Blood viral load predicts the severity of Mpox symptoms

Blood viral load predicts the severity of Mpox symptoms

In August 2024, the World Health Organization declared MPOX a second “public health emergency of international concern.” The current outbreak in Africa is primarily driven by the Clade I variant, with several countries reporting their first MPOX cases from this more serious strain. Researchers and their collaborators at Nagoya University have found that measuring the amount of virus in the blood when skin lesions first appear can predict whether patients will have mild or severe disease progression. The study analyzes viral loads during early infection to predict how sick patients will fare, improving treatment strategies for future outbreaks.

The MPOX virus causes characteristic skin rashes and flu-like symptoms. It spreads primarily through direct contact with skin lesions, so patients must avoid contact with others until they heal completely. Skin lesions change dramatically over time and vary among patients, making it difficult to predict when someone is no longer contagious.

There are two strains of the virus: clade I (with subclades IA and IB) and clade II (with subclades IIa and IIB). The research team analyzed medical records from 2007 to 2011 of Clade IA MPOX patients in the Democratic Republic of Congo, the most affected country. They analyzed the amount of viruses present in patients' blood when skin lesions first developed and how their lesions changed over time. Patterns in the data were examined to determine whether patients could be grouped based on how long skin lesions took to heal and how severe their symptoms became.

According to co-lead author Shingo Iwami, a professor at Nagoya University Graduate School, patients with blood virus levels above a certain threshold - when skin lesions begin to appear - 40,000 viral copies per milliliter - are at higher risk of developing severe, long-lasting symptoms, even with a longer duration of infection exposed to the appearance of times of misfortune.

"Our results suggest that patients naturally fall into two distinct groups: those with mild cases who recover relatively quickly, and those with severe symptoms where skin lesions persist for weeks. By combining mathematical modeling and machine learning, we identified a specific threshold that reliably predicts which group a patient belongs to."

The clade IA strain has a mortality rate of approximately 10%, significantly higher than the 1% mortality rate of clade IIB during the 2022 global outbreak. The current outbreak, extending from the Democratic Republic of Congo to neighboring countries, affects clade IB in addition to clade IA. Testing the method in the Clade IB variant is the focus of the team's future research.

Early prediction of disease severity could help physicians provide intensive treatment and monitoring of MPOX patients who are expected to have severe cases, as well as more vigilant monitoring protocols compared to patients with milder predicted outcomes.

If this method can be applied to current circulating MPOX strains, we can move toward more personalized, data-driven medicine. For patients and their families, this could allow for clearer expectations about recovery timelines and the reassurance of more accurate medical predictions after a frightening diagnosis. “

Shingo Iwami, Professor of Nagoya University Graduate School of Science

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