CDC has issued a Health Alert Network (HAN) advisory following the confirmation of the first case of clade I mpox diagnosed in the United States. On November 15, 2024, the California Department of Public Health (CDPH) confirmed the first reported case of clade I mpox. The person had recently traveled to areas with ongoing clade I monkeypox virus (MPXV) transmission and sought medical care for mpox symptoms. Fortunately, the patient is experiencing relatively mild illness and is currently recovering. As of November 18, no additional cases have been detected in the U.S., and the public risk remains low.
Since March 2024, CDC has collaborated with local, state, tribal, and territorial public health authorities to enhance surveillance and reporting systems in anticipation of potential clade I mpox cases. This confirmed case reflects the effectiveness of these public health measures.
Clinicians are advised to be vigilant for mpox symptoms and to inquire about recent travel history and other risk factors in patients exhibiting similar signs. Testing for MPXV should be considered, particularly given the current outbreaks in Central and Eastern Africa, which may lead to more travel-related cases in the U.S. It is crucial for suspected and confirmed mpox cases to be reported promptly to local and state public health authorities, as well as to CDC. This includes any non-variola orthopoxvirus positive and negative clade II results from individuals with relevant travel history.
CDC continues to recommend vaccination for individuals eligible for the mpox vaccine, especially those who may have had recent exposure to MPXV. Clinicians should remain informed and prepared to implement preventive measures as necessary to manage and mitigate the spread of mpox.