top of page
KPHD logo
Scenic Kitsap landscape: lake, houses, mountains.

Our vision: A safe and healthy Kitsap County for all.

Healthcare Advisory: Be Alert for Mpox

  • katiebaker9
  • 12 hours ago
  • 5 min read

Clade I Mpox Virus Detected in Wastewater; Rise in Cases of Clade II Mpox

CURRENT SITUATION


Mpox (formerly "monkeypox"), the infection caused by the mpox virus (MPXV), has been circulating at low levels in Washington state since the 2022 global outbreak of clade II mpox. Recently, an increase in clade II mpox cases has been reported in the the Puget Sound area associated with sexual and intimate contact among gay, bisexual, and other men who have sex with men, transgender people, and non-binary people.


Since Aug. 1, 2025, there have been 77 cases diagnosed in Washington state, the largest number of new diagnoses in a two-month period since the end of the 2022 outbreak. 


In addition, the Washington State Department of Health (WA DOH) has been monitoring for a potentially more severe strain of mpox (clade I) since 2024. On Sept. 24, 2025, WA DOH detected clade I MPXV in wastewater in Pierce County.


Until recently, all cases of clade I mpox detected in the United States occurred in individuals with international travel. However, on Oct. 17 the California Department of Public Health reported three unrelated cases of clade I mpox in individuals who had not traveled internationally, suggesting some level of community spread. WA DOH has not yet been notified of a case of clade I mpox, and the risk to the community remains low. 

ACTIONS REQUESTED



Clinical Considerations 


  • Mpox can cause a rash that looks like bumps, blisters or ulcers. The rash can be on a small area of the body (including the genitals) or can cover a larger area of the body. 

  • Some people develop flu-like symptoms before the rash develops. 

  • Co-infection with other sexually transmitted infections is common. 

  • May present subtly as proctitis without anogenital lesions 

  • May occur in individuals with prior mpox vaccination, but symptoms tend to be mild in those cases. 

  • There is no clinical distinction in the signs and symptoms of clade I mpox and clade II mpox. 


Diagnostic Testing  


  • Testing may be available through your facility’s clinical or commercial laboratory.   

  • If possible, choose a PCR test option that allows for clade determination. 

  • Follow mpox specimen collection guidelines for your facility, or refer to specimen collection guidelines from WA DOH. 

  • If you do not have access to clade determination testing and suspect clade I mpox, contact Kitsap Public Health District (KPHD) to request testing at the WA Public Health Laboratories (PHL).

    • Do NOT send specimens to the PHL without prior approval from KPHD. 


Clinical Management


  • The treatment for patients with clade I mpox is the same for clade II mpox.  

  • Most immunocompetent patients with mpox will improve with supportive care alone.  

  • Antiviral treatment for mpox may be indicated in patients with severe disease or certain underlying conditions. Please consult with an infectious disease specialists.  


Prevention


  • Vaccinate individuals who are eligible to receive mpox vaccination 

  • Mpox vaccine is effective against both mpox clades. 

  • Booster doses are currently not recommended  

  • Vaccine can be obtained from commercial suppliers.  

  • Offer the mpox vaccine as post-exposure prophylaxis (PEP) to individuals who have had direct contact with someone with mpox. PEP is effective against both mpox clades. 

    • PEP should be offered as soon as possible after exposure to someone with mpox: 

      • Within 4 days of exposure to prevent illness.

      • Up to 14 days after exposure to reduce risk of severe disease.

BACKGROUND


Mpox infection (formerly “monkeypox”) is caused by the mpox virus (MPXV), a zoonotic virus belonging to the Orthopoxvirus genus. In 2022, the U.S. and several other countries experienced a surge in clade II mpox transmission, leading the World Health Organization (WHO) to declare a global public health emergency on July 23, 2022. The outbreak in the U.S. lasted from May 2022 through January 2024, during which over 32,000 cases were detected, including 58 deaths; of these, 737 cases were in Washington State residents. 


Mpox has continued to be detected at lower levels in Washington following the outbreak, with most cases reported in the Puget Sound area. Over the past few months, case reports have increased across the state, with 77 cases reported since the beginning of August 2025. 


In Kitsap County, there have been seven laboratory-confirmed cases of mpox reported since 2022, with the most recent case reported in September 2025. 


Mpox is often associated with a painful rash, frequently located on the genitals or anus, along with other symptoms, that progresses through several stages. Mpox is spread through close contact with a person with mpox, direct contact with contaminated materials, or direct contact with infected animals.  


There are two clades of MPXV, clade I and clade II. While both clades cause similar symptoms, there is historical evidence that clade I MPXV is more transmissible, and often causes more severe disease than clade II, with case fatality rates reported up to 10%, with higher risk for children and pregnant people. However, people with clade I mpox who are provided high-quality supportive care have a significantly lower mortality than those who were not connected to care. The management of clade I mpox is similar to that for clade II mpox. Clade II mpox continues to be reported across the United States, and six clade I mpox cases have been reported in the United States.  


Tecovirimat, or TPOXX, is an antiviral for smallpox that was used for mpox treatment during the 2022 global clade II outbreak. Initial results from two clinical trials have demonstrated that tecovirimat is safe to use for people with mpox, but that it did not reduce the time to resolution of mpox lesions. Tecovirimat efficacy is still being evaluated for patients who are immunocompromised and for those with severe disease. Tecovirimat, along with other investigational drugs, are still available under CDC’s expanded access Investigational New Drug Protocol for eligible patients. 

ADDITIONAL RESOURCES


CONTACTING THE HEALTH DISTRICT


  • Call: 360-728-2235 and leave a message. Includes reporting notifiable conditions 24 hours a day, 7 days a week. Leave the patient’s name, date of birth and disease. 

  • Fax: 360-813-1168

Related Posts

See All
bottom of page