2022–2023 mpox outbreak: Difference between revisions

An ongoing outbreak of monkeypox was first detected in the United Kingdom on 29 April 2022 with the presentation of monkeypox symptoms in a British resident who had travelled to Nigeria, where the disease is endemic. The individual subsequently returned to the United Kingdom on 4 May, importing the index case of the outbreak into the country.^[1]

The source of several of the cases of monkeypox in the United Kingdom is unknown; however, it appears that community transmission is taking place in the London area as of mid-May.^[2] Cases of the virus have also been reported in North East England as well as outside the UK: five in Portugal, one in Sweden, one in Italy, one in Belgium, one in the United States, seven in Canada, seven in Spain as of 19 May 2022.^[3]

Human monkeypox is a viral infection caused by the monkeypox virus (MPV), a relative of now-eradicated smallpox. Monkeypox generally presents with similar symptoms to smallpox, although usually milder; however, the case fatality rate for monkeypox may still be as high as 10% without prompt treatment.^[4]

Monkeypox is endemic to West and Central Africa.^[5] Prior to the 2022 outbreak, the United Kingdom had only recorded seven previous cases of monkeypox,^[6] all of which were imported cases from Africa or healthcare workers involved in their treatment. The first three such cases were in 2018,^[7] followed by a further case in 2019^[8] and three more in 2021.^[9] The only major monkeypox outbreak to be recorded in a Western country prior to 2022 was the 2003 Midwest monkeypox outbreak in the United States; however, this outbreak did not feature community transmission.^[10][11]

Monkeypox is spread primarily through close contact with infectious individuals.^[12] Prior to the 2022 outbreak, monkeypox was not considered to be a sexually transmitted infection. However, the rapid spread of the virus between sexual partners in the initial stages of the outbreak has prompted discussion that sexual intercourse may be a further route of transmission.^[2]

The index case was a British resident who travelled to Lagos and Delta State in Nigeria in late April 2022,^[12] areas in which monkeypox is considered to be an endemic disease. The individual developed symptoms of monkeypox, including a rash, on 29 April while still in Nigeria. They subsequently flew back to the United Kingdom, arriving on 4 May. They presented to hospital later the same day; monkeypox infection was immediately suspected, and the individual was hospitalised at Guy's Hospital^[7] and isolated after testing positive for the virus.^[12] Testing of patient swab samples by polymerase chain reaction revealed the outbreak to be of the West African clade of monkeypox, which is the less deadly of the two known monkeypox variants with a case fatality rate of around 1%.^[12]

Extensive contact tracing of people who had been in contact with the index case both on the international flight from Nigeria to the United Kingdom and within the country following their arrival was carried out, with potential contacts advised to remain aware of the symptoms of monkeypox and immediately isolate if any were to develop within 21 days of the contact event.^[12] Following this contact tracing effort, the World Health Organization (WHO) considered further transmission of the virus within the United Kingdom to be of "minimal" risk.^[12]

Contact tracing in response to the index case was extended to Scotland on 14 May according to Public Health Scotland. A "small number" of people in Scotland were ordered to self-isolate following close contact with the index case, although overall risk to the general public remained "very low".^[7]

Two new cases of monkeypox were confirmed by the UK Health Security Agency (UKHSA) on 12 May, both of which were in London.^[13] These two individuals lived together in the same household; however, there was no known link between either of them and either the index case or travel to endemic regions. One of the new cases was hospitalised at St Mary's Hospital, while the other case with milder symptoms was said to be self-isolating at home.^[13]

Four additional cases of monkeypox were confirmed by the UKHSA on 17 May, three of which were in London plus one case in North East England who had previously travelled to London.^[14] None of these new cases had any known contact history with the previous three confirmed cases, suggesting that wider community transmission of the virus was now underway in the London area. However, the UKHSA stated that the risk to the general public remained "very low".^[14][2] Patients with active monkeypox infection were confirmed to be hospitalised at the Royal Victoria Infirmary in Newcastle upon Tyne and at the Royal Free Hospital and Guy's Hospital in London.^[14]

On May 18 in Portugal, 14 cases of monkeypox were reported by health authorities out of total of 20 suspected cases, with 2 samples still awaiting for test results.^[15] In Spain, there are 7 confirmed cases as of May 18.^[16] On the same day, the United States confirmed its first 2022 case of monkeypox and Canada reported 13 suspected cases.^[17][18]

On May 19, Sweden and Belgium reported their first cases of monkeypox,^[19][20] while Italy confirmed its first case in a traveller who had arrived from the Canary Islands.^[21]

On May 20, Australia reported its first suspected case, in a man who fell ill after returning from travel in Europe.^[22]

Cases by country and territory

Country	Confirmed	Suspected	Last update	First confirmed case
United Kingdom	9	1	19 May 2022[23]	4 May 2022[24]
Spain	7	29	19 May 2022[25][26]	18 May 2022[27]
Portugal	20	14	18 May 2022[28]	18 May 2022[29]
United States	1	1	19 May 2022[30]	18 May 2022[31]
Sweden	1	—	19 May 2022[32]	19 May 2022[32]
Italy	1	2	19 May 2022[33]	19 May 2022[33]
Belgium	1	1	19 May 2022[20]	19 May 2022[20]
Canada	2	15	19 May 2022[34]	19 May 2022[35]
France	—	1	19 May 2022[36]	—
Australia	1	1	20 May 2022[37]	20 May 2022[38]
Total	43	65

• Monkeypox outbreak - by World Health Organization