Study finds over one-third of Congo mpox PCR positives were environmental false alarms
Researchers say about 35% of mpox PCR positives in the Democratic Republic of Congo were caused by sample contamination rather than genuine infection.
A multinational research team led by the University of Geneva examined over 2,700 PCR results collected between April 2024 and April 2025 in Goma, Kamituga, Kinshasa and Uvira. They determined that about 35% of the positive mpox tests were false positives, caused by environmental contamination with residual viral DNA that can persist on surfaces and in the air for weeks. Serology indicated that roughly 89% of these cases had no antibodies, confirming the absence of true infection.
The study identified two distinct viral-load patterns across sites, suggesting both high viral loads and low residual traces. The World Health Organization had classified the outbreak as a public-health emergency in August 2024 and ended the alert in September 2025. Researchers recommend reducing the PCR positivity threshold to cut false-positive rates without substantially raising false negatives, and are collaborating with the WHO to improve virus detection in other nations.
Why it matters
False mpox diagnoses can lead to unnecessary treatment, quarantine and misallocation of limited public-health resources.
In this story
