Zoonosis. Keep this term in mind, because for the MonkeyPox (hence the acronym Mpox or the translation monkeypox) as with many other infectious diseases, the relationship between humans and animals is fundamental. And so we talk about One Health, in an approach that must take into account the human sphere, the animal one and the environment.
But what does it mean? zoonosis? We are talking about an infectious disease that recognizes its reservoir in an animal species and which is transmitted, directly or indirectly, to humans. A classic example of a directly transmitted zoonosis is angerlike the salmonellosis can be taken as a model of zoonosis with predominantly indirect transmission. In this sense, monkeypox represents a model of zoonotic disease, which means that can spread between animals and people.
As reported by the CDC (Centers for Disease Control) in Atlanta, the source of the infection is not entirely clear. It is believed, however, that there are “carrier” animals such as some types of rats and dormice, in some parts of West and Central Africa. That said, let’s try to understand what we know today, based on data from the CDC themselves and the Istituto Superiore di Sanità.
What is monkeypox and why is it called that?
As we said, Mpox is a zoonosis. Therefore, it is a disease transmitted from animals to humans and monkeys are certainly not the main culprits of the possible contagion. It is called this because the virus, which is part of the Poxvirus family, the same one that also includes the human smallpox virus, was first recognized in primates. We are talking about 1958. The first human case was instead initially observed in 1970.
Did the virus only recently leave Africa?
No. Although endemic in some areas of the continent, particularly in the central and western areas, the viral strain has already caused “human microepidemics since the beginning of this century. Consider: in 2003, there was an outbreak of Mpox in the USA in the so-called “Prairie Dogs” (the name can be misleading, since they are not dogs but small rodents). These animals had shared a litter box and cage with a shipment of infected small mammals from West Africa. There was then the first human micro-epidemic, with 47 human cases in six states. And it was the first time that this virus was spoken of outside of Africa.
Which animals can transmit the virus?
According to the CDC, humans can become infected through direct contact with infected animals, such as hunting, catching, and processing infected animals or their body parts and fluids. Particular attention should be paid to small mammalssuch as squirrels, hedgehogs, shrews and the like, also because it has been seen that small mammals can be carriers of the virus without symptoms, while non-human primates such as monkeys can get monkeypox, but still show signs of the disease like humans.
How does the infection manifest itself?
Generally speaking, the picture may initially remind one of the of the flu. The person may in fact have fever, weakness, muscle pain, chills when the body temperature rises. The lymph nodes, or lymph glands, may also “swell”. This may be followed by classic skin lesionswith the typical sequence of these forms, that is, with the appearance of small blisters that fill with yellowish liquid and become pustules, to then give way to crusts. It must also be said that the sequence of symptoms and signs is not always so clear: sometimes the initial signals can be milder. And there are cases in which skin lesions precede or accompany more nonspecific disorders such as fever or asthenia.
Where are monkeypox lesions located?
Generally speaking, blisters with subsequent transformations into pustules almost always tend to be located around the genitals and the anus, as well as the upper and lower limbs, the palms of the hands and the soles of the feet. The trunk and face are also frequently involved. Finally, it should be remembered that only rarely can lesions related to the viral infection be present inside the mouth and pharynx.
How is the diagnosis made?
It is up to the doctor to suspect the presence of the infection and give advice. Given the picture, however, for those who suspect a Monkeypox virus infection it is essential to be aware insulationto avoid possible risks of human-to-human contagion. On the technical front, even if the doctor may suspect this condition based on the observation of the picture, it is always advisable to undergo targeted laboratory tests.
How can the infection be transmitted?
As we said, we are talking about a zoonosis. Therefore, the possible transmission of the virus can occur through close contact with an infected animal or rather from person to person. In this second case, direct contact with the skin, kissing or during sexual intercourse can allow the virus to pass from one individual to another. This is why we speak of close contacts. It must be said, however, that contagion, as recently observed, is not easy. Particular attention must be paid to prolonged proximity of the facewith exposure to particles emitted by the respiratory tract.
It is very important to avoid contact with potentially contaminated objects, such as towels, clothing and bed sheets.
One last recommendation. During the pregnancy the virus can pass from mother to fetus and even immediately after birth it can be transmitted through the skin. It should be remembered that close contact with an infected person represents a risk.
How is the infection treated?
Monkeypox usually causes symptoms that can resolve on their own in a few weeks. In these cases, following the doctor’s instructions, you can take drugs that reduce fever or help control pain. However, there are situations in which the infection can have a more serious course: it happens especially in people who have specific weaknesses of the defensive systemdue to pathology or treatments they are undergoing, and in those whose immunity is not perfectly functioning as can happen in children.
Finally, the following are fundamental: self-protection rules (it is advisable to avoid scratching the area of the lesions and to maintain good hand hygiene) isolation and the use of a mask.
What should be done to reduce the risks?
Following the timely circular from the Ministry of Health, the Working Group “Prevention and Management of Emergencies” of the Italian Society of Hygiene, Preventive Medicine and Public Health (SItI) – with the editorial supervision of Matteo Riccó – has prepared a Slide Kit for doctors.
The document recalls that at the moment the risk of contracting Mpox is considered “low/very low” for subjects residing in the European Union. The following recommendations can however be shared:
- avoid direct contact with people who have skin lesions similar to those of Mpox,
- avoid contact with objects or clothing of a person with Mpox (or suspected infection),
- wash your hands often
- monitor your symptoms and the appearance of suspicious rashes within 21 days of a risky contact.
At the same time, some information was also released recommendations for travellers:
- contact with wild animals (especially primates and rodents) should be avoided,
- avoid sexual contact (or close contact) with individuals who are known (or suspected) to have recently been infected with Mpox (or who have been in contact with cases of Mpox),
- avoid sexual contact (or close contact) with individuals who have suspicious skin lesions.
It is always advisable to consult the host country’s guidelines before traveling.
Is there a vaccine?
As experts from the Istituto Superiore di Sanità point out, it is possible that people who have been vaccinated against smallpox (vaccination abolished in Italy in 1981) are at lower risk of infection with Monkeypox due to the similarity of the smallpox virus with Monkeypox. In the current epidemiological context Vaccination is not recommended for the general population.
SItI in its document recalls that “given the affinity with the human smallpox virus, clinical research has been interested in Mpox for many years and this has led to the development of some vaccine preparations. The MVA-BN vaccine, currently usable in Italy on high-risk subjects, it requires subcutaneous administration, with 2 separate doses with the second dose no less than 28 days after the first”.
