How useful and accurate are self-collected samples for diagnosing monkeypox?


In a recent study published in medRxiv*Servant, a team of researchers evaluated the performance of patients with self-collected monkeypox virus (MPXV) against clinician-collected clinical samples, including skin lesions and pharyngeal and rectal swabs on diagnostic tests.

Study: Assessment of the accuracy of self-collected swabs for the diagnosis of monkeypox.  Image Credit: Corona Borealis Studio / Shutterstock
Stady: Assessing the accuracy of self-collected swabs for the diagnosis of monkeypox. Image Credit: Corona Borealis Studio / Shutterstock

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Self-sampling has shown to be a reliable strategy for diagnosing sexually transmitted diseases (STDs), such as chlamydia and gonorrhea, based on nucleic acid Amplification testing and recent coronavirus disease 2019 (COVID-19). However, this approach has not been tested and validated for the diagnosis of monkeypox.

about studying

In this study, researchers evaluated the diagnostic accuracy of self-sampling in MPXV settings. They recruited individuals from three centers in Spain who developed lesions indicating MPXV infection within ten days prior to study examination. A dermatologist or STD specialist clinically evaluated these patients and enrolled those with suspected MPXV infection in the study.

All study participants received a home testing kit containing instructions, including Dacron-tipped swabs for sample collection, pre-addressed swabs containers, and a mailing envelope. The team trained these individuals to self-collect samples and asked them to self-collect swabs from skin, pharyngeal and rectal lesions on the first day of the study.

Participants stored the self-collected samples at 4 °C after collection and contacted the courier service, which transported these samples to a microbiology laboratory in Spain for diagnostic testing.

The researchers analyzed the swabs using quantitative polymerase chain reaction (qPCR), and all patients with positive physician-collected samples on day 0 were included in the study analyses. All of these participants confirmed MPXV infection.

Results

In all, the study included 50 patients with suspected MPXV infection. All patients were male, with a mean age of 33.5 years. They had qPCR-confirmed MPXV infection in at least one of the diagnostic self-collected samples. At baseline, the number of cutaneous lesions and pharyngeal and rectal smears were 49, 38, and 11, respectively. All self-collected skin lesion smears were positive for MPXV DNA. However, only 68% and 82% of the pharyngeal and rectal smears were positive for MPXV DNA.

The researchers observed the highest overall agreement of 98% in the smears of skin lesions. Surprisingly, only one individual tested negative in the physician-collected skin lesion swab and was positive in the self-collected skin lesion swab sample. Similarly, the overall agreement for throat and rectal samples was 79% and 90%, with kappa values ​​of 0.49 and 0.6, respectively.

Furthermore, the researchers noted no significant differences in cycle threshold (CT) values ​​between physician-collected skin and throat lesion samples and throat samples. Conversely, self-collected rectal swabs had a higher CT values ​​from samples collected by the physician, with an absolute difference of 5.5; and a 95% confidence interval (CI). C . meansT The values ​​for physician-collected swabs and self-collected swabs were 22.5 and 23.2, respectively, with an absolute difference of 0.7; and 95% CI.

Conclusions

According to the authors, this is the first study to demonstrate the feasibility of a self-sampling approach for MPXV diagnosis. In general, the self-collected swabs had high resolution and viral loads similar to physician-collected swabs. Skin swabs collected by the patient are not usually used to diagnose common ulcerated skin diseases, such as herpes or varicella. However, the swabs samples collected by the patient from the skin lesions had similar high performance characteristics to the swabs samples collected by the physician.

The general agreement between clinician and self-collected pharyngeal swabs was lower than that of the other samples, likely due to the variance in sample quality. However, fluctuations in Viral burden Inside the pharynx is also possible.

To summarize, the self-sampling approach explored in the current study offered several important advantages for patients and disease control. facilitated the integration of monkeypox into routine testing with other STDs in high-risk groups. Future studies should improve sample collection and include more samples, such as saliva, to highlight the ease of diagnostic testing.

*Important note

medRxiv publishes preliminary scientific reports that have not been peer-reviewed and therefore should not be considered conclusive, guide clinical practice/health-related behavior, or be treated as established information.



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