Babesiosis Causes False-Positive HIV Test Results

Babesiosis may rarely trigger false-positive HIV test results
Acute Babesia infection may complicate laboratory interpretation and diagnosis
Repeat testing after treatment may help clarify confusing results

Investigators describe the case of a patient with acute babesiosis who tested positive for HIV prior to treatment.

The 60-year-old man was admitted to the emergency department with intermittent fever, fatigue, anorexia, and worsening jaundice for three weeks. He was referred by his primary care physician because of abnormal laboratory values and parasites identified in the blood.

A blood smear showed Babesia microti with 1–2% infected red blood cells. “Given the patient’s severe presentation but relatively low percentage of infected red blood cells, HIV testing was done,” the authors explain. [1]

The fourth-generation HIV 1/2 antigen/antibody test was initially positive, but repeat HIV testing after treatment was negative.

Acute babesiosis may complicate HIV test interpretation

“Our case report adds to the small amount of literature showing that false-positive HIV testing in patients with babesiosis is possible,” the authors write.

The patient was treated with atovaquone and azithromycin for babesiosis and doxycycline to cover possible concurrent tick-borne infections.

“An exchange transfusion was performed due to the patient’s severe presentation,” according to the authors.

The patient’s symptoms resolved following treatment, and repeat HIV testing was negative.

False-positive fourth-generation HIV tests are considered uncommon. However, several case reports have described false-positive HIV results occurring during acute babesiosis.

Clinicians evaluating patients with severe tick-borne illness may need to consider that acute inflammatory or infectious states could interfere with laboratory interpretation.

This case also highlights the broader diagnostic complexity associated with Lyme coinfections, particularly in patients presenting with systemic symptoms, abnormal laboratory findings, or severe inflammatory illness.

Patients with babesiosis may also experience overlapping neurologic or constitutional symptoms similar to those discussed in neurologic complications of Babesia.

The authors conclude

• “While the reasons for false-positive HIV tests in acute babesiosis remain unclear, physicians who see patients with a positive HIV test in the setting of acute babesiosis should pursue further workup.”

Frequently Asked Questions

Can babesiosis cause a false-positive HIV test?

Rarely, yes. Case reports suggest that acute babesiosis may occasionally trigger false-positive fourth-generation HIV test results.

Why would babesiosis affect HIV testing?

The exact mechanism remains unclear, but severe inflammatory or immune responses during acute infection may interfere with laboratory assays.

Should HIV testing be repeated after babesiosis treatment?

In some situations, repeat testing may help clarify whether an initial HIV result was falsely positive during acute illness.

What symptoms can occur with babesiosis?

Symptoms may include fever, fatigue, sweats, jaundice, anemia, shortness of breath, and constitutional symptoms.

Can babesiosis occur with Lyme disease?

Yes. Babesiosis commonly overlaps with Lyme disease and other tick-borne infections in endemic regions.

Clinical Takeaway

Babesiosis may rarely lead to false-positive HIV test results during acute infection.

Clinicians evaluating patients with severe tick-borne illness should recognize that inflammatory or immune responses may occasionally complicate laboratory interpretation.

Repeat testing and careful clinical correlation may help avoid diagnostic confusion and unnecessary anxiety for patients.

Related Articles

These related articles explore babesiosis complications, tick-borne coinfections, neurologic symptoms, and diagnostic challenges associated with Lyme disease.

Lyme coinfections
Neurologic complications of Babesia
Can Lyme disease trigger a cascade of costly unnecessary tests?
Delayed Lyme disease diagnosis
Lyme disease misdiagnosis

References

1. He JZ, Rezwan M, Arif A, Baroud S, Elhaj M, Khan A. Acute babesiosis causing a false-positive HIV result: an unexpected association. Case Rep Infect Dis. 2023;2023:6271710.

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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