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Monkeypox – the Next Pandemic?
Hello! A quick note before we get into things. This article was kindly produced (and gratefully received!) for the SDC by Dr Michael Gliksman, BMed(Hons), MPH, PhD, FAFPHM(RACP), FRSMed. This article does not constitute individual medical advice. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Consult your doctor before making any lifestyle or treatment changes based on the information contained in this article.
Monkeypox vs Smallpox
Monkeypox is a viral zoonosis (a virus transmitted to humans from animals) with symptoms like those seen in the past in smallpox patients. The clinical presentation of monkeypox resembles that of smallpox.
How does it compare against smallpox and COVID? Image Source: OpenAI
Thankfully monkeypox appears less easily transmitted than smallpox and less deadly. At this stage, the fatality rate of monkeypox looks to be around 3% - 10% in Africa - dependent on the viral subtype, compared to about 30% for smallpox.
The last known case of naturally acquired smallpox occurred in 1977, and in 1980 smallpox was declared to have been eradicated worldwide after a global vaccination campaign. It has been more than 40 years since all countries ceased routine smallpox vaccination, but as it also protected against monkeypox, populations are once more susceptible to monkeypox.
Monkeypox vs COVID19
SARS-CoV-2, the COVID virus, is a small single-stranded RNA virus. On the other hand, the monkeypox virus is a large double-stranded DNA virus. Why is that important?
Firstly, RNA is much less stable than DNA. It breaks down if you look at it the wrong way. DNA is much more stable and can persist on surfaces, remaining infective for longer.
Secondly, DNA is less subject to mutations than RNA. It has been estimated the mutation rate of the COVID virus is up to one hundred times higher than the Monkeypox virus. The importance of this is seen in the rapid emergence of mutations of SARS-CoV-2 virus that evade, to some degree, the immunity conferred by earlier vaccines, whereas one type of vaccine was sufficient to eradicate smallpox from the world.
Natural host of monkeypox virus
Various animal species have been identified as susceptible to the monkeypox virus. This includes squirrels, some species of rats, dormice, non-human primates and other species. Uncertainty remains on the natural history of monkeypox virus and further studies are needed to identify the exact reservoir(s) and how virus circulation is maintained in nature.
Human monkeypox was first identified in humans in 1970 in the Democratic Republic of the Congo, where smallpox had been eliminated in 1968. In 2003, the first monkeypox outbreak recorded outside of Africa occurred in the United States of America. This outbreak led to over 70 cases of monkeypox in the USA.
In May 2022, multiple cases of monkeypox were identified in several other non-endemic countries. This may reflect declining immunity in all communities due to the cessation of smallpox vaccination.
Transmission
Animal-to-human (zoonotic) transmission of a mutated virus can occur from direct contact with the blood, bodily fluids, or lesions of infected animals or humans. Eating inadequately cooked meat and other animal products of infected animals is a possible risk factor.
Human-to-human transmission of the monkeypox virus can result from close contact with respiratory secretions, skin lesions of an infected person or recently contaminated objects. Transmission via droplet respiratory particles usually requires prolonged face-to-face contact. This puts health workers, household members and other close contacts of active cases at risk.
Transmission can also occur via the placenta from mother to foetus (congenital monkeypox) or during close contact during and after birth. The latest data also indicates that monkeypox can be transmitted via unprotected sexual intercourse.
Prevention
Surveillance and rapid identification of new cases are critical for outbreak containment. During human monkeypox outbreaks, close contact with infected persons is the most significant risk factor for monkeypox virus infection.
Apart from following behaviours that minimise the risk of transmission via the above routes, vaccination may become the main means by which transmission is prevented among human populations.
Vaccination against smallpox was demonstrated through several observational studies to be about 85% effective in preventing monkeypox. Prior smallpox vaccination may also result in milder illness. Evidence of vaccination against smallpox can usually be found as a distinctive circular scar on the upper arm. The original smallpox vaccines are no longer available to the public.
A newer two-dose vaccine based on a modified virus (a DNA virus from the orthopox family) was approved for the prevention of monkeypox in 2020.
Symptoms and Signs
The monkeypox virus typically spreads through direct contact with body fluids or skin lesions. Skin lesions traditionally appear soon after infection as a rash – small pimples on the face, hands and/or genitalia.
These lesions may also appear inside the mouth, eyes and other parts of the body that produce saliva or mucus. They can last for several weeks and be a source of virus before they are fully healed. Symptoms can include fever, swollen lymph nodes, fatigue, and headache.
Many patients reported mild symptoms without fever or swollen lymph nodes, symptoms that typically appear before a skin rash is visible. While most people do develop skin lesions, many reported having only a single papule (pimple) that was often obscured inside a mucosal area, such as inside the mouth, throat or rectum, making it easier to miss.
Some patients reported no symptoms at all. Infections without symptoms are more likely to go undiagnosed and unreported than those with symptoms. This increases the difficulty of containing outbreaks among the unvaccinated.
Is monkeypox a sexually transmitted disease (STD)?
While sexual encounters are currently the predominant mode of transmission among newly reported cases, monkeypox is not primarily an STD.
Monkeypox can spread through any form of close contact. Anyone who has close contact with an infected person is at risk, including partners, parents, children or siblings.
The virus has no regard for age, gender, ethnicity, or sexual orientation.
Will monkeypox become the next worldwide pandemic?
The short answer is: we don’t know. The long answer is: it’s complicated.
Historically, monkeypox has been transmitted from animals to humans, with some limited person-to-person spread. The current strain is spreading throughout different countries in the world, and we don’t fully understand why.
Monkeypox has been declared a public health emergency by the World Health Organisation (WHO), and the USA’s Department of Health and Human Services. This does not mean that we’re all in imminent danger of being infected but it does serve to call attention (and resources) to prevent it from becoming so.
If monkeypox develops into the next pandemic, it’s likely to be a different kind of pandemic than COVID. That’s because monkeypox appears – at least at this stage, more difficult to catch than COVID and is less likely to mutate and thereby evade the current vaccine.
