In this study, we chose WOSCC as the data source, which, as a highly respected database of high-quality digital literature resources, has been embraced by many researchers and is regarded as the database of choice for bibliometric analyses (Ding and Yang, 2022) Although the HRTV was first detected in Missouri in 2009, it only received further reporting and attention in 2012. During this time, although the virus was discovered, the associated scientific research had not yet developed sufficient scale and depth to reach the level of public publication. In our initial process of determining the start and end of the screening, our search keywords and strategy focused primarily on the literature in which the HRTV was a core research component; therefore, literature on the HRTV in 2012 was not directly identified as key literature, and thus the final determination was made that the screening would begin in 2013. We set the search formula as [“Heartland virus” OR “HRTV” OR (“Heartland” AND “virus”)] and then retrieved the literature from the WOSCC database for the period of January 1, 2013, to July 25, 2024. Document types included original research articles, reviews, and research letters in “English.” To ensure the timeliness and accuracy of the data, both researchers conducted an exhaustive literature search and screening of HRTV-related literature on the same day. A comprehensive database search was conducted based on title, abstract, and keywords as screening criteria. The full text of the literature was read to ensure its relevance to the purpose of the study when necessary. During the screening process, we need to pay special attention to well-documented literatures that contain important citation information and export these documents from the Web of Science platform to “TXT” format files for subsequent research and analysis. Figure 1 is a flowchart of the process of screening the literature focusing on HRTV as a core research component, demonstrating the process from the identification of keywords to the inclusion and exclusion of relevant literature, culminating in the analysis of multiple aspects of the included HRTV-related literature using three tools, CiteSpace, VOSviewer, and Bibliometrix for the write-up. Given that the data for this study were all sourced from a public database, there was no need to obtain additional ethics committee approval.

The beginnings of bibliometrics can date back to the dawn of the 20th century and it has subsequently played an important role in the field of literature analysis (Diem and Wolter, 2013). During the analysis phase, we can extract rich details covering authors, keywords, journal sources, country of affiliation, research organizations, and references. With this detailed data, we could gain insight and grasp a field’s history, current status, and future trends through bibliometric analysis (Abramo et al., 2011). In constructing the knowledge graph, we relied on two tools: CiteSpace software (version 6.2.4.24) and VOSviewer software (version 1.6.20). These two types of software complement each other and offer distinct advantages, significantly enhancing the efficiency of constructing knowledge graphs. CiteSpace is an interactive visualization tool based on set theory, focusing on data standardization. It uses clustering functions, combined with similarity measures and algorithms for knowledge units, aiming to deeply analyze and visualize the development lineage, research hotspots, and trends in HRTV and then gain insight into and predict the research frontier dynamics in the field (Synnestvedt et al., 2005). VOSviewer is probabilistic-based application software for scientific knowledge graphs, primarily used to create visual representations of knowledge graphs based on keyword co-occurrence, co-institution, and co-authorship. The software can vividly depict the development progress, coordination, and other relevant aspects of the HRTV field and is characterized by easy mapping and flexible operation. In addition, VOSviewer provides a variety of visualizations, such as network view, overlay view, and density view, offering a rich selection of data presentation options (van Eck and Waltman, 2010).

The bibliometric approach evaluates scientific research trends, impact, and quality by quantitatively analyzing academic literature. To enhance rigor and minimize limitations in our bibliometric study, we implemented the following strategies during the analysis: (1) A thorough literature screening was conducted to ensure data accuracy and reliability. (2) The characteristics and differences across various subject areas and types of literature were meticulously considered; for instance, we included only articles, reviews, and research letters to ensure the applicability and precision of our analysis results. (3) We gained a comprehensive understanding of the background of studies on HRTV diagnosis, transmission, and pathological processes, recognizing these as external factors that could influence the study outcomes.

VOSviewer is known for presenting a more comprehensive network structure, highlighting multiple relationships between nodes, which may result in a denser network but enable the identification of clear clusters and key nodes. Conversely, CiteSpace tends to focus on depicting critical paths and major clusters, offering more concise results. In our study, the key parameters of the CiteSpace software were consistently set, with the years per slice at 1. The sources for terms were concentrated on “Title,” “Author keywords,” and “Keywords Plus,” and the links’ scope was confined within slices. In the g-index, the scale factor k was set to 25. Despite formal differences in the outcomes presented by the two tools, there is significant overlap regarding major clusters and key nodes. These clusters highlight the distribution of various research topics or fields, while the key nodes represent influential literature or authors within the field. Analyzing these clusters and key nodes allows for an in-depth understanding of the research area.

In the data pre-processing stage, we used CiteSpace’s data processing utilities to de-duplicate and organize the included literature in WOSCC to ensure its accuracy. Moreover, we conducted a detailed standardization process for the overall collection of literature to guarantee its quality and uniformity. We created a fresh “TXT” file adhering to the “thesaurus_authors” format in the VOSviewer directory, where we consolidated synonyms. The implementation in the “TXT” file adhered to the following format: (1) Merging of synonymous terms, (2) Integration of subordinate units into higher-level entities, and (3) Consolidation of subordinate territories into their respective countries. Subsequently, we imported this file into the “VOSviewer thesaurus file” section on the clustering page of VOSviewer, achieving data reintegration. This data integration approach applies to countries, institutions, and references.

The search results of the WOSCC database were processed using CiteSpace, and a total of 82 relevant records were included, including 68 articles (82.93%), 13 reviews (15.85%), and one research letter (1.22%). Figure 2 shows the trend of publications and citations in the field of HRTV. From 2013 to 2024, the research in HRTV has maintained a steady and progressive growth trend. The average annual literature output has remained stable over the past decade, reflecting the broad interest and importance of the field in the research community. While some progress has been made in exploring HRTV, more in-depth research is still needed in pathogenesis, epidemiology, clinical manifestations, and therapeutic and prevention strategies. Since this study began in July 2024, the number of publications retrieved in that year showed a decreasing trend compared to previous years.

A total of 17 countries and regions have published articles in the field of HRTV, and the top 5 countries with the most publications are shown in Table 1. Researchers in the United States published the largest number of papers in the HRTV field, 56 in total, followed by China and Japan, with 14 and 9 papers, respectively. The higher value of total link strength (TLS), as a measure of the tightness of connectivity between countries, reflects that the country is more actively engaged in cooperation with other countries. Table 1 shows that the United States and China are at the top of the list regarding excellence in international cooperation.

We used VOSviewer software to visualize the countries and regions that have published at least one article. The results show that 17 countries and areas fulfill this condition, as presented in Figure 3A. The node size in the figure directly reflects the number of articles published in these countries and regions; the larger the node means, the more articles are published; while the connecting line between the nodes represents the strength of the cooperation association between these countries, the thicker the connecting line, the stronger the cooperation between the two countries. In Figure 3B, the size of the nodes is used to indicate the number of citations of articles from each country. The figure shows that the United States leads the total number of articles citations, followed by China, and Japan. Meanwhile, the color shades of the nodes indicate the articles’ publication year, with the darker color representing the earlier year. Summarizing the above analysis, the United States, China, and Japan are the most important contributors to the field of HRTV. The United States has many articles issued and the most frequent cooperation with China and Japan. However, there is an obvious imbalance in the distribution of issuing countries, with a few countries occupying a large number of research resources, forming a significant “top effect.” Academics pen a significant proportion of the papers in this domain from a limited number of nations. Figure 3C presents a map of the geographical distribution of international collaborations, with colored regions marking the core clusters of countries that have published significant papers in the field of HRTV. The thickness of the lines connecting these regions intuitively reflects the closeness of the collaborations between countries, with thicker lines implying a more significant number of papers published in collaboration between those two countries. In particular, within the field of HRTV research, the United States, China, and Japan all occupy a central position and have made key contributions to research in this area. Teamwork can effectively integrate resources, and international cooperation can introduce advanced technologies and concepts to enhance the research level and global influence.

A total of 135 institutions published articles related to HRTV, and the top five institutions with the most publications, as shown in Table 2, were all from the United States and China, respectively, indicating that these two countries have the largest number of researchers in HRTV-related fields. The Centers for Disease Control and Prevention-USA had the highest number of publications (n = 20), followed by the Chinese Academy of Sciences (n = 8) and the University of Texas Medical Branch Galveston (n = 6). Setting the VOSviewer parameter to the minimum number of documents for an institution = 2 yielded 32 institutions. As shown in Figure 4A, the various colors symbolize different collaboration clusters, while the vast majority of collaboration clusters are confined to a single country. The connecting lines represent the strength of collaboration; the thicker the connecting lines represent the more collaborative documents between two institutions; the node size represents the number of documents; the larger the node, the more documents are sent. As illustrated in Figure 4B, we mapped the knowledge network of the collaborating institutions with the help of CiteSpace software. In this graph, the size of an organization’s node is directly related to its Betweenness Centrality (BC) in the knowledge network, with a larger node size indicating a higher BC value. This metric profoundly reveals the centrality of each node in the overall network architecture, thus effectively quantifying the extent of each institution’s contribution to the research results in the HRTV domain (Li and Zheng, 2022). Organizations such as the Centers for Disease Control and Prevention-USA (BC = 0.24), the Chinese Academy of Sciences (BC = 0.16), and the National Institutes of Health(NIH)-USA (BC = 0.15) play an important role in the collaborative network. Figures 4A,B illustrate that most publications in the field of HRTV originate from a select few organizations, such as ‘The Centers for Disease Control and Prevention-USA’ and ‘The Chinese Academy of Sciences,’ among others. Institutions with abundant resources are well-equipped to support research, and those prioritizing innovation tend to produce higher-quality and more influential literature. These institutions possess substantial academic foundations and significant professional advantages in HRTV research, thereby attracting numerous researchers to conduct studies in this field.

The top three authors in terms of the number of published articles were Kristen L Burkhalter (n = 8), Savage HM (n = 7), and J. Erin Staples (n = 7) (Table 3). After analysis using CiteSpace software, we have included researchers who have published more than four articles related to HRTV in the co-author network mapping. The graph comprises 26 nodes and 87 connecting lines (Figure 5). This author collaboration graph is designed to reveal the most active and productive authors or co-authors and visualize their strong collaborative links. This tool provides researchers with information about influential research teams and facilitates their identification of potential partners, which in turn helps them build closer and more productive collaboration networks (Xia et al., 2022). As can be observed from the presentation in Figure 5, the 26 authors are divided into 4 different colored clusters. The connectivity between these clusters is sparse or almost non-existent, reflecting the very limited or practically non-existent cooperation between various clusters. Table 3 and Figure 5 indicate that a limited group of authors have both a high number of publications and a high citation count in the field of HRTV. The work of these highly influential authors tends to be more visible and frequently cited. Their research findings can significantly drive the development of the field. Although each of these authors possesses deep professional attainments in the field, they are fully capable of jointly producing more high-quality papers and scientific research results through enhanced cooperation and communication among themselves, thus promoting the further development of the field.

The 82 articles included in this study cited a total of 2,236 references. As shown in Table 4, the article by McMullan et al. (2012) featured prominently in terms of the number of co-citations, which strongly suggests that this paper’s research value and impact in the field of HRTV are extremely prominent. By applying VOSviewer for co-cited literature analysis, we set a minimum value of 5 for co-cited literature and found that 97 articles reached this threshold. As presented in Figure 6A, the figure demonstrates a reference network consisting of three different clusters. Thirteen major sub-themes related to HRTV were identified using the reference clustering feature of CiteSpace, as shown in Figure 6B. Based on the analyzed data, we can see that the Modularity Q is as high as 0.7825 (>0.3), and the weighted mean Silhouette S reaches 0.8797 (>0.7), both of which are high. The clustering structure is clear and significant in the co-cited cluster analysis, and the clustering results are highly convincing. The Modularity Q and the weighted mean Silhouette S demonstrate excellent clustering results. Citation explosion depicts the phenomenon of certain keywords suddenly emerging or the citation frequency climbing dramatically within a short period, which becomes a key indicator and a significant manifestation of the evolution of research hotspots over time. As shown in Figure 6C, this figure depicts the top 10 documents with the strongest citation explosion. “Heartland Virus Epidemiology, Vector Association, and Disease Potential” was the strongest citation outbreak in 2018, with an intensity of 8.32, reflecting the importance of this article to the HRTV field. This literature provides a more detailed assessment of the natural transmission cycle of HRTV, and it utilizes the dual strategy of serological surveys and enhanced HRTV disease surveillance to provide in-depth insights into the transmission mechanisms and dynamics of HRTV, thereby more accurately assessing the potential risk it poses to human health. These efforts have provided a valuable scientific basis for the development of effective HRTV prevention and control strategies and have made a notable contribution in this area.

The 82 articles included in this study were published in 33 journals. As shown in Table 5, among the top 10 published journals in HRTV, the top 3 journals were Emerging Infectious Diseases (IF = 7.2), Journal of Virology (IF = 4.0), and American Journal of Tropical Medicine and Hygiene (IF = 1.9), with 12, 9, and 6 articles published, respectively. Journal of Virology (IF = 4.0), Emerging Infectious Diseases (IF = 7.2), and American Journal of Tropical Medicine and Hygiene (IF = 1.9) were the top 3 cited journals. Figure 7A presents an overview of the density visualization of journals publishing literature in the field of HRTV, where the shade of the colors directly maps the amount of literature on HRTV published by the journal. Specifically, darker colors indicate that the journal is more prolific in publishing literature in this field. The three journals that contributed the most to the field were the Emerging Infectious Diseases, the Journal of Virology, and the American Journal of Tropical Medicine and Hygiene. Figure 7B shows the trends in publication volume related to HRTV in five different journals from 2013 to 2024. Emerging Infectious Diseases and the Journal of Virology have been important in the HRTV-related field for decades. Figure 7C is a biplot overlay of HRTV research journals. The cluster positioned on the left signifies the group of journals engaging in citations, whereas the cluster situated on the right encapsulates the collection of journals that are being cited. The citing journals are mainly concentrated in one field: Molecular, Biology, Immunology. The cited journals are mainly concentrated in three fields: (1) Molecular, Biology, Genetics; (2) Health, Nursing, Medicine; (3) Veterinary, Animal, Parasitology. Figures 7A,B show that most articles in the field of HRTV are concentrated in specific journals, such as “Emerging Infectious Diseases” and the “Journal of Virology.” These journals are noted for their high professionalism and authority in this area, ensuring the quality and academic rigor of the articles they publish. Consequently, they are often the preferred choice for authors in this field. Furthermore, HRTV research is interdisciplinary, encompassing medical, biological, and chemical aspects, and its advancement relies on the development of related disciplines and multidisciplinary collaboration. Compared to similar viruses like SFTSV, (Zhang and Zhang, 2024) HRTV research is still in its nascent stages, with research hotspots needing to transition from exploring basic technology to applying cutting-edge technology.

The keyword refinement accurately summarizes a paper’s core content and essence, and the keyword co-occurrence analysis can be used to identify the research hotspots in HRTV-related fields. The most common keyword is “Heartland virus” (Table 6). The keywords that exhibited the greatest centrality were “Heartland virus” and “identification,” while other keywords with higher centrality included “thrombocytopenia syndrome virus,” “hemorrhagic fever,” and “severe fever” (Table 7). Figure 8A shows the overlay visualization of the keywords using VOSviewer. The node size represents the average frequency of the keyword per year; the larger the node, the higher the average annual frequency of the keyword. The four colors, from dark to light, represent the time order of the keywords from first to last; the darker the color, the earlier the year the keyword appears. The darker the color, the earlier the year in which the keyword appeared. It can be seen that the keywords with the highest average annual frequency in recent years are “Heartland virus” and “severe fever.” Figure 8B shows the keyword co-occurrence map produced by CiteSpace; each node consists of different colored annual rings, where the larger the node means, the higher the total frequency of the keyword, and the shades and thicknesses of the annual rings represent the early and late time of the occurrence and the frequency of the corresponding year, respectively. From the figure, it can be seen that “Heartland virus” and “severe fever” are the focus of HRTV research. Cluster analysis using CiteSpace keywords resulted in 9 clusters with a Modularity Q of 0.5689 and a weighted mean Silhouette S value of 0.8719, which resulted in a significant cluster structure and credible clustering results (Figure 8C). In the timeline visualization (Figure 8D), the keywords of the nine clusters were depicted along the horizontal timeline, which depicted the research pulse and developmental dynamics in the field of HRTV as well as the diagnostic methods, risk factors, pathogen transmission routes related to HRTV, and the potential interconnections among them between 2013 and 2024.