Mpox | |
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Mpox rash on arm and leg of a four-year-old girl in 1971 | |
Pronunciation | |
Specialty | Infectious disease [1] |
Symptoms | Rash, fever, exhaustion, swollen lymph nodes, muscle aches, sore throat [2] |
Complications | secondary infections, pneumonia, sepsis, encephalitis, and loss of vision with severe eye infection [1] |
Usual onset | 5–21 days post exposure [2] |
Duration | 2 to 4 weeks [2] |
Types | Clade I, Clade II [1] |
Causes | Monkeypox virus [3] |
Diagnostic method | Testing for viral DNA [1] |
Differential diagnosis | Chickenpox, smallpox [4] |
Prevention | Smallpox & mpox vaccine, hand washing, covering rash, PPE, social distancing [1] |
Treatment | Supportive [1] |
Medication | Tecovirimat, antivirals [1] |
Prognosis | Most recover [5] |
Mpox (formerly known as monkeypox) [6] is an infectious viral disease that can occur in humans and other animals. [1] Symptoms include a rash that forms blisters and then crusts over, fever, and swollen lymph nodes. [1] The illness is usually mild and most of those infected will recover within a few weeks without treatment. [5] The time from exposure to onset of symptoms ranges from five to twenty-one days and symptoms typically last from two to four weeks. [2] Cases may be severe, especially in children, pregnant women or people with suppressed immune systems. [7]
The disease is caused by the monkeypox virus, [lower-alpha 1] a zoonotic virus in the genus Orthopoxvirus . The variola virus, the causative agent of the disease smallpox, is also in this genus. [1] Human-to-human transmission can occur through direct contact with infected skin or body fluids, including sexual contact. [1] People remain infectious from the onset of symptoms until all the lesions have scabbed and healed. [7] It may spread from infected animals by handling infected meat or via bites or scratches. [7] Diagnosis can be confirmed by PCR testing a lesion for the virus' DNA. [1]
Vaccination is recommended for those at high risk of infection. [1] Evidence shows that the MVA-BN [lower-alpha 2] vaccine is 86% effective at reducing the risk of mpox illness. [8] [9] [10] The aim of treatment is to manage the symptoms and prevent complications [1] as there is no specific treatment for the disease. [11] Antiviral drugs such as tecovirimat can be used to treat mpox, [1] although their effectiveness has not been proved. [12]
Mpox is endemic in central and western Africa, where several species of mammals are suspected to act as a natural reservoir of the virus. [1] The first human cases were diagnosed in 1970 in Basankusu, Democratic Republic of the Congo. [13] Since then the frequency and severity of outbreaks has significantly increased, possibly as a result of waning immunity since the cessation of routine smallpox vaccination. [13] The 2022–2023 mpox outbreak represents the first incidence of widespread community transmission outside of Africa. This was initially identified in the United Kingdom in May 2022, with subsequent cases confirmed in 111 countries as of May 2023. [14] The World Health Organization (WHO) declared the outbreak a Public Health Emergency of International Concern (PHEIC) between 23 July 2022 and 10 May 2023. [15]
The name monkeypox was originally coined because the disease was first identified in laboratory monkeys. [3] This was subsequently criticised as a misnomer, because monkeys are not the main host or reservoir. It was also criticized because the name reinforced stigma about African countries as a source of disease. [16]
After requests by a number of public health organisations and scientists, who argued that these issues were harming the fight to contain the disease outbreak, [17] the subtypes of monkeypox virus were renamed Clade I and Clade II in August 2022. The World Health Organization announced in November 2022 that it "will adopt the term mpox in its communications, and encourages others to follow these recommendations". [6]
Initial symptoms of mpox infection are fever, muscle pains, and sore throat, followed by an itchy or painful rash, headache, swollen lymph nodes, and fatigue. Not everyone will exhibit the complete range of symptoms. [1] [2]
Most mpox patients become symptomatic 4–11 days after infection. However, the incubation period can be as short as 1 day. The 2022–2023 outbreak revealed that incubation periods of up to 4 weeks are possible, with 5% of cases having incubation periods longer than the previously assumed 21 days. [1] [19]
The rash comprises many small lesions which may appear on the palms and soles, face, mouth and throat, genitals or anus. [1] They begin as small flat spots, before becoming small bumps which then fill with fluid and subsequently burst and scab over, persisting for around ten days. [2]
Some patients may manifest only a single sore from the disease while others may have hundreds. [1] It is possible for a person to be infected with monkeypox virus without showing any symptoms. [1] Symptoms typically last for two to four weeks, but may last longer if the patient has a weakened immune system. [2] [1]
Complications include secondary infections, pneumonia, sepsis, encephalitis, and loss of vision following corneal infection. [1] Persons with weakened immune systems, whether due to medication, medical conditions, or HIV, are more likely to develop severe disease. [1] If infection occurs during pregnancy, this may lead to stillbirth or other complications. [7]
Provided there are no complications, sequelae are rare; after healing, the scabs may leave pale marks before becoming darker scars. [20]
Prior to the 2022 outbreak, the risk of death in those infected was estimated from 0% to 11%. [13] With other historic case fatality rates being reported as 6% in Nigeria and 10-15% in the Democratic Republic of Congo and the Central African Republic, with a higher death rate in the more virulent Clade 1 variant that is endemic to central Africa. [21] However, in the 2022 global outbreak 112 deaths were reported in 87,000 cases, with other sources reporting a risk of death as high as 0.025%. [1] [21] Most reported deaths in this outbreak were among those who were immunocompromised either due to medication or poorly controlled HIV infection. [1]
It is thought that small mammals provide a reservoir for the virus in endemic areas. [22] Spread among animals occurs via the fecal–oral route and through the nose, through wounds and eating infected meat. [23] The disease has also been reported in a wide range of other animals including monkeys, anteaters, hedgehogs, prairie dogs, squirrels, and shrews. Signs and symptoms in animals are not well researched and further studies are in progress. [22]
There have been instances of animal infection outside of endemic Africa; during the 2003 US outbreak, prairie dogs (Cynomys ludovicianus) became infected and presented with fever, cough, sore eyes, poor feeding and rash. [24] There has also been an instance of a domestic dog (Canis familiaris) which became infected displaying lesions and ulceration. [25]
Mpox in both humans and animals is caused by infection with the monkeypox virus – a double-stranded DNA virus in the genus Orthopoxvirus , family Poxviridae, making it closely related to the smallpox, cowpox, and vaccinia viruses. The two subtypes of virus are Clade I and Clade II. [1] Clade II is further divided into subclades: Clade IIa and Clade IIb. Cases identified as part of the 2022-2023 global outbreak are caused by Clade IIb. [1] Clade I is largely limited to the DRC and is estimated to cause more severe disease and higher mortality than Clades IIa and IIb. [26]
The virus is considered to be endemic in tropical rainforest regions of Central and West Africa. [27] In addition to monkeys, the virus has been identified in Gambian pouched rats (Cricetomys gambianus), dormice ( Graphiurus spp.) and African squirrels ( Heliosciurus , and Funisciurus ). The use of these animals as food may be an important source of transmission to humans. [1]
Mpox can be transmitted from one person to another through contact with infectious lesion material or fluid on the skin, in the mouth or on the genitals; this includes touching, close contact and during sex. It may also spread by means of respiratory droplets from talking, coughing or sneezing. [1] [28] During the 2022–2023 outbreak, transmission between people was almost exclusively via sexual contact. [29] There is a lower risk of infection from fomites (objects which can become infectious after being touched by an infected person) such as clothing or bedding, but precautions should be taken. [28]
The virus then enters the body through broken skin, or mucosal surfaces such as the mouth, respiratory tract, or genitals. [1]
The natural reservoir of monkeypox virus is thought to be small mammals in tropical Africa. [27] The virus can be transmitted from animal to human from bites or scratches, or during activities such as hunting, skinning, or cooking infected animals. [1]
Clinical differential diagnosis must consider other rash illnesses, such as chickenpox, measles, bacterial skin infections, scabies, syphilis and medication-associated allergies. Diagnosis can be verified by testing for the virus. Polymerase chain reaction (PCR) testing of samples from skin lesions is the preferred laboratory test. [1]
The MVA-BN vaccine, originally developed for smallpox, has been approved for use by persons who are either considered at high risk of exposure to mpox, or who may have recently been exposed to it. [8] [9] [10] The United States Centers for Disease Control and Prevention (CDC) recommends that persons investigating mpox outbreaks, those caring for infected individuals or animals, and those exposed by close or intimate contact with infected individuals or animals should receive a vaccination. [3]
Historically, smallpox vaccine had been reported to reduce the risk of mpox among previously vaccinated persons in Africa. The decrease in immunity to poxviruses in exposed populations is a factor in the increasing prevalence of human mpox. It is attributed to waning cross-protective immunity among those vaccinated before 1980, when mass smallpox vaccinations were discontinued, and to the gradually increasing proportion of unvaccinated individuals. [30]
The CDC has made detailed recommendations in addition to the standard precautions for infection control. These include that healthcare providers don a gown, mask, goggles, and a disposable filtering respirator (such as an N95), and that an infected person should be isolated a private room to keep others from possible contact. [31]
Those living in countries where mpox is endemic should avoid contact with sick mammals such as rodents, marsupials, non-human primates (dead or alive) that could harbour monkeypox virus and should refrain from eating or handling wild game (bush meat). [32] [7]
During the 2022–2023 outbreak, several public health authorities launched public awareness campaigns in order to reduce spread of the disease. [33] [34] [35]
Most cases of mpox present with mild symptoms and there is complete recovery within 2 to 4 weeks. [7] There is no specific treatment for the disease, although antivirals such as tecovirimat have been approved for the treatment of severe mpox. [12] [36] [11] A 2023 Cochrane review found no completed randomised controlled trials studying therapeutics for the treatment of Mpox. [37] The review identified non-randomised controlled trials which evaluated the safety of therapeutics for Mpox, finding no significant risks from tecovirimat and low certainty evidence that suggests brincidofovir may cause mild liver injury. [37] Pain is common and may be severe; supportive care such as pain or fever control may be administered. [7] [38] Patients with mild disease should isolate at home, stay hydrated, eat well, and take steps to maintain their mental health. [1]
Patients who are at high risk from the disease include children, pregnant women, the elderly and those who are immunocompromised. [39] For these patients, or those who have severe disease, hospital admission and careful monitoring of symptoms is recommended, [38] Symptomatic treatment is recommended for complications such as proctitis, and pruritis. [38]
This section needs to be updated. The reason given is: More recent evidence is available.(May 2023) |
Mpox was first identified as a distinct illness in 1958 among laboratory monkeys in Copenhagen, Denmark. [40] The first documented cases in humans were in 1970, in six unvaccinated children during the smallpox eradication efforts; the first being a 9-month-old boy in the Democratic Republic of the Congo (DRC). [13] [41] From 1981 to 1986, over 300 cases of human mpox were reported in the DRC, the majority being due to contact with animals. [42] The virus has been detected In Gambian pouched rats, dormice and African squirrels, which are often used as food. [43] [1]
Many more mpox cases have been reported in Central and West Africa, and in the Democratic Republic of the Congo in particular: 2,000 cases per year are known between 2011 and 2014. The collected data is often incomplete and unconfirmed, which hinders realistic estimations of the number of cases of mpox over time. [44] Originally thought to be uncommon in humans, cases increased since the 1980s, [45] [13] possibly as a result of waning immunity since the stopping of routine smallpox vaccination. [4]
Historically, the case fatality rate (CFR) of past outbreaks was estimated at between 1% and 10%, with Clade I considered to be more severe than Clade II. [46] However the CFR of the 2022–2023 global outbreak (caused by Clade IIb) has been very low - estimated at 0.16%, with the majority of deaths in individuals who were already immunocompromised. [47] The huge difference between these estimates is attributed to: -
The natural reservoir of monkeypox virus has not been conclusively determined, although small rodents are the most likely candidate. Without a major vaccination campaign, mpox outbreaks in humans will continue indefinitely in the endemic areas, with an ongoing risk that disease outbreaks will spread to non-endemic areas. Other evidence – that the virus is evolving to be more transmissible among humans, that it can infect a wide range of host species, and that human-to-animal transmission can occur – led to concerns that mpox may either become established in new natural reservoirs outside of Africa, or cause future global epidemics. [49] [50] [51] [52]
Following the 2022–2023 outbreak, mpox (clade IIb) remains present in the human population outside Africa at very low levels. [53] In November 2023, the WHO reported increasing numbers of cases of mpox (clade I) in the Democratic Republic of the Congo, with 12,569 cases year-to-date and 651 fatalities; there was also the first evidence of sexual transmission of clade I. [54]
This section is an incomplete list of disease outbreaks which have been reported, including significant outbreaks in the endemic countries in tropical Africa (Benin, Cameroon, the Central African Republic, the Democratic Republic of the Congo, Gabon, Ghana, Ivory Coast, Liberia, Nigeria, the Republic of the Congo, Sierra Leone, and South Sudan). [55] Outbreaks of mpox are frequent in areas where the disease is endemic - these areas often have poor healthcare infrastructure and outbreaks are rarely documented. [56] [57] [58]
Year | Country | Clade | Human cases | Human deaths | Case fatality rate | Notes |
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1970 | Democratic Republic of the Congo | Clade I | 5 | ? | N/A | |
1971 | Nigeria | Clade II | 2 | ? | N/A | |
1981-1986 | Democratic Republic of the Congo | Clade I | 338 | ? | N/A | |
1995-1996 | Democratic Republic of the Congo | Clade I | >500 | ? | N/A | |
2001-2004 | Democratic Republic of the Congo | Clade I | 2,734 | ? | N/A | |
2003 | United States | Clade II | 71 | 0 | 0% | |
2015 | Central African Republic [59] | Clade I | 10 | 2 | 20% | |
2017-2022 | Nigeria | Clade II | 558 | 8 | 1.4% | |
2020 | Democratic Republic of the Congo [60] | Clade I | 4,600 | 171 | 3.7% | |
2022-2023 | Global Pandemic | Clade IIb | 93,327 | 179 | 0.2% | |
2023-2024* | Democratic Republic of the Congo Republic of the Congo | Clade I | 18,245 | 919 | 5% | *ongoing |
In May 2003, a young child became ill with fever and rash after being bitten by a prairie dog purchased at a local swap meet near Milwaukee, Wisconsin. [61] In total, 71 cases of mpox were reported through 20 June 2003. All cases were traced to Gambian pouched rats imported from Accra, Ghana, in April 2003 by a Texas exotic animal distributor. No deaths resulted. [62] Electron microscopy and serologic studies were used to confirm that the disease was human mpox. [63] Everyone affected reported direct or close contact with prairie dogs, later found to be infected with the monkeypox virus. [64]
In July 2021, in the US, an American returning from a trip in Nigeria was diagnosed with mpox. Subsequent testing identified the virus as belonging to clade II. The patient was hospitalized and treated with tecovirimat and was discharged after 32 days. [65]
During 2022, an outbreak of Clade I mpox was reported in refugee camps in Sudan. [1]
In September 2017, monkeypox virus was reported in Nigeria. The subsequent outbreak was, at that time, the largest ever outbreak of clade II of the virus, with 118 confirmed cases. Unlike previous outbreaks of this clade, infection was predominantly among young male adults and human-to-human transmission appears to have readily occurred. Seven deaths (5 male, 2 female, case fatality rate of 6%) were reported, including a baby and four HIV/AIDS patients. Additionally, a pregnant woman in her second trimester had a spontaneous miscarriage attributed to monkeypox virus infection. [66]
In May 2022, the Nigerian government released a report stating that between 2017 and 2022, 558 cases were confirmed across 32 states and the Federal Capital Territory. There were 8 deaths reported, making for a 1.4% Case Fatality Ratio. In 2022, NCDC implemented a National Technical Working Group for reporting and monitoring infections, strengthening response capacity. [67]
In September 2018, the United Kingdom's first case of mpox was recorded. The person, a Nigerian national, is believed to have contracted mpox in Nigeria before travelling to the United Kingdom. [68] A second case was confirmed in the town of Blackpool, with a further case that of a medical worker who cared for the case from Blackpool. [69]
In December 2019, mpox was diagnosed in a person in South West England who had travelled to the UK from Nigeria. [70]
In May 2021, in the UK, three cases of mpox from a single household were identified by Public Health Wales. The index case had travelled from Nigeria.
In May 2019, a 38-year-old man who travelled from Nigeria was hospitalised in an isolation ward at the National Centre for Infectious Diseases in Singapore, after being confirmed as the country's first case of mpox. As a result, 22 people were quarantined. [71] The case may have been linked to a simultaneous outbreak in Nigeria. [72]
An outbreak of mpox caused by Clade IIb of the virus was first identified in May 2022. [73] The first case was detected in London, United Kingdom, on 6 May in a patient with a recent travel history from Nigeria (where the disease is endemic). [74] [75] Subsequent cases were reported from an increasing number of countries and regions. [82] In July 2022, the World Health Organization (WHO) declared the outbreak a public health emergency of international concern (PHEIC); in May 2023, the PHEIC was terminated due to steady progress in controlling the spread of the disease. [83] As of January 2024, Clade IIb mpox cases outside of endemic regions in Africa continue to be reported at a low level. [84]
During 2023, a Clade I outbreak of mpox disease in the Democratic Republic of Congo (DRC) resulted in 14,626 suspected cases being reported, with 654 associated deaths, making for a case-fatality rate (CFR) of 4.5%. The outbreak continued into 2024 with an additional 3,576 suspected mpox cases and 265 deaths being reported in the DRC through the first 9 weeks of the year, making for an estimated CFR of 7.4%. [85]
The outbreak appears to be of a primarily sexually transmitted nature and cases are occurring in areas without a history of mpox, such as South Kivu and Kinshasa. The outbreak seems to consist of two separate sub-variants of clade I, with one of the sub-variants having a novel mutation making detection with standard assays unreliable. [85]
The outbreak spread to the neighbouring country of the Republic of Congo, with 43 mpox cases being reported in March 2024. [85]
The monkeypox virus, is a species of double-stranded DNA virus that causes mpox disease in humans and other mammals. The monkeypox virus is a zoonotic virus belonging to the orthopoxvirus genus, making it closely related to the variola, cowpox, and vaccinia viruses. MPV is oval-shaped with a lipoprotein outer membrane. The genome is approximately 190 kb.
Beginning in May 2003, by July a total of 71 cases of human monkeypox were found in six Midwestern states including Wisconsin, Indiana (16), Illinois (12), Kansas (1), Missouri (2), and Ohio (1). The cause of the outbreak was traced to three species of African rodents imported from Ghana on April 9, 2003, into the United States by an exotic animal importer in Texas. These were shipped from Texas to an Illinois distributor, who housed them with prairie dogs, which then became infected.
In May 2022, the World Health Organization (WHO) made an emergency announcement of the existence of a multi-country outbreak of mpox, a viral disease then commonly known as "monkeypox". The initial cluster of cases was found in the United Kingdom, where the first case was detected in London on 6 May 2022 in a patient with a recent travel history from Nigeria. On 16 May, the UK Health Security Agency (UKHSA) confirmed four new cases with no link to travel to a country where mpox is endemic. Subsequently, cases have been reported from many countries and regions. The outbreak marked the first time mpox had spread widely outside Central and West Africa. There is evidence that the disease had been circulating and evolving in human hosts over a number of years prior to the outbreak. The outbreak was of the Clade IIb variant of the virus.
The 2022–2023 mpox outbreak in the United Kingdom is part of the larger outbreak of human mpox caused by the West African clade (type) of the monkeypox virus. The United Kingdom was the first country, outside of the endemic African areas, to experience an outbreak. As of 22 July 2022, there were 2,208 confirmed cases in the United Kingdom, with 2,115 in England, 54 in Scotland, 24 in Wales, and 15 in Northern Ireland.
The 2022–2023 mpox outbreak in the United States is part of the larger outbreak of human mpox caused by the West African clade of the monkeypox virus. The United States was the fourth country outside of the African countries with endemic mpox, to experience an outbreak in 2022. The first case was documented in Boston, Massachusetts, on May 17, 2022. As of August 22, mpox has spread to all 50 states in the United States, as well as Washington, D.C., and Puerto Rico. The United States has the highest number of mpox cases in the world. California has the highest number of mpox cases in the United States.
The 2022–2023 mpox outbreak in Canada is a part of the outbreak of human mpox caused by the West African clade of the monkeypox virus. The outbreak started in Canada on May 19, 2022, with the country since then becoming one of the most affected in the Americas.
The 2022–2023 mpox outbreak in Portugal is part of the larger outbreak of human mpox caused by the West African clade of the monkeypox virus. Portugal was the third country, outside of the African countries with endemic mpox, to experience an outbreak in 2022.
The 2022–2023 mpox outbreak in Italy is part of the larger outbreak of human mpox caused by the West African clade of the monkeypox virus. Italy was the sixth country, outside of the African countries with endemic mpox, to experience an outbreak in 2022. The first case was documented in Rome, Italy, on May 19, 2022. As of August 5th, Italy has 505 cases.
The 2022–2023 mpox outbreak in Belgium is part of the larger outbreak of human mpox caused by the West African clade of the monkeypox virus. Belgium was the fifth country, outside of the African countries with endemic mpox, to experience an outbreak in 2022. The first case was documented in Antwerp, Belgium, on 19 May 2022. As of 10 August, Belgium has 546 cases and 1 suspected case.
The 2022–2023 mpox outbreak in Australia is a part of the outbreak of human mpox caused by the West African clade of the monkeypox virus. The outbreak reached Australia on 20 May 2022. By 28 October 2022 there were over 140 confirmed cases. The Chief Medical Officer of Australia stood down the country's Communicable Disease Incident of National Significance declaration on 25 November 2022.
The 2022–2023 mpox outbreak in Israel is a part of the ongoing outbreak of human mpox caused by the West African clade of the monkeypox virus. The outbreak was first reported in Israel on 20 May 2022 when the Health Ministry announced a suspected case which was confirmed on 21 May 2022. One month later, on 21 June, the first locally transmitted case was reported.
The 2022–2023 mpox outbreak in Austria is part of the larger outbreak of human mpox caused by the West African clade of the monkeypox virus. Austria is the fifteenth country outside of Africa to experience an endemic mpox outbreak. The first case was reported in Vienna, Austria, on 22 May 2022. As of 2 December, Austria has confirmed a total of 327 cases.
The 2022–2023 mpox outbreak in Brazil is a part of the ongoing outbreak of human mpox caused by the West African clade of the monkeypox virus. The outbreak was first reported in Brazil on 9 June 2022 when a man in São Paulo was registered as the country's index case.
The 2022–2023 mpox outbreak in India is a part of the ongoing outbreak of human mpox caused by the West African clade of the monkeypox virus. The outbreak was first reported in India on 14 July 2022 when Kerala's State Health Minister Veena George announced a suspected imported case which was confirmed hours later by the NIV. India was the tenth country to report a mpox case in Asia and the first in South Asia. Currently, India has reported 23 cases of mpox.
Mpox is endemic in western and central Africa, with the majority of cases occurring in the Democratic Republic of the Congo (DRC), where the disease is reportable. There, the more virulent Congo basin virus type has been affecting some of the world's poorest and socially excluded communities.
The 2022 mpox outbreak in Asia is a part of the ongoing outbreak of human mpox caused by the West African clade of the monkeypox virus. The outbreak was reported in Asia on 20 May 2022 when Israel reported a suspected case of mpox, which was confirmed on 21 May. As of 10 August 2022, seven West Asian, three Southeast Asian, three East Asian and one South Asian country, along with Russia, have reported confirmed cases.
The 2022–2023 mpox outbreak in the Netherlands is an ongoing global outbreak which has also spread in the Netherlands. The RIVM declared the disease an A-disease which makes it mandatory to report suspected cases to the GGD. The first human case of mpox in the Netherlands has been identified at the 21 May 2022. The outbreak does have a noticeable impact at the society, especially with people spreading misinformation related to the virus. The ongoing COVID-19 pandemic in the Netherlands has increased the fear among the community for a new pandemic like mpox.
The 2022–2023 mpox outbreak in South Africa is a part of the larger outbreak of human mpox caused by the West African clade of the monkeypox virus. South Africa was the forty-seventh country, outside of the African countries with endemic mpox, to experience an outbreak in 2022. The first case of mpox in South Africa was on June 23, 2022.
The 2022–2023 mpox outbreak in Chile is a part of the outbreak of human mpox caused by the West African clade of the monkeypox virus. The outbreak reached Chile on 17 June 2022.
The 2022–2023 mpox outbreak in Ghana is a part of the larger outbreak of human mpox caused by the West African clade of the monkeypox virus. As opposed to its West African neighbours, Ghana had no endemic presence of mpox, only experiencing it during the 2022 outbreak. The first 5 cases of mpox in Ghana was detected on June 8, 2022.