Babesia in Children - A Parent's Guide to Babesiosis
- Aug 16
- 11 min read
Updated: 6 minutes ago
Babesia in Children: What Babesiosis Is and Is Not
Written by Amy Patton, DNP, APRN, CPNP-PC - pediatric nurse practitioner and founder of Happy Kid Functional Medicine, Omaha.
Babesia is a parasite that gets inside red blood cells. Someone probably said the word to you in the same breath as Lyme disease, and you nodded and then went home and typed it into a search bar. That is exactly how most parents meet this one.
So let me start with the part that actually changes decisions, and then work outward from there.
What do parents ask me most about this?
Short answers first. The full reasoning is below.
What is Babesia?
Babesia is a parasite that infects red blood cells. It is not a bacterium. That one fact drives everything else, because the antibiotics used for Lyme disease have no effect on a parasite.
Where is Babesia found?
Babesia microti is endemic in the Northeast and the upper Midwest, and it causes most human babesiosis in the United States. Its vector is the blacklegged tick, Ixodes scapularis. CDC counted 3,586 US cases in 2023, up from 2,111 in 2022. Geography is the single most useful clue you have.
What does babesiosis look like?
Babesiosis has no rash to look for. IDSA says it directly: "Babesiosis has no easily recognized clinical features such as the erythema migrans skin lesion of Lyme disease." What babesiosis looks like is a flu that will not quit. Fever is the most common feature, at 85%.
Is babesiosis dangerous for children?
For most previously healthy children, babesiosis is uncommon and mild. In CDC's 2011–2015 surveillance of 7,612 cases, ages 0–9 accounted for 90 cases, which is 1.2%, and ages 10–19 for 137 cases, or 1.8%. Hospitalization was lowest in the 10–19 group at 16.0%.
How is Babesia tested for?
IDSA recommends a blood smear or PCR over antibody testing. That is a strong recommendation on moderate-quality evidence. The logic is clean. Antibodies tell you a body met the parasite at some point. A smear or a PCR tells you the parasite is there now.
What about Lyme and Babesia together?
They do travel together, because they share a tick, and the numbers are specific. About 11% of early Lyme patients also have babesiosis, with a range across studies of 2% to 40%. Going the other way, about 52% of people with babesiosis are also diagnosed with Lyme, range 23% to 72%.
What Is Babesia in Children?
Babesia is a parasite that infects red blood cells. It is not a bacterium. That one fact drives everything else, because the antibiotics used for Lyme disease have no effect on a parasite. A child can finish a full, correct course for Lyme and still have Babesia doing exactly what it was doing before.
Babesia is a parasite, not an immune-triggered condition like PANS and PANDAS, and not Lyme disease itself.
The technical name is an apicomplexan protozoan, which is the same broad family that malaria belongs to. CDC counts more than 100 Babesia species, but only a few have been identified as causing human infection: Babesia microti, Babesia divergens, Babesia duncani, and an unnamed strain labeled MO-1.
Because it is a parasite, the medicine is different. CDC and the 2020 IDSA babesiosis guideline both call for atovaquone plus azithromycin, or clindamycin plus quinine, given for 7–10 days in a child whose immune system is working normally. That is a short, defined course. Not months. Not a moving target.
I say that early because it takes a certain kind of fear off the table. Babesiosis is not an open-ended condition with no answer. It is a specific parasite with a specific, short regimen, prescribed by the child's medical team. My Lyme disease and tick-borne illness hub puts it next to the other infections that share the same tick.
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Where is Babesia found?
Babesia microti is endemic in the Northeast and the upper Midwest, and it causes most human babesiosis in the United States. Its vector is the blacklegged tick, Ixodes scapularis. CDC counted 3,586 US cases in 2023, up from 2,111 in 2022. Geography is the single most useful clue you have.
Species | Where US cases come from | Vector |
|---|---|---|
B. microti | Northeast and upper Midwest; most US cases | Ixodes scapularis, the blacklegged tick |
B. duncani | Washington and California | Tentatively identified as Dermacentor albipictus |
MO-1 | Missouri | Not established |
That second row matters more than it looks. CDC's parasite reference says B. duncani's vector "tentatively has been identified as Dermacentor albipictus," so West Coast babesiosis should not be pinned on the blacklegged tick.
The map is also moving. Swanson and colleagues reported in MMWR in 2023 that babesiosis rose significantly in eight states between 2011 and 2019: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Rhode Island and Vermont. On the strength of that, CDC now considers Maine, New Hampshire and Vermont endemic, adding three states to the previous list. In 2023 the highest counts were New York with 1,169 cases, Massachusetts with 841, and New Jersey with 406.
Nebraska is not among the states CDC now considers endemic, and it did not appear among the states reporting cases in 2023. That is the honest local picture, and it is the same reason I write about ticks in Nebraska and Iowa as a separate, much smaller risk than what families read about online.
What are the symptoms of Babesia in children?
Babesiosis has no rash to look for. IDSA says it directly: "Babesiosis has no easily recognized clinical features such as the erythema migrans skin lesion of Lyme disease." What babesiosis looks like is a flu that will not quit. Fever is the most common feature, at 85%.
Here is the frequency table from the Vannier and Krause review of 214 patients.
Symptom | How often |
|---|---|
Fever | 85% |
Fatigue | 79% |
Chills | 63% |
Sweats | 53% |
Headache | 39% |
Muscle aches | 33% |
Poor appetite | 24% |
Cough | 22% |
On labs, babesiosis tends to show anemia, low platelets, elevated liver enzymes, and signs that red blood cells are breaking down. CDC notes that when red cells break down fast enough it can cause yellowing of the skin and dark urine.
Now the part I want to be straight with you about. You will see two phrases repeated on almost every page about this: "air hunger" and "drenching night sweats." I went looking for them. Neither phrase appears in CDC's babesiosis pages, in the IDSA guideline, or in the Vannier and Krause review. All three say only "sweats." Those exact phrases come from clinician websites, and nobody should attribute them to CDC or IDSA.
What is supportable is quieter and more useful. Cough shows up in 22% of patients. Vannier and Krause report up to 20% of patients developing fluid in the lungs that is not from the heart. CDC lists respiratory failure among severe outcomes. So unexplained trouble breathing in a sick child is worth urgent attention. Just not because of a phrase somebody put in bold on the internet.
Is babesiosis dangerous for children?
For most previously healthy children, babesiosis is uncommon and mild. In CDC's 2011–2015 surveillance of 7,612 cases, ages 0–9 accounted for 90 cases, which is 1.2%, and ages 10–19 for 137 cases, or 1.8%. Hospitalization was lowest in the 10–19 group at 16.0%.
The best pediatric data available is a MaineHealth series published by McCarthy and colleagues in 2025. Nineteen children, ranging from 4 weeks old to 17 years, average age 7.4 years. All of them were previously healthy. Only two needed hospital care, and both were young infants who needed blood transfusions. Both did well on atovaquone and azithromycin.
One detail in that paper stopped me: "Except in 1 case, babesiosis was not suspected when testing was done." Eighteen of nineteen times, somebody found it while looking for something else. That is worth holding onto, in both directions. It means babesiosis gets missed. It also means these children were not desperately sick with an obvious syndrome.
There are real risk groups, and they are specific:
A child with no spleen, or a spleen that does not work well
A suppressed immune system, especially with rituximab
Advanced age, which is not your child but may be a grandparent
Newborns exposed through a blood transfusion or across the placenta
One more finding, from a study on Block Island: 40% of infected children had no symptoms at all, compared with 19% of infected adults. Children seem to carry this more quietly than adults do. That cuts both ways, and it is another argument for exposure history rather than symptom-hunting.
How is Babesia diagnosed in children?
IDSA recommends a blood smear or PCR over antibody testing. That is a strong recommendation on moderate-quality evidence. The logic is clean. Antibodies tell you a body met the parasite at some point. A smear or a PCR tells you the parasite is there now.
Test | What it shows | The limits |
|---|---|---|
Blood smear | The parasite itself, under a microscope | Often under 1% of red cells are infected early; may need repeat smears over several days; 200–300 fields under oil immersion |
PCR | Babesia DNA | More sensitive, especially when parasite numbers are low, but DNA can persist for months after the infection has resolved |
Antibody (IFA) | Past or present exposure | Detects 88–96% of B. microti infections but cannot separate active from past; titers persist a year or more |
Two practical notes on the smear. Babesia ring forms can be mistaken for the malaria parasite by an eye that is not expecting them. And the "Maltese cross" shape that clinches the diagnosis is rarely seen. CDC's own guidance is that providers should explicitly request a manual, non-automated review of the blood smear, because the machine will not catch it.
There is also a species blind spot that matters if a family travels. The B. microti antibody test does not detect B. duncani antibody, and the B. duncani test does not detect B. microti. A negative result on one says nothing about the other.
And the line I want parents to have in hand: IDSA states that treating a patient who is antibody-positive but smear-negative and PCR-negative is not indicated. That is a strong recommendation. A positive antibody alone is not a reason for medication. I take the same approach to Lyme testing in children, for the same reason.
Can children have Babesia and Lyme disease together?
They do travel together because they share a tick, and the numbers are specific. About 11% of early Lyme patients also have babesiosis, with a range across studies of 2% to 40%. Going the other way, about 52% of people with babesiosis are also diagnosed with Lyme, with a range of 23% to 72%.
Read those two numbers side by side. Most children with Lyme do not have babesiosis. But about half of the children who do have babesiosis also have Lyme. Babesia rarely shows up alone in this part of the world.
IDSA's practical guidance follows from that. Consider babesiosis in a Lyme patient with severe illness, or in one who does not respond well to standard antibiotic therapy for Lyme. And now the reason from the first section comes back around: doxycycline does nothing to a parasite. A child who was correctly diagnosed with Lyme, correctly medicated, and is still sick weeks later is a child who deserves a second look rather than a longer prescription.
That is a different question from the ones I get about sudden behavior change, which usually belong with PANS and PANDAS or with Bartonella in children. Different infections, different evidence, different answers.
What I do with this in my practice
Babesiosis is uncommon in Nebraska children, and I am not going to manufacture it. That is the first thing I say. Nebraska DHHS states that Nebraska will likely remain a low-prevalence state for Lyme disease, and Nebraska has never appeared among the states reporting babesiosis. That is not true of every tick-borne illness here, and I'd rather be precise about it: Nebraska's tularemia rate is one of the highest in the country. Inventing a diagnosis to explain a struggling child costs that child real time.
But I do ask about travel. Every time. Summer trips to the Northeast or the upper Midwest, camp in Wisconsin or Minnesota, two weeks at a lake house in Maine, the grandparents in Connecticut. That history is what makes a test worth running, and it is free to collect. Without it, a Babesia test on a Nebraska child is a number in search of a story.
When I do suspect babesiosis, I bring in the child's pediatrician and infectious disease. Not eventually. Right away. This is a parasite with a real, effective, short course of treatment, and it is not a functional medicine problem to solve alone. My job in that room is to notice the pattern, ask the travel question nobody asked, and hand off cleanly to the people who prescribe.
What I keep doing in the meantime is the work that helps any child in any scenario: sleep, gut, nutrition, and the daily rhythms that let a body recover. Those hold steady no matter which way the workup goes. If you have questions about your own child's picture, you can reach me directly.
What this means for your child
If somebody said "Babesia" to you and your stomach dropped, here is the shape of it. Babesia is a parasite, not a bacterium. It has a defined 7–10 day course of medicine. In children who are previously healthy, it is usually mild, and in one Maine series of 19 children, only two needed hospital care and both did well.
The children who need close watching are the ones without a working spleen, the ones with suppressed immune systems, and newborns. If your child is not in one of those groups and has not spent time in the Northeast or upper Midwest, babesiosis is unlikely to be the answer.
What I will not do is let "unlikely" turn into "not looked at." I would rather ask the travel question and get a boring answer than skip it. If a tick bite is what started this whole search for you, start with what to do after a tick bite, and go from there.
You asked a good question. That is how these things get caught.
Book My Free 15-Minute Call get clarity and learn more.
Free. No obligation. Not a sales call. Or call or text me directly at 402-988-1873.
References
Krause PJ, Auwaerter PG, Bannuru RR, et al. Clinical Practice Guidelines by the IDSA: 2020 Guideline on Diagnosis and Management of Babesiosis. Clin Infect Dis. 2021;72(2):e49–e64. Source for the no-rash statement, the smear-or-PCR-over-serology recommendation, the co-infection percentages, and the treatment regimens.
CDC DPDx. Babesiosis (Parasite Biology; Laboratory Diagnosis). Reviewed June 3, 2024. Species list including MO-1, the Dermacentor albipictus vector note for B. duncani, and the 88–96% antibody sensitivity figure.
CDC. Clinical Overview of Babesiosis. Reviewed February 13, 2024. Risk groups including asplenia, rituximab, and neonates; severe outcomes such as respiratory failure; and the manual smear request.
CDC. About Babesiosis. Reviewed February 12, 2024. General parent-facing overview of babesiosis and how it spreads.
CDC. Signs and Symptoms of Babesiosis. Reviewed July 9, 2024. Source for jaundice and dark urine from red blood cells breaking down.
Vannier E, Gewurz BE, Krause PJ. Human Babesiosis. Infect Dis Clin North Am. 2008;22(3):469–488. The n=214 symptom frequency table, the smear limitations, the 20% non-cardiac pulmonary edema figure, and the Block Island asymptomatic data.
CDC. Data and Statistics on Babesiosis. Updated March 3, 2026. 3,586 US cases in 2023, up from 2,111 in 2022, with state-level counts.
Swanson M, Pickrel A, Williamson J, Montgomery S. Trends in Reported Babesiosis Cases — United States, 2011–2019. MMWR. 2023;72(11):273–277. Significant increases in eight states; CDC now considers Maine, New Hampshire, and Vermont endemic.
Gray EB, Herwaldt BL. Babesiosis Surveillance United States, 2011–2015. MMWR Surveill Summ. 2019;68(SS-6):1–11. Of 7,612 cases, 90 were ages 0–9 and 137 were ages 10–19; hospitalization was lowest at 16.0% in the 10–19 group.
McCarthy CA, Elias SP, Smith RP. Spectrum of Pediatric Babesia Infection: A Retrospective Case Series. J Maine Med Cent. 2025;7(2):Art 15. Nineteen children aged 4 weeks to 17 years; two hospitalised infants who needed transfusion and did well on atovaquone and azithromycin.
Nebraska DHHS. HAN Update: Tickborne Diseases in Nebraska, 2026. Nebraska DHHS states that Nebraska will likely remain a low-prevalence state for Lyme disease.
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