Monkeypox virus found to be persistent after resolution of lesions
A Melbourne Sexual Health Centre research study shows that it is common for monkeypox virus to persist at oral and anal sites and be infectious after the patient appears to have recovered and is asymptomatic.
A Melbourne Sexual Health Centre (MSHC) research study shows that it is common for monkeypox* virus to persist at oral and anal sites and be infectious after the patient appears to have recovered and is asymptomatic.
This means that individuals who have been diagnosed with monkeypox virus are still infectious at or after lesion resolution, and release from isolation (according to Victorian Department of Health guidelines) and should abstain from kissing and sexual activity for a longer period of time, to avoid onward transmission to their sexual partners. This period of time needs to be investigated in further studies.
This study, a collaboration between MSHC and Victorian Infectious Diseases Reference Laboratory at the Peter Doherty Institute for Infection and Immunity used different laboratory techniques - monkeypox polymerase chain reaction (PCR) and viral culture – to determine both the detection of the monkeypox virus (positive PCR) and viability (positive viral culture) at oral, anal and urine sites, at the patient’s first presentation and at weekly intervals. These findings were then matched with the duration of symptoms and clinical resolution of lesions (when release from isolation is permitted according to Victorian Department of Health guidelines).
This is the first study to demonstrate that the monkeypox virus can persist (and is infectious) at oral and anal sites, at or after lesion clearance. Although asymptomatic detection, and prolonged detection and viability of the monkeypox virus has been shown by other research groups, no one has previously correlated these finding to the clinical improvement of the patient, resolution of lesions and the date of release from isolation.
Lead researcher and Monash University Post-Doctoral Research Fellow Dr Janet Towns said, "The important thing about this research is that it is not just the detection of the virus by PCR that we have demonstrated, but the ability for the virus to reproduce in viral culture indicates viability of the monkeypox virus and potential transmissibility to others".
*Mpox (previously known as monkeypox ) is a zoonotic disease caused by a virus of the Orthopox genus, and is closely related to the variola (smallpox) virus. Mpox cases previously had been largely confined to endemic areas of Central and West Africa with few imported cases reported outside Africa. Since May 2022 there has been a global outbreak of mpox across non-endemic regions, including Europe, North America and many other countries, already with over 84,000 identified cases. Mpox is an infectious disease that requires isolation of cases and notification of close contacts to prevent onward transmission. The sustained transmission of mpox in the current global outbreak, including Australia, has different features to previous outbreaks in non-endemic settings, being predominantly in men who have sex with men (MSM), with strong evidence of sexual transmission in high-risk sexual networks. The first case of mpox was recognised in Australia in May 2022, and the first case at MSHC was diagnosed on the 23 Jun 2022. Melbourne Sexual Health Centre, between June & October 2022, saw one third of the mpox cases in Australia.
Reference:
Towns JM, Lim CK, Chow EPF, Lee D, Fairley CK, Bradshaw CS, Samra RS, Williamson DA, Chen MY. Persistence of monkeypox virus at oral and rectal sites. Lancet Microbe. 2023 Jan 12. Open Access. DOI: 10.1016/S2666-5247(22)00382-2. Epub ahead of print.
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