Monkeypox ― exotic infection outbreak or a new global challenge to global Health system?

BACKGROUND: Monkeypox, a zoonotic disease caused by an orthopoxvirus, results in a smallpox-like or a chickenpox-like disease. Monkeypox in human was first diagnosed in 1970 in the Democratic Republic of the Congo and subsequently has spread to other regions of Africa (primarily West and Central). In 2003 the first monkeypox outbreak occurred outside of Africa in USA. The latest outbreak of monkeypox in May 2022 is characterized by the simultaneous involvement of several hundred people. The appearance of cases outside of Africa highlights the risk for geographical spread and the global relevance of the disease requiring the epidemiologic studies and the search for effective methods of prevention and therapy.

AIMS: To summarize and systematize the results of studies on the epidemiology, diagnosis, clinical picture, the role of vaccination and treatment of monkeypox, including taking into account the last outbreak of the disease in May 2022 in non-endemic regions.

MATERIALS AND METHODS: A systematic literature search was conducted in MEDLINE (Ovid), MEDLINE (PubMed), and the Google Scholar database published up to May 31, 2022, using the keywords "monkeypox" or "monkeypox virus" or "smallpox human monkeys". We primary selected 112 abstracts. After removing duplicates and irrelevant articles, 48 full-text articles have been selected. After reviewing the full-text article versions, 15 articles were excluded due to highly specialized biological topics, poor study design, quality of results, or their unavailability. Ultimately, this review included 33 articles, in addition to which 6 founding and supporting websites were cited.

RESULTS: Monkeypox cases among humans have been on the rise since the 1970s, primarily in endemic areas. The median age at the time of treatment increased from 4 (1970s) to 21 (2010–2019). Since 2003, the spread of monkeypox outside Africa has been noted, associated with the importation of infected animals, migration and tourism. Transmission to humans occurs through close contact with an infected animal (70%), a person or material contaminated with the virus. Monkeypox presents with fever, vesicular rash, and lymphadenopathy lasting 2 to 4 weeks. Mortality is associated with the development of complications and is 10.6% for the Central African clade compared to 3.6% for the West African clade. There have been no deaths outside of Africa. Our review shows an escalation of monkeypox cases, especially in endemic Africa and spread to other countries, which is likely due to the discontinuation of smallpox vaccination, which provided cross-protection against monkeypox. Unfortunately, smallpox vaccination is contraindicated in immunocompromised individuals, despite the availability of recommended vaccines. The effectiveness of existing antiviral drugs (tecovirimate and brincidofovir) has been little studied in humans.

CONCLUSION: The weakening of population immunity, associated with the cessation of vaccination against smallpox, created the prerequisites for the outbreaks of monkeypox, including in non-endemic areas. Surveillance and detection programs are important tools for understanding the ever-changing epidemiology of this disease. In light of the emergence of cases outside of Africa, the potential for human-to-human transmission of the virus, the public health significance of monkeypox should not be underestimated.