Delayed onset of Babesia highlights importance of follow-up visits
A recent case report published in the British Medical Journal demonstrates the importance of monitoring patients with Lyme disease even after initial treatment, as co-infections can surface at a later stage.
by Daniel J. Cameron, MD, MPH
Doctors diagnosed and treated a 67-year-old woman for early Lyme disease with a 21-day course of amoxicillin after she presented with an erythema migrans rash. (The woman was allergic to doxycycline.)
Near the end of her treatment, the woman developed fevers (102.92°F), myalgias, dizziness, and fatigue. Due to concerns that she may be septic or have an ongoing tick-borne infection, the woman was admitted to the local hospital.
Clinicians were particularly worried about anaplasmosis and babesiosis, given the patient’s thrombocytopenia and low neutrophil count.
“When patients present with a tick bite or suspected tick-borne infection, it is important to recognize that a single tick can serve as a common vector for multiple infections.”
The woman’s haemoglobin and platelets continued to drop, and she was transferred to Mayo Clinic in Rochester, MN. Laboratory tests revealed pancytopenia, a deficiency in red cells, white cells, and platelets.
PCR testing was positive for Babesia and a Babesia parasite load of 0.4% by thick smear, writes Hoversten from the Mayo Clinic. 
The patient underwent PCR testing for Anaplasma, Borrelia burgdorferi and Ehrlichia. All were negative. But DNA PCR was positive for Babesia microti.
After receiving a 10-day course of azithromycin and atovaquone, the woman’s symptoms resolved except for some lingering fatigue.
The authors could not explain why there was a delay in diagnosis. “However, it is possible that patients have mild parasite load during their initial evaluation, not severe enough to cause systemic symptoms to warrant further evaluation.“
Hoversten suggests “that concurrent babesiosis infection be considered in patients with Lyme disease who remain febrile after 48 hours of appropriate antimicrobial therapy or those with unexplained anaemia and/or thrombocytopenia.”
Hoversten points out, “the patient’s abnormalities in CBC are not typical of Borrelia infections; therefore, a co-infection was of greater concern than recrudescent Lyme disease.”
Ehrlichia is transmitted by a different type of tick and is not commonly seen in the Midwestern USA. (The patient lived in Wisconsin.)
Cases of Babesia have increased in the western Wisconsin region over the past few years.
Viral infections, HIV, Hepatitis C, malaria and drug-induced cytopenias were also considered as a possible cause.
Other cases in the literature
The authors point out that a delayed diagnosis of Babesia, along with concurrent infections of Babesia and Lyme disease have all been reported in the literature.
“A delay in babesiosis diagnosis was also suggested by Krause et al; however, duration of delay was not reported,” writes Hoversten.
“Case reports by Marcus et al.  and Surgers et al , both describe patients presenting with an erythematous rash 3 – 4 weeks prior to a worsening of symptoms leading to the diagnosis of babesiosis, similar to our patient.”
Delayed Babesia diagnosis in newborns
A delayed Babesia diagnosis is not limited to adults. One study describes 2 newborn infants who were diagnosed with Babesia several weeks after the mother was treated for Lyme disease.
The first infant, a 4 1/2-week-old male, presented with a fever of 101.7, sleepiness and periodic irritability. His mother had been diagnosed with Lyme disease during her third trimester at 32 weeks gestation. She exhibited an erythema migrans (EM) rash and was treated successfully with amoxicillin.  Testing of the infant included a blood smear which revealed 2% parasitemia for Babesia.
The second infant presented with symptomatic anemia including malaise, tachycardia, and pallor. The mother had been diagnosed with Lyme disease during her third trimester at 37 weeks gestation. The infant was born at 38 weeks and had no perinatal complications.
The 18-day-old female infant was initially asymptomatic despite a positive Babesia microti PCR assay. But, 1 week later she developed neutropenia (an abnormally low count of a type of white blood cell) and anemia. 
“Because the Ixodes scapularis tick can harbour and transmit multiple parasites simultaneously,” the authors explain, “the possibility of co-infection should be considered in any patient not responding to appropriate initial medical therapy.”
- Hoversten K, Bartlett MA. Diagnosis of a tick-borne coinfection in a patient with persistent symptoms following treatment for Lyme disease. BMJ Case Rep. 2018;2018.
- Marcus LC, Steere AC, Duray PH, Anderson AE, Mahoney EB. Fatal pancarditis in a patient with coexistent Lyme disease and babesiosis. Demonstration of spirochetes in the myocardium. Ann Intern Med. 1985;103(3):374-376.
- Surgers L, Belkadi G, Foucard A, Lalande V, Girard PM, Hennequin C. Babesiosis and Lyme disease co-infection in a female patient returning from the United States. Med Mal Infect. 2015;45(11-12):490-492.
- Saetre K, Godhwani N, Maria M, et al. Congenital Babesiosis After Maternal Infection With Borrelia burgdorferi and Babesia microti. J Pediatric Infect Dis Soc. 2017.