Symptoms, types of transmission and prevention explained by Rita Lucchetti, Lecturer in General and Applied Hygiene at UniCamillus University
On 14th August 2024, the World Health Organization (WHO) declared a public health emergency of international concern due to the spread of Mpox, previously known as monkeypox. The reason was an increase in the number of cases in Congo: 15,600 cases in 2024, resulting in 537 deaths, most of them children under the age of 15.
However, very little time had passed since the last state of emergency declared by the WHO for the same reason, from 23rd July 2022 to 11th May 2023.
Mpox belongs to the same family as human smallpox (orthopoxvirus), which was eradicated in 1980 thanks to mass vaccination campaigns. The increase in the incidence of Mpox in recent years appears to be the result of the end of vaccination against human smallpox. But this is not the only reason, as other causes must also be taken into account, since “humans are increasingly entering the habitats of animals that carry the virus”, explains Rita Lucchetti, lecturer in General and Applied Hygiene at UniCamillus University. “The improvement in diagnostic tests, which has led to an increase in diagnoses, must also be taken into account”.
What is Mpox?
Mpox is a zoonotic viral infection, in other words it is transmitted from animals to humans, and is caused by the Mpox virus, which belongs to the Poxyiridae family, the same as human smallpox. “It is a double-stranded DNA virus”, says Lucchetti. “There are two genetically distinct clades of MPXV: clade I (formerly Central African clade, Congo Basin) and clade II (formerly West African clade). Clade II is further subdivided into clades IIa and IIb. Clade I, which is further subdivided into clades Ia and Ib, is clinically more severe, with greater transmissibility between humans and greater mortality”.
It was originally called ‘monkeypox’ because it was first identified in this particular species in a Danish laboratory in 1958. Monkeys and small rodents are the animal hosts of the virus.
The first human case, however, dates back to 1970 and then became endemic in regions of Central and West Africa. The first outbreak outside Africa was recorded in the United States in 2003 and then spread to Europe through travel and importation of infected mammals.
The first case of Mpox in Italy dates back to 20th May 2022. From that date until 8th August 2024, the Ministry of Health confirmed 1056 cases, most of which occurred in the summer of 2022.
Transmission
How is the virus transmitted from animal to human? “Through the bite or direct contact with the blood, flesh, body fluids or skin lesions of an infected animal, such as small wild mammals, but also small domestic rodents such as hamsters, rabbits, and guinea pigs”, explains Lucchetti.
Human-to-human transmission also occurs through close contact with a symptomatic infected person. “It can occur through sexual intercourse, but also simply by the infected person contaminating objects that are then used by people with skin and mucous membrane abrasions, or by touching the eyes, nose, mouth and mucous membranes with contaminated hands”.
As our expert points out, maternal-foetal transmission through the placenta or even during and after birth through close contact has also been documented.
And what about human-to-animal transmission? Although it has not been proven, contamination in this direction is also possible”, warns Lucchetti, “so sick people should avoid direct contact with pets or report any contact to the veterinary service so that they can be quarantined”.
Symptoms, diagnosis and treatment
The symptoms of Mpox are varied, but generally include fever, headache, fatigue, enlarged lymph nodes and muscle pain. A few days after the onset of fever, a rash develops into scabs and pustules. These lesions mainly affect the genital or perianal area, upper body, arms, legs, face, hands and feet.
Specific tests are used to make the diagnosis. “These are nucleic acid amplification tests (NAATs) such as polymerase chain reaction (PCR), which is the preferred laboratory test because of its specificity and sensitivity”, explains our expert. “It is carried out on biological samples taken from a skin lesion swab, oropharyngeal and/or anal swab”. But there is more: as Lucchetti explains, there are also serological tests for IgG and IgM anti-Mpox levels.
Once Mpox has been diagnosed, the patient can be considered infected until all the scabs have fallen off, leaving new skin underneath. These symptoms usually resolve spontaneously within a month without treatment. “As with all viral infections, treatments are symptomatic and supportive”, says Lucchetti. “However, in the most severe cases, the antiviral medication Tecovirimat can be used”. Antiviral therapy should be considered in severely immunocompromised patients or those at high risk of disseminated infection.
In the event of infection, patients should be isolated, and should use a separate toilet as well as avoid contact with other people. It is good practice to wear a surgical mask, rest and maintain good hydration and nutrition.
Prevention: precautions and vaccine
Good practices to limit the spread of the disease include following the recommendations of the Italian Health Ministry’s Circular of 20 August 2024, including
- practising safe sex
- avoiding sexual intercourse with infected people
- avoiding handling objects from infected patients without protection
- considering vaccination if travelling to endemic areas.
There is in fact a vaccine against Mpox. “To prevent Mpox, there is a third-generation vaccine called MVA-BN (Modified Vaccinia Ankara-Bavarian Nordic)”, says Prof Lucchetti. “Vaccination is recommended for laboratory workers with possible direct exposure to orthopox virus, men who have sex with multiple male partners, people travelling to endemic areas, and immunocompromised individuals and children”.
Complications and long-term risks
Among the most common complications, our expert lists secondary bacterial infections, bronchopneumonia, sepsis, encephalitis and corneal infection. Genital, perianal and oral complications have also been described, including proctitis and tonsillitis”, she explains.
Recently, however, the prodromal symptoms of Mpox seem to have receded and appear to be milder than in the past. The clade II variant underwent a mutation that led to the 2022 epidemic disease in Nigeria”, Lucchetti adds. “This variant is the one circulating worldwide, including in Europe, which is less lethal, less aggressive and less severe in its symptoms”.
Global health measures to contain the virus
The control of the spread of Mpox appears to be moderate, but more attention is needed in certain areas and sectors. “In the West, the prevention and public health measures adopted at international level are able to control the spread, but there is a need for greater awareness and information, both at the level of the general public and in the specific sectors concerned, such as institutions and health workers”.
The situation is different in African countries. “More specifically, in the Democratic Republic of Congo, the WHO, the Centers for Disease Control and Prevention (CDC) and Amref Health Africa are working with African governments to implement and support the development of national contingency and response plans, strengthen surveillance and provide technical support for outbreak investigation, awareness-raising and community involvement, especially at border entry points and in hard-to-reach areas”, concludes Lucchetti.