Seizures after tick bite signal a medical emergency requiring immediate investigation for tick-borne infection. A 66-year-old woman reported removing a tick two weeks before admission, then developed fever, fatigue, rash, and altered mental status — yet tick-borne disease wasn’t considered until she had generalized tonic-clonic seizures 38 hours into hospitalization. Her diagnosis was human monocytic ehrlichiosis (HME), a tick-borne infection that causes neurologic complications in 22% of patients. This diagnostic delay could have been fatal, demonstrating why seizures and altered mental status after tick exposure demand urgent evaluation for tick-borne infections, not delayed treatment while ruling out other conditions first.
The Initial Presentation
The patient had been well until five days prior to hospital admission. Her illness was never attributed to a tick-borne disease, although she had reported removing a tick from her groin two weeks before being admitted.
Her husband reported she began slurring her speech and had gradually worsening fatigue and fevers. Additional symptoms included generalized joint pain, most pronounced in the elbows and knees, as well as a faint rash along the eyelids, anterior neck, chest, abdomen, and legs. Fevers reached 102.7°F at home.
Geier and colleagues described this case in BMJ Case Reports.
The pattern was classic for tick-borne infection: fever, rash, joint pain, neurologic symptoms (slurred speech, fatigue), and recent tick exposure. Yet the diagnosis was missed.
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Rapid Deterioration
She also complained of a constant throbbing headache, unsteadiness on her feet, the need for assistance while walking, diarrhea with mild abdominal pain, decreased appetite, and a mild cough that began two days prior to admission.
Initial lab work revealed significant abnormalities: hyponatremia (sodium 127), leukopenia, thrombocytopenia, markedly elevated liver enzymes, and elevated C-reactive protein. Chest X-ray showed mild pulmonary edema and small bilateral pleural effusions.
She was empirically treated with intravenous azithromycin and ceftriaxone for presumed community-acquired pneumonia.
The laboratory abnormalities — low white blood cells (leukopenia), low platelets (thrombocytopenia), elevated liver enzymes — are hallmark findings in Ehrlichiosis. Combined with fever, rash, and recent tick exposure, the diagnosis should have been obvious. But she was treated for pneumonia instead.
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Seizures and ICU Transfer
Approximately 12 hours after initial presentation, the patient developed worsening respiratory distress and marked confusion. She was transferred to the intensive care unit. Due to deteriorating mental status, her antibiotic regimen was adjusted — but tick-borne infection was still not considered.
Around 38 hours into her hospitalization, she experienced generalized tonic-clonic seizures, treated with intravenous lorazepam and levetiracetam.
Only then did infectious disease specialists evaluate the patient and immediately recommend intravenous doxycycline due to concern for a tick-borne infection.
It took seizures — 38 hours into hospitalization — for tick-borne infection to finally be considered. This represents a dangerous diagnostic delay when the patient had reported tick exposure on admission.
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Diagnosis: Ehrlichiosis
The diagnosis of human monocytic ehrlichiosis (HME) was confirmed. A Wright-Giemsa peripheral smear demonstrated cytoplasmic Ehrlichia morulae in a monocyte. E. chaffeensis was also identified by PCR. Other tick-borne infections including Lyme disease and Babesia were ruled out.
Neurologic findings have been reported in 22% of HME patients, most commonly photophobia, confusion, hallucinations, stupor, meningitis, and coma. Seizures are rare, occurring in only 2.4% of patients.
This woman fell into the severe 2.4% with seizures — yet even with reported tick exposure, altered mental status, and classic lab findings, Ehrlichiosis wasn’t considered until neurologic deterioration forced specialist involvement.
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Treatment and Complete Recovery
The patient was treated with a 10-day course of doxycycline — given intravenously for the first four days until she was alert enough to take it orally.
The 66-year-old woman made a complete recovery and was able to return to work as a language professor at a local university.
Once the correct diagnosis was made and appropriate treatment initiated, she recovered completely. But the 38-hour delay in diagnosis exposed her to preventable risks including ICU transfer, intubation risk, and potential long-term neurologic damage.
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Why Ehrlichiosis Causes Seizures
Ehrlichiosis causes seizures and neurologic complications through several mechanisms:
- Direct CNS invasion: Ehrlichia organisms can invade the central nervous system
- Meningitis: Inflammation of brain and spinal cord membranes
- Encephalitis: Brain inflammation affecting neuronal function
- Vasculitis: Inflammation of blood vessels can cause cerebral ischemia
- Metabolic derangements: Hyponatremia (low sodium) itself can trigger seizures
- Cytokine storm: Severe systemic inflammation affecting brain function
This patient had multiple seizure triggers: CNS infection, hyponatremia (sodium 127), and systemic inflammatory response.
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Clinical Perspective
This case illustrates how important it is to consider tick-borne infection following a tick bite — even when the presentation is atypical. The woman reported removing a tick two weeks before admission, yet tick-borne disease was not considered until seizures developed nearly two days into her hospitalization.
Her neurologic deterioration, ICU transfer, and seizures may have been prevented if physicians had considered a tick-borne cause early on. The pattern — sudden onset of fever, fatigue, joint pain, rash, and altered mental status after tick exposure — should prompt immediate evaluation for tick-borne infections including Ehrlichiosis, Lyme disease, and Babesia.
Seizures and altered mental status after a tick bite are medical emergencies that deserve urgent investigation for infection — not delayed treatment while waiting for standard workups to rule out other conditions first.
Several aspects of this case warrant emphasis. First, the patient reported tick removal on admission. This single piece of information should have immediately elevated tick-borne infection on the differential diagnosis. Instead, she was treated for community-acquired pneumonia despite having no respiratory complaints until after admission.
Second, the laboratory findings were classic for Ehrlichiosis: leukopenia, thrombocytopenia, elevated liver enzymes. When these findings occur together with fever and tick exposure, Ehrlichiosis should be the presumptive diagnosis, not an afterthought.
Third, the progression from mild symptoms to ICU-level illness was rapid — within 12 hours of admission. Tick-borne infections can deteriorate quickly, which is why empiric treatment with doxycycline should begin immediately when suspected, not delayed pending confirmatory testing.
Fourth, the neurologic involvement — slurred speech, confusion, altered mental status, seizures — represents severe disease. The 22% rate of neurologic complications in Ehrlichiosis is substantial. When neurologic symptoms develop in a patient with suspected tick-borne infection, this signals severe disease requiring aggressive treatment.
Fifth, the hyponatremia (sodium 127) is both a complication of Ehrlichiosis and an independent seizure trigger. Severe hyponatremia can cause seizures regardless of infection, so this patient had dual mechanisms for neurologic deterioration.
Sixth, the diagnostic delay had real consequences. ICU transfer, seizure management with anti-epileptic medications, invasive monitoring — all could have been avoided with earlier recognition and treatment. More importantly, she was at risk for permanent neurologic damage or death during the 38 hours before appropriate antibiotics were started.
Finally, the complete recovery validates the diagnosis and treatment. Once doxycycline was initiated, she recovered fully and returned to work. This demonstrates that Ehrlichiosis, when recognized and treated appropriately, is curable — but delays in diagnosis can be fatal.
The lesson is clear: when a patient reports recent tick exposure and presents with fever, altered mental status, cytopenias, and elevated liver enzymes, empiric doxycycline should be started immediately. Don’t wait for seizures to develop before considering tick-borne infection.
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Frequently Asked Questions
Can a tick bite cause seizures?
Yes. Tick-borne infections including Ehrlichiosis and Lyme disease can cause neurologic complications including seizures, altered mental status, confusion, and coma. Seizures occur in 2.4% of Ehrlichiosis patients.
What is Ehrlichiosis?
Human monocytic ehrlichiosis (HME) is a tick-borne infection caused by Ehrlichia chaffeensis. It can cause fever, fatigue, leukopenia, thrombocytopenia, elevated liver enzymes, and in severe cases neurologic involvement including seizures.
How is Ehrlichiosis treated?
Doxycycline is the standard treatment. In this case, intravenous doxycycline was given for four days followed by oral doxycycline to complete a 10-day course, with full recovery.
Why was the tick-borne infection missed initially?
Despite a reported tick removal two weeks prior, the patient was treated for presumed pneumonia. Tick-borne infection was not considered until seizures developed nearly 38 hours into hospitalization — a dangerous diagnostic delay.
Can Ehrlichiosis and Lyme disease occur together?
Yes. Multiple tick-borne infections can be transmitted by a single tick bite. In this case Lyme and Babesia were ruled out, but co-infection should always be considered when treating tick-borne illness.
What are warning signs of severe Ehrlichiosis?
Altered mental status, seizures, confusion, severe headache, hyponatremia, leukopenia, thrombocytopenia, and markedly elevated liver enzymes indicate severe disease requiring immediate treatment. Neurologic involvement occurs in 22% of cases.
Should doxycycline be started before test results confirm Ehrlichiosis?
Yes. When clinical presentation and laboratory findings suggest Ehrlichiosis, empiric doxycycline should begin immediately. Waiting for confirmatory testing can result in preventable deterioration, ICU admission, and neurologic complications.
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Related Reading:
Ehrlichiosis: What Lyme Patients Need to Know
Neurologic Lyme Disease: When Infection Affects the Brain
Can Lyme Disease Cause Seizures?
Lyme Disease Co-infections
Babesia and Lyme Disease
Brain Fog and Lyme Disease
Psychiatric Lyme Disease: Misdiagnosed as Mental Illness
Bartonella Psychiatric Symptoms
References:
- Geier C, Davis J, Siegel M. Severe human monocytic ehrlichiosis presenting with altered mental status and seizures. BMJ Case Rep. 2016;doi:10.1136/bcr-2016-215967.
My husband was diagnosed with Lyme’s 12 yrs. Ago. Had 4 months of rocephin and a yr of triple antibiotics. He now has severe fatigue, dizziness, and tremors. Has been diagnosed with Parkinson’s. Can another round of I’ve rocephin help him this late in the disease. He has been on a constant decline for the past 12 yrs.
Doctors are divided on an approach. It might help to have doctor familiar with tick borne illnesses e.g. Babesia to look again. He may even have been reinfected with another tick borne illness. I would also be important to make sure there in not a third illness.
About 12 years ago, while camping, I got a tick stuck in me in the worst place imaginable for a man (yep, ouch.) My wife removed it from me. I never got tested for Lyme’s Disease. However, about 3 years later, I started having seizures. I am on two anti-seizure meds (4000mg daily of Keppra and 900mg daily of Trileptal) because it’s the only thing that is currently keeping me seizure free. I also have chronic fatigue, and I’ve noticed my memory is getting worse lately when it comes to remembering names, dates, etc. I’m only 51. Do you recommend that I get tested for Lyme’s Disease?
yes.
25 years ago when 9Years Old when bitten by a tick but never tested for Lyme Off shore in diagnosed with epilepsy 2.5years after bitten currently on 2000mg Keppra & 600mg epilim daily to easing pain. while marginally reducing seizures .Having Chronic fatigue & noticing Rhinitis with my memory getting massively worse only being 34years not being able to remember what I had for breakfast or what day it is along with names & events.Is there still a point in getting Lyme tested ?As have always wanted to get well as my greatest wish since a child.
I have had patients with both Lyme disease and epilepsy. It is not clear if they are connected. I typically recommend adding a Lyme disease specialist if there are unresolved problems. Call my office at 914 666 4665 if you need our help.
Hello. My husband was bit by a deer tick around May 1st of this year and we found it and removed it on the 4th of May. He had symptoms he hadn’t had before (he’s had Lyme disease once before this one) he had joint and leg pain, and he had a stiff neck that lasted a couple of days and he wouldn’t go get checked out even though I insisted he go get checked out because of the tick that removed was a deer tick and I was worried about Lyme.. he finally got checked out after he discovered he had swollen lymph nodes and the aches and pains got worse. He went to the hospital on May 23rd and was given the antibiotic Doxycycline 100mg. The hospital tested for Lyme disease and we got a call that he tested positive for Lyme just this past week (June 5th). The other nite (July 7th) he was asleep and he often wakes form what I believe are night terrors.. well he sat up and I grabbed his arm and when he I did he just fell back down on the bed and his entire body was shaking like convulsing and at that exact moment I felt like he was having a seizure (growing up my parents neighbor has epilepsy and I have seen and helped with him having seizures so I know what they look like) and I did everything I could to wake him up.. He finally woke up and had couldnt remember what had happened and what he was dreaming about. He went back to sleep and we didn’t talk about the incident until he had gotten home later that nite and he said that he had a strange dream the nite before that he was a local hospital sitting outside and a woman was standing there and she just started having a seizure and when he went to help her something stopped him ( in real life that was me grabbing his arm) and then he fell and started having a seizure (which is what was happening in real life).. I am curious and I can’t seem to find this anywhere on the internet is there any way to have more than one tick borne disease/virus at the same time from the same tick? He tested positive for Lyme but could it be more serious? He has never had prior seizures and also he has been having cognitive difficulties (memory loss, confusion, etc.) I am really worried and not really sure what to do from here. This is his 2nd time being infected with Lyme disease could it just be the Lyme disease causing this or could it be something different? I have done as much research as possible about this but am extremely worried about him..
It is worth looking at a recurrence or reinfection. You also need to rule out another illness.
I’m a 48 year old man. Recently I have been having problems with memory (remembering where to turn for work, finding the right words to say and such). I have also had strange bouts with massive mood swings and strange chest/lung pain. Night time is the worst part. Bed soaking sweats, nightmares, fevers and chills. I figured I was just getting the flu. A new problem started to occur when I decided to go to the dr. I woke up one morning and it felt as if I was having micro seizures. Only lasting for a few seconds each occurence. Let the Dr know about the problems she ordered blood panel tests. The results came back with 1.256 positive Ehrlichiosis. Having had no idea or memory of being bitten by a tick in the past 6 months. Can Ehrlichiosis cause such problems? I am now on Doxycycline 100mg twice a day. As of now it’s the 3rd day. Still have stabbing chest pain and breathing issues with occasional mood swings out of the blue, all which is abnormal for me. How long does it take to subside if it’s related to Ehrlichiosis or should they also look for another firm of tick-borne illness as wellm
I have seen patients with evidence of one tick-borne-illness who have another without a positive test. I have to individualize treatment. I also follow them to rule out other medical problems.
Hi Christopher,
I know this is a late response but I was infected with Erhlichiosos 3 years ago. I went a few months untreated, and even though I have recovered, I still get occasional seizures. I have never really been the same since, and I still suffer from a lot of the symptoms that you’ve described.
Hi,
My son had western Blot showed band 18 present back in Feb 2020, doctor did a repeat test in August with band 93 present only. He is having memory changes. I hear there are lyme specific bands and if present should be treated. Any suggestions.? He does have a appt follow up Infectious Disease next few weeks.
Each of the ten IgG bands were identified to identify Lyme disease. Some are better than others. I do not find focusing on one or two bands all that helpful. I prefer to use clinical judgement based on the complete presentation to determine whether I should treat.
Great article. In your practice, are patients with pre-existing concussions/migraines are more likely to present with headaches, seizures, etc as main symptoms of Lyme disease?
My Lyme disease patients with a history of concussions/migraines are more likely to delay treatment as they assume their symptoms are related to headaches and seizures.
I contracted Lyme Disease in 2007 which went undiagnosed for 9 months but when diagnosed was treated with doxycycline . During the course of the 9 months I suffered various monthly symptoms including Tinnitus, Bell’s palsy, the phrenic nerve on L side freezing causing difficulty in breathing , violent headaches and aura migraines . I also suffered two tonic clonic seizures. All symptoms disappeared under exception of the migraines and the two seizures I had were preceded half hour earlier by an aura migraine. I was prescribed Epilim to inhibit further risk of seizure and albeit I have experienced aura migraines since diagnosis none has been followed by a seizure until recently. I had been advised to reduce my reliance on Epilim 6 months ago. I had been taking 1400mg pd but during the 6 month period had reduced to 200 pd alternating occasionally with 400pd . 7 days ago ( 13th June 2022) I suffered an aura migraine whilst on my own at home. I lay down in the expectation that it would dissipate in about 20 minutes as usual and leaving me slightly nauseous . I fell asleep and about 15 mins later woke up with a start and screaming . I got up but remember nothing further until sometime later ( half hour?) I woke up on the floor in another room with a very painful back and sides (cause -seizure ?) as also did my wife notice when she returned other areas of my back which were bruised – I assume from falling . The experience was terrifying I have put myself back on to 600mg Epilim pending an appointment with my GP. The reason why my GP recommended reduction of Epilim was that he advised that long term use could cause Parkinson’s Disease. I appear to be between a rock and a hard place ! Any advice ?
I also find it hard to balance the risk rare events with the risk of seizures. I am sorry I do not have and insight to offer.
My son who is now 19 had contracted Luke’s disease at the age of 5, luckily I caught it with the rash and he was treated right away. Fast forward to several years later my son started having seizures after many test mris eeg blood work etc they never could exactly find out what has been causing them so they just diagnosed him as epileptic. I did however mention that he had lymes disease when he was little. Dr said yes I can see the scarring in the mri from the lymes disease. My question is. Can this be the cause of the seizures? He does suffer from insomnia depression and anxiety as well. And I have read that a lot of people with lymes disease even after treatment can be effected with these things. So is it possible that it could be causing his seizures even 14 years later?
I advise my patients to look a second time at Lyme disease while working with their neurologist. It could have been a reinfection. The “scarring” that you refer to may be demyelination that comes from many causes.
Any one have an idea about prevalence in relationship between seizures and Lyme disease (only detected at a very late stage, and which I continue to have to this day)? Please help!!!
I have not read any information of the prevalence. We are still dealing with case reports.
I am currenlty being treated for borrelia and Rickettsia bugs, which I have had for eight years, despite “recommended” treatment with Doxy TWICE. Now that I have learned that Lyme (AKA many tick borne diseases) can survive two courses of Doxy and my symptoms would just come back each time, I have been reading and reading. During my learning curve, I realized I might have ANOTHER bug. I was scratched by a cat when I was six (I am 60) and nearly died. i was hospitalized and had surgery and penicillin. About six years later, I started having “absence seizures.” I had IBS from my early teens onwards for my whole life. My absence seizures continued and became more frequent until, at 28, I had my first “grand mal” seizure. My brain scans and MRI showed nothing, so they don’t know what part of my brain is wonky. I read some studies that showed a correlation between Bartonella (Cat Scratch Fever bug – it didn’t have a name when I was scratched) and epilepsy, and I was told by the author of one of these studies that it is quite possible that the Bartonella has survived 54 years and upteem illnesses with short courses of antibiotics. So, I see my Lyme doctor tomorrow to ask if my current antibiotic regime will take care of Bartonella in my body as well, but the other question is, what are the chances of my epilepsy being cured after 50 years if I get rid of all these bugs? Are there ANY neurologists who specialize in epilepsy caused by infections?
I have Lyme patients with absence seizures. I include a neurologist to evaluate for other causes. I have not been able to answer address your questions on Bartonella.
My nine-year old grand was recently diagnosed with Lyme disease and is on day eight of doxycycline treatment. I was asked to come help the family as over the last five days he has expressed three episodes of “can’t not wake him in the morning”. His physicians think the “cant not wake him in the morning” is strange. He was seen by a medical care worker during one of these episodes. His father took him in and three times during that visit my grandson just laid down and went to sleep. One physician told his mother to “take him to the emergency department” the next time this happens and have them do a MIR on his head. The word “encephalitis” is being tossed around by one of the doctors. Also, another doctor is saying things like “It may be due to another tick-born pathogen”.
Your thoughts will be appreciated.
I have children in my practice with Lyme disease who cannot sleep and others who are exhausted even when waking. I have not found an MRI or spinal tap as helpful for diagnosing Lyme disease. These tests and others may be ordered by neurologists to rule out other conditions.
I was diagnosed with Parkinson’s disease four years ago. For over two years, I relied on Levodopa and several other medications, but unfortunately, the symptoms kept getting worse. The tremors became more noticeable, and my balance and mobility started to decline quickly. Last year, out of desperation and hope, I decided to try a herbal treatment program from NaturePath Herbal Clinic.
Honestly, I was skeptical at first, but within a few months of starting the treatment, I began to notice real changes. My movements became smoother, the tremors subsided, and I felt steadier on my feet. Incredibly, I also regained much of my energy and confidence. It’s been a life-changing experience I feel more like myself again, better than I’ve felt in years.If you or a loved one is struggling with Parkinson’s disease, I truly recommend looking into their natural approach. You can visit their website at www. naturepathherbalclinic .com