Monkeypox Virus - Credit CDC PHIL
While there is limited information on Monkeypox infection in non-endemic countries, over the past 4 years the UK has seen a handful of imported cases (see here, here, here and here), which resulted in at least 3 local infections (1 HCW, 2 family members).
During this time there have also been imported cases in the United States (see here and here), and in a small number of other countries (Singapore, Israel, etc.), making this month's global outbreak a bit less surprising.
Conventional wisdom holds that people are no longer contagious once symptoms (usually rash or pustules) disappear (see RIVM FAQ) - generally after about 3 weeks.
Asymptomatic transmission has not been documented (cite), and despite recent developments, it isn't clear whether Monkeypox is sexually transmitted (via semen or vaginal fluids) or is simply being spread by intimate or `close contact'.
Given the intense epidemiological and clinical investigations ongoing, over the next few months we may find that some of the above mentioned `conventional wisdom' on Monkeypox will be rewritten, just as we've seen with COVID, Zika, and Ebola.
We should know a great deal more about the transmission and treatment of Monkeypox six months or a year from now. Good reasons why blanket statements made today about the virus should be taken with a grain of salt.
Yesterday The Lancet published a review of 7 human monkeypox cases (4 imported, 3 local) reported in the UK between 2018 and 2021. The authors present data suggesting cases may be contagious longer than previously suspected, and they identify at least one antiviral medication that showed promise in treating cases.
The full report is behind a paywall, but a fairly detailed summary/abstract is available at the link below.
Clinical features and management of human monkeypox: a retrospective observational study in the UK
Hugh Adler, PhD, Susan Gould, MRCP, Paul Hine, MRCP, Luke B Snell, MRCP, Waison Wong, MRCPCH, Catherine F Houlihan, PhD, et al.
Published:May 24, 2022 DOI:https://doi.org/10.1016/S1473-3099(22)00228-6
A few of the highlights from the summary include:
- Notable disease features included viraemia, prolonged monkeypox virus DNA detection in upper respiratory tract swabs, reactive low mood, and one patient had a monkeypox virus PCR-positive deep tissue abscess.
- Five patients spent more than 3 weeks (range 22–39 days) in isolation due to prolonged PCR positivity.
- Three patients were treated with brincidofovir (200 mg once a week orally), all of whom developed elevated liver enzymes resulting in cessation of therapy. One patient was treated with tecovirimat (200mg twice daily for 2 weeks orally), experienced no adverse effects, and had a shorter duration of viral shedding and illness
- One patient experienced a mild relapse 6 weeks after hospital discharge.
- Prolonged upper respiratory tract viral DNA shedding after skin lesion resolution challenged current infection prevention and control guidance
All of this is based on a very small subset of cases (n=7), making it difficult to draw any firm conclusions, but this report does seem to offer some red flags on how long a person may potentially remain contagious.
While we take comfort in absolutes and generalities, viruses often surprise us by coloring outside the lines. Over the past 10 years we've unexpectedly seen:
- A deadly coronavirus (MERS-CoV) spread by camels in the Middle East
- A previously known enterovirus (EV-D68) suddenly becoming neurotropic, and causing `polio-like paralysis' in children and adolescents
- A multi-nation Ebola outbreak in West Africa that defied longstanding `conventional wisdom' that Ebola was too virulent to spread massively in an urban environment.
- Evidence men who recovered from Ebola infection could shed the virus in their semen for months.
- A mosquito-borne virus (Zika) that not only could be transmitted sexually, but caused severe congenital birth defects through maternal infection.
- A coronavirus (COVID) that could spread as efficiently as chickenpox, even through asymptomatic carriers.
We live in interesting times.