Hidden HIV infection discovered following rare blood disorder relapse
Case study highlights need for repeat HIV testing before immune therapy
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A recent report describes the case of a woman with acquired thrombotic thrombocytopenic purpura (TTP) who was later found to have an undetected human immunodeficiency virus (HIV) infection.
Although HIV was present when her first TTP episode occurred, it was not detected until months after her diagnosis. The case highlights the importance of repeat testing for infections such as HIV in people diagnosed with TTP, especially before starting immune-suppressing treatment, researchers said.
The report, “Acquired thrombotic thrombocytopenic purpura and HIV infection: a case report and review of the literature,” was published in the Annals of Hematology.Â
How acquired TTP affects the blood
Acquired TTP, or aTTP, is an autoimmune disorder in which antibodies attack ADAMTS13, a protein that helps regulate blood clotting. In aTTP, tiny clots form in small blood vessels. These clots can damage red blood cells and interfere with normal clotting.
The underlying causes of aTTP aren’t fully understood, but certain infections, including HIV, are known to be associated with the condition. Research suggests people living with HIV have an estimated 15- to 40-fold higher risk of thrombotic microangiopathy, a group of disorders that includes aTTP, compared with the general population.
In this report, researchers at a specialty center in Italy described the case of a 46-year-old woman referred to their clinic after being diagnosed with aTTP at another hospital. She initially sought care for fatigue and digestive symptoms. Tests showed very low ADAMTS13 activity and antibodies targeting the enzyme, findings consistent with aTTP. The other hospital reported that viral tests, including for HIV, had been negative.
At the specialty center, the woman received standard aTTP treatment with plasma exchange, corticosteroids, and Cablivi (caplacizumab-yhdp). Her symptoms improved, and she was discharged after stopping plasma exchange and, later, Cablivi.
Two months later, she was hospitalized with interstitial pneumonia and acute respiratory failure. She was treated and testing at the time suggested her aTTP was still stable.
Again, two months later, she returned to the center with worsening fatigue. Lab tests showed her ADAMTS13 activity had dropped again, suggesting her aTTP was flaring up. Doctors planned to treat the flare-up with rituximab, an immune-suppressing medication sometimes used to control aTTP.
Repeat testing reveals hidden HIV infection
Since rituximab suppresses the immune system, it is standard practice to test patients for infections prior to starting the drug. In this woman, the routine infection screen returned positive for HIV.
Clinicians realized that an HIV diagnosis might help explain not only the woman’s aTTP, but also her recent episode of interstitial pneumonia and acute respiratory failure. When they tested a blood sample stored from her initial visit, they found she had been HIV-positive at the time of her aTTP diagnosis, despite reportedly testing negative at another hospital.
“It was only at the time of her ADAMTS13 relapse that the HIV infection was firstly detected; consequently, by repeating HIV testing on retention of blood sample stored at the moment of the first hospitalization, we clarified that the viral infection was already present when the first episode of aTTP occurred,” the researchers wrote.
After her HIV diagnosis, the woman began standard combination antiretroviral therapy. Her condition stabilized, with ADAMTS13 activity increasing substantially within about a month of starting HIV treatment. She later experienced additional complications related to advanced immunosuppression and medication side effects, but her aTTP has remained under control since starting HIV treatment. The researchers noted that, in HIV-associated aTTP, the condition often improves once the underlying infection is controlled.
This patient’s case underscores the importance of thorough testing for infections in people with aTTP, including repeat testing when appropriate, the researchers said.
“The frequency of HIV re-testing in aTTP and other immune-mediated diseases is not clearcut, but this case suggests the importance of repeating viral [testing] before starting new treatments or even routinely in patients with risk behaviours,” the scientists wrote.
