Mpox (Monkeypox): causes, symptoms, treatment, and prevention

The World Health Organization (WHO) declared on August 14, 2024, that the monkeypox virus infection constitutes a public health emergency of international concern, amid the rapid rise in infections in Central and East Africa and the high risk of global spread. The incidence of confirmed cases is 160% higher than last year, with a 19% higher mortality rate. (The Johns Hopkins University, 2024) The new variant currently circulating is believed to be highly contagious and aggressive.

The first European country to confirm a case of infection with this virus was Sweden (August 15, 2024), with the individual being infected with sub-clade Ib following travel to Africa in an area with many mpox cases. In 2022, there were a few cases of monkeypox (mpox) recorded in Romania, but they were mild forms.

What is monkeypox (mpox)?

Mpox (formerly known as monkeypox) is a disease caused by infection with the monkeypox virus (MPXV), an enveloped virus belonging to the genus Orthopoxvirus in the Poxviridae family. This genus also includes vaccinia virus, cowpox virus, variola virus, and several other pathogenic animal poxviruses (International Committee on Taxonomy of Viruses, 2009).

There are two genetically distinct strains/clades of the virus: clade I (formerly called the Congo Basin clade – Central Africa), with sub-clades Ia and Ib, and clade II (formerly called the West African clade), with sub-clades IIa and IIb (Likos, et al., 2005) (Team, 2022). Clade I has been associated with more severe symptoms and higher mortality – 3.6% compared to 0.2% for clade II, which was the one that drove the 2022 global epidemic originating in West Africa. (McCollum & Damon, 2013)

Poxviruses have long-term stability in the environment (they exhibit greater tolerance to drying, temperature, and pH) (Essbauer, Meyer, Porsch-Ozcürümez, & Pfeffer, 2007), and MPXV can be detected on household surfaces even 15 days after contamination (Morgan, et al., 2022). However, it is sensitive to common disinfectants, though less so to organic ones.

The virus that causes mpox was discovered in Denmark in 1958, following the appearance of two outbreaks of a pox-like disease in several colonies of monkeys used for research, hence the initial name "monkeypox." However, the exact source is not known; it may also be African rodents, which simultaneously infect humans.

The first human case of mpox was recorded in 1970 in what is now the Democratic Republic of the Congo, nine months after the eradication of smallpox in that country (Giulio & Eckburg, 2004). In 2022, it spread worldwide, whereas until then there were usually only isolated cases linked to travel in endemic regions and animal imports from these areas (WHO, 2024). In the same year, the WHO renamed the disease "mpox" to follow modern naming guidelines for diseases. These recommend that “disease names should avoid offending any cultural, social, national, regional, professional, or ethnic group and minimize unnecessary negative effects on trade, travel, tourism, or animal welfare.” However, the virus itself retains its name. (***, About Mpox, 2024)

How is it transmitted?

MPXV is transmitted through prolonged close physical contact with an infected human or animal (even through scratching, biting, or consuming meat) or through contact with contaminated materials. The virus enters the body through broken skin or mucous membranes, as follows: (***, Mpox – How It Spreads, 2024)

• Direct contact with skin rashes or scabs from an infected person
• Direct face-to-face contact with saliva, respiratory droplets, bodily fluids, or lesions around the anus, rectum, or vagina
• Intimate contact (sexual activity, touching genital areas, hugging, massage, kissing): however, it is not considered a sexually transmitted disease
• Touching contaminated and unsterilized objects and textiles (bed linen, towels, etc.)
• During and immediately after childbirth (Mbala, et al., 2017)
• Nosocomial infections (Likos, et al., 2005)

Evidence indicates that infected people can transmit the virus up to four days before the onset of symptoms (Brosius, et al., 2022). A study in the UK demonstrated that 53% of transmission occurred during the pre-symptomatic period (Ward, Christie, Paton, Cumming, & Overton, 2022).

The infectious period ends when all skin lesions develop a scab and re-epithelialization occurs (Mitjà, et al., 2023).

Following some studies, it was found that the percentage of positive samples decreased substantially within a period of three weeks to 40 days after the onset of symptoms (Palich, et al., 2023) (Suñer, et al., 2023). People with severe HIV infection have a longer illness duration. (O, et al., 2023)

There have been cases where between 1.3% and 6.5% of infected people never showed symptoms (Agustí, et al., 2023). The incubation period is usually between 6 and 13 days but can range from 5 to 21 days.

Who is most at risk of infection?

Anyone who has prolonged close contact with an infected person is at risk of becoming infected, but there are certain categories of people who are more susceptible to illness: people living with an infected person, healthcare staff who may come into contact with infected patients, sex workers, and men who have sex with other men. (WHO, 2024)

What are the signs and symptoms?

The duration of signs and symptoms is estimated to be between 2 to 4 weeks.

The disease begins with non-specific symptoms such as: fever, chills, headache, back pain (lumbago), muscle aches (myalgia), fatigue, and lethargy. Lymphadenopathy (swelling of the lymph nodes) is a characteristic symptom of this infection that differentiates it from others that present similar symptoms, and it occurs in up to 90% of patients. (Petersen, et al., 201 9)

After 1 to 3–5 days from the onset of fever, rashes of various sizes appear, first on the face, hands (including palms), or feet (including soles) and then on the rest of the body. In the 2022 epidemic, the rash usually started in the genital area, mouth, or throat (Tosh, 2024). The rash goes through several stages of evolution: macules (flat-based lesions: lasts 1-2 days), papules (firm, slightly raised lesions: lasts 1-2 days), vesicles (fluid-filled lesions: lasts 1-2 days), and pustules (yellowish fluid-filled lesions: lasts 5-7 days). Subsequently, scabs appear, which dry out and fall off over a period of 7 to 14 days. Their number varies from a few to hundreds or more, and in more severe cases, they may merge until large areas of skin peel off. (Petersen, et al., 2019)

In some cases, inflammation of the cornea, conjunctival, pharyngeal, and genital mucosa, as well as pain and difficulty with urination or swallowing, can be observed (WHO, 2024).

Mortality is higher among children and young adults, and the progression is more severe in immunocompromised individuals.

When should you see a doctor?

You should contact your family doctor if you feel unwell and:

• have a fever, pain, or swollen lymph nodes
• have a new rash or sores
• have been in close contact with an infected person

Contact emergency services if the following occur (***, Mpox, 2023):

• difficulty breathing
• new or worsening chest pain
• difficulty speaking or moving
• confusion
• stiff neck
• seizures
• loss of consciousness

How can it be diagnosed?

Identifying mpox can be difficult considering that other infections have similar symptoms: chickenpox, measles, bacterial skin infections, scabies, medication-induced allergies, or sexually transmitted diseases (herpes, syphilis). A patient can be infected with several pathogens at the same time (e.g., mpox and chickenpox), so testing is essential for early diagnosis and correct treatment. (WHO, 2024). Usually, swollen lymph nodes indicate that we are dealing with mpox, but a laboratory test will demonstrate this.

The most appropriate test is PCR (detecting viral DNA via polymerase chain reaction). Samples are taken directly from skin lesions (skin, fluids, or scabs) by vigorous swabbing. In the absence of these, swabbing of the throat or anus can be performed. (WHO, 2024).

Blood testing is not recommended because it does not distinguish between orthopoxviruses.

Additional testing is also recommended for HIV, varicella-zoster virus, and herpes. (WHO, 2024).

What are the complications?

People who are at higher risk of developing complications are:

• The immunocompromised
• Those with a history of eczema
• Pregnant women
• Children under one year of age

Possible complications that may arise include secondary skin infections (leading to abscesses or lesions), blood infections (sepsis), or corneal infections (leading to vision loss), inflammation of the brain (encephalitis), heart (myocarditis), rectum (proctitis), genitals (balanitis), urinary tract (urethritis), vomiting and diarrhea (with dehydration or severe malnutrition), respiratory distress, bronchopneumonia, and in severe cases, even death. (WHO, 2024).

The mortality rate has ranged between 1% and 10% in outbreaks; deaths occur mainly among children and young adults, with the immunocompromised being exposed to the risk of severe disease. (Petersen, et al., 2019)

What is the treatment?

Mpox is usually a self-limiting disease (it improves without treatment), but nevertheless, the doctor may prescribe antipyretics, painkillers, vitamins, and ointments to alleviate certain symptoms and prevent dehydration (through fluid intake). (***, Clinical Treatment, 2024)

In the case of more severe forms, patients will be hospitalized and antiviral medication will be administered; if secondary bacterial infections occur, the administration of certain antibiotics will be necessary.

How can we prevent illness?

Previous vaccination against smallpox provides some cross-protection against monkeypox, with milder symptoms, but this is valid for people who received this vaccine before 1980, when smallpox was eradicated and mass vaccination was stopped.

One of the vaccines approved in Europe for preventing both smallpox and mpox is JYNNEOS®, a third-generation vaccine that has been used since 2019. This vaccine, also known as Imvamune® or Imvanex® internationally, was approved in August 2022 by the US Food and Drug Administration (FDA) for use against mpox intradermally (requires a smaller dose of vaccine – 0.1 ml) in people over 18 and subcutaneously (0.5 ml) in those under 18. (***, JYNNEOS—Frequently Asked Questions)

Smallpox and mpox vaccines can be used in two situations: pre-exposure to prevent infections or post-exposure to ameliorate the disease. Pre-exposure vaccination aims to protect those at the highest risk of infection. Post-exposure vaccination is ideally administered within 4 days of exposure to prevent infection, but can be used up to 14 days after exposure to decrease the severity of the disease (Poland, Kennedy, & Tosh, 2022). In the case of both types of vaccination, the greatest protection is provided by a second or third-generation vaccine.

According to health experts, none of the approved vaccines are recommended for mass administration, but only if deemed necessary following a correct medical evaluation.

The most accessible prevention methods remain following general hygiene rules and avoiding contact with contaminated people or animals:

• After using the toilet, before meals, and after contact with other people or potentially contaminated surfaces or textiles, it is recommended to wash hands with soap and water and use a hand sanitizer, with the alcohol-based one being a suitable choice;
• Disinfect potentially contaminated surfaces;
• Avoid travel to endemic areas;
• In case a person is suspected of being infected with the monkeypox virus, they must be isolated. If the presence of another person near the patient is necessary, it is recommended to cover the patient's lesions, wear a mask and gloves, and perform proper disinfection at the end. (***, Isolation & Infection Control at Home, 2022)

Early identification of mpox cases through correct diagnosis, isolation of infected people, initiation of treatment, and careful identification and monitoring of contacts are the effective methods by which the spread of the disease can be controlled.

Note: The information in this article is for informational purposes only. If you exhibit symptoms specific to the disease, contact your family doctor to receive the necessary recommendations.

Photo source: Shutterstock

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