristen Bastug:white blood cell count suggest to me that this is an aseptic meningitis,
Kristen Bastug:which would include viral processes.
Kristen Bastug:The MRI findings of multiple T2 hyperintensities also seems
Kristen Bastug:more consistent with a viral process rather than bacterial.
Kristen Bastug:The aerobic CSF cultures have been negative for 48 hours at this point
Kristen Bastug:without any antibiotic pretreatment, which further supports that a bacterial
Kristen Bastug:cause such as Staph aureus, Strep pneumoniae, or meningococcus are unlikely.
Kristen Bastug:The negative meningitis encephalitis panel offers some reassurance that this
Kristen Bastug:patient does not have HSV or enterovirus, though the sensitivity of the ME panel is
Kristen Bastug:not as high as other testing modalities, such as an HSV 1 or HSV 2 specific PCR.
Kristen Bastug:I would be interested to hear my attending's perspective on when
Kristen Bastug:we should consider ordering those additional specific PCR tests
Kristen Bastug:in addition to the ME panel.
Kristen Bastug:Finally, I note that her fever curve is uptrending to 104, though given
Kristen Bastug:that we have good evidence that this is not a bacterial process, I would not
Kristen Bastug:add any new antibiotics at this time.
Kristen Bastug:We also have good evidence this is not HSV, and so I
Kristen Bastug:would not add acyclovir either.
Kristen Bastug:What I would make sure to do is to follow her neurologic exam closely, and
Kristen Bastug:if she develops any new symptoms, such as areflexia or paralysis, then I would
Kristen Bastug:want rapid imaging of her spinal cord and a neurology consult in order to
Kristen Bastug:evaluate for inflammatory or demyelinating diseases, such as transverse myelitis.
Kristen Bastug:She should be monitored closely if those processes are suspected
Kristen Bastug:because respiratory status can rapidly decompensate in that setting.
Beth Thielen:Thanks, Kristen.
Beth Thielen:Yeah, I agree that at this point, 48 hours into illness, I think my suspicion
Beth Thielen:for atypical bacterial meningitis is much, much lower and particularly
Beth Thielen:given we have negative cultures and negative meningitis encephalitis panel
Beth Thielen:and fevers that have persisted despite appropriately doses of ceftriaxone.
Beth Thielen:I think at this point where I'm thinking about going is moving on to our next
Beth Thielen:tier testing for more unusual pathogens.
Beth Thielen:Um, but I also want to spend a couple minutes just talking about the performance
Beth Thielen:characteristics of the testing thus far.
Beth Thielen:And so I'm a little bit less reassured that we've adequately ruled out HSV
Beth Thielen:when the clinical picture and in this case, new onset focal seizures would
Beth Thielen:potentially be clinically compatible.
Beth Thielen:And so it's well described that HSV PCR can be falsely negative,
Beth Thielen:particularly early in the disease course.
Beth Thielen:Um, and I think there's also, there's also been several systematic reviews
Beth Thielen:now with increasing number of patients that have showed lower sensitivity
Beth Thielen:of the multiplex panels for HSV.
Beth Thielen:So I'm really thinking about wanting to repeat the LP, both for more
Beth Thielen:specific testing for things like HSV, but also to see how the CSF
Beth Thielen:parameters have evolved over time.
Beth Thielen:And I think this would also have the benefit of allowing us to get additional
Beth Thielen:specimen volume to send for that second tier testing, and oftentimes we're
Beth Thielen:limited in terms of CSF volume for the things that we we want to test for.
Beth Thielen:And so we have to be a little bit strategic sometimes about
Beth Thielen:prioritizing our testing and making sure that we have enough sample
Beth Thielen:to get those high priority tests.
Beth Thielen:Um, in terms of specific microbes, and I'm thinking about, so I think things
Beth Thielen:like arboviruses, LCMV, and Lyme disease or some of the pathogens that aren't
Beth Thielen:included on those multiplex panels.
Beth Thielen:Um, certainly respiratory viruses like flu are associated sometimes
Beth Thielen:with neurological symptoms.
Beth Thielen:Like in her case, we have a negative respiratory panel on admission,
Beth Thielen:so those seem less likely.
Beth Thielen:Um, I think I also want to ask about TB risk factors, and so that's one of the
Beth Thielen:other, uh, you know, disease processes that wouldn't come up on routine
Beth Thielen:testing and could present with seizures and, and a meningitis type picture.
Sophie Samson:And a big question brought up by the neurology team was
Sophie Samson:whether to treat with steroids or IVIG for a possible autoimmune encephalitis.
Sophie Samson:Beth, what were the considerations there?
Beth Thielen:Yeah, so I think I'd want to know a bit more about how
Beth Thielen:consistent the neurology team thinks the features are with an autoimmune process.
Beth Thielen:Um, and in this case, talking with them, I feel like they, um, were not, really
Beth Thielen:super convinced that this is what they thought was going on and at this point, I
Beth Thielen:don't feel like we have a clear diagnosis and so in cases like that when we have
Beth Thielen:the two immunomodulatory therapies mentioned, I think IVIG would be the
Beth Thielen:safer option, but it still has downsides.
Beth Thielen:Um, so some of the infectious processes that I'm thinking about,
Beth Thielen:maybe we may need serology to diagnose them and IVIG would impact, um, our
Beth Thielen:ability to make those diagnoses.
Beth Thielen:Um, furthermore, when an untreated infection is in the differential,
Beth Thielen:I prefer to hold off on steroids.
Beth Thielen:There's definitely some infections where steroids may make things look better
Beth Thielen:for a while before they get worse due to the impairment to the immune control.
Beth Thielen:And so I think if there's not a compelling reason why urgent treatment
Beth Thielen:is needed, I would, really focus our efforts on making the diagnosis
Beth Thielen:before we embark on a treatment.
Kristen Bastug:Yeah, it sounds like we are in agreement that a viral process is
Kristen Bastug:at least very likely, um, and we want to recommend additional studies at this time.
Kristen Bastug:It would be helpful to also obtain additional exposure history for
Kristen Bastug:this patient, particularly outdoor exposure, travel history, animal
Kristen Bastug:exposures, and social history.
Kristen Bastug:Sophie, do you have any more of that for us?
Sophie Samson:Yeah, um, and the neurology team doesn't feel strongly
Sophie Samson:that this looks like an autoimmune process, but don't have any other ideas.
Sophie Samson:They've sent autoantibodies, but these will take days to come back.
Sophie Samson:Um, so to fill you in on some of the social history, it's currently mid July.
Sophie Samson:The patient lives in a suburb of the Twin Cities and has been
Sophie Samson:regularly active outside around the family's home this summer.
Sophie Samson:The family has dogs, cats, and chickens.
Sophie Samson:And one of the dogs had ticks earlier in the spring, but no
Sophie Samson:ticks were found on family members.
Sophie Samson:She did not have any rodent or bat exposures.
Sophie Samson:Her family camped along a river five days before symptom onset.
Sophie Samson:The patient's mom recalls that there was a transient red bump on her torso
Sophie Samson:present at the time of her initial seizure, but has since resolved.
Sophie Samson:She has not traveled outside of Minnesota, notably.
Sophie Samson:How does this additional information influence the differential
Sophie Samson:diagnosis and management?
Kristen Bastug:Thanks, Sophie.
Kristen Bastug:That history is really helpful.
Kristen Bastug:It stands out to me that her symptoms started five days after
Kristen Bastug:the family went camping in July.
Kristen Bastug:I wonder if the skin bump that was described could be a mosquito bite.
Kristen Bastug:The outdoor exposure brings into question if her illness is potentially caused by
Kristen Bastug:a vector borne disease, which we do see more of in the summer months in Minnesota.
Kristen Bastug:There are many diseases in this category, so I'm glad that we have
Kristen Bastug:obtained her travel history to help narrow the list down a little bit.
Kristen Bastug:It sounds like she and her family have only been in in Minnesota, so I
Kristen Bastug:would start building my differential with this location in mind.
Kristen Bastug:Given that we already suspect a viral process based on her CSF results, I'm
Kristen Bastug:suspicious of an arboviral infection.
Kristen Bastug:West Nile virus, Western Equine Encephalitis, and La Crosse encephalitis
Kristen Bastug:are considered endemic to Minnesota.
Kristen Bastug:More recently, Jamestown Canyon virus is also emerging as a
Kristen Bastug:cause of disease in our state.
Kristen Bastug:Of these possibilities, La Crosse encephalitis more often affects
Kristen Bastug:children compared to adults.
Kristen Bastug:In fact, the most common arboviral cause of central nervous system
Kristen Bastug:infection in children in the United States is La Crosse virus.
Kristen Bastug:There are about 80 to 100 cases reported annually in the U.
Kristen Bastug:S., and 90 percent of those occur in children.
Kristen Bastug:This is in contrast to West Nile virus, which shows a peak incidence
Kristen Bastug:in adults over 60 years old.
Kristen Bastug:Jamestown Canyon epidemiology also indicates a lower percent of children
Kristen Bastug:with these cases, at about 7%.
Kristen Bastug:These viruses are all spread from animal reservoirs to humans through mosquitoes.
Kristen Bastug:However, we do have other important vector borne diseases in Minnesota.
Kristen Bastug:With the outdoor exposure, I think it's worth considering if there are
Kristen Bastug:other etiologies we could be missing.
Kristen Bastug:Sophie, what are some additional vector borne diseases that we could consider?
Sophie Samson:Well, Kristen, thanks for covering viruses spread by mosquitoes
Sophie Samson:that we think about in Minnesota.
Sophie Samson:We also want to think about vector borne diseases spread by ticks in this area.
Sophie Samson:This includes Lyme and other Borrelia species, Anaplasma and
Sophie Samson:Babesia, as well as tularemia, ehrlichiosis, and Powassan virus.
Sophie Samson:It's important to note that lacking known exposure has a low negative
Sophie Samson:predictive value for these vector borne diseases since bites often go unnoticed.
Sophie Samson:Knowing a patient is in a general location where they may have been
Sophie Samson:exposed to a specific tick or mosquito is more helpful to keep in mind.
Kristen Bastug:Thanks, Sophie.
Kristen Bastug:At this point for our patient, I think we need to obtain additional testing
Kristen Bastug:to evaluate for arboviral disease.
Kristen Bastug:I want to contact the Minnesota Department of Health at this time
Kristen Bastug:because their laboratory will be the one to process the studies.
Kristen Bastug:I often find it helpful to know ahead of time what types of specimens
Kristen Bastug:they'll require for the testing.
Kristen Bastug:Particularly for samples such as cerebrospinal fluid, I want
Kristen Bastug:to make sure that it's processed appropriately and not wasted.
Kristen Bastug:The Minnesota Department of Health requested blood, serum, and CSF samples
Kristen Bastug:for IgM antibody and RNA detection.
Kristen Bastug:They had listed some specific tests, such as an IgM for West Nile virus,
Kristen Bastug:Powassan virus, Jamestown Canyon, Western and Eastern Equine Encephalitis,
Kristen Bastug:California Group Encephalitis, and St.
Kristen Bastug:Louis encephalitis, which was ordered.
Kristen Bastug:Urine, blood, and urine RT PCR for West Nile virus was also ordered.
Kristen Bastug:Given this large panel of viruses, I'm bracing myself for the potential of
Kristen Bastug:some cross reactivity and I'll need to discuss these results carefully with my
Kristen Bastug:attending in order to interpret them.
Kristen Bastug:In the event that we had used our in house laboratory for testing, I
Kristen Bastug:think it's important for everyone to note that arbovirus disease is
Kristen Bastug:reportable, at least in Minnesota, to our state health department.
Kristen Bastug:And it has to be reported within one working day.
Sophie Samson:A lumbar puncture was repeated for this patient due to her
Sophie Samson:high grade fevers despite starting ceftriaxone, as well as the seizures.
Sophie Samson:Opening pressure of the repeat lumbar puncture was 21.
Sophie Samson:5 centimeters of water.
Sophie Samson:CSF studies show evolution over time with an increase to 578 nucleated cells per
Sophie Samson:microliter with 78 percent lymphocytes, stable glucose, and now protein elevation.
Sophie Samson:Kristen, how does this new information impact your diagnostic thinking?
Kristen Bastug:This lumbar puncture shows an increased white blood cell
Kristen Bastug:count that is predominantly lymphocytic.
Kristen Bastug:As long as her clinical status is stable, this is consistent with the evolution
Kristen Bastug:of a viral central nervous infection.
Kristen Bastug:I'm glad that we can send a CSF to the health department and
Kristen Bastug:hopefully identify the etiology.
Sophie Samson:You mentioned that both serology and nucleic acid based testing
Sophie Samson:was sent to the health department.
Sophie Samson:What is the role of serology versus molecular or nucleic acid
Sophie Samson:based tests in arboviral disease?
Beth Thielen:Yeah, so for many arboviral infections, the period during
Beth Thielen:which virus can be detected in any body fluid is typically quite short.
Beth Thielen:And for this reason, PCRs can be helpful if they're positive, but
Beth Thielen:are not necessarily sensitive enough to rule out disease.
Beth Thielen:So our health department offers a PCR for West Nile virus, but not the
Beth Thielen:other viruses in our differential.
Beth Thielen:And so therefore, serological testing is the mainstay for diagnosis.
Beth Thielen:Focusing in on those serologies, a single positive IgG is difficult to
Beth Thielen:interpret given the relatively high risk of past undiagnosed exposure
Beth Thielen:in our region, but a fourfold rise between an acute and a convalescent
Beth Thielen:collected sample would be supportive.
Beth Thielen:For this case where we're looking at acute testing, we're really looking for
Beth Thielen:positive IgMs to indicate that acute infection, but they may be falsely
Beth Thielen:positive in other inflammatory disorders or cross reactive against related viruses.
Beth Thielen:And so, uh, typically a positive result in an IgM is followed up with a plaque
Beth Thielen:reduction neutralization assay in which serial dilutions of patient serum or
Beth Thielen:CSF are incubated with virus in vitro to determine the concentration of the virus
Beth Thielen:at which antibodies are able to inactivate viruses such that they can no longer
Beth Thielen:infect cells and replicate in culture.
Beth Thielen:So in this case, higher titers would be indicate a more specific
Beth Thielen:reaction against a particular virus and would support it being a true
Beth Thielen:pathogen and not cross reactive.
Beth Thielen:So such confirmatory plaque neutralization assays are really commonly used
Beth Thielen:in arbovirology to distinguish between cross reactive viruses.
Beth Thielen:So, examples would be the California serogroup bunyaviruses, which
Beth Thielen:would include Jamestown Canyon virus and La Crosse virus, and then
Beth Thielen:also the flaviviruses like West Nile, yellow fever, and dengue.
Sophie Samson:So, for our patient, an initial screening arbovirus IgM
Sophie Samson:IFA that tests for California group encephalitis viruses, EEEV, WEV, and SLEV
Sophie Samson:was positive for the California group.
Sophie Samson:Initial IgM EIA testing done at MDH on serum was positive for Jamestown
Sophie Samson:Canyon virus, equivocal for Powassan and negative for West Nile virus.
Sophie Samson:Serum PCR was negative for West Nile virus.
Sophie Samson:CSF IgM EIA testing was positive for Jamestown Canyon virus and
Sophie Samson:Powassan and negative for West Nile virus by both IgM and PCR.
Sophie Samson:Urine PCR for West Nile virus was also negative.
Sophie Samson:Confirmatory testing was sent to Arboviral Diseases Branch Diagnostic and Reference
Sophie Samson:Laboratory in Fort Collins, Colorado.
Sophie Samson:Serum testing revealed positive IgM for Jamestown Canyon Virus
Sophie Samson:and La Crosse by IgM capture ELISA and negative for IgM for Powassan.
Sophie Samson:La Crosse plaque reduction neutralization occurred at a greater than 1:4096 titer,
Sophie Samson:but unfortunately there was not sufficient sample for Jamestown Canyon virus testing.
Sophie Samson:Plaque duction, neutralization testing was also performed on CSF
Sophie Samson:and was positive at a 1:128 titer against La Crosse, 1:4 for Jamestown
Sophie Samson:Canyon and was negative for Powassan.
Sophie Samson:Beth, can you discuss the interpretation of these results?
Sophie Samson:Sure
Beth Thielen:In this case, our initial testing was a little bit
Beth Thielen:confusing because the results supported, uh, potential, potentially
Beth Thielen:either or both, uh, California group encephalitis virus, of which Jamestown
Beth Thielen:Canyon was one, uh, and Powassan.
Beth Thielen:Uh, and there's, uh, since there was not a specific screening IgM for La
Beth Thielen:Crosse, uh, we, we were not able to test for that and then specifically
Beth Thielen:in the initial round of testing.
Beth Thielen:And this is an example where the confirmatory plaque
Beth Thielen:reduction neutralization assays were really critical.
Beth Thielen:So the results came back with very high titers against La Crosse virus
Beth Thielen:encephalitis pathogen with much lower titers against the Jamestown
Beth Thielen:Canyon virus and a negative capture IgM against Powassan.
Beth Thielen:So overall, these results were interpreted as being confirmatory
Beth Thielen:of La Crosse virus infection being the primary pathogen in this case.
Sophie Samson:And Beth, what do we know about the epidemiology
Sophie Samson:of La Crosse encephalitis?
Beth Thielen:Yeah, so this, uh, this pathogen was first described
Beth Thielen:in the literature in 1965, uh, in a 4-year-old child from south southeastern
Beth Thielen:Minnesota who sought care in La Crosse, Wisconsin, and ultimately died
Beth Thielen:from an acute neurological illness.
Beth Thielen:So that's the, hence the origin of the name.
Beth Thielen:Um, so as, as Kristen mentioned, there's really a range of any, anywhere
Beth Thielen:as low as 30 up to 90 or, or more, uh, cases per year of neuro invasive
Beth Thielen:disease reported in the United States.
Beth Thielen:Uh, and the vast, vast majority of those are among children.
Beth Thielen:Um.
Beth Thielen:The neurological disease is probably just the tip of the iceberg as there's
Beth Thielen:substantial under-diagnosis and under-reporting of less severe cases.
Beth Thielen:And so, so how do we know this?
Beth Thielen:So there was a serological survey that was done, um, in, in a town in
Beth Thielen:southeastern Minnesota called Winona, and they had sero positivity rates of
Beth Thielen:up to 28% in some of the rural areas.
Beth Thielen:So I think in places where there's the right geographic exposure in
Beth Thielen:sort of a high risk population, like residents in a rural region, there's
Beth Thielen:probably quite a lot of exposure on an infection that we're not - it's not,
Beth Thielen:it's not coming to medical attention.
Beth Thielen:Um, and so there's really a couple of pockets of this, of where this
Beth Thielen:disease is predominantly diagnosed.
Beth Thielen:So it's the upper Midwest, so Minnesota and Wisconsin are really high, high areas,
Beth Thielen:and then also through, through Appalachia.
Beth Thielen:So Ohio, Kentucky, West Virginia, North Carolina are big pockets of this disease.
Beth Thielen:Um, it's really not clear why only a small fraction of the people who are
Beth Thielen:exposed develop neuroinvasive disease.
Beth Thielen:Um, And something that my lab is particularly interested in
Beth Thielen:is, is host susceptibility.
Beth Thielen:Um, and there's really been some interesting data that have come out
Beth Thielen:in the last year, looking at, uh, the prevalence of auto antibodies against
Beth Thielen:type one interferons in patients who develop neuroinvasive West Nile.
Beth Thielen:And so I think there's more, more to come and more to learn about what,
Beth Thielen:why it is that some people are more susceptible to these severe manifestations
Beth Thielen:of viral pathogens than others.
Beth Thielen:So Sophie, you had some time to interact with our health department.
Beth Thielen:Uh, what can you tell us about what can be done to prevent lacrosse encephalitis?
Sophie Samson:Yeah, so as the medical student on the team, I was able to
Sophie Samson:speak with an epidemiologist on the Vector Borne Disease Unit at the
Sophie Samson:Minnesota Department of Health and learn more about the follow up and
Sophie Samson:prevention measures taken at this case.
Sophie Samson:So early on, MDH involved the Metropolitan Mosquito Control District and the family
Sophie Samson:allowed them to inspect their property.
Sophie Samson:The initial evaluation involved removal of old tires and
Sophie Samson:containers from the family's yard.
Sophie Samson:The mosquito control district removed 8 tires, 4 of which had larvae, and
Sophie Samson:32 containers, 20 of which had larvae.
Sophie Samson:Aedes triseriatus was found in seven of the larval habitats.
Sophie Samson:The family was educated on the importance of dumping standing water in toys and
Sophie Samson:containers since they can serve as a breeding site for this mosquito.
Sophie Samson:They filled one tree hole near the residence with soil, although mosquito
Sophie Samson:larvae was absent upon further inspection.
Sophie Samson:The Mosquito Control District also sampled adult mosquitoes and sprayed
Sophie Samson:adulticides the following day.
Sophie Samson:They attempted similar surveillance and control measures in the surrounding
Sophie Samson:area and notified neighboring houses about lacrosse risk in the area.
Sophie Samson:The neighborhood will have continued surveillance for
Sophie Samson:several years to eliminate larvae that may carry lacrosse virus.
Sophie Samson:MDH provided their unique perspective on the epidemiology of
Sophie Samson:previous La Crosse cases they've been involved in and educated the
Sophie Samson:family on mosquito bite prevention.
Sophie Samson:Kristen, can you tell us more about standard mosquito precautions?
Kristen Bastug:Absolutely, Sophie.
Kristen Bastug:There are several approaches to reduce the risk of mosquito bites.
Kristen Bastug:First, bug spray can be used on the skin whenever there's a risk for
Kristen Bastug:exposure to mosquitoes or ticks, particularly during the months of
Kristen Bastug:April through November in Minnesota.
Kristen Bastug:There are many products available, but you want to make sure it's a
Kristen Bastug:product registered by the Environmental Protection Agency, or the EPA.
Kristen Bastug:The most common active ingredients include DEET, picaridin,
Kristen Bastug:and oil of lemon eucalyptus.
Kristen Bastug:The American Academy of Pediatrics recommends selecting a concentration
Kristen Bastug:of DEET that matches your expected outdoor exposure time.
Kristen Bastug:For example, 10 percent DEET provides protection for about 2
Kristen Bastug:hours and 30 percent DEET provides protection for about 5 hours.
Kristen Bastug:The maximum concentration you should buy is 50 percent because anything
Kristen Bastug:beyond that does not actually provide longer protection, despite
Kristen Bastug:a potentially higher price for something that says 100 percent DEET.
Kristen Bastug:Picaridin is another active ingredient that can repel mosquitos and ticks.
Kristen Bastug:Similar to DEET, the concentration correlates with duration of protection.
Kristen Bastug:5 percent picaridin provides about 3 4 hours of protection, while 20 percent
Kristen Bastug:can provide protection for 8-12 hours.
Kristen Bastug:Oil of lemon eucalyptus is the other option I mentioned, but
Kristen Bastug:it's important to know that this is not the same as lemon oil.
Kristen Bastug:You should make sure that your OLE product is registered by the EPA and it should
Kristen Bastug:not be used in children under 3 years old.
Kristen Bastug:OLE of a concentration of 8-10 percent can protect for up to 2
Kristen Bastug:hours and 30 percent concentration, up to 40 percent concentration
Kristen Bastug:can protect for about 6 hours.
Kristen Bastug:For all of these products, it's important to read the label and avoid applying them
Kristen Bastug:directly to a child's hands because we all know that the hands are going to end
Kristen Bastug:up in the mouth and the eyes and increase risk for ingestion or eye irritation.
Kristen Bastug:When using insect repellent with sunscreen, the sunscreen
Kristen Bastug:should be applied first.
Kristen Bastug:Other than topical bug spray, you can also choose to wear long sleeve clothing and
Kristen Bastug:pre treat the clothing with permethrin.
Kristen Bastug:You could also choose to avoid areas with dense vegetation.
Kristen Bastug:Finally, mosquito nets are a great option and you can pre treat
Kristen Bastug:those with an insecticide as well.
Kristen Bastug:So for our patient, it sounds like Sophie, you had some excellent communication with
Kristen Bastug:the Department of Health and they worked with the family to talk about prevention.
Kristen Bastug:What did you learn from talking to the family or from MDH about
Kristen Bastug:how the child's doing now and what the future might look like?
Sophie Samson:Well, when I was able to speak with the family, they updated
Sophie Samson:me on her six week follow up after discharge and shared that at that time
Sophie Samson:she was having headaches about every two weeks, but she has had no new seizures.
Sophie Samson:She's doing well in school and remains social and active with
Sophie Samson:some activity modification to follow seizure precautions,
Sophie Samson:but overall is doing excellent.
Sophie Samson:Repeat brain imaging, um, both MRI and EEG done at the follow up
Sophie Samson:showed resolution of prior lesions.
Sophie Samson:She's tapering off levetiracetam and will continue to follow up with neurology.
Sophie Samson:The parents shared that while seeing their daughter so sick and having seizures was
Sophie Samson:incredibly scary, they felt supported by all the teams involved in her care,
Sophie Samson:and they're happy to see her back on track and doing the things she enjoys.
Sara Dong:Thanks again to Sophie, Kristen, and Beth
Sara Dong:for joining Febrile today.
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Sara Dong:Stay safe and we'll see you next time.