Monkeypox and chickenpox tend to appear in very different demographic groups. How to differentiate between the two?
1. What is monkeypox?
Monkeypox is a rare disease caused by the monkeypox virus. It leads to rash and flu-like symptoms. Like the better known virus that causes smallpox, it’s a member of the family called orthopoxvirus.
Monkeypox was discovered in 1958 when two outbreaks of a pox-like disease occurred in groups of monkeys being used for research. It’s spread mainly through human contact with infected rodents, but can sometimes be spread through skin-to-skin contact with a person who is infected. There are two known types (clades) of monkeypox virus — one that originated in Central Africa and one that originated in West Africa. The current world outbreak (2022) is caused by the less severe West African clade.
How common is monkeypox?
Monkeypox is rare. But the number of cases is increasing in Africa, as well as in regions that haven’t seen these infections before.
Where else is monkeypox found?
For decades, Monkeypox was mostly been seen in Africa. However, it’s occasionally found in other countries, including the United States. In the spring of 2003, the first outbreak of monkeypox outside of Africa occurred in the U.S. A shipment of infected animals from Ghana was imported into Texas. The infected rodents spread the virus to pet prairie dogs, which then infected 47 people in the Midwest.
As international travel becomes more common, viruses that were once fairly confined to certain locations can more easily spread around the world. In the summer of 2021, a case of monkeypox was found in a U.S. resident who had traveled from Nigeria to the United States. Then, 2022 brought outbreaks to regions outside of Africa, including Europe, the Americas and Australia.
Who does monkeypox affect?
Anyone can get monkeypox. In Africa, most cases are among children under 15 years old. Outside of Africa, the disease appears to be more common in men who have sex with men, but there are numerous cases in people who don’t fall into that category.
What are the signs and symptoms of monkeypox?
After exposure, it may be several days to a few weeks before you develop symptoms. Early signs of monkeypox include flu-like symptoms, including:
Fever.
Chills.
Headache.
Muscle aches.
Fatigue.
Swollen lymph nodes.
After a few days, a rash often develops. The rash starts as flat, red bumps, which can be painful. Those bumps turn into blisters, which fill with pus. Eventually, the blisters crust over and fall off — the whole process can last two weeks to four weeks. You can also get sores in your mouth, vagina or anus.
Not everyone with monkeypox develops all the symptoms. In fact, in the current (2022) outbreak, many cases aren’t following the usual pattern of symptoms. This atypical presentation includes only a few lesions, no swollen lymph nodes, less fever and other signs of illness. You can have it and not know it. Even if you don’t show many signs of infection, you can spread still spread it to others through prolonged close contact.
How do you catch monkeypox?
Monkeypox is spread when you come into contact with an animal or a person infected with the virus. Animal-to-person transmission occurs through broken skin, like from bites or scratches, or through direct contact with an infected animal’s blood, bodily fluids or pox lesions (sores).
Monkeypox can spread from person to person, but it’s less common. Person-to-person spread (transmission) occurs when you come in contact with the sores, scabs, respiratory droplets or oral fluids of a person who is infected, usually through close, intimate situations like cuddling, kissing or sex. Research is ongoing, but researchers aren’t sure if the virus is transmitted through semen or vaginal fluids.
You can also get monkeypox by coming into contact with recently contaminated materials like clothing, bedding and other linens used by a person who is infected or an infected animal.
2. What is chickenpox?
Chickenpox is an infection that causes a skin rash. The disease is caused by a germ called varicella-zoster virus. (Chickenpox itself is also called varicella-zoster.) Most people will get the virus when they’re young if they haven’t had a chickenpox vaccine.
A child with chickenpox can easily give the virus to other children. Chickenpox today is much less common because most children are vaccinated when they are young. Before the first vaccine against chickenpox was approved in the U.S. in 1995, almost everyone got chickenpox. Very few had complications.
Once you’ve had chickenpox, you won’t catch it again from another person. If you’re not vaccinated, you can get chickenpox at any age. Adults who get chickenpox may become very sick, so it’s better to have chickenpox when you’re a child, or prevent getting it by being vaccinated.
How is chickenpox spread?
Children can get chickenpox at any age. After being exposed to chickenpox, your child may appear to be fine for one to three weeks before feeling sick. Children can spread the virus from one day before they show signs of illness to about five days after a skin rash appears. The virus is spread by:
Coming in contact with someone who has chickenpox.
Breathing air from an infected person who sneezes or coughs.
Coming in contact with fluids from an infected child’s eyes, nose or mouth.
What are the signs and symptoms of chickenpox?
Signs of chickenpox are easy to see. Healthcare providers often can look at a child’s skin and know if he or she has chickenpox. Signs of chickenpox usually happen in the following order:
Fever.
Feeling tired.
Headache.
A stomachache that lasts for one or two days.
A skin rash that is very itchy and looks like many small blisters.
Bumps filled with a liquid that looks like milky water.
Scabs after the blisters break.
Skin that looks blotchy.
Spots that fade away.
3. How to tell monkeypox from chickenpox?
It’s actually not easy for most people to tell the difference, says Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York.
“They’re both viral infections that cause pox-like lesions,” he says. “Rarely in our lifetimes have we had we had two pox diseases co-circulating at the same time.”
In general, monkeypox and chickenpox tend to appear in “very different demographic groups,” Dr. Russo says. (Monkeypox has largely shown up in men who have sex with men; chickenpox typically is more common in kids).
However, he points out, “adults can get chickenpox if they’re not vaccinated” and there have been at least two cases of monkeypox in children.
There are some potential cues with the rashes, too, which “are both similar and different,” says William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine.
Chickenpox, for example, creates a “very thin-walled, fragile blister” that’s usually filled with clear fluid, Dr. Schaffner says. But monkeypox causes a “deep-seated, firm, or rubbery kind of lesion—it’s much more firm and stable than the chickenpox lesion,” he explains.
Chickenpox lesions can “break easily, whereas monkeypox lesions do not,” Dr. Schaffner says. Monkeypox lesions also tend to change over time and may “umbilicate,” which means they form an indentation or little crater in the middle, Dr. Schaffner says.
How long you’re sick for factors in, too. “It will take two to four weeks for those monkeypox lesions to resolve completely, whereas chickenpox lesions resolve much more quickly,” Dr. Schaffner says. (The CDC notes that chickenpox usually lasts about four to seven days.)
4. What should you do if you develop pox-like bumps?
Again, depending on where you live and who you interact with, the risk to the general population at this time of contracting either virus is low. But, if you suspect you may have monkeypox or chickenpox, or you’re just not sure what’s going on, Dr. Russo says it’s really best to call your doctor.
“The safest thing to do is get tested,” Dr. Russo says. “There is a test for chickenpox and a test for monkeypox.” You’ll want to call your doctor in advance to make sure they actually have the tests in the office, just to be safe.
And, given that both illnesses are contagious, it’s recommended that you cover your bumps and wear a face mask when you go in to your doctor’s office, just to be safe.