Labcorp is running the FDA-cleared, PCR-based mpox (orthopoxvirus) DNA assay developed by the CDC
At a hospital, healthcare provider office or other designated testing location under supervision of a healthcare provider
At an individual's home using Provider-initiated Mpox At Home Collection Kit
The mpox test is qualitative and will indicate a detected, not detected, equivocal or inconclusive result for the presence of DNA from non-variola orthopoxvirus species, of which mpox is one. Here is what these results indicate:
Detected: A non-variola orthopoxvirus was detected. In addition to mpox, there are several viral species in the genus orthopoxvirus. But since there are no current epidemiological concerns about those other viruses, a positive result is presumptive positive for mpox. Variola is the virus that causes smallpox. This test will not detect smallpox.
Not Detected: This means that an orthopoxvirus was not detected, and the patient is therefore negative for mpox.
Equivocal: This result can occur when the virus is detected at levels close to the limit of detection of the assay, and a definitive result cannot be determined. For any equivocal result, the CDC recommends that a new patient sample is collected and tested.
Inconclusive: This result can occur when the assay control criteria are not met and no virus is detected. The concern here is a poorly collected sample, and the CDC recommends that a new patient sample should be collected and tested.
The appearance of mpox lesions may resemble those of STIs such as herpes or syphilis. For this reason, the CDC recommends comprehensive evaluations in patients presenting with genital or perianal ulcers for STIs. Patients co-infected with mpox virus and other infectious agents (e.g., varicella zoster, herpes, syphilis) have been reported, and should therefore have mpox on their differential diagnosis when presented with an STI-associated or STI-like rash.
Furthermore, a recent study by the CDC showed amongst 1,969 persons with mpox in eight U.S. jurisdictions, 38% had HIV infection, and 41% had an STI in the preceding year. Therefore, screening for HIV and other STIs and other preventive care should also be considered for persons evaluated for mpox.
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