Can Babesia Infection Be Asymptomatic?
Babesia infections can remain unnoticed for months or years.
Some individuals may have few symptoms or none at all.
Undiagnosed infections can create risks for blood transfusion recipients.
Asymptomatic Babesia infection may be more common than many people realize. Some immunocompetent individuals can carry Babesia microti without recognizable symptoms, and persistent asymptomatic infection has been documented for as long as two years. [3]
Babesia is one of several important tick-borne coinfections that can complicate Lyme disease. While some patients develop significant symptoms, others may remain asymptomatic and never realize they have been infected.
Can Babesia infection go unnoticed?
Yes. Some individuals infected with Babesia may develop significant symptoms, while others remain asymptomatic and never realize they are infected. These individuals may unknowingly transmit the parasite if they donate blood.
Linden and colleagues from the Wadsworth Center at the New York State Department of Health found that both community-acquired and transfusion-transmitted babesiosis increased significantly during the 12-year period they studied. The geographic range of ticks and tick-borne infections also expanded. [1]
In 2004, there were 91 cases of community-acquired babesiosis in New York, compared with 576 cases in 2015, Linden explains. The investigators also identified 55 cases of transfusion-transmitted babesiosis during the study period.
Overall, 3,799 cases of babesiosis were reported in New York during the 12-year period. Fifty-five individuals acquired Babesia through blood transfusions from donors who were unaware they were infected. More than half of the transfusion recipients were 60 years of age or older.
The infected donors were identified after recipients of their blood donations became ill. Two recipients were infected on separate occasions by repeat donations from the same respective donors. In one instance, two units were donated 56 days apart. In the other, two units were donated 69 days apart.
The authors found that 50% of the implicated donations occurred between July and September, when Ixodes scapularis tick activity is high. However, at least one implicated donation occurred during every month of the year.
[bctt tweet=”Asymptomatic Babesia infection can create risks for blood transfusion recipients.” username=”DrDanielCameron”]
Most of the donors lived in counties where Babesia microti was endemic, including counties in New York. Other implicated donations came from New Jersey, Massachusetts, Rhode Island, and Pennsylvania. One upstate New York resident had traveled to Connecticut.
How has Babesia blood donor screening changed?
At the time of the Linden study, no licensed test for screening blood donors was available. Two individuals who acquired babesiosis through transfusions ultimately died from the infection, underscoring the need for effective donor screening. [1]
Blood donor screening has changed since that study was published. The FDA licensed donor-screening tests for Babesia microti in 2018. In 2019, the FDA recommended year-round screening of blood donations collected in 14 states and the District of Columbia, where the risk of Babesia transmission was considered greatest. [4,5]
These screening measures have improved blood safety. Nevertheless, asymptomatic infection remains clinically and epidemiologically important, particularly as the geographic range of babesiosis continues to expand.
Tests designed to screen for B. microti may not necessarily detect every Babesia species. In addition, the same ticks may carry other pathogens, including Anaplasma phagocytophilum, which can produce symptoms that overlap with babesiosis.
Can people have mild symptoms without recognizing them?
The distinction between asymptomatic and mildly symptomatic infection is not always clear. Some people may initially consider themselves asymptomatic but later recognize fatigue, night sweats, cognitive difficulties, or other symptoms that they had not associated with a tick-borne infection.
I have seen patients whose infection was first identified through blood donor screening. Several had been experiencing fatigue, night sweats, cognitive difficulties, or other symptoms but had not appreciated their potential significance until abnormal screening results led to further investigation.
Frequently Asked Questions
Can Babesia infection be asymptomatic?
Yes. Some individuals infected with Babesia may have few symptoms or none at all. These asymptomatic carriers can remain unaware of their infection.
How long can an asymptomatic Babesia infection persist?
Persistent asymptomatic Babesia microti infection has been documented in immunocompetent individuals for as long as two years. [3]
Can Babesia be transmitted through blood transfusions?
Yes. Transfusion-transmitted babesiosis has been documented in the United States. Asymptomatic individuals can carry the parasite in their blood without realizing they are infected.
Why is Babesia screening important for blood donors?
People may donate blood while unknowingly infected. Screening helps reduce the risk of transmitting Babesia to blood transfusion recipients.
Is Babesia commonly found with Lyme disease?
Babesia is an important tick-borne coinfection in regions where Lyme disease is endemic. The same Ixodes ticks can transmit both pathogens.
Clinical Takeaway
Babesia infections do not always cause obvious symptoms. Some individuals may carry the parasite without realizing they are infected, while others may have mild symptoms whose significance is not initially recognized.
Babesia microti infection can persist without recognizable symptoms for months and, in documented cases, for as long as two years. Although modern blood donor screening has reduced transfusion risk, asymptomatic infection remains an important clinical and public health concern.
Related Articles
Blood donor infects premature infants with Babesia
Study raises concerns for Babesia patients and blood banks
Transfusion-transmitted babesiosis popping up in more states in USA
Lyme disease coinfections
References
- Linden JV, Prusinski MA, Crowder LA, et al. Transfusion-transmitted and community-acquired babesiosis in New York, 2004 to 2015. Transfusion. 2018;58(3):660–668.
- Diuk-Wasser MA, Vannier E, Krause PJ. Coinfection by Ixodes Tick-Borne Pathogens: Ecological, Epidemiological, and Clinical Consequences. Trends Parasitol. 2016;32(1):30–42.
- Bloch EM, Kumar S, Krause PJ. Persistence of Babesia microti Infection in Humans. Pathogens. 2019;8(3):102.
- U.S. Food and Drug Administration. Babesia microti NAT/Babesia microti NAT for Blood Screening. FDA. 2018.
- U.S. Food and Drug Administration. Recommendations for Reducing the Risk of Transfusion-Transmitted Babesiosis: Guidance for Industry. FDA. 2019.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
I had a strange attack, after being fatigued for the first time in my life. I had no energy, my left leg and arm are numb and don’t work well, brain fog, headaches for the first time in my life, facial numbness, trouble speaking sometimes, deteriorating eyesite, formication horribly, ringing in my ears and severe muscle weakness and muscle wasting and atrophy. Though I’m an avid outdoorsman, my doctors all ignored this information and focused on MS, myositis and other disorders. I showed antibodies for lyme, but refused to treat me though I told them I believed I possibly contracted lyme around a year and a half earlier, which is about 4 yrs ago now. I finally tested positive last November and was given 3 weeks of doxy which did absolutely nothing. My myelin sheaths have been damaged, found in a lumbar puncture and doctors just seem to stop treating and/or testing me. I truly need someone that will run the tests needed and treat me accordingly. Where can I get this help? I’m in upstate new york. I’m honestly on my last leg on this.
Thanks for sharing your story. Many of my patients in my New York Practice face the same uncertainty. It would seem reasonable to look at a tick borne illness a second time for other approaches that a single 3 week course of doxycycline.
Is it possible to transmit Babesia in plasma products such as IVIG or sub-q IG products?