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Division of Communicable Disease Control

Mpox

The current mpox situation continues to evolve and the information below will be updated as new information emerges. The California Department of Public Health (CDPH) is closely monitoring mpox transmission in California and the U.S. to ensure the identification of cases during this outbreak. The risk of mpox to the general public is currently very low based on the latest information; however, anyone can become infected with mpox virus if they are exposed.

Mpox Data in California

Find the number of reported probable/confirmed cases and demographic data in California by visiting the mpox data webpage.

About Mpox

Mpox is a rare disease that is caused by infection from the mpox virus. The mpox virus belongs to the Orthopoxvirus genus, which includes the variola (smallpox) virus as well as the vaccinia virus, which is used in the smallpox vaccine. Mpox is a public health concern because it can be transmitted person-to-person and can cause severe illness and even fatalities in humans. Although mpox virus is in the same family of viruses as smallpox, it is less transmissible and typically less severe than smallpox.

Mpox was first identified in 1958 and primarily occurs in Central and West African countries. Historically, mpox has been rare in the U.S. and has mostly been related to international travel or the importation of animals. In 2022, there has been a significant increase in reported cases in locations where mpox is not commonly seen, including Europe, Canada, and the United States, including California. While it's good to stay alert about any emerging public health threat, as noted above, the current risk of mpox for the general public is very low.   

Symptoms 

Mpox often starts with symptoms like the flu, with fever, low energy, swollen lymph nodes, and general body aches. Within 1 to 3 days (sometimes longer) after the appearance of fever, most infected people will develop a rash or sores. The sores go through several stages, including scabs, before healing. The sores can look like pimples or blisters and may be painful and itchy.

The rash or sores may be located on or near the genitals (penis, testicles, labia, and vagina) or anus (butt). They can also appear on other areas like the hands, feet, chest, face, or inside the mouth. They may also be limited to one part of the body.

People with mpox may experience all or only a few of these symptoms, with most people developing the rash or sores. Some people have also reported developing a rash or sores before (or without) the flu-like symptoms. 

Monitoring Period

The estimated incubation period from infection to illness onset (i.e., rash or other related symptoms) ranges from 3 days to approximately 3 weeks. In addition to being infectious while symptoms are present (i.e., rash or other related symptoms); people can also transmit the virus to others up to four days before developing signs or symptoms. If you have been exposed to mpox, avoiding sexual contact with others during the 21-day monitoring period is highly recommended to prevent transmission of infection.​

Infectious Period 

A person with mpox can spread it to others from the start of symptoms until all sores have healed, scabs have fallen off, and a fresh layer of skin has formed underneath, which can take several weeks. Th​ere is a growing body of scientific evidence that shows some people can spread mpox virus to others from one to four days prior to symptoms appearing (CDC Science Brief: Detection and Transmission of Mpox). To date, there is no evidence that people who never developed symptoms have spread the virus to others. ​

Transmission

Mpox can be spread by:

  • Direct skin-to-skin contact with the sores or scabs of people with mpox or people that are in the 21-day monitoring period due to pervious mpox exposure.
  • Direct contact with body fluids of people with mpox, such as drainage from skin sores or saliva that was in contact with mouth sores.
  • Contact with the respiratory secretions of people with mpox, such as saliva, during prolonged, face-to-face contact or during intimate physical contact, such as kissing, cuddling, or sex.
  • Touching items (such as bedding, towels, clothing, cups and utensils) that previously touched the sores or body fluids of people with mpox.

To date, there has been no evidence that mpox is spread by:

  • Attending an outdoor event with fully clothed people.
  • Trying on clothes or shoes at a store.
  • Traveling in an airport, on a plane or on other public transit.
  • Swimming in a pool or body of water.
  • Casual contact with other people. 

If you believe you may have exposed someone to mpox while you were infectious, you can let them know anonymously, so they can self-monitor for 21-days, get vaccinated to reduce the risk of serious infection (see more information below), and be tested as soon as possible if symptoms develop. Ple​​ase visit the CDPH Sexually Transmitted Disease (STD​​) website and refer to Quick Links. Getting tested if you have symptoms is strong​​ly encouraged to help identify infections and prevent infections in others.

If you have been exposed to mpox, monitoring for symptoms and avoiding sexual contact with others for 21 days is highly recommended. For people who haven't already ​been vaccinated, mpox vaccination is most effective when obtained as soon as possible after exposure and is strongly encouraged for at-risk patients to prevent severe illness. For more information visit CDPH Mpox Vaccine Q&A.

Prevention

There are a number of ways to prevent the spread of mpox, including:

  • Getting vaccinated if you are at risk for mpox. See the CDPH mpox vaccine page to learn more about the JYNNEOS vaccine and where to get vaccinated.
  • Open conversations with your sexual partner/s about any recent illness or symptoms, any possible exposures to mpox, and being aware of new or unexplained sores or rashes on your body or your partner's body, including on the genitals and anus.
  • Avoiding close contact, including hugging, kissing, cuddling, and sexual activity with people who have symptoms, like sores or rashes, and people  who were exposed and are in their 21-day monitoring period.
  • Not sharing materials (bedding, towels, clothing, utensils, cups) with someone who has symptoms.
  • Washing your hands often with soap and water or an alcohol-based hand sanitizer.
  • Using appropriate personal protective equipment (PPE) like a mask, gown, and gloves when caring for others with mpox symptoms. 

Vaccination after Exposure (Post-Exposure Prophylaxis)

Vaccination helps protect against mpox when given before or shortly after an exposure and is highly recommended for at-risk persons who have not alre​​ady received two doses of JYNNEOS vaccine. See the CDPH mpox vaccine page to learn more about the JYNNE​OS vaccine and where to get vaccinated.​

Testing & Isolation

If you have a new or an unexplained rash or other symptoms, seek medical care for further testing and evaluation.

  • Wear a well-fitting mask, ensure your rash is covered, and tell your health care provider that you have possible mpox symptoms. 
  • If you do not have a health care provider or healthcare insurance, visit a public health clinic or local county clinic. You may also contact the Department of Healthcare Services for more available resources.
  • Avoid crowds and close contact, including sexual or intimate contact, with other people until you see your health care provider.

For more information about isolation recommendations, please refer to the CDPH Mpox Home Isolation Guidance for the General Public.

Treatm​ent

Most mpox infections are mild and heal without any treatment. However, antiviral drugs, such as tecovirimat (TPOXX), may be used to treat mpox. This drug is recommended for people who are more likely to become severely ill or are experiencing severe illness. It may also be recommended for people who have a rash or sores in areas that are at higher risk for severe complications, such as the eyes or the genital area.

People who may be at risk for more severe illness include those with a weakened immune system, young children (less than 8 years of age), those who are pregnant or breastfeeding, and those with a history of certain skin diseases like eczema.

Tecovirimat should be administered early in the course of illness along with supportive care and pain control relief for those that are at high risk for  severe illness.

For more information on treatment, please visit the CDC Patient's Guide for Tecovirimat and the CDPH Mpox Tecovirimat Treatment Information for Providers.

Additional information for treatment of severe manifestations of mpox can be found at CDC's Interim Clinical Treatment Considerations for Severe Manifestations of Mpox. 

It is important to talk to your health care provider if you have symptoms of mpox and are experiencing pain or irritation due to the rash or sores. Your provider may also be able to offer treatments that are not specific to mpox, but can help reduce your symptoms and discomfort, like prescribed mouth rinses, stool softeners, or topical gels or creams.​​

Additional Information

For more information about mpox, visit the CDPH Mpox Q&A

How Can We Help You?

Connect with CDPH for additional mpox resources.

Contact CDPH Guidance and Policy

If you need further clarification or have questions, comments, and concerns regarding CDPH Mpox Guidance and Policy submit an inquiry

Contact Your Local Public Health Department

Reach out to your local health department with any questions.

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