Washington State Department of Health and University of Washington researchers detected the clade I mpox virus in Pierce County wastewater September 24, prompting increased surveillance despite no confirmed local cases.
The Tacoma-Pierce County Health Department is collaborating with the Centers for Disease Control and Prevention and state health officials to expand wastewater testing following the discovery. The CDC reports six clade I mpox cases identified nationally, all linked to recent travel to countries experiencing outbreaks.
No sustained clade I mpox transmission has occurred in the United States.
Dr. James Miller, Health Officer for Tacoma-Pierce County, emphasized public health surveillance importance. “This is a rare occurrence, and also a great example of how public health keeps a close eye on disease spread to assess risk and inform the community when needed,” Miller said.
Miller reassured residents that risk remains low and advised individuals experiencing symptoms to consult healthcare providers.
Healthcare providers should consider mpox in patients presenting with characteristic rashes and evaluate travel history. All mpox cases require reporting to the Health Department.
Wastewater surveillance complements traditional clinical reporting for early clade I mpox detection. The methodology allows public health officials to identify potential community transmission before clinical cases emerge.
Mpox spreads through close physical contact including sexual contact and household interactions. Prevention methods apply to both clade I and clade II variants. Symptoms include rashes appearing as bumps, blisters, or ulcers, sometimes preceded by flu-like symptoms.
Most individuals recover within two to four weeks, though disease can be severe for children, pregnant individuals, or those with compromised immune systems.
Residents experiencing new rashes or symptoms should avoid skin-to-skin contact and seek medical advice. Vaccines are available for higher-risk individuals through healthcare providers or the health department.
The wastewater detection does not necessarily indicate active infections in Pierce County residents, as the virus can be shed by asymptomatic individuals or those traveling through the area. Wastewater surveillance serves as an early warning system allowing public health officials to prepare response measures.
Clade I mpox has caused larger outbreaks in Central African countries, prompting international concern about potential spread. The World Health Organization has monitored the situation closely as cases emerge outside traditional endemic regions.
