The California Department of Public Health (CDPH) would like to increase awareness of a recent increase in mpox cases in California and the nation. The number of California mpox cases has significantly increased from an average of approximately 1 to 7 cases per week from February to August 2023, up to approximately 17 cases per week in the most recent three-week period (September 20-October 10, 2023); 15 counties across California reported new cases in the most recent three-week period compared with 11 counties in the prior three weeks. In addition, the percent of positive mpox tests has increased from approximately 10% in July and August to 15-25% in September and early October. Case increases are also being seen in other parts of the country, including
King County, Washington,
North Carolina, and
Hawaii. Importantly, most cases did not report travel or attending any specific event, suggesting ongoing transmission within sexual networks. Notably, since the beginning of September, over 40% of cases had at least one dose of vaccine and 31% had two doses, highlighting that while mpox vaccine is effective at reducing infections and disease severity, infections after vaccination are possible and testing is warranted among vaccinated persons.
Furthermore, wastewater surveillance data has detected mpox virus throughout the state for the past several months, indicating continued mpox circulation in California, including in areas without identified or reported infections. While the average number of weekly cases remains low compared with last year at this time, mpox continues to circulate in California, and recent data indicate that transmission levels are increasing.
Identifying Patients with Mpox
1. It is important to remember that any person, regardless of gender identity or sexual orientation, can become infected and transmit mpox if exposed.
- Close, sustained skin-to-skin contact, including sexual contact, with a person with mpox appears to be the most significant risk factor associated with mpox transmission.
- In this outbreak, most of the reported infections have been in gay, bisexual, or other men who have sex with men (MSM).
2. Keep mpox on the differential diagnosis for any diffuse or localized rash (including genital or perianal areas), particularly for those at high-risk for exposure.
3. Provide comprehensive sexual health services.
- Perform a complete physical exam (skin, oral mucosa, anal areas), as not all lesions are painful, and patients may be unaware of (or cannot see) lesions.
- Consider mpox in people who are already fully vaccinated or have been infected before, as
mpox has occurred in people with prior infection or
a partial or complete vaccination course.
- Mpox may present with atypical, subtle, or mild symptoms and clinical presentation may depend on vaccination status or stage of lesion.
- Evaluation for mpox in patients with rashes that may look like other common infections (e.g., syphilis, herpes, varicella, and molluscum contagiosum) should be considered.
Reported complications of mpox include severe pain, bacterial superinfection, severe pharyngeal swelling with concern for airway compromise, inability to eat/drink, and death.
Patients being evaluated for mpox should be tested for HIV (if status is unknown) and other STIs.
- Previous gonorrhea, chlamydia, and syphilis diagnoses are established risk factors for HIV and mpox. Among persons with mpox, 38% had HIV infections and 41% had an STI in the preceding year,
highlighting the importance of co-testing.
- If negative for HIV, counsel on HIV pre-exposure prophylaxis (PrEP) initiation to eligible persons (CDC). If negative for syphilis, gonorrhea, and chlamydia
consider DoxyPEP prophylaxis (PDF).
Provide comprehensive preventative sexual health counseling and education (PDF) to all sexually active individuals, including HIV/STI screening, condom use,
HIV PrEP (PDF)/HIV post-exposure prophylaxis (PEP (PDF)),
vaccinations (e.g. Hepatitis A/B,
Human Papilloma Virus,
expedited partner therapy (PDF) and/or contraception where warranted.
4. Re-familiarize yourself with Health Care Provider (HCP) safety for mpox.
Mpox Specimen Collection, Lab Procedures and Reporting Requirements
For guidance on specimen collection, please see the National Emerging Special Pathogens Training and Education Center (NETEC)
mpox specimen collection training video.
- Testing for mpox virus is currently available through multiple commercial laboratories and local public health laboratories. If interested in sending specimens to your public health lab, coordinate with your local health department (LHD).
- Healthcare providers must specify the ordering facility and provider address on commercial lab orders to ensure results are routed to the appropriate LHD.
- Contact your laboratory to determine criteria for acceptable specimens. Many laboratories now accept swabs in viral transport medium.
CDPH May 2023 Dear Colleague Letter (PDF) has further details on specimen collection and shipping. If interested in submitting specimens to CDC, see the CDC
- Of note, mpox and other Orthopoxvirus infections are explicitly reportable by healthcare providers and laboratories to the LHD based on the residence of the patient (Sections 2500 and 2505 of Title 17 of the California Code of Regulations).
Mpox Vaccine Guidance
- Mpox vaccination with JYNNEOS (2-dose series) reduces the risk of severe illness, hospitalization and death. Recent mpox infections have occurred in people that were previously vaccinated, and it is important to note this is possible. However, studies have shown that persons who receive vaccination are less likely to be hospitalized with mpox.
The vaccine is available to anyone who requests it. However, people
in high-risk groups for exposure should be offered mpox vaccination, which includes:
- Gay, bisexual, and other men who have sex with men, transgender or nonbinary people who have had one of the following in the last 6 months:
- a new diagnosis of one or more STIs
- more than one sexual partner
- sex at a commercial venue
- sex in association with a large public event in a geographical area where mpox is occurring
- Sexual partners of people with the risks described above
- Persons who anticipate experiencing any of the above
- People with HIV infection or other causes of immunosuppression who have had a recent or anticipate potential mpox exposure
- Second doses confer a
strong benefit and efforts should be made to bring in individuals for their second dose. The second dose is ideally given
28 days after the first dose, but can be given any time after 28 days without restarting the series.
exposed to mpox can receive vaccination
up to 14 days after exposure to reduce the risk of infection (i.e., post-exposure prophylaxis).
The risk of severe disease is greater in persons with HIV and less than 30% of people with HIV have received at least one dose of JYNNEOS in California. Persons with HIV infection and risk factors for mpox exposure should be prioritized for vaccination.
- Vaccine appointments can be scheduled through LHDs, via on-line locators such as My Turn, or through regular health care providers.
- Providers can request JYNNEOS vaccine in
myCAvax. Providers who do not have a
myCAvax account and want to administer vaccine should
contact their LHD.
Mpox Treatment Options and Access
- Supportive care and treatment of symptoms should be initiated for all patients with mpox infection. This may include topical medicines or other clinical interventions to control itching, nausea, vomiting, and pain (CDC Mpox Pain Management). For further information, see
CDPH Supportive Care Suggestions.
- Tecovirimat (TPOXX), an antiviral medication, is available orally through an expanded access Investigational New Drug (EA-IND) protocol and a clinical trial (STOMP) for the treatment of mpox infection.
- Clinical suspicion and a pending test are sufficient to initiate treatment with oral TPOXX in eligible patients.
STOMP study is the preferred mechanism for patients to receive oral TPOXX. Enrollment is critical to measure TPOXX efficacy for possible FDA approval and commercial availability. Providers are encouraged to inform patients about STOMP and to recommend they consider
enrollment in STOMP.
- Eligibility criteria for oral TPOXX include patients with mpox who have severe disease or involvement of anatomic areas that might result in serious sequelae or are at high risk for severe disease under CDC’s
expanded access Investigational New Drug (EA-IND) protocol.
- Providers should reach out to their local
Medical Health Operational Area Coordinator (MHOAC) to order TPOXX through the state warehouse. See
CDC guidance on obtaining and using TPOXX for the required forms and documentation.
Identification of exposed people and effective isolation of suspect cases will help reduce community spread of mpox. Further detail information can be found in the
CDPH Mpox Public Health Guidance and the
CDPH All Guidance page.