In 2024, the World Health Organization (WHO) re-declared the Monkeypox (also called mbox) as a health emergency of international concern, underlining the seriousness of the situation following the spread of a new strain of the virus. Sweden and Spain have recently recorded their first cases of mpox. In this context, we interviewed Nicolò Binello, technical officer at the World Health Organization in Geneva and a master’s degree in Control of Infectious Diseasesto learn more about the differences between the symptoms of Covid-19 and monkeypox, the ways in which the two viruses are transmitted, and strategies for preventing and controlling their spread.
What are the differences between the symptoms of Covid-19 and Monkeypox?
“Monkeypox, more correctly called mboxis an infectious disease of animal origin, caused by Monkeypox virusfirst isolated in 1958 in Denmark in a colony of laboratory monkeys. In humans it was isolated and identified in 1970 as a cause of disease in a child who was in a remote region of what is now Democratic Republic of Congoin Africa.
This already shows us the first fundamental difference between Covid-19 and monkeypox: we already know about monkeypox. Instead, at the beginning of the Covid-19 pandemic, the coronavirus responsible for the disease, SARS-CoV-2, was a virus we knew nothing about, against which we had no effective weapons to fight it. In contrast, monkeypox virus is a viruses that we have known for a long time and for which we have tools for diagnosis, treatment and, above all, for the prevention and control of infection.
We know that Covid-19 is a predominantly respiratory disease that can manifest itself, in some cases, in the form of severe pneumonia with potentially lethal complications, especially in elderly subjects or those with one or more chronic diseases. We also know the long-term effects of Covid-19, the so-called “long Covid”, which can manifest themselves in a minority of patients after the infection. On the contrary, mpox is characterized by a substantially benign and mild clinical coursewhich tends to resolve spontaneously in most cases.
Clinically, monkeypox is characterized by the onset of arash which can affect any part of the body, although it most commonly involves the face, arms and legs, including the soles of the feet and palms of the hands. The rash may resemble chickenpox in some ways, although with fundamental differences. The rash typically begins with flat or slightly raised lesions (macules or papules respectively), which first evolve into vesicles (lesions filled with a clear liquid) then in pustules (lesions filled with a yellowish fluid). Eventually, these lesions turn into scabs that dry up and fall off.
Similar lesions can be found not only on the skin, but also on the mucous membranes, in particular the oral, anorectal and genital mucosa. In addition to skin and mucosal lesions, it is particularly common to find feverwhich typically precedes the appearance of lesions and is associated with other symptoms such as headache, back pain, muscle pain, a profound feeling of weakness, general malaise and swollen lymph nodes.
The disease can last a total of from two to four weeks and, as mentioned, resolves spontaneously in most cases. Complications may be more frequent in some subjects considered at risk of serious disease, such as pregnant women, children and immunocompromised subjects, i.e. those patients who, due to alterations of the immune system, are unable to mount an effective response against the infection. The most frequent complication is the appearance of secondary bacterial infectionswhich overlap with the original viral infection and can cause purulent manifestations, up to the formation of actual abscesses in the skin or underlying soft tissues.”
What are the differences between the methods of transmission of the Covid virus (Sars-cov-2) and monkeypox?
“The second important difference between Covid-19 and monkeypox concerns the mechanisms of transmission. Covid-19 is a disease that is transmitted mainly by respiratory tractthrough inhalation of infected droplets or aerosol particles. In contrast, monkeypox virus is transmitted from person to person through close and close contact with the lesions skin or mucous membranes of an infected subject.
Close and close contact can occur, for example, duringsexual activity. We know that both during the large-scale epidemic that occurred between 2022 and 2023, and in the current epidemic, direct contact during sexual activity represents the main mechanism of person-to-person transmission.
In addition, it is true that monkeypox virus can also be transmitted by respiratory route, but it is unclear how much this mechanism contributes to the global spread of the virus. The virus can also be transmitted through contact with contaminated objects or surfaces, such as linens, towels, sheets, or electronic devices that have come into contact with an infected person.
We also know that the virus has been found in the semen of infected subjects, but it is not clear how much sexual transmissionthat is, through seminal fluid or vaginal secretions, contributes to the spread of the virus. This should not be confused with close, intimate, and close contact during sexual activity, which represents the main mechanism of transmission of the virus, at least in the recent epidemics of 2022, 2023, and 2024.
Finally, it should be remembered that, precisely because it is a disease of exotic origin, transmission from infected animals is possible, for example due to bites, scratches and exposure to body fluids during the processing of skins or the preparation for consumption of game from infected animals. We don’t know the reservoirwhich is the natural reservoir of the infection, but we know that several rodent species are susceptible to the infection and could play a key role in the propagation and maintenance of the infection in nature.”
What are the differences between the mechanisms of prevention and control of the spread of the two viruses?
“First of all, we know that containing a predominantly respiratory disease like Covid-19 can be challenging from the point of view of the public health measures that need to be implemented. In contrast, the prevention of monkeypox relies primarily on the importance of avoid close and close contact with subjects with confirmed or suspected infection, and to prevent contact with contaminated objects or surfaces.
The good news is that There are extremely effective vaccines against monkeypox. This is because the virus belongs to the same family, or rather the same genus, as the human smallpox virus, an extremely contagious infectious disease that was declared eradicated in 1980. This affinity between the two viral species explains why many vaccines used against human smallpox are also effective against monkeypox.
However, after the eradication of smallpox and the discontinuation of vaccination programs against it, the unvaccinated population has progressively increased and, therefore, susceptible to both monkeypox and, theoretically, human smallpox. This explains the progressive increase in monkeypox cases recorded in recent decades in several countries of sub-Saharan Africa, particularly in Central and West Africa.
The good news, as mentioned, is that the available and historically used vaccines against smallpox are extremely effective both in preventing transmission and in reducing the risk of severe disease. It should be noted that vaccines must be administered to subjects at risktherefore mass vaccination against monkeypox is not recommended at this time.
Subjects at risk include contacts with cases of mpox, in particular subjects who have been in contact with an infected subject within 4 days or categories at risk of infection, such as sex workers, people with multiple sexual partners and laboratory health workers professionally exposed to the virus. These vaccines, as we have said, are characterized by excellent efficacy against all strains of the Monkeypox virus currently known, and allow both break the transmission chain both to prevent the risk of serious illness, particularly in at-risk groups such as children, pregnant women and immunocompromised individuals.”
