False-positive HIV and viral hepatitis serologic test results in a cluster of pork processing plant workers

Background

Accuracy of screening tests is vital in the diagnosis of HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) infection.

Objective

Our goal is to report false-positive serologic tests secondary to heterophile antibodies in a group of pork processing plant workers.

Methods

We conducted a case series study of seven pork processing plant workers referred to our clinic between 2017 and 2020 for a positive fourth-generation HIV test.

Results

All patients had undetectable HIV-1 and HIV-2 RNA viral load, ruling out HIV infection. Five patients had initial positive HBV serologies but were negative upon retesting with neutralizing antibodies or heterophile antibody binding reagent. Three patients presented with respiratory symptoms. After extensive workup, they were diagnosed with interstitial lung disease of unknown etiology. For patients who left the plant, their symptoms resolved, and serologic test results reverted to negative.

Conclusions

: Occupational exposure to pork meat products may elicit heterophile antibody development and yield false-positive serologic results for HIV and viral hepatitis. Clinicians should interpret serologic tests carefully together with other relevant patient history and molecular tests. Further investigation is warranted to determine the etiology, pathophysiology, and occupational link of the pneumonitis syndrome.