By Ethan Covey
The factors that have led to the multicountry outbreak of monkeypox remain unknown, and present an imminent public health challenge, according to presentations given during the World Health Organization Health Emergencies Programme Meeting on Monkeypox Research Priorities, held on June 2.
“No doubt about it, this is a public health problem,” said Maria van Kerkhove, PhD, an infectious disease epidemiologist with the WHO Health Emergencies Programme. “It is a critical moment.”
Monkeypox is considered endemic in almost a dozen African nations. During 2022, cases in Africa have been reported in Cameroon, Central African Republic, the Democratic Republic of the Congo, Nigeria and the Republic of the Congo.
In addition, cases have emerged elsewhere—including among people with no known travel links to endemic countries.
From May 13 through June 1, 2022, 643 cases have been identified in 24 countries across four WHO regions. The highest number of cases outside of Africa have been in the United Kingdom (190), Spain (142) and Portugal (119). Eighteen cases have been identified in the United States.
Since May 18, a total of 373 cases have been confirmed in the European Union, most among patients with no travel history. The majority of cases have been in young men who have sex with men (MSM), who have presented to either primary care or sexual health clinics.
“These patterns are not typical to what we’d expect to see,” Dr. van Kerkhove added.
Surveillance efforts are increasing, including a recently launched WHO/Europe program aimed at tracking the outbreak, and experts hope that newly focused attention will help clarify the extent of the outbreak.
“As surveillance increases, as attention increases, we expect more cases will be identified,” Dr. van Kerkhove said. “We have to acknowledge this virus has been circulating for decades, and we now are paying attention. [The data] suggest wide human-to-human transmission is underway and has likely been taking place for many months.”
Gianfranco Spiteri, MD, an STI surveillance expert at the European Centre for Disease Prevention and Control, agreed.
“This is the first time that chains of transmission have been reported in Europe without known epidemiological links to West or Central Africa,” he said. “We hypothesize that monkeypox has been circulating below the detection of surveillance systems, even in Europe.”
Although most cases have been among MSM, Dr. van Kerkhove noted, current surveillance has been biased toward this community, and thus is likely not painting a full picture of existing disease spread.
“We need a much better understanding of transmission problems and the factors that facilitate spillover and human-to-human spread,” she said.
In addition, the increased surveillance efforts should address a current knowledge gap by allowing for more detailed research on epidemiology, disease characteristics, the effect of immunity both from infection and vaccination, and the efficacy of current interventions.
