Monkeypox virus: past and present

World Journal of Pediatrics https://doi.org/10.1007/s12519-022-00618-1 REVIEW ARTICLE Monkeypox virus: past and present Ya‑Mei Dou1 · Hang Yuan1 · Hou‑Wen Tian1 Received: 23 June 2022 / Accepted: 4 September 2022 © The Author(s) 2022 Abstract Background The objective of this paper is to analyze the current status of monkeypox worldwide. In the face of this public health threat, our purpose is to elucidate the clinical characteristics and epidemiology of monkeypox, the developmental progress of monkeypox-related drugs and the vaccines available. Data sources The literature review was performed in databases including PubMed, Science Direct and Google Scholar up to July 2022. Results Since May 2022, the World Health Organization has reported more than 45,000 confirmed cases from 92 nonendemic countries, including nine deaths. Although some women and children have been infected so far, most cases have occurred among men who have sex with other men, especially those with multiple sexual partners or anonymous sex. Conclusions Pediatric monkeypox infection has been associated with a higher likelihood of severe illness and mortality than in adults. Severe monkeypox illness in pediatrics often requires adjunctive antiviral therapy. It is crucial for all countries to establish sound monitoring and testing systems and be prepared with emergency preparedness. Keywords Monkeypox · Orthopoxvirus · Smallpox · Zoonotic Introduction Monkeypox is a rare, sporadic, smallpox-like zoonotic infectious disease caused by monkeypox virus, an orthopoxvirus genus of the Poxviridae family [1, 2]. The disease frequently occurs in Central and West African countries, especially the Democratic Republic of Congo (DRC), where it is considered endemic [3, 4]. Early research indicates that human infection with monkeypox virus occurs most commonly in the 5- to 9-year-old age group, particularly in small villages where the children hunt and eat squirrels and other small mammals [5]. In the last few years, the United Kingdom, the United States, Singapore and Israel have reported the existence of imported cases in individuals with an African travel history [6–8]. Monkeypox has recently grown to be a global concern, as the World Health Organization reported over 45,000 confirmed and suspected cases (as of August 29, * Hou‑Wen Tian 1 NHC Key Laboratory of Medical Virology and Viral Disease, Chinese Center for Disease Control and Prevention, National Institute for Viral Disease Control and Prevention, 155 Changbai Road, ChangPing District, Beijing 102206, China 2022) in more than 90 countries in Europe, the Americas, the Eastern Mediterranean, the Western Pacific and Southeast Asia [9, 10]. Moreover, the number of cases is expected to continuously increase. Significantly different from the past, the vast majority of cases recently reported have no established travel links with endemic areas, involve community transmission and include a small number of women and children [most of the original cases occurred in men who have sex with other men (MSM)] [11], indicating that cases in children may be more frequently reported in the future. The uncertainty of monkeypox epidemic control and the risk of transmission at the social level have increased the possibility of cross-border spread and onward transmission of monkeypox disease. Therefore, this manuscript not only briefly introduces the family Poxviridae but also reviews the clinical manifestations, epidemiology, drug treatment and vaccine application, prevention and control strategies of monkeypox in detail. Family Poxviridae The virus that causes monkeypox, monkeypox virus (MPXV), was first discovered in 1958 as the source of infection that caused an outbreak of pustular rash illness in 13 Vol.:(0123456789) World Journal of Pediatrics cynomolgus monkeys shipped from Africa to Copenhagen, Denmark, for research purposes. Hence, the name “monkeypox” [12–15]. Later, in 1970, human monkeypox was discovered in an infant who had presented with smallpoxlike eruptions in the DRC [16]. Two main clades of human MPXV have been identified: the Central African strains and the West African (WA) strains, the former being more virulent in nonhuman primates. Evidence indicates that the lethality rates are 10.6% and 3.6% for the strains, respectively [17, 18]. MPXV is a double-stranded DNA virus of the orthopoxvirus (OPXV) genus of the family Poxviridae [19, 20]. Poxviridae are classified into two subfamilies: Entomopoxvirinae and Chordopoxvirinae [21]. There are four genera of the subfamily Chordopoxvirinae that can induce human diseases. Among them, viruses from the genera orthopoxvirus, parapoxvirus and yatapoxvirus harbor zoonotic potential [22]. The genus OPXV mainly contains viruses that infect humans: monkeypox virus, cowpox virus, vaccinia virus, and smallpox virus. According to previous studies, gene homology within OPXV can reach 90% based on immune cross protection and cross reactivity [23]. The cross protection allows individuals who had been infected by any member of the genus to be protected against an infection with another virus from the same genus. This is the scientific basis behind Edward Jenner’s cowpox inoculations and vaccinia virus Tian Tan strain isolated in China protecting against variola virus (VARV) [24–26]. Clinical presentation In most cases, monkeypox is a rare but potentially serious viral illness that usually begins with a flu-like illness and swollen lymph nodes and progresses to a widespread rash on the face and body [27]. Monkeypox and smallpox have similar appearance, distribution and pathological progression; however, monkeypox is often less severe [2, 14]. The severity of disease depends on the patient’s age and comorbidities, and case fatality in monkeypox has been reported up to 15%, with younger children being at highest risk [28]. In 1987, pronounced lymphadenopathy was identified as the only clinical sign differentiating monkeypox from smallpox and chickenpox (varicella) [29]. In general, adults or children infected with monkeypox will experience three stages: incubation, prodromal, and rash periods. The incubation period of monkeypox is usually 7–14 days, but it can be longer (5–21 days), with symptoms and signs lasting two to five weeks [30]. Notably, using vaccination after exposure to monkeypox (within four days) given the long incubation period (versus COVID, where the incubation period is shorter) 13 is essential for children and adults [31]. The following prodromal features include fever, muscle aches, headache, backache, sore throat and swollen lymph nodes, followed by a broad, well-circumscribed rash typical of an eccentric pattern. Within one to three days (sometimes longer) after the patient develops fever, the patient develops skin rash, which usually starts from the face and then spreads to other parts of the body. These rashes then go through five stages: macular stage, papule phase, vesicular phase, pustular (...truncated)