On May 18, 2022, Massachusetts health officials and the Centers for Disaster Control and Prevention confirmed a single case of monkeypox in a patient who had recently traveled to Canada. Cases have also been reported in UK and Europe.
Monkeypox is not a new disease. the the first confirmed human case dates back to 1970, when the virus was isolated from a child suspected of having smallpox in the Democratic Republic of Congo (DRC). Monkeypox is unlikely to cause another pandemic, but with COVID-19 in mind, the fear of another major outbreak is understandable. Although rare and usually mild, monkeypox can still potentially cause serious illness. Health officials fear more cases will arise with increased travel.
I am a researcher who has worked in medical and public health laboratories for more than three decades, particularly in the field of diseases of animal origin. What exactly is happening in the current epidemic and what does history tell us about monkeypox?
A cousin of smallpox
Monkeypox is caused by the monkeypox virus, which belongs to a subset of the Poxviridae family of viruses called Orthopoxvirus. This subset includes smallpox, the vaccine and cowpox viruses. While a the animal reservoir of monkeypox virus is unknown, African rodents are suspected to play a role in transmission. Monkeypox virus has only been isolated twice from an animal in the wild. Diagnostic Tests for Monkeypox is currently available only from Laboratory Response Network labs in the United States and worldwide.
The name “monkeypox” comes from first documented cases disease in animals in 1958, when two outbreaks occurred in research monkeys. However, the virus did not jump from monkeys to humans, and monkeys are not the main carriers of the disease either.
Since the first reported human case, monkeypox has been discovered in several other countries in Central and West Africa, with the majority of infections in the DRC. Cases outside of Africa have been linked to international travel or imported animals, including to the United States and somewhere else.
the first reported cases of monkeypox in the United States was in 2003, an outbreak in Texas linked to a shipment of animals from Ghana. There have also been cases related to travel in November and July 2021 in Maryland.
Since monkeypox is closely related to smallpox, the smallpox vaccine can provide protection against infection by both viruses. However, since smallpox has been officially eradicated, routine smallpox vaccinations for the general population of the United States were stopped in 1972. For this reason monkeypox was appearing more and more in unvaccinated people.
The virus can be transmitted through contact with an infected person or animal or contaminated surfaces. As a rule, the virus enters the body through damaged skin, by inhalation or through the mucous membranes of the eyes, nose or mouth. Researchers believe human-to-human transmission occurs primarily through inhalation of large respiratory droplets rather than direct contact with bodily fluids or indirect contact through clothing. Human-to-human transmission rates of monkeypox have been limit.
Health officials fear that the virus is currently spreading undetected through community transmission, possibly through a new mechanism or pathway. Where and how infections occur are still under investigation.
Signs and symptoms
Once the virus has entered the body, it begins to replicate and disseminate through the body via the bloodstream. Symptoms usually do not appear until one to two weeks after infection.
Monkeypox produces smallpox-like skin lesions, but symptoms are generally milder than those of smallpox. Flu-like symptoms are common at first, ranging from fever and headache to shortness of breath. One to 10 days later, a rash may appear on the extremities, head, or torso that eventually turns into pus-filled blisters. Overall, symptoms usually last two to four weeks, while skin lesions usually heal in 14 to 21 days.
Although monkeypox is rare and usually non-fatal, a version disease kills about 10% of those infected. The form of the virus currently in circulation would be more benign, with a mortality rate of less than 1%.
Vaccines and treatments
Monkey pox treatment is primarily focused on symptom relief. According to the CDC, there is no treatment available to cure monkeypox infection.
Evidence suggests that the smallpox vaccine can help prevent monkeypox infections and reduce the severity of symptoms. A vaccine known as Imvamune or Imvanex is licensed in the United States to prevent monkeypox and smallpox.
Vaccination after exposure to the virus can also help reduce the risk of serious illness. The CDC currently recommends smallpox vaccination only in people who have been or are likely to be exposed to monkeypox. Immunocompromised people are high risk.