Human monkeypox – epidemiology, clinical characteristics, diagnosis and prevention

an introduction
World monkeypox outbreak in 2022
Transmission of monkeypox virus to humans
Through immunity and protection
Clinical manifestations
mixed diagnosis
treatment or treatment
protection
references
in-depth reading


Human monkeypox virus, which belongs to the genus Orthopoxvirus of the family Poxviridae, is a double-stranded deoxyribonucleic acid (DNA) virus. As of June 9, 2022, more than 1,000 people have been confirmed to have been infected with monkeypox in nearly 30 countries around the world.

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World monkeypox outbreak in 2022

Although monkeypox virus is endemic in many African countries, its incidence has generally remained low in these countries. However, the past two decades have seen a huge rise in the number of monkeypox cases, exceeding the statistics accumulated over the 45 years since it was first discovered.

There are two genetic families of the virus that include West Africa and Central Africa. Although all confirmed monkeypox cases from the current outbreak have been confirmed to belong to the West African branch, none of these cases have been linked to travel to an endemic area.

Instead, these cases were identified primarily, but not exclusively, in men who have sex with men (MSM) who were seeking healthcare services in primary and sexual health clinics. However, the extent of local transmission of monkeypox virus during the current outbreak remains unclear due to current limitations in its surveillance. Global healthcare organizations such as the World Health Organization (WHO) expect that additional cases of monkeypox infection will be identified in non-endemic countries.

Since transmission of monkeypox virus is rare in individuals without any travel history to an endemic area, there is an urgent need for rapid identification and isolation of infected individuals, as well as for effective contact tracing to reduce transmission of this disease. virus.

Importantly, previous reports indicated that the incidence of the West African bloc typically causes less severe disease compared to the Central African bloc (Congo Basin). Moreover, mortality rates from these wards are estimated at 3.6% and 10.6%, respectively.

To date, not a single death has been reported in the current outbreak of monkeypox. However, as the World Health Organization expects to identify additional cases of monkeypox in the future, it is imperative that countries around the world initiate effective surveillance strategies to mitigate the spread of this virus.

These efforts should also include raising awareness of the current outbreak for potentially affected communities. Furthermore, some countries may also wish to consider giving smallpox vaccines to individuals who have been in close contact with an infected person, as well as prophylactically to certain vulnerable populations, such as health care workers.

Transmission of monkeypox virus to humans

The transmission of monkeypox virus to humans remains a mystery. While aerosol transmission between animals has been confirmed, direct or indirect contact with infected animals or their carcasses has been implicated in animal-to-human transmission events. Aerosol transmission also poses a threat to veterinary professionals and hospital staff.

Rodents are often hunted for food, as they provide a protein-rich food alternative to the poor. Unfortunately, these animals are carriers of the monkeypox virus.

The incidence of monkeypox infection is usually higher among people who live near forests and in areas where smallpox eradication programs have been curtailed as a result of diminished cross-immunity between non-immunized and lower age groups. These mechanisms have been implicated in the rising number of human cases in Central and West Africa.

Another major factor contributing to the spread of monkeypox infection in humans is the increased contact of humans with small mammals. For this reason, the conquest of forest areas, civil wars, refugee displacement, deforestation and agriculture, climate change, demographic changes, and population shifts are to blame.

This pathogen can invade through compromised skin, respiratory tract or mucous membranes. Human-to-human transmissions are also not uncommon through respiratory droplets, contact with bodily fluids, pests, contaminated surfaces, or smokestacks.

Color electron micrograph of transport of monkeypox virus particles (yellow) cultured and purified from cell culture.  The image was taken at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland.  Credit: NIAIDColor electron micrograph of transport of monkeypox virus particles (yellow) cultured and purified from cell culture. The image was taken at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland. Credit: NIAID

Through immunity and protection

Vaccine virus vaccines protect against monkeypox. Furthermore, neutralizing antibodies generated by these vaccines are responsible for the primary immune mechanism of such cross-protection. Apart from humans, even monkeys benefit from smallpox vaccines, as they provide protective effects against monkeypox disease.

The widespread induction of smallpox vaccines was withdrawn in 1978. Thereafter, the protective immunity against orthopoxviruses declined, especially among the younger generation who were still not immunized and susceptible to these viruses. These factors are likely to contribute to the increased number of cases and increased transmission of the virus.

Clinical manifestations

The clinical signs and symptoms of this infection are identical to those of smallpox in terms of appearance, duration, and locations of affected skin.

The incubation period for monkeypox virus is between five and 21 days, and symptoms usually last two to five weeks. Characteristic features of monkeypox virus infection include fever, chills, lethargy, asthenia, headache, back pain, muscle pain, and enlarged lymph nodes.

A rash is one of the primary symptoms of this infection, with lesions of various sizes usually beginning on the face and later spreading throughout the body. The rash turns into macules, papules, vesicles, and then blisters, and usually resolves with the formation of a crust and scab, which peels off spontaneously upon recovery. Areas of erythema and hyperpigmentation are also common.

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Additional symptoms of this infection are inflammation of the mucous membrane of the pharynx, conjunctiva and genitals. Clinically, the symptoms and lesions are much milder and indistinguishable from smallpox. However, the mortality rate is 1-10%, which can be more significant in children and adults who are immunocompromised.

Complications of monkeypox infection can include secondary infections, shortness of breath, encephalitis, and corneal infection that can cause vision loss, as well as infection of the gastrointestinal tract, which can include vomiting and diarrhea with dehydration. The clinical presentation of individuals infected with monkeypox virus who have not received smallpox vaccination is more severe and is associated with higher mortality rates.

mixed diagnosis

Distinguishing between chickenpox, monkeypox and herpes virus infection remains a clinical challenge during outbreaks. As a result of the nonspecific signs of monkeypox infection, many other diseases and conditions must also be ruled out. These infections may include molluscum contagiosum, bacterial skin infections, scabies, syphilis, measles, rickettsial infections, anthrax, and drug interactions.

The lesions of monkeypox infection differ from those of chickenpox in their prevalence and cutaneous extent, which is more important with monkeypox lesions. Furthermore, chickenpox lesions tend to appear more intensely on the trunk rather than spreading all over the face and extremities as in monkeypox. The clinical differentiation of monkeypox infection is lymphadenopathy.

The diagnosis of this infection is often based on clinical signs and investigations. These include viral culture of swabs from the mouth or nasopharynx and laboratory analysis of skin samples and secretions from lesions.

Other diagnostic methods can include skin biopsies, electron microscopy culture, molecular analysis by polymerase chain reaction (PCR) and sequencing, serological testing for the detection of immunoglobulin M (IgM) or IgG, as well as histology and immunohistochemistry of lesions.

Color scanning electron micrograph of monkeypox virus (orange) on the surface of infected VERO E6 cells (green).  The image was taken at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland.  Credit: NIAIDColor scanning electron micrograph of monkeypox virus (orange) on the surface of infected VERO E6 cells (green). The image was taken at the NIAID Integrated Research Facility (IRF) in Fort Detrick, Maryland. Credit: NIAID

treatment or treatment

There is no specific treatment for monkeypox infection. Management is aimed at symptomatic relief and supportive care. This may also include treatment of secondary bacterial infections in complex cases.

In 2022, the U.S. Food and Drug Administration (FDA) approved tekovirimat, which is also known as TPOXX or ST-246, to treat human smallpox caused by smallpox virus In both adults and children. Although tecovirimat is not approved for the treatment of other orthopoxvirus infections, the US Centers for Disease Control and Prevention (CDC) permits the use of this agent in the treatment of non-parietal orthopoxvirus infections, including monkeypox, in both adults and children of all ages. Are at risk of developing severe illness or are currently experiencing serious complications of this infection.

protection

Preventive measures should target reducing contact with rodents, prohibiting direct exposure to blood, body fluids and uncooked meat, halting the bushmeat trade, and spreading awareness of the dangers of consuming wild animals.

Strong health awareness efforts are needed, and reuse of protective equipment among susceptible populations is essential. In addition, infection control measures are of paramount importance, especially for healthcare professionals, along with smallpox vaccination.

Suspected cases should be isolated in a negative air pressure isolation room. Furthermore, contact and droplet precautions are also essential.

references

in-depth reading

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