Usefulness of Non-Skin Samples in the PCR Diagnosis of Mpox (Monkeypox)

Cases of mpox have been reported in several European countries, including Spain. Our objective was to evaluate the usefulness of serum and nasopharyngeal samples for diagnosis of mpox. The presence of MPXV DNA was studied using real-time PCR (CerTest Biotec, Zaragoza, Spain) in 106 samples from 50 patients: 32 skin, 31 anogenital, 25 sera, and 18 nasopharyngeal/pharyngeal, in the Hospital Clinico Universitario of Zaragoza (Spain). Sixty-three samples from twenty-seven patients were MPXV PCR-positive. The real-time PCR Ct values in the anogenital and skin samples were lower than serum and nasopharyngeal samples. More than 90% of anogenital (95.7%), serum (94.4%), and skin (92.9%) samples were real-time PCR-positive. Eighteen (66.7%) of the twenty-seven patients who were MPXV PCR-positive had antecedents or presented with one to three sexually transmitted infection (STI) agents. Our results indicate that the use of serum samples can help facilitate the diagnosis of MPXV infections.

Automated summary

This study evaluated the usefulness of serum and nasopharyngeal samples for the diagnosis of mpox. MPXV DNA was detected in 63 out of 106 samples from 27 patients. Real-time PCR Ct values were lower in anogenital and skin samples compared to serum and nasopharyngeal samples. Over 90% of anogenital, serum, and skin samples were positive for MPXV using real-time PCR. 66.7% of the 27 MPXV PCR-positive patients had a history of or were co-infected with one to three sexually transmitted infection (STI) agents.