On 23 July 2022, Dr Tedros Adhanom Ghebreyesus, Director General of the WHO, overruled the majority verdict of the Emergency Monkeypox Committee, an expert advisory panel of epidemiologists, public health specialists, and virologists, and declared monkeypox a Public Health Emergency of International Concern. Nine committee members were against this move towards a more coordinated global response to the monkeypox outbreak, with the remaining six in favour. To put matters in context, as of 26 July, and according to the CDC (Centers for Disease Control and Prevention) 2022 Monkeypox Outbreak Global Map, a total of 19,188 cases had been confirmed worldwide, including 18, 867 from 68 countries from where monkeypox had not previously been reported.
Monkeypox, a viral zoonotic disease, was first reported in 1958 from Copenhagen, in two outbreaks of a pox-like disease within captive colonies of laboratory macaque monkeys, imported from Singapore for polio vaccine research. The first human case, a nine-month-old boy, was identified in the Democratic Republic of Congo in 1970. It remained a rare and relatively low-profile illness over the coming years, with only 54 cases identified by WHO between 1970 and 1979, and a further 338 between 1981 and 1986.
In scientific language, monkeypox is caused by a large, enveloped, double-stranded DNA virus, belonging to the Orthopox genus of the Poxviridae family, which also includes variola virus (smallpox), vaccinia virus, cowpox virus, and other animal-related poxviruses. Genomic sequencing has identified two clades, or family trees of virus, each with its own common ancestor: the Central African (Congo Basin) clade (CAC) and the West African clade (WAC).
Monkeypox has been identified in eleven countries in West and Central Africa ever since 1970, where it is endemic in the tropical rainforest, with the majority of infections in the Democratic Republic of Congo. Outside of Africa, sporadic, travel-related cases, spread by humans, have been reported in recent years, although the very first non-African cases were linked to the importation of infected “exotic” pets in the US from Ghana in 2003.
The index cases in the present outbreak, which now involves Asia, Europe, the Americas, and Australia, were reported from the UK. The WHO was notified on 13 May 2022 of two laboratory-confirmed British cases of monkeypox, along with a third probable case. Genomic analysis suggests that the present outbreak may reflect previously undetected community spread of a constantly mutating virus. It is also likely that global spread may be facilitated by waning herd immunity against smallpox, ever since its eradication in 1980 and a subsequent drop in numbers of those vaccinated against the disease, which would normally provide cross-protection against monkeypox.
Although a zoonotic infection, no particular animal reservoir has been linked to the present monkeypox outbreak. Rodents are the usual primary reservoir of infection, with humans and non-human primates (monkeys) serving as incidental, or accidental, hosts. In West and Central Africa, infected rodents (mice, rats, squirrels) can transmit the virus to humans through bites, direct contact with skin, blood, and bodily fluids, as well as through the consumption of inadequately cooked meat. The virus is then spread from person-to-person by close contact, either face-to-face, skin-to-skin (hugging, cuddling, kissing, holding hands), mouth-to-mouth, or skin-to-mouth.
Sexual transmission is common, leading to many cases being picked up in sexual health clinics. Gay, bisexual, and other men who have sex with men (GBMSM) are at increased risk of infection, as are other people with multiple sexual partners, such as sex workers. It has been suggested that “highly interconnected sexual networks within the MSM community” may fuel further spread of the virus. People sharing the same household as an infected person are also at risk-from contaminated bedding, clothing, or towels. Sores in the mouth can lead to airborne spread, as respiratory droplets or short-range aerosols, with coughs and sneezes.
The incubation period for the illness is usually between five days to three weeks. Following exposure to the virus, there is a prodromal period of flu-like symptoms, which include fever, chills, fatigue, headache, muscle ache, back pain, and swollen lymph glands. A rash develops within one to four days of these initial symptoms and may be seen on the face, palms, soles, groins, genital and anal regions, often accompanied by sores inside mouth. The rash progresses through a series of stages, starting off as flat lesions(macules), which successively turn into blisters (vesicles), pustules, crusts, and scabs. These scabs then fall off and are replaced by new skin. Unlike the successive crops of rashes seen in chickenpox, all skin lesions are at the same stage of evolution in monkeypox. The illness generally lasts between two to four weeks. Victims remain infective until all crusts have fallen off and are replaced by new skin. In the UK, those worried about having contracted monkeypox are being advised to contact 111 or the local sexual health service in the first instance. Confirmation of the diagnosis in the UK requires specialised orthopoxvirus testing at the Rare and Imported Pathogens Laboratory (RIPL) at Porton Down. Antibody testing is not useful for diagnosis, as antibodies only confirm vaccination against smallpox or monkeypox or past exposure to orthopoxviruses.
Vaccines can be used both before or after exposure to the monkeypox virus, depending on circumstances. The Joint Committee on Vaccination and Immunisation in the UK has recommended two doses, at least four weeks apart, of Modified Vaccinia Ankara (MVA) vaccine, a modified attenuated live vaccinia virus vaccine, to protect people at risk. This vaccine is available as Imvanex in the EU and UK, Imvamune in Canada, and Jynneos in the US, where it has FDA approval for use in monkeypox. The limited supply of vaccines means that immunisation efforts are being targeted at health workers caring for patients, high-risk GBMSM people, and close contacts of confirmed cases. Vaccines have to be administered within 4-14 days of exposure to be effective.
Sufferers must self-isolate, ensure adequate fluid and food intake, and may take pain-relieving and fever-lowering medication as required. Sterilised water or antiseptic may be used to clean skin lesions and to prevent secondary bacterial infections. Although the rash may be intensely painful, the agony is inevitably short-lived as the symptoms subside spontaneously, irrespective of treatment. Tecovirimat (TPOXX), an antiviral agent approved for treatment of smallpox in 2018, has been licensed by the European Medicine Agency to treat monkeypox.
Thankfully, the monkeypox virus is just not in the same league as SARS-CoV-2. It is much less contagious and seems less virulent, with vaccines and potential antiviral treatments already to hand, and has not been responsible for any deaths so far outside Africa. Asymptomatic infections also appear to much less likely than with COVID-19, making it easier to control spread within the community.
The current monkeypox outbreak demands a nuanced approach, with efforts at control targeting high risk individuals and communities, as well as high-risk venues, such as those offering sex-on-the-premises. In the aftermath of the AIDS crisis, the LGBTQ+ community has demonstrated a remarkable ability to mobilise resources and commandeer support to their advantage and it is expected that they will vigorously lobby governments across the world in support of their demands. There seems little doubt, however, that monkeypox, despite the growing numbers of cases, is most unlikely to replicate the global shock inflicted by COVID-19. The hope is that the outbreak will be more readily containable with targeted and focused public health initatives, guided by lessons learned in the recent pandemic, and marked by better collaboration between countries when it comes to the sharing of stockpiled smallpox vaccines.
Ashis Banerjee
PS: The first monkeypox-related death outside Africa was reported on 29 July 2022, that of a 41-year-old man with other coexisting medical conditions who died in the south-eastern Brazilian city of Belo Horizonte. Shortly thereafter, another monkeypox-related death was identified in Spain.