The most recent report from the World Health Organization (WHO) showed that as of February 16, 2023, the monkeypox epidemic in 2022-23 had spread to 110 Member States across all 6 WHO regions, with a total of 85 860 laboratory-confirmed cases including 93 deaths.1 Monkeypox is a viral zoonosis caused by the monkeypox virus (MPV) that is transmissible between animals and humans, as well as between humans for secondary transmission.Reference Harris 2 , Reference Kozlov 3 MPV is an enveloped double-stranded DNA virus with an approximate length of 197 kb, belonging to the genus Orthopoxvirus of the family Poxviridae.Reference Nakhaie, Arefinia and Charostad 4 Monkeypox is mainly transmitted through direct skin contact.Reference Guarner, Del Rio and Malani 5 In humans, the most common monkeypox symptoms are fever, severe headache, muscle soreness, back pain, fatigue, and swollen lymph nodes, followed by or accompanied with a rash, typically lasting 2 to 3 weeks.Reference Tarín-Vicente, Alemany and Agud-Dios 6 –Reference Thornhill, Barkati and Walmsley 8 Most patients recover within a few weeks, but newborns, children, and those with immunodeficiency may become gravely ill or even die.Reference Thornhill, Barkati and Walmsley 8
On July 23, 2022, the WHO declared the current monkeypox outbreak a public health emergency of international concern (PHEIC), as it has posed a great threat to human health.Reference Nuzzo, Borio and Gostin 9 The spread of monkeypox has increased the burden of existing infectious diseases and placed significant strain on global health systems. In addition, measures taken to control the spread of the virus have had a large impact on daily life, the economy, and transportation.Reference Nuzzo, Borio and Gostin 9
The outbreak of human monkeypox in numerous nations has sparked intense research interest. There has been a dramatic increase in the number of publications on monkeypox, providing information on epidemiology, prevention, vaccine development, and potential treatments, which may play a vital role in the fight against the monkeypox pandemic.
Bibliometrics, first proposed by American bibliographers in 1969, refers to the quantitative analysis of literature using methods such as mathematics and statistics.Reference Xu, Zhao and Xing 10 –Reference Şenel and Topal 12 Based on the construction of the citation graph, it can quantitatively analyze citation scientific publications.Reference Xu, Zhao and Xing 10 In addition, VOSviewer software can be used to construct and visualize bibliometric networks.Reference van Eck and Waltman 13 This study aimed to conduct a comprehensive scientific quantitative evaluation of MPV literature to guide future research efforts.
Methods
Literature Search
All monkeypox-related literature was searched in the Web of Science (WoS) Core Collection from inception to February 23, 2023. According to the mesh and entry terms, search terms including “monkeypox virus” or “monkeypox viruses” or “monkeypoxvirus” or “monkeypoxviruses” or “monkey pox virus” or “monkey pox viruses” were used to gain complete access to relevant publications. All studies investigating MPV were enrolled in this analysis. No language restrictions existed.
Bibliometric Analytic Approach
Full records and cited references from the literature that met inclusion criteria that the publications involved participants who had monkeypox virus were included in this study and exported to a tab-delimited file. VOSviewer software (version 1.6.18, Leiden University, Leiden, Netherlands) was used for bibliometric analysis. The citation and the top 10 most active categories, including authors, countries, organizations, journals, research areas, and document types, were analyzed to determine the most recent research trends. Microsoft Excel 2016 was used to store and analyze the data of the included literature.
Results
Number and General Characteristics of the Literature
A total of 1646 publications were associated with the search terms in the WoS Core Collection from inception to February 23, 2023. Of these, 669 (40.64%) articles were published in 2022, whereas only 31 (1.88%) and 42 (2.55%) articles were published in 2021 and 2020, respectively. The number of research articles on MPV increased significantly in 2022. An evaluation of the annual distribution of publications is presented in Figure 1, and the frequency of occurrence of the keyword “monkeypox” by year is presented in Figure 2. The distribution trend reflected that there were relatively fewer studies on MPV before 2022, which might suggest that the virus was not a significant public health concern at that time.
Figure 1. Annual distribution of publications, wherein publications about monkeypox virus increased significantly in 2022.
Figure 2. Frequency of occurrence of the keyword “monkeypox” by year.
Bibliometric Analysis of Keywords
Keywords (provided by the included articles) with at least three occurrences were analyzed. A sample of 761 keywords from a total of 4025 met this minimum threshold. In the network visualization of keywords, each circle represents a keyword and the lines between the circles represent the correlations between keywords. Specifically, the larger the circle, the higher the frequency of the keyword, and the shorter the distance between the two circles, the stronger the correlation between these two keywords. The keywords were grouped into 13 clusters by different colors. As shown in Figure 3, the most prevalent keyword was “monkeypox” (551 occurrences, total link strength 3847), which had a strong link to “orthopoxvirus”. “Smallpox” (300 occurrences, total link strength 2628) and “monkeypox virus” (282 occurrences, total link strength 1896) were the other two most popular keywords (Figure 3A). Density visualization is provided to show the frequency of keywords that occurred more than 3 times, revealing that “monkeypox” and “infection” were the most frequently used terms (Figure 3B). The top 10 keywords are presented in Figure 3C.
Figure 3. Bibliometric analysis of keywords in the included papers from the WOS Core Collection database. (A) Network visualization of keywords, with the most prevalent keyword being “monkeypox” (551 occurrences, total link strength 3847); (B) density visualization of keywords that occurred more than three times, with “monkeypox” and “infection” as the most frequently used terms; (C) bar chart of the top ten keywords.
The Most Active Authors, Organizations, and Countries
Table 1 lists the top 10 most active MPV publication authors, countries, and organizations. A total of 121 countries/regions and 2480 affiliations contributed scientifically. Inger K. Damon (Centers for Disease Control & Prevention, Poxvirus Program, Atlanta, GA) was the top contributing author, with 75 publications and 4653 citations, although this author’s articles were published before 2022. The other 2 of the top 3 most active authors were Mary G. Reynolds (total of 55 publications, 2710 citations) and Victoria A. Olson (total of 44 publications, 2314 citations). After 2022, they published one (total of 86 citations) and two articles (total of 86 citations), separately. The top two countries with the highest numbers of publications were the United States, with 764 publications (46.42%, with 24 532 citations) and Germany, with 133 publications (8.08%, with 4337 citations) with a wide disparity in the number of studies between the 2 countries. The top 3 affiliations with the highest numbers of publications were the Centers for Disease Control and Prevention (United States), with 187 publications and 8359 citations; the National Institutes of Health (NIH, United States), with 99 publications and 4606 citations; and the NIH National Institute of Allergy and Infectious Diseases (NIAID, United States), with 77 publications and 3023 citations.
Table 1. The top ten most active authors, organizations, and countries of monkeypox virus publications
The Most Active Journals, Document Types, and Research Areas
Table 2 lists the top 10 most active MPV publication journals, document types, and research areas. Journal of Virology had the highest number of both publications (54 [3.28%]) and citations (2343). Virology was, as expected, the largest research area, with 368 (22.36%) publications and 9858 citations. Research articles (1090, 66.22%), review articles (290, 17.62%), editorial materials (105, 6.38%), and letters (104, 6.32%) were the most popular document types. The article “The detection of monkeypox in humans in the Western Hemisphere”, published in the New England Journal of Medicine in January 2004, and since the date of publication to the search date, has received the most citations (total of 479 times).
Table 2. The top ten most active journals, research areas, and document types of monkeypox virus publications
Bibliometric Analysis of Themes and Trend Topics
The bibliometric analysis of themes and trend topics is shown in Figure 4A, B. As indicated in Figure 4A, 5 themes of MPV studies were found. The red cluster focused on the theme of examining the body’s reaction and challenges after infection with MPV. The green cluster investigated epidemiological characteristics of monkeypox. The yellow cluster investigated measures of diagnosis associated with the MPV. The blue cluster mainly examined characteristics and the pathogenic mechanism of MPV, and the purple cluster focused on the host range of the MPV. Figure 4B depicts the network map of trending topics according to the terms (extracted from titles and abstracts) used from inception to 2022. The indicator shifted from purple to yellow to display current publications, and some new subject words appeared in the recent period. This visualization demonstrated that research on MPV is gradually increasing.
Figure 4. Bibliometric analysis of themes and trend topics. (A) Five themes of monkeypox virus studies were included, and nodes with different colors represent various research directions. The red cluster focused on the body’s reaction and challenges after infection with monkeypox virus. The green cluster investigated the epidemiological characteristics of monkeypox. The yellow cluster investigated diagnostic measures associated with the monkeypox virus. The blue cluster examined characteristics and the pathogenic mechanism of monkeypox virus, and the purple cluster focused on the host range of the monkeypox virus; (B) network map of the trend topics according to the terms (extracted from titles and abstracts), with some new subject words appearing in 2022, indicating that research on the monkeypox virus is gradually increasing.
Discussion
Due to the persisting prevalence of monkeypox, the number of scientific publications in this field has continued to rise, particularly in 2022. The importance of evaluating the quality of these publications and extracting useful information from them for future research cannot be overlooked. In the current studies, 1646 publications about monkeypox indexed in the WoS Core Collection database were analyzed. Three research areas were represented in the published literature: virology, immunology, and infectious diseases. The most frequently used keyword, “monkeypox” was closely related to “orthopoxvirus” and “smallpox.” The United States has made the most outstanding contributions to this vital field.
Monkeypox is a rare infectious disease, first discovered in a laboratory monkey in 1958.Reference Mitjà, Ogoina and Titanji 14 The first recorded human case was in 1970 in Zaire.15MPV occurred mainly in African countries before 2003. Since the outbreak of monkeypox in the United States in 2003, cases have emerged in many other countries outside AfricaReference Martín-Delgado, Martín Sánchez and Martínez-Sellés 16 and have continued to spread globally, predominantly in Europe and North America. The spike in the number of infectious cases may be related to a mutation making MPV more transmissible. WHO declared monkeypox a PHEIC in July 2022, indicating that global solidarity is needed to address its rapid spread. According to the case reports to date, the outbreak of monkeypox has been associated with close intimate contact, primarily involving men who have sex with men. In addition to the aforementioned direct contact form of transmission, airborne transmission is also a way by which the virus spreads.
The monkeypox epidemic is still raging throughout the world. This rapid global spread has heightened researchers’ vigilance and led to the development of numerous effective strategies for combating the epidemic. With the highest number of published articles and citations, the Journal of Virology has become the most popular publication, demonstrating its great advantages.
Monkeypox is caused by the MPV. Both the MPV and smallpox virus belong to the orthopoxvirus family, and their typical clinical manifestations are similar.Reference Harris 2 , Reference Kozlov 3 , Reference Bayer-Garner 17 , Reference Simpson, Heymann and Brown 18 Therefore, as the top 10 most frequently used keywords, “monkeypox” and “orthopoxvirus” were closely associated with “smallpox”. In addition, many people are extremely concerned due to the outbreak of monkeypox and the lack of effective prevention and treatment methods. Therefore, “outbreak” and “smallpox vaccine” were another 2 top 10 keywords.
Most articles on monkeypox published in 2022 were written by American scholars. This is likely because the pandemic is mainly spreading in Europe and North America, particularly the United States, which has become one of the countries with the highest monkeypox infection rate worldwide.Reference Khan, Akbar and Yahiro 19 The United States reported its first case of monkeypox on May 7, 2022, and by August 9, 2022, nearly 9500 confirmed cases had been reported. At the same time, on August 4, the United States government declared monkeypox a public health emergency.Reference Khan, Akbar and Yahiro 19 In addition, the United States has a robust information and data management system.
With the in-depth study of monkeypox, more clinical studies have been carried out in other countries.Reference Rao, Schulte and Chen 20 , Reference Mileto, Riva and Cutrera 21 Current research focuses primarily on understanding the epidemiology and diagnosis of monkeypox, studying changes at the organ and cell levels, and exploring potential pathogenesis and treatment methods. For the diagnostic method of monkeypox, besides determining monkeypox-specific DNA sequences, AI-based detection is a valid method to identify this disease at the early stage, and AI-based diagnostic methods may be appropriate for mass screening.Reference Sitaula and Shahi 22 Currently, the treatment for most patients is symptomatic, and there is no antiviral drug approved for monkeypox.Reference Adler, Gould and Hine 7 , Reference Del Rio and Malani 23 Three antivirals—tecovirimat, cidofovir, and brincidofovir—have been shown to be effective against monkeypox infection.Reference Matias, Koshy and Nagami 24 , Reference Grosenbach, Honeychurch and Rose 25 These antivirals, approved to treat smallpox, are expected to be potential options for treating monkeypox as well. However, none of these antivirals has been evaluated in randomized trials. Tecovirimat is the first choice for the treatment of monkeypox, and it has been approved by the European Medicines Agency (EMA) for monkeypox but not yet by the FDA.Reference Sherwat, Brooks and Birnkrant 26 Cidofovir has been shown to be effective against monkeypox in animal models, but its dose-dependent nephrotoxicity restricts its use in the clinic.Reference Stittelaar, Neyts and Naesens 27 As an analogue of cidofovir, brincidofovir has decreased nephrotoxicity. However, it has the risk of derangement in liver function.Reference Adler, Gould and Hine 7 Consequently, effective treatment will undoubtedly become one of the primary concerns of future researchers. In addition, there are 2 main vaccines (the JYNNEOS and ACAM2000 vaccines) that can presently be used to prevent monkeypox, both of which have been proven to be 85% effective.Reference Rizk, Lippi and Henry 28 , Reference Rao, Petersen and Whitehill 29 However, the supply of vaccines is severely limited at the moment, so further research and development of vaccines will also be a focus of future research. Finally, beyond vaccination, a comprehensive strategy to prevent monkeypox should be applied, including maintaining personal hygiene, avoiding contact with infected animals, controlling health-care environments, education and awareness, and early diagnosis and treatment.
In this study, the WoS Core Collection database was searched for publications on monkeypox, and VOSviewer was applied to conduct a quantitative analysis of the relevant literature to gain an objective and comprehensive understanding of the epidemic. However, there are some limitations in this research. First, only using the WoS Core Collection database to screen the literature may have caused some publications, which they might be included in other databases, to be excluded from our analysis. In addition, “grey” literature may hold significance in research, but this study mainly focused on publications that are widely recognized in academia; therefore, the “grey” literature, such as WHO’s situation reports, will be included for more comprehensive analysis in a future study. Second, as time goes on, more articles may be published, and the number of articles included based on the search terms may be varied. In future reports, research results will be updated according to the latest number of articles, thereby improving the reliability of the study. Finally, the studies included were analyzed based on the citations rather than other evaluation methods, and thus, the collected literature was of variable quality. Impact Factor, CiteScore, Eigen Factor, and the h-index are significant indicators for evaluating the quality of literature. Therefore, future research may utilize evaluation criteria that include these indicators to control for the impact of the variable quality of literature on conclusions.
Conclusions
With the spread of the monkeypox epidemic, related publications showed a trend of rapid growth. The bibliometric analysis of monkeypox is particularly important for understanding the current situation and guiding future research directions. The current study found that the United States has played a crucial role in studying the monkeypox virus. Research topics have mainly involved bodily reaction after monkeypox infection, epidemiology, diagnosis, pathological mechanisms, and host range of monkeypox infection. Effective diagnostic methods, treatment schemes, and vaccine research are still the focus of future research.
Data availability statement
The corresponding author will supply the data for reasonable requests. Bo Jiao and Liyun Deng made equal contributions.
Acknowledgments
Not applicable.
Author contribution
BJ and CC designed this bibliometric analysis and constructed the search strategy. BJ and LYD completed the literature search and data collection. BJ and LYD performed the data synthesis and analysis. BJ, LYD, and YC were the major contributors to the draft writing. CC revised the manuscript critically. All authors have read and approved the final version.
Funding statement
All authors declared that no specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interest
The authors declared they have no competing interests.
Ethical standard
Ethical approval is not required since all data were extracted from previously published studies.
