Overview of global trends of Publication Outputs
The number of studies published in a period reflects the trends of research in this field. Our search identified 4408 publications on Hantaviruses from the WOS core database between 1980 and 2020. These publications included original research articles (3338, 75.73%), review articles (378, 8.58%), meeting abstracts (234, 5.31%), letters (204, 4.63%), and other forms of publications, such as editorial materials (108, 2.45%) and papers from proceedings (72, 1.63%). The annual number of publications increased from 2 in 1981 to 173 in 2020 (Figure 2A). Before 1993, the annual number of publications was less than 100, and this number increased slowly over time. After 1994, the annual number of publications increased rapidly, which means that this field of Hantaviruses began to receive attention of scholars. After 2000, there were more than 100 annual publications, with high variability among years since 2010. The largest number of annual publications was 234 during 2014.
Distribution of Countries/Regions and Institutions
A total of 3716 publications (3338 research articles and 368 reviews) were indexed from 125 countries/regiions and 3312 institutions since 1980. Figure 2B indicates the top 5 countries were the United States, Germany, Finland, Switzerland, and France until 2006. After 2006, the number of studies from China gradually increased every year. After 2011, China was second only to the United States. Figure 3 shows spatial distribution of the publications and these top countries were almost in North America, Asia, Europe, and South America. As is shown in Table 1, the most significant number of publications came from the USA (1333, 35.87%) and China (402, 10.82%), followed by Germany(379, 10.20%), Finland(343, 9.23%), Sweden(289, 7.78%), and the University of Helsinki ranked first, with 288 publications, followed by the University of New Mexico (222 publications) and the Centers for Disease Control Prevention of the United States (193 publications). Analysis of the top 10 institutions indicated 4 were in Europe, 3 were in the United States, and 3 was in Asia and this results was consistent with the spatial distribution of countries. Figure 4A, 4B show that the top 10 countries/institutions were the center of network maps which were visualized by the countries that had at least 30 publications and the productive institutions that published at least 30 papers. Each node represents a country or institution, the size of the node repersents the number of articles published. The line between nodes represent cooperation between countries or institutions; the more coarse line means closer cooperation. The color in Figure 4A represents timeline and represents cluster in Figure 4B. These maps suggest that there is active cooperation among countries and institutions, including USA, China, Germany, Finland, Sweden, the University of Helsinki, the University of New Mexico, the US Centers for Disease Control Prevention, and these countries and institutions may have played a critical role in Hantaviruses research. China and Brazil are the most active countries in the past decade in this field.
Table 1
Countries and institutions that had the most publications on Hantaviruses from 1980 to 2020.
Rank | Country (Continent) | Publications (n) | Institution (Country) | Publications (n) |
1 | USA (North America) | 1333 | University of Helsinki (Finland) | 289 |
2 | China (Asia) | 402 | University of New Mexico (USA) | 222 |
3 | Germany (Europe) | 379 | US Centers for Disease Control Prevention (USA) | 193 |
4 | Finland (Europe) | 343 | Karolinska Institute (Sweden) | 153 |
5 | Sweden (Europe) | 289 | Hokkaido University (Japan) | 118 |
6 | France (Europe) | 181 | Medical Research Institute of Infectious Disease (USA) | 116 |
7 | Brazil (South America) | 178 | Swedish Institute for Infectious \Disease Control (Sweden) | 102 |
8 | Argentina (South America) | 169 | Umea University (Sweden) | 93 |
9 | Japan (Asia) | 165 | Fourth Military Medical University (China) | 78 |
10 | South Korea (Asia) | 145 | Korea University (South Kora) | 74 |
Journals and Co-Cited Academic Journals
The 3716 publications were published in 821 academic journals, 10 journals published over 71 papers, and 6 of these 10 journals were based in the United States (Table 2). The Journal of Virology published the most papers (n = 175, IF2020 = 5.103, Q2), followed by Emerging Infectious Diseases (n = 138, IF2020 = 6.883, Q1).
Table 2
Journals that had the most publications and co-cited on Hantaviruses.
Rank | Journal (Country) | Count | IF2020* | Q** | Co-cited journal (Country) | Citations | IF2020* | Q** |
1 | Journal of Virology (USA) | 175 | 5.103 | Q2 | Journal of Virology (USA) | 10100 | 5.103 | Q2 |
2 | Emerging Infectious Diseases (USA) | 138 | 6.883 | Q1 | Emerging Infectious Diseases (USA) | 7039 | 6.883 | Q1 |
3 | American Journal of Tropical Medicine and Hygiene (USA) | 107 | 2.345 | Q3 | Virology (USA) | 5841 | 3.616 | Q3 |
4 | Journal of General Virology (England) | 104 | 3.891 | Q3 | Journal of Infectious Diseases (England) | 5720 | 5.226 | Q2 |
5 | Virus Research (Netherlands) | 100 | 3.303 | Q3 | American Journal of Tropical Medicine and Hygiene (USA) | 4687 | 2.345 | Q2 |
6 | Journal of Medical Virology (USA) | 92 | 2.327 | Q4 | Journal of General Virology (England) | 4549 | 3.891 | Q3 |
7 | Viruses-Basel (Switzerland) | 88 | 5.048 | Q2 | Lancet (England) | 2956 | 79.321 | Q1 |
8 | Vector-Borne and Zoonotic Diseases (USA) | 86 | 2.133 | Q4 | Journal of Medical Virology (USA) | 2699 | 2.327 | Q4 |
9 | Virology (USA) | 81 | 3.616 | Q3 | Proceedings of the National Academy of Science of the United States of America (USA) | 2696 | 11.205 | Q1 |
10 | Archives of Virology (Germany) | 78 | 2.574 | Q4 | Archives of Virology (Germany) | 2501 | 2.574 | Q4 |
Note. IF2020*: Impact factor in 2020; Q*: Quartile in category. |
We also performed an analysis of journal co-citations and the influence of a journal depends on its co-citation ferquency, which reflects the impact of a journal in a scientific field. Among 13,138 co-cited journals, 6 journals had more than 3000 citations, and 3 of them were based in the United States. The Journal of Virology (n = 10,100, IF2020 = 5.103, Q2) had the most co-citations, followed by Emerging Infectious Diseases (n = 7039, IF2020 = 6.883, Q1). Among the top 10 co-cited journals, Lancet had the highest IF (IF2020 = 79.321).
A dual-map overlay indicated that the main active research areas of 3716 publications and relevant research were molecular biology, immunology, clinical medicine, genetics and health nursing medicine. There were three main paths (indicated by the 1 orange path and 2 green paths in Figure 5). The orange path represented studies published in the journals of molecular biology and genetics that were usually cited by publications in the journals of molecular biology and immunology. The green paths represented studies that were published in the journals of molecular biology and genetics and the journals of health nursing medicine that were usually cited by publications in the journals of clinical medicine.
Authors and Co-Cited Authors
There were 12,529 authors of thes publications on Hantaviruses. As shown in Table 3, Vaheri. A had the highest number of publishend literatures (209), followed by Lundkvist. A (146) and Plyusnin. A(125). Co-cited authors means two or more authors who were cited by another paper at the same time,these two or more authors have co-cited relationship. Among 41526 co-cited authors, Schmaljohn. C (2354) was the most frequently cited author, followed by Lee. HW(1726) and Plyusnin. A (1443). Co-authorship of all authors who had at least 20 publications was visualized and Figure 4C shows that these top authors were at the center of the network map. Each node represents an author,with larger cicle meaning more articles. Thicker lines means closer cooperation between two authors. Different colors represent different cluster of the cooperation. These results probably means that these top authors were the influencial scholars in this field and had closer cooperations with other authors.
Table 3
Top 10 Authors and co-cited authors on Hantaviruses.
Rank | Author | Publications (n) | Co-cited Author | Co-citations (n) |
1 | Vaheri A | 209 | Schmaljohn C | 2354 |
2 | Lundkvist A | 146 | Lee HW | 1726 |
3 | Plyusnin A | 125 | Plyusnin A | 1443 |
4 | Vapalahti O | 120 | Hjelle B | 1064 |
5 | Arikawa J | 108 | Mills JN | 1040 |
6 | Krueger D | 105 | Lundkvist A | 1006 |
7 | Hjelle B | 98 | Vapalahti O | 972 |
8 | Yoshimatsu K | 98 | Nichol ST | 841 |
9 | Ksiazek TG | 84 | Klempa B | 786 |
10 | Peters CJ | 78 | Childs JE | 743 |
Basic knowledge and hot topics in Hantavirus research
References represent the basic knowledge of a a specific research field. Analysis of the 3716 publications indicated there were 64,713 references, with an average of 17 references per publication. On December 31, 2020, we compiled a list of the 10 most frequently cited references related to research on Hantaviruses (Table 4). Among these cited references, 92 references were cited more than 100 times, and the references listed in the top 10 were all cited more than 300 times. The most cited paper was Genetic identification of a hantavirus associated with an outbreak of acute respiratory illnes, a genetic analysis of a new serotype of hantaviruses reported in the southwestern United States. We also analyzed the top 90 references (each of which was cited at least 100 times) to generate a network map.(Figure 6). This network showed 4 clusters (indicated by 4 colors). suggesting that these main references represents four main fields of research.
Table 4
Most-cited publications on Hantaviruses.
Rank | First author (year) | Journal | Title | Citations (n) |
1 | Nichol ST (1993) | Science | Genetic identification of a hantavirus associated with an outbreak of acute respiratory illness. | 653 |
2 | Schmaljohn C (1997) | Emerging Infectious Diseases | Hantaviruses: A global disease problem | 622 |
3 | Lee HW (1978) | The Journal of Infectious Diseases | Isolation of the etiologic agent of Korean hemorrhagic fever | 492 |
4 | Jonsson CB (2010) | Clinical Microbiology Reviews | A global perspective on Hantavirus ecology, epidemiology, and disease | 450 |
5 | Duchin JS (1994) | New England Journal of Medicine | Hantavirus pulmonary syndrome: A clinical description of 17 patients with a newly recognized disease | 391 |
6 | Vapalahti O (2003) | Lancet Infectious Diseases | Hantavirus infections in Europe. | 362 |
7 | Zaki SR (1995) | American Journal of Pathology | Hantavirus pulmonary syndrome. Pathogenesis of an emerging infectious disease. | 355 |
8 | Childs JE (1994) | The Journal of Infectious Diseases | Serologic and genetic identification of Peromyscus maniculatus as the primary rodent reservoir for a new Hantavirus in the southwestern United States | 349 |
9 | Schmaljohn CS (1985) | Science | Antigenic and genetic properties of viruses linked to hemorrhagic fever with renal syndrome | 305 |
10 | Plyusnin A (1996) | The Journal of General Virology | Hantaviruses: Genome structure, expression and evolution | 300 |
Keywords are the core of a published article and represent the research topics. Through analyzing these keywords, we can summarize the focuses and research directions in a specific field. We used VOSviewer to cluster the keywords that occurred at least 20 times. Each node represents a keyword and the larger node represents the more repetition for a keyword. The color of node identifies the cluster to which it belongs. Figure 7 shows that these keywords were divided into 3 clusters of green, red, and blue, suggesting three research fields. Green clusters are consist of nephropathia epidemica, puumala hantavirus, bank vole, dobrava virus, thrombocytopenia. Red clusters are composed of HFRS, rodents, epidemiology, seoul virus, vaccine. The keywords of blue clusters are HCPS, andes virus, sin nombre virus, deer mice. We used Citespace to visualize a time-zone view of keywords. This kind of networkmap is designed based on the interactions between keywords, and it helps viewer to explore the evolution track and stage characteristics.Figure 8 shows that the research mainly based on the clinical syndrome and serotypes of Hantaviruses from 1980 to 2000, and the main keywords are renal syndrome, hemorrhagic fever, pulmonary syndrome, hantaan virus, puumala virus. From 2000 to 2020, the research mainly focuses on the epidemiology and influence factors in this field, and the main keywords were transmission, rodents, ecology, evolution, vaccine.