“With viruses that spill over from animals, you just never know what’s going to happen."
- Jay Hooper, Chief, Molecular Virology Branch, U.S. Army Medical Research Institute of Infectious Diseases
“We do have a level of concern that this is very different than what we typically think from monkeypox."
- Jennifer McQuiston, deputy director, division of high consequence pathogens and pathology, U.S. Center for Disease Control and Prevention
Once again a zoonotic virus is in the news. In early May, monkeypox first erupted in the U.K., Spain, and Portugal before making its way to the U.S. by mid-month. As of May 21, 2022, the U.S. had one confirmed case and four suspected cases of monkeypox.
While monkeypox is endemic in certain countries in Africa, outbreaks in non-endemic countries, e.g.. European nations and the U.S., are rare. Therefore, for many Americans, this recent outbreak may be the first time they have heard of monkeypox. But, as Agam Rao, a scientist in the poxvirus and rabies branch of the Centers for Disease Control and Prevention (CDC), stated, “[T]he outbreak is not likely to become a major threat to the general U.S. population.” He said: “Only a small subset of the population are currently affected and while I would not be surprised if there are more cases, we don’t expect it to be taking off the way COVID-19, for example, took off.”
In this Germ Gems post, I provide you with a brief overview of monkeypox, discuss the recent outbreak and explain why we should all be concerned with but not panicked by this outbreak.
What is monkeypox? Monkeypox is an infectious disease that occurs in certain animals including humans. It is caused by monkeypox virus, a species of the Orthopoxvirus genus that includes variola virus, the cause of the now eradicated smallpox. (While the monkeypox virus is most commonly found in rodents, such as squirrels, pouched rats, or dormice, the first documented cases of illness occurred in 1958 in monkeys in a research facility in Denmark—hence its name.)
In 1970, physicians first recognized a case of monkeypox in humans. Some experts think it’s likely, however, that monkeypox had infected people for many centuries but was confused with smallpox as the two diseases are indistinguishable clinically.
The signs and symptoms of monkeypox begin with fever, headache and muscle pain before the development of a telltale rash: vesicles with clear fluid that become pustules that burst and scab over. Most people recover from monkey pox within a few weeks—after the disease has run its course. The death rate of monkeypox is between 1% to 10%, compared with a mortality of 30% with smallpox (which has been eradicated).
Where is monkeypox found and how is it transmitted? Following its discovery in humans in 1970, about 50 cases were reported between 1970 and 1979, with more than two-thirds of these occurring in Zaire (now the Democratic Republic of the Congo [DRC]). Other cases originated in Liberia, Nigeria, Ivory Coast, and Sierra Leone. Monkeypox is now considered endemic to western and central Africa.
The primary route of infection is thought to be contact with infected rodents or small mammals through bites or scratches or during preparation of bushmeat, a staple in the diet of some African countries. Person-to-person transmission is not common and requires close contact with bodily fluids, such as saliva from coughing or pus from skin lesions. In some cases, individuals can also be infected through contact with clothing or bedsheets of infected people, or by droplets from the respiratory tract.
The smallpox vaccine works quite well in protecting against monkeypox. But once smallpox was eradicated in 1980 and vaccination for smallpox was curtailed, outbreaks of monkeypox in West Africa and Central Africa shot up. In 2020, there were nearly 4,600 suspected monkeypox cases in the DRC with171 deaths from the disease.
The first outbreak of monkeypox outside of the African continent occurred in the U.S. in 2003 in the states of Illinois, Indiana, Kansas, Missouri, Ohio, and Wisconsin. There were 47 confirmed and probable cases. Scientists traced this outbreak to prairie dogs infected by an imported Gambian pouched rat. The disease ran its course in these patients and no deaths occurred.
While there is no specific treatment for monkeypox, there is a vaccine that was licensed in the U.S. in 2019 for people 18 years of age and older that protects against both monkeypox and smallpox. Should the need arise, this vaccine could be used to curb this recent outbreak. Recently, the CDC reported that it had received a request for release of the vaccine from the National Stockpile for some of the contacts of the early patients. Right now vaccination of the general public is, however, not necessary.
Current outbreak. As of May 21, 2022, the World Health Organization reported that 12 non-endemic countries had reported 92 cases with an additional 28 suspected cases under examination. As mentioned earlier, people typically contract monkeypox virus from infected animals mainly in West Africa or Central Africa and then carry the virus to other countries.
In the U.K., seven of the eight patients hadn’t travelled to Africa, and the U.S. patient recently traveled only to Canada where health officials in Montreal are investigating 17 suspected cases. According to Susan Hopkins, the chief medical officer of the U.K. Health Security Agency, “This [outbreak] is rare and unusual. Exactly where and how [the patients] acquired their infections remains under urgent investigation.”
One feature of the current monkeypox outbreak that is unique is evidence that the virus could be spreading by sexual contact between men. In Spain, where cases climbed to 23, most were young men who are gay or bisexual, who had lesions exclusively in the perigenital and perianal areas and around the mouth, pointing towards transmission through mucus during sexual relations. In neighboring Portugal, all five confirmed cases involved young men, and sexual transmission also seemed likely. As monkeypox is not known to be sexually transmitted, the leading hypothesis is that transmission is occurring during close contact with lesions that comes with sex.
How concerned should you be? In his article “So, Have Your heard about Monkeypox?” in the May 19th issue of The Atlantic, science writer Ed Yong stated “While the news is alarming, you probably shouldn’t be overly concerned with monkeypox at the moment.” I agree. The chances of contracting the virus are exceedingly low, and to date there have been no deaths.
The good news is that a great deal is already known about monkeypox, including information coming from the current outbreak. The fact that the current outbreak of monkeypox erupted during our ongoing battle with the zoonotic pandemic COVID-19 is, in my mind, also good news because the global health and scientific communities are already geared up for this challenge (see the article in Nature News on May 20, “Monkeypox goes global: why scientists are on alert”).
It is of critical importance to unravel the epidemiology of this outbreak as quickly as possible to curb the number of new infections. Primary care physicians, urgent care doctors, emergency medicine physicians, dermatologists, and those working in Sexually Transmitted Infection clinics need accurate information to manage patients who present with monkeypox symptoms. And accurate information is needed to temper concerns of the general public as we confront this viral “outbreak.”