Since 13 May 2022, cases of monkeypox have been reported to World Health Organisation (WHO) from 12 Member States that are not endemic for monkeypox virus, across three WHO regions. Epidemiological investigations are ongoing. However, reported cases thus far have no established travel links to endemic areas. Based on currently available information, cases have mainly but not exclusively been identified amongst men who have sex with men (MSM) seeking care in primary care and sexual health clinics.
The objective of this Disease Outbreak News is to raise awareness, inform readiness and response efforts, and provide technical guidance for immediate recommended actions.
The situation is evolving and WHO expects there will be more cases of monkeypox identified as surveillance expands in non-endemic countries. Immediate actions focus on accurately informing those who may be most at risk for monkeypox infection in order to stop further spread. Current available evidence suggests that the ones who are most at risk are those who have had close physical contact with someone with monkeypox, while they are symptomatic. WHO is also working to provide guidance to protect frontline health care providers and other health workers who may be at risk such as cleaners.
Monkeypox endemic countries:
Benin, Cameroon, the Central African Republic, the Democratic Republic of the Congo, Gabon, Ghana (identified in animals only), Ivory Coast, Liberia, Nigeria, the Republic of the Congo, Sierra Leone, and South Sudan.
Description of the outbreak
As of 21 May, 13:00, 92 laboratory confirmed cases, and 28 suspected cases of monkeypox with investigations ongoing, have been reported to WHO from 12 Member States that are not endemic for monkeypox virus, across three WHO regions. No associated deaths have been reported to date.
To date, all cases whose samples were confirmed by PCR have been identified as being infected with the West African clade. Genome sequence from a swab sample from a confirmed case in Portugal, indicated a close match of the monkeypox virus causing the current outbreak, to exported cases from Nigeria to the United Kingdom, Israel and Singapore in 2018 and 2019.
The identification of confirmed and suspected cases of monkeypox with no direct travel links to an endemic area represents a highly unusual event. Surveillance to date in non-endemic areas has been limited, but is now expanding. WHO expects that more cases in non-endemic areas will be reported. Available information suggests that human-to-human transmission is occurring among people in close physical contact with cases who are symptomatic.
Public health response
Further public health investigations are ongoing in non-endemic countries that have identified cases, including extensive case finding and contact tracing, laboratory investigation, clinical management and isolation provided with supportive care. Genomic sequencing, where available, have been used to determine the monkeypox virus clade(s) in this outbreak.
WHO risk assessment
Endemic monkeypox disease is normally geographically limited to West and Central Africa. The identification of confirmed and suspected cases of monkeypox without any travel history to an endemic area in multiple countries is atypical. Hence, there is an urgent need to raise awareness about monkeypox and undertake comprehensive case finding and isolation (provided with supportive care), contact tracing and supportive care to limit further transmission.
Cross-protective immunity from smallpox vaccination will be limited to older persons, since populations worldwide under the age of 40 or 50 years no longer benefit from the protection afforded by prior smallpox vaccination programmes. There is little immunity to monkeypox among younger people living in non-endemic countries since the virus has not been present there.
Historically, vaccination against smallpox had been shown to be protective against monkeypox. While one vaccine (MVA-BN) and one specific treatment (tecovirimat) were approved for monkeypox, in 2019 and 2022 respectively, these countermeasures are not yet widely available.
Based on current information, cases have mainly but not exclusively been identified amongst men who have sex with men, seeking care in primary care and sexual health clinics. No deaths have been reported to date. However, the extent of local transmission is unclear at this stage, as surveillance has been limited. There is a high likelihood of identifying further cases with unknown chains of transmission, including in other population groups. With a number of countries in several WHO regions reporting cases of monkeypox, it is highly likely that other countries will identify cases.
The situation is evolving and WHO expects there will be more cases of monkeypox identified as surveillance expands in non-endemic countries. So far, there have been no deaths associated with this outbreak. Immediate actions focus on informing those most at risk for monkeypox infection stopping further spread and protecting frontline workers.
Vaccination for monkeypox, where available, is being deployed to manage close contacts, such as health workers. WHO is convening experts to discuss recommendations on vaccination.
WHO will be providing more technical recommendations in the coming days.