Monkeypox is now a public health emergency in the United States. The World Health Organization (WHO) has also declared it a global health emergency. This means that monkeypox is viewed as an illness that poses a substantial risk for widespread transmission.

Monkeypox is a rare viral infection that is caused by a virus similar to the one that causes smallpox. It is spread from person to person when someone has contact with an infected person’s rash, bodily fluids, or respiratory droplets. The current outbreak has spread more among people who’ve had close contact with others—particularly sexual contact.

There are many signs and symptoms of monkeypox. While a person may not show all signs of infection, here is what you should look for:

1. Bumps

A rash with raised bumps may be the first noticeable symptom of monkeypox. These bumps have an indentation or dimple in the center. They will eventually become filled with pus, scab over, and fall off. Sometimes they can leave a scar. “They’re fairly deep-seated and can be quite painful,” says Sankar Swaminathan, M.D., chief of the Division of Infectious Diseases at University of Utah Health. “Especially if they’re in the mouth, genitals, or rectum, these bumps can cause a lot of pain.” People may mistake these bumps for chickenpox, shingles, or herpes.

2. Vesicles or pustules

Once these bumps fill with clear liquid or pus, they are called vesicles or pustules. This alarming symptom often compels people to seek help because the lesions can become very painful and form an open sore. They can appear anywhere on the body or mucous membranes, such as the inside of the mouth or genitals. Eventually, they will scab over, crust, and fall off.

A person with open sores is most contagious and at risk of spreading the virus to others. If another person contacts these open sores, the virus can easily transmit. A person with skin lesions should quarantine and have little to no contact with others. The process usually takes two to four weeks to fully clear.

3. Other signs of illness

Fever, fatigue, exhaustion, chills, headache, muscle aches, and swollen lymph nodes are other symptoms of monkeypox. In past outbreaks, monkeypox started with flu-like symptoms. However, with the current outbreak, these symptoms have been less common, and a rash may be the first or only symptom.

If you are showing any signs or symptoms of monkeypox, call your health care provider right away. Delaying medical attention could expose more people to the virus. Depending on the severity of the infection, treatment with antiviral medication may also be appropriate. Before getting tested and while waiting for results, a person suspected of having monkeypox should isolate and not have direct contact with others.