Description of the cases
On 13 May 2022, the United Kingdom notified WHO of two laboratory
confirmed cases and one probable case of monkeypox to WHO. All three
cases belong to the same family.
The probable case is
epidemiologically linked to the two confirmed cases and has fully
recovered. The first case identified (index case) developed a rash on 5
May and was admitted to hospital in London, the United Kingdom on 6 May.
On 9 May, the case was transferred to a specialist infectious disease
centre for ongoing care. Monkeypox was confirmed on 12 May. Another
confirmed case developed a vesicular rash on 30 April, confirmed to have
monkeypox on 13 May, and is in a stable condition.
West African clade of monkeypox was identified in the two confirmed
cases using reverse transcriptase polymerase chain reaction (RT PCR) on
vesicle swabs on 12 May and 13 May.
On 15 May, WHO was
notified of four additional laboratory confirmed cases, all identified
among GBMSM attending Sexual Health Services and presenting with a
vesicular rash. All four were confirmed to have the West African clade
of the monkeypox virus.
Epidemiology of the disease
is a sylvatic zoonosis with incidental human infections that usually
occur in forested parts of Central and West Africa. It is caused by the
monkeypox virus which belongs to the orthopoxvirus family. Monkeypox can
be transmitted by droplet exposure via exhaled large droplets and by
contact with infected skin lesions or contaminated materials. The
incubation period of monkeypox is usually from 6 to 13 days but can
range from 5 to 21 days. The disease is often self-limiting with
symptoms usually resolving spontaneously within 14 to 21 days. Symptoms
can be mild or severe, and lesions can be very itchy or painful. The
animal reservoir remains unknown, although is likely to be among
rodents. Contact with live and dead animals through hunting and
consumption of wild game or bush meat are known risk factors.
are two clades of monkeypox virus: the West African clade and Congo
Basin (Central African) clade. Although the West African clade of
monkeypox virus infection sometimes leads to severe illness in some
individuals, disease is usually self-limiting. The case fatality ratio
for the West African clade has been documented to be around 1%, whereas
for the Congo Basin clade, it may be as high as 10%. Children are also
at higher risk, and monkeypox during pregnancy may lead to
complications, congenital monkeypox or stillbirth.
Milder cases of monkeypox may go undetected and represent a risk of person-to-person transmission. There is likely to be little immunity to
the infection in those travelling or otherwise exposed, as endemic
disease is normally geographically limited to parts of West and Central
Africa. Historically, vaccination against smallpox was 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, and populations worldwide under the age of 40 or 50 years no longer benefit from the protection afforded by prior smallpox