Even as new COVID-19 variants rage, a new health scare is lurking.
Outbreaks of monkeypox have occurred in at least 12 countries that don’t normally see cases of the disease, sparking new concern over possible health implications.
The United States had between one and five confirmed cases as of May 21, according to surveillance from the World Health Organization (WHO).
While that’s a small amount of cases, compared to outbreaks of the virus in Africa over the years, the hashtag #Monkeypoxalypse soon began circulating on Twitter.
Scientists are still learning about this disease, including the extent of human transmission. But here is what we know so far about this smallpox cousin.
Monkeypox is caused by the monkeypox virus, which belongs to a subset of the Poxvirida family of viruses called Orthopoxvirus. Viruses also grouped into this subset include cowpox and smallpox, making monkeypox related, according to WHO.
While the presentation of monkeypox resembles smallpox, the former is less contagious and causes less severe illness. That’s not to say the virus should be underestimated, however. Of the two clades of monkeypox referred to as the West African clade and Congo Basin clade, the former has a case fatality rate of 3.6%, compared to the latter’s 10.6%, according to WHO. The U.S. Food and Drug Administration noted that variola major, the severe form of smallpox, had a case fatality rate of 30%.
Like cowpox, monkeypox is a viral zoonotic disease, meaning it can spread from animals to humans. Unlike cowpox, however, there has been evidence of human-to-human transmission, primarily through close contact with lesions, body fluids, respiratory droplets and contaminated materials, such as bedding, according to WHO.
SARS-CoV-2 is also zoonotic, though that doesn’t necessarily mean that transmission of monkeypox will explode in the same way COVID-19 did.
Monkeypox has been around since it was discovered in monkeys in a Danish laboratory in 1958. The first human case was identified in a child in the Democratic Republic of the Congo (DRC) in 1970, according to WHO.
Since its discovery, human cases have been reported across 11 countries in Central and West Africa, with the DRC recently experiencing an outbreak involving more than 1,200 cumulative cases from Jan. 1 to May 1, 2022, with at least 57 recorded deaths. Cameroon, the Central African Republic and Nigeria also experienced monkeypox outbreaks between Dec. 15 and May 1 this year. While no human cases have been reported in Ghana, WHO also counts it among the endemic countries, due to the animal infections reported.
If monkeypox has been around since the 1970s, then why is it making headlines now?
Recorded cases of monkeypox outside of Africa, specifically in the U.S., are usually rare. Monkeypox doesn’t occur “naturally” in the U.S., though cases have been previously reported that were associated with international travel or importing animals from where the disease is more common, according to the CDC.
However, as of May 21, roughly 92 laboratory-confirmed cases and 28 suspected cases of monkeypox have been reported in at least 12 countries outside of Central and West Africa that typically don’t see frequent cases — referred to as “non-endemic” countries. This includes several European nations, Australia, Canada and the U.S.
No deaths have been reported regarding this group of outbreaks to date, according to WHO.
The first recorded case this year in the U.S. was on May 18, 2022, when a Massachusetts resident tested positive for monkeypox after returning to the U.S. from Canada, according to the CDC.
While monkeypox in the U.S. is rare, that’s not to say that it hasn’t been previously detected here. The CDC confirmed two cases of the virus in 2021, one in a Texas resident in July and another in a Maryland resident in November. Both had returned from their respective trips from Nigeria.
The first time monkeypox was reported in the U.S. was 2003, when a shipment of animals, including various rodents, from Ghana to Texas, introduced the virus into the U.S., according to investigators. CDC laboratory testing later showed that a few of the rodents were infected, though not before the animals had been housed near prairie dogs at an animal vendor facility. The prairie dogs were later sold as pets before developing signs of infection.
In total, there were 47 cases of confirmed and probable cases of monkeypox across six states — Illinois, Indiana, Kansas, Missouri, Ohio and Wisconsin, according to the CDC. A study later conducted showed that certain activities such as touching a sick animal and receiving a bite or scratch that broke the skin, were more likely to lead to an infection. Cleaning the cage or touching the bedding of a sick animal were also important factors.
No instances of the 2003 outbreak were attributed exclusively to person-to-person contact, per the CDC.
The reported cases in this recent outbreak have no established travel links to an endemic area, which is unusual, compared to cases from over the years, according to WHO. The agency said it expects more cases in non-endemic areas to be reported with available information suggesting human-to-human transmission is occurring among people in close physical contact with people who are symptomatic.
WHO said it is investigating the mechanics of exactly how monkeypox is transmitted, and it likely differs from SARS-CoV-2. The general precautions recommended against COVID-19 are also expected to protect against monkeypox virus transmission in cases of large gatherings.
Transmission via droplet respiratory particles usually requires prolonged face-to-face contact, and WHO stressed that health workers, household members and other close contacts of active cases are at greater risk.
Transmission can also occur via the placenta from parent to fetus or during close contact during and after birth.
It’s currently unclear if monkeypox can be transmitted specifically through sexual transmission.
The incubation period, or time from infection to the onset of symptoms, is typically between six and 13 days, though it can range from five to 21 days, health experts said.
The infection itself can be divided into two stages: the invasion period, which may feel similar to the flu, and a period characterized by skin eruptions.
The invasion period may include fever, intense headache, swollen lymph nodes (lymphadenopathy), back pain, muscle aches (myalgia) and a lack of energy (asthenia).
Rashes that form during the second stage tend to be more concentrated on the face and extremities and evolve from lesions with a flat base to ones filled with a clear or yellow fluid.
Earlier studies found vaccination against smallpox had previously been about 85% effective in preventing monkeypox, according to WHO, meaning prior vaccination against the virus may result in milder illness. However, the vaccination of the general public against smallpox came to an end after the World Health Assembly declared smallpox eradicated in 1980. Due to this, people younger than 50 may be more susceptible to monkeypox.
Severe cases have occurred more commonly among children, relating to factors such as the extent of exposure, the patient’s health status and any health complications. It can also be severe in pregnant people and persons with immune suppression, due to other health conditions, according to WHO.
A vaccine (MVA-BN) and the treatment Tecovirimat were approved for the treatment of monkeypox in 2019 and 2022, respectively, but they are not yet widely available.
Produced in association with AccuWeather.