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Monkeypox typically presents with fever, rash, and swollen lymph nodes; from a clinical point of view, the symptoms are similar to those seen in the past in patients with smallpox, although they are generally less severe.
The monkeypox virus is mainly transmitted to people by wild animals, such as rodents and primates, but human-to-human infection, by air or through secretions and body fluids, is also possible.
In humans, cases of the disease are observed sporadically and, occasionally, in an epidemic form. Most cases have been reported in the Democratic Republic of the Congo, where monkeypox is considered endemic, but is occasionally found in other countries, including Asia, the United Kingdom and the United States (where the latest cases date back to July 2021).
) which produces symptoms similar to those seen in the past in smallpox patients, although clinically less severe.
Monkeypox: Why is it called Monkeypox?
The disease is called "monkeypox", as the causative virus was first isolated and identified in 1958 in some monkeys. Macaca fascicularis laboratory.
In fact, it is assumed that the reservoir of infection, responsible for maintaining the virus in nature, is represented by small rodents (such as squirrels, rats and mice) that inhabit the tropical rainforests of central and western Africa.
What does it have to do with smallpox?
The clinical presentation of monkeypox is reminiscent of smallpox, an infectious disease declared to be eradicated around the world in 1980 after a global vaccination campaign.
Unlike monkeypox, smallpox was more easily transmitted and more often fatal (approximately 30% of patients).
The last case of naturally acquired smallpox was detected in 1977. In African countries, the end of smallpox vaccinations coincided with an exponential increase in cases of monkeypox, so it is likely that the "increase in" incidence depends on it " event. In other words, the protective effect of the smallpox vaccine against monkeypox has waned over time, making unvaccinated populations more susceptible to monkeypox virus infection.
For further information: Smallpox Monkeypox is a large double-stranded DNA virus, closely related to the human smallpox virus. As anticipated, this pathogen belongs to the Orthopoxvirus genus, Poxviridae family, similar to the Variola virus (the smallpox virus) and the Vaccinia virus (the virus used in the smallpox vaccine).
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So far, two distinct clades of the virus (groups with similar genetic traits and functions) have been identified: those of the Congo Basin (more virulent and transmissible) and those of West Africa. The geographical division between the two clades is thought to be in Cameroon, as this is the only country where both clades of the monkeypox virus have been detected.
Monkeypox: How Much and Where is it Widespread?
- In humans and other primates, cases of the disease are observed sporadically and, occasionally, in epidemic form. Most of the reported cases come from the rural rainforest regions of the Congo Basin, particularly the Democratic Republic of the Congo, where it is considered endemic.
- The first human case of monkeypox was recorded in 1970 in the Democratic Republic of the Congo (then known as Zaire), during a period of intense efforts to eradicate smallpox. Since then, monkeypox has been found in humans in other countries.
- Since 2003, the virus has been exported from Africa. In particular, some cases of monkeypox have also been reported in the United States of America, when some infected rodents imported from Ghana infected prairie dogs that later came in contact with some human subjects. Recently, monkeypox was recorded in Israel in September 2018, in the UK in September 2018 and December 2019 and in Singapore in May 2019. In 2017, Nigeria experienced the largest documented outbreak to date.
Natural Host of the Monkeypox Virus
Various animal species have been identified as susceptible to monkeypox virus infection. The mechanism for maintaining the pathogen in nature is not yet fully understood, but it is certain that humans and non-human primates do not constitute the true reservoir of the pathogen. disease, represented rather by various species of rodents. Therefore, further studies are needed to identify the exact reservoir of the monkeypox virus and how it is maintained in the wild.
(interval from "infection to" onset of symptoms) of monkeypox is usually between 6 and 13 days, but can vary from 5 to 21 days.
Monkeypox Symptoms: How Does It Manifest?
The Monkeypox virus is responsible for a "systemic infection characterized by:
- Fever;
- Chills;
- Headache
- Myalgia;
- Back pain;
- Exhaustion;
- Lymphadenopathy;
- Skin rash with blisters and pustules (usually first on the face).
From a clinical point of view, monkeypox is similar to human smallpox; however, skin lesions often take on a cluster configuration and lymph node enlargement is more common.
Course of the smallpox of the monkeys
The infection can be divided into two periods:
- Invasion period (lasts 0-5 days): characterized by fever, severe headache, lymphadenopathy (swollen lymph nodes), back pain, myalgia (muscle aches) and intense asthenia (lack of energy). Lymphadenopathy is a distinctive feature of monkeypox from other diseases that may initially appear similar (chickenpox, measles, smallpox).
- Skin rash: usually starts within 1 to 3 days after the onset of fever. The rash tends to be more concentrated on the face and extremities rather than the trunk. It affects the face (95% of cases), palms of the hands and soles of the feet (75% of cases). the oral mucous membranes (in 70% of cases), the genitals (30%) and the conjunctiva (20%), as well as the cornea. The rash progresses sequentially from macules (lesions with a flat base) to papules (firm lesions slightly raised), blisters (lesions filled with clear fluid), pustules (lesions filled with yellowish fluid), and scabs that dry out and fall off. The number of lesions varies from a few to several thousand. In severe cases, the lesions can fuse until large sections of skin break off.
People living in or near wooded areas may have indirect or low-level exposure to infected animals, which can lead to subclinical (asymptomatic) infections.
Duration of the disease
As a rule, the disease has a benign and self-limiting course with symptoms lasting 2 to 4 weeks, but it can occur with greater severity in immunocompromised individuals and children.
Possible Complications
Severe cases occur most commonly among children and are related to the extent of exposure to the virus, the patient's health status and the nature of the complications.
Complications of monkeypox can include:
- Secondary infections;
- Bronchopneumonia;
- Sepsis;
- Encephalitis;
- Corneal infection resulting in loss of vision.
In the general population, the mortality rate of monkeypox is about 10% of those affected; most deaths occur in the younger age groups and among young children.
of the skin, scabies, syphilis and drug associated allergies. Where possible, biopsy is an "option.
Since Orthopoxviruses are serologically cross-reactive, antigen and antibody detection methods do not provide specific confirmation for monkeypox. Serological and antigen detection methods are therefore not recommended for the diagnosis or investigation of antigen. cases where resources are limited. In addition, recent or remote vaccination against smallpox (eg anyone who has been vaccinated before smallpox eradication or vaccinated more recently due to a higher risk of the Orthopoxvirus, such as staff laboratory) could lead to false positive results.
To interpret the test results, it is critical that patient information is provided with the samples, including:
- Date of onset of fever;
- Date of onset of the rash;
- Sample collection date;
- Current state of the individual (stage of the rash);
- Age.
