09/26/2024: Lab Advisory: CDC Issues Alert for Prevention Strategies for U.S. Travelers Visiting Countries with Clade I Mpox Outbreaks

CDC's Laboratory Outreach Communication System (LOCS)

Audience: Clinical Laboratory Professionals

Level: Laboratory Advisory

On September 23, 2024, the U.S. Centers for Disease Control and Prevention (CDC) issued a Health Alert Network (HAN) Health Update about the ongoing outbreak of clade I monkeypox virus (MPXV). Initial HAN messages about clade I mpox outbreaks were issued via HAN Health Advisory 501 in December 2023 and HAN Health Update 513 in August 2024.

Although there is an ongoing global outbreak of clade II mpox that began in 2022, no domestic cases of clade I mpox have been identified in the U.S. at this time. Active monitoring for mpox continues to occur in the United States. Follow CDC’s current vaccine guidance to protect against clade II MPXV infection and to also protect against clade I MPXV.

For all laboratories performing mpox testing using an orthopoxvirus or monkeypox virus (MPXV) generic test without any additional clade-specific testing occurring, CDC recommends that laboratories send clinical specimens collected from patients who traveled from the Democratic Republic of the Congo, its neighboring countries, or any country with clade I mpox cases, or had close or intimate contact with symptomatic people from these countries, to a laboratory that can perform clade-specific testing as quickly as possible. If clade-specific testing is warranted but is not available in a jurisdiction, specimen submission to a capable public health laboratory or to CDC is encouraged. Specimen submission to CDC can be coordinated through your state or local health department. Due to mutations that may impact clade-specific PCR tests, laboratories should use a test that targets a viral essential gene (e.g., the CDC NVO test) as part of a testing strategy to ensure mpox cases are not missed.

Laboratories using CDC’s non-variola orthopoxvirus (NVO) test should continue submitting the duplicate specimen to CDC from all patients with positive NVO test results for routine MPXV clade-specific testing if they are not performing clade-specific testing in their laboratory. Specimens that cannot be accepted at CDC for clinical testing under Clinical Laboratory Improvement Amendments (CLIA) will be redirected for surveillance purposes and tested, providing critical data on MPXV clade(s) circulating in the United States. Some non-CDC laboratories may have other options available for clade-specific testing (e.g., molecular testing or genetic sequencing). These laboratories should alert their state health department and CDC (poxvirus@cdc.gov) if results from such tests indicate detection of clade I MPXV.

Please review the HAN for more information, including recommendations for clinicians and public health practitioners, travelers, and the public.

We encourage you to share this message widely with your network(s).

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Centers for Disease Control and Prevention (CDC)

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