A-Z Index × Submit A-Z Index × Submit A-Z Index Search Dropdown × Submit Facebook Twitter LinkedIn Syndicate Emerging Infectious Disease journal ISSN: 1080-6059 Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.
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In September 2023, the North Carolina Department of Health and Human Services identified a new case of mpox clade II 5 months after the last previous report. To assess possible unrecognized transmission, nonvariola orthopoxvirus testing was implemented at select wastewater sites. During October 29, 2023–May 2025, a total of 801 samples were collected across 16 treatment plants serving ≈2 million residents. We analyzed wastewater detections (n = 47) and clinical cases (n = 45) using a + 17-day window. Overall sensitivity of identifying the presence of > 1 temporally aligned mpox case within a sewershed was 10.6% (95% CI 6.5%–16.7%); specificity was 95.1% (95% CI 93.2%–96.5%), positive predictive value was 31.9% (95% CI 20.4%–46.2%), and negative predictive value was 83.2% (95% CI 80.3%–85.7%). Restricting detections above the limit of detection reduced sensitivity but increased specificity. Overall, wastewater surveillance showed low sensitivity but provided complementary awareness for public health response.
Since the first case was identified in a nonendemic region, mpox has emerged as an increasing public health concern in the United States. The global outbreak in 2022 affected 75 countries and territories; >2,300 cases had been confirmed in the United States by July 2022 ( 1 ). Because of evolving transmission dynamics, severity, and uncertainty surrounding social and economic impacts, the World Health Organization declared mpox a public health emergency of international concern on July 23, 2022 ( 2 – 3 ).
Mpox is an infectious disease endemic to regions of Central and West Africa. It is caused by the enveloped DNA virus monkeypox virus (MPXV) and is characterized by fever, headache, myalgia, lymphadenopathy, and a vesiculopustular rash that can involve the face, extremities, and genital region ( 3 ). Mpox is primarily transmitted through direct contact with active lesions, contaminated materials, bodily fluids, or respiratory transmission at close range ( 4 , 5 ). Mpox infections are categorized into 2 genetically distinct clades, clade I and clade II. Clade II infections, which were responsible for the global outbreak that began in 2022, are generally associated with less severe disease and reduced transmissibility ( 5 ). Historically, clade I mpox infections have demonstrated greater virulence, mortality, and transmission ( 6 ).
The Centers for Disease Control and Prevention (CDC) National Wastewater Surveillance System initiated wastewater testing for MPXV in October 2022, five months after the mpox outbreak began in the United States. For underreported and stigmatized infections such as mpox, traditional case-based surveillance can present challenges, including incomplete capture of subclinical or unreported cases, making wastewater surveillance a valuable complementary approach to clinical mpox surveillance ( 5 , 6 ). Early work demonstrated that viral shedding through urine, feces, respiratory secretions, and skin lesions can result in detectable MPXV in wastewater, supporting wastewater-based epidemiology as a viable approach for monitoring and…