(Bloomberg) -- Mpox cases caused by the fast-spreading clade Ib variant and at least one other strain were detected in Kinshasa, the Democratic Republic of the Congo’s densely populated capital, which has direct flights to more than a dozen countries.
Co-circulation of clades Ia and Ib was reported for the first time in the central African city of more than 17 million people, researchers said in a study Wednesday. The finding, based on 11 mpox cases detected since July, indicates a fresh outbreak area 900 miles from the epicenter in eastern Congo, where a surge in mpox cases and subsequent spread to neighboring Burundi triggered a global health emergency last month.
The clade Ib strain “was not expected to be circulating” in western Congo, said Eddy Lusamaki, one of the study’s authors, in a separate report. Its detection in Kinshasa is of particular concern due to the city’s high population density, proximity to Brazzaville, the capital of the Republic of Congo, and international connections via air travel. Cases have been reported in several African nations as well as Thailand and Sweden.
In August, the first case of a person infected with the new variant of the mpox virus outside the African continent was reported in Sweden. The patient, who contracted the disease in central Africa, didn’t need to be hospitalized and no further cases have been identified in the country since then. Thailand also reported a case of clade Ib last month.
In Congo, more than 550 people have died from mpox this year. While clade Ia variants are the most commonly reported in the sprawling nation, the Ib strain has sparked increasing international attention since emerging in South Kivu Province last year because of its association with sustained human-to-human transmission driven by close physical contact with infected individuals, including through sex.
The co-circulation of two distinct strains was detected using genomic sequencing of viral specimens from cases in July and August in Kinshasa, according to the study, which was released ahead of peer-review and publication.
The finding illustrates the complexity of mpox outbreaks in Congo and the need for enhanced community surveillance and further investigation to better understand and address the factors contributing to outbreaks, said the paper’s multinational authors, led by Placide Mbala-Kingebeni and Tony Wawina-Bokalanga of the Congo’s National Institute of Biomedical Research.
The World Health Organization released a draft mpox response plan last week that focuses on vaccinating health-care and front-line workers and people known to have been exposed to the virus. Congo received its first mpox vaccines on Thursday.
--With assistance from Niclas Rolander.
(Updates to add cases in Sweden and Thailand in fourth paragraph.)
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