The strain has been spreading in the Democratic Republic of Congo since 2023.
The current mpox outbreak in Democratic Republic of Congo (DRC) has already seen around 27,000 cases and claimed more than 1,100 lives, most of them children, since the beginning of 2023.
The CDC said its alert was about the spread of a subtype of the mpox virus called Clade I from DRC to some neighboring countries. Clade I generally leads to more severe infections than another subtype called Clade II. However, the risk of Clade I infection spreading in the United States is considered to be very low, the CDC added.
The CDC said no cases of mpox have been reported outside central and eastern Africa at this time.
But, it cautioned, “because there is a risk of additional spread, CDC recommends clinicians and jurisdictions in the United States maintain a heightened index of suspicion for mpox in patients who have recently been in DRC or to any country sharing a border with DRC … with signs and symptoms consistent with mpox.
“These can include: rash that may be located on the hands, feet, chest, face, mouth, or near the genitals; fever; chills; swollen lymph nodes; fatigue; myalgia (muscle aches and backache); headache; and respiratory symptoms like sore throat, nasal congestion, and cough,” the agency said.
Mpox has been spreading across at least 10 African nations in recent months, sparking an alarm from the WHO earlier this week about whether it could expand outside the continent.
Although he did not provide a date or timetable for a possible emergency declaration, Tedros added the “WHO committee will meet as soon as possible and will be made up of independent experts from a range of relevant disciplines from around the world.”
A public health emergency of international concern is the WHO’s highest alarm and allows the U.N. agency to use emergency responses under its international health regulations. Since 2005 to now, there have been seven such declarations, including for COVID-19 in 2020, the zika virus epidemic in 2015, a previous mpox outbreak in 2022 and 2023, and more.
A WHO emergency committee is made up of international health officials and researchers who provide technical advice and recommendations to the WHO chief about whether a disease outbreak should be declared an emergency. The final decision is made by the director general.
His comments were made as mpox has surged in the DRC owing to a more severe strain strain of the virus that is now being reported in neighboring countries in recent months. So far, it has been detected in 10 African countries in 2024, according to the Africa Centres for Disease Control and Prevention in a recent update.
Tedros noted that the severe strain, which he called Clade Ib, has been circulating in the Congo for years. The strain that caused the global outbreak in 2022 that spread to the United States and Europe, he added, is Clade II.
“The current outbreak in the Eastern [Congo] is caused by a new offshoot of Clade I, called Clade Ib, which causes more severe disease than Clade II,” he said, adding that the 1b strain has been found in Uganda, Kenya, Rwanda, and possibly Burundi. Cases of Clade Ia and Clade II have been found in the Central African Republic, the Republic of Congo, Cameroon, Cote d’Ivoire, Liberia, Nigeria, and South Africa.
Reuters contributed to this report.