Monkeypox has been making the news lately, and it has a lot of people wondering what it is, how it spreads and if they should be concerned. Understandably, we are all a little jumpy when we start hearing about a new viral outbreak, but tmonkeypox isn’t new. While the virus gained its unfortunate name from its discovery in monkeys in 1958 (1), it exists in a wide range of mammals including rodents, anteaters, hedgehogs, prairie dogs, squirrels and shrews (2) and can spread to humans through close contact with an infected animal.
A member of the Poxviridae family, monkeypox is closely related to the variola virus that causes smallpox; however, monkeypox causes milder symptoms and is rarely fatal (3). The genetic variant of the virus that is causing the recent outbreaks has a fatality rate of <4% (4). In contrast, smallpox fatality rate was close to 30% (4). Symptoms can include fever, headache, muscle and back pain, swollen lymph nodes, chills and exhaustion (2). The most distinguishing symptom is the blister-like rash.
Much like its cousin smallpox, monkeypox spreads in humans through close contact with the infectious rash, scabs, or bodily fluids, as well as through contact with contaminated clothing or linens. The virus can also spread through respiratory secretions with prolonged face-to-face contact or during intimate physical contact. Because it is a zoonotic virus, it can also be transmitted through contact with an infected animal either through a scratch or bite, or by preparing or eating meat and other products from an infected animal.
Making the Move to Humans
In 1970, a 9-month old baby in Zaire (now the Democratic Republic of the Congo, DRC) became the first reported case of monkeypox in humans (5). Since that time, monkeypox has become endemic in West and Central Africa, with the number of cases growing over time (5). Along with the increase in case numbers, the age of those infected has also been rising. In the 1970s, the virus mostly infected young children (median age 4 years); in the years between 2010 and 2019, that age rose to 21.
Ironically, some of the increase in monkeypox cases might be because we successfully eradicated smallpox. The two viruses are similar enough that the smallpox vaccine offered approximately 85% cross-protection against monkepox (5). Routine vaccination against smallpox ceased after the 1980s, when the world was declared free from the virus. As a result, there is now a much larger population with no existing immunity who are more vulnerable to a monkeypox infection. In the United States, there are vaccines that can be used against monkeypox. Currently these are being given post-exposure to control community spread (6).
Emerging Global Relevance
Monkeypox has been a known pathogen for humans since 1970, so why have the recent outbreaks garnered such attention? Although the virus is considered endemic in parts of Africa, cases outside these regions have been rare, and typically linked to recent travel to or through an endemic region. The recent outbreaks are different. With these outbreaks, monkeypox has appeared more or less simultaneously in many different countries and across different continents, which is something we have never seen before. It has also never shown a surge in cases like the current outbreaks. In early June, 2022, there were 600 confirmed or suspected cases in 30 different countries (7), as of July, 2022, the WHO reported more than 14,000 cases in 70 countries (8). This broad geographical dispersion and rapid spread has raised concerns that the virus is spreading undetected via human-to-human contact and has been for some time.
It is important to note that although many—but not all—cases have been reported in men who identify as men who have sex with men (MSM), monkeypox is not a sexually transmitted diseases. Anyone can get this virus, and any type of close contact with an infected person can result in infection (3).
Monitoring and Testing for Monkeypox Virus
The current global monkeypox surge is a dynamic, rapidly changing public health concern. Although most patients can be treated in an outpatient setting, there are rare instances of more sever disease. Currently in the United States, a PCR tested followed by confirmation from the CDC is needed to confirm a monkeypox infection (9).
Any time there is an outbreak of an infectious disease, public health officials want to try to contain the outbreak and stop the disease from spreading. With monkeypox, officials in some areas are looking to lessons from the SARS-CoV-2 pandemic to find ways to better protect their communities. One approach is to monitor wastewater to try to detect the presence of the infectious agent early. Testing wastewater for infectious diseases such as SARS-CoV-2 and monkeypox can help public health departments get a better idea of the rate of infection in their areas and even identify communities where the disease is just emerging. This information can help officials decide where to focus public outreach activities as well as where to send valuable medicine and vaccines.
Learn how wastewater monitoring has been used to track waves during the COVID-19 pandemic.
Monkeypox: Treatment and Vaccines
Although there are no treatments specifically for monkeypox, antiviral treatments that were effective against smallpox may be used with monkeypox because the two viruses are so genetically similar. For communities experiencing outbreaks in the United States, there are two vaccines that are available through the Strategic National Stockpile (6). Both vaccines are being used as post-exposure prophylaxis and are administered after exposure. If given within a few days of exposure, this approach can help prevent illness, when a longer time has lapsed since exposure, vaccination may help reduce disease symptoms (6).
The threat to public health from zoonotic pathogens is not new. West Nile virus, plague and Lyme disease are all examples of zoonotic diseases that have and continue to cause dangers to public health. Scientists estimate that 3 out of every 4 new or emerging infectious diseases in people come from animals (10). The SARS-CoV-2 pandemic has clearly illustrated the chaos an emerging zoonotic disease can cause when it finds ways to spread rapidly in humans. For this reason, scientist around the world spend their lives studying animal diseases, and institutions such as the World Health Organization (WHO) and the Center for Disease Control (CDC) pay close attention to new outbreaks.
- von Magnus, P. et al. (1958) Acta Path Microbial Scand. 46, 159.
- Monkeypox in Animals, CDC website https://www.cdc.gov/poxvirus/monkeypox/veterinarian/monkeypox-in-animals.html Accessed July 19, 2022.
- About Monkeypox, CDC website https://www.cdc.gov/poxvirus/monkeypox/about.html Accessed July 19, 2022.
- Haris, E. (2022) JAMA 327, 2278.
- Bunge, E.M. et al. (2022) PLOS Negl. Trop. Dis. 16, e0010141.
- Considerations for Monkeypox Vaccination, CDC website https://www.cdc.gov/poxvirus/monkeypox/considerations-for-monkeypox-vaccination.html Accessed July 19, 2022.
- Kozlov, M. (2022) Nature 606, 15.
- CDC 2022 Monkeypox Outbreak Global Map https://www.cdc.gov/poxvirus/monkeypox/response/2022/world-map.html accessed July 19 2022 Accessed July 19, 2022.
- Diagnostic Process for Monkeypox Virus Testing CDC website https://www.cdc.gov/poxvirus/monkeypox/pdf/Monkeypox-lab-process.pdf Accessed July 19, 2022.
- Zonotic Diseases CDC website https://www.cdc.gov/onehealth/basics/zoonotic-diseases.html Accessed July 19, 2022.