Dengue research: a bibliometric analysis of worldwide and Arab publications during 1872–2015

Background Dengue is an important emerging and re-emerging arboviral infection globally as a rapidly growing and widespread public health problem, with transmission occurring in more than 128 countries in Asia, Americas, southeast Africa, western Pacific, and eastern Mediterranean regions. Therefore, the aim of this study was to characterize and quantify the scientific output of dengue research in Arab countries relative to that worldwide by using a bibliometric analysis. Methods The standardized search approach based on the use of the the keyword “dengue” in the title, abstract, and keyword field was used to get research output related to dengue at a global level. All data related to dengue were collected from the past to December 31, 2015. Results A total of 19,581 dengue-related documents identified in the Scopus database. The results show that the study of dengue exhibits an overall upward trend from 1872 to 2015 with peak publications in 2014. The leading countries in dengue research were the USA (4,709; 24.05 %), India (1,942; 9.92 %), Brazil (1,530; 7.81 %), Thailand (1,260; 6.43 %), the UK (1,129; 5.77 %), and France (1,087; 5.55 %). Only 226 (1.16 % of the overall global research effort in the dengue field) articles were published from the Arab region. The total number of citations for all publications was 352,710, with an average of 18.0 citations per publication. Furthermore, the h-index for all extracted data related to dengue research was 186. Kingdom of Saudi Arabia (KSA) was the most productive country in Arab region with 102 documents representing 45.1 %. Furthermore, the h-index for all extracted data related to dengue research was 27. The USA was Arab’s most main cooperative partner (46, 20.4 %), followed by India (36, 15.9 %). Conclusions The amount of literature related to dengue research has considerably increased over the last decade. This bibliometric analysis has demonstrated the leading role that the USA, India, Brazil, Thailand, the UK, and France play in dengue research. The Arab world produced fewer publications related to dengue with lower quality than other world countries.


Background
Dengue is an important emerging and re-emerging arboviral infection globally as a rapidly growing and widespread public health problem, with transmission occurring in more than 128 countries in Asia, Americas, southeast Africa, western Pacific, and eastern Mediterranean regions [1,2]. It is estimated that each year, around 390 million people are infected with dengue, of which 96 million develop any level of disease severity [3], leading to approximately 21,000 deaths [3,4]. The clinical spectrum of dengue infection can vary from asymptomatic to severe manifestations of haemorrhagic fever, hypovolaemic shock, and organ impairment [1,5]. However, some cases are often accompanied with symptoms such as sore throat, arthralgia, febrile illness anorexia, headaches, myalgia, and a macular skin rash [6][7][8].
Many research fields use bibliometric analysis to assess the scientific research patterns of publication year, document type, countries, journal, impact factors (IF), institution, number of citations, h-index, and international collaboration in global trends studies of specific fields [28][29][30][31][32][33][34]. It is thought that health research productivity from Arab region is still lagging far behind compared to worldwide publishing production [35][36][37]. Although the research output in some world regions such as India, China, and Brazil has been evaluated for dengue research [38][39][40], no study has focused on the scientific output of dengue research in Arab countries relative to that worldwide. Therefore, the aim of this study was to characterize and quantify the scientific output of dengue research in Arab countries relative to that worldwide by using a bibliometric analysis.

Data source
This bibliometric study was built on April 2, 2016 based on the online version of Scopus database, which was developed by Elsevier. Note that there are several other databases that could be used in the bibliometric analysis including Web of Science, Google Scholar, and PubMed. However, this study only focuses on the data of Scopus which are assumed to be of the largest database [42,43].

Search strategy
For bibliometric analysis, the standardized search approach based on the use of the the keyword "dengue" in the title, abstract, and keyword field was used to get research output related to dengue at a global level. All data related to dengue were collected from the past to December 31, 2015. For further analysis, data retrieved from Scopus were limited to Arab countries, including 22 countries (The Kingdom of Saudi Arabia (KSA), Tunisia, Egypt, Morocco, Algeria, Oman, Iraq, Jordan, United Arab Emirates, Syrian Arab Republic, Lebanon, Qatar, Palestine, Libyan Arab Jamahiriya, Kuwait, Bahrain, Sudan, Yemen, Mauritania, Somalia, Djibouti, and Comoros). The analysed bibliometric indicators included publication year, document type, language of publications, publication distribution by countries/ territories, journal, impact factors (IF), institution, number of citations, h-index, and international collaboration. As the 2016 data did not represent a complete year, such data were excluded from the analysis. Furthermore, items coded as errata were excluded from further analysis.

Ethical issues
As there were no humans involved in this study, research using existing data from secondary sources is considered it to be exempt from the institutional review board (IRB) approval process.

Data analysis
Data downloaded from Scopus were and organized into Microsoft Excel 2007 and then be used for further analysis to get the ten top-ranked for most bibliometric indicators and they were appeared in descending order from 1 to 10 using the standard competition ranking (SCR); (1-2-2-4 rule). Descriptive statistics were used to determine the frequency, percentage, sum, and average. The h-index and IF had been used to assess the quality and quantity of research output. The h-index was introduced in bibliometric analysis by Hirsch [44] to illustrate the scientific output of a country, organization, researcher, etc. Therefore, the h-index covers both the quantity (number of publications) and the impact (number of citations) [45][46][47]. The impact factor for journals was obtained from the Journal Citation Reports (JCR) © Ranking: 2014 [48].

Results
There were a total of 19,581 dengue-related documents identified in the Scopus database that were published between 1872 and 2015. These documents were published from the across 12 document types. There were 14,434 paper articles comprising 73.71 % of the total production, followed by reviews (10.26 %), and letters (4.31 %). Other document types such as editorial materials, proceedings papers, notes, and book reviews covered approximately 11.73 % of the published literature.  Table 1 illustrates the top 10 countries in terms of absolute research production, their h-index and number of publication from international collaboration. The leading countries in dengue research were the USA (4,709; 24.05 %), India (1,942; 9.92 %), Brazil (1,530; 7.81 %), Thailand (1,260; 6.43 %), the UK (1,129; 5.77 %), and France (1,087; 5.55 %). As expected, most publications related to dengue were carried out in North America, Europe, South Asia, and Latin America. This bibliometric analysis has demonstrated the leading role that the USA, India, Brazil, Thailand, the UK, and France play in dengue research (Table 1).
In case of number of publications with multinational researchers, France tops the list with 147 countries, followed by the USA with 146 countries, and the UK with 126 countries. Furthermore, the UK (71.12 %) had the highest percentage of documents in collaboration, followed by 56.03 % for France, 52.54 % for Thailand, and 52.11 % for India from the total number of documents for each country. The total number of citations for all publications was 352,710, with an average of 18.0 citations per publication. Furthermore, the h-index for all extracted data related to dengue research was 186. The best h-index value is achieved by the USA (159) followed by the UK (92), Thailand (78), and France (76); ( Table 1).
The Arab world produced fewer publications related to dengue. Only 226 (1.16 % of the overall global research effort in the dengue field) articles were published from the Arab region across 7 document types.  There were 187 paper articles comprising 82.7 % of the total production, followed by reviews (7.5 %), and letters (3.1 %). Editorial materials, proceedings papers, notes, and book reviews covered approximately 6.7 % of the published literature. The total publications per year are demonstrated in Fig. 1. The results from Arab world show that the study of dengue exhibits an overall upward trend from 1968 to 2015 with peak publications in 2015.
The top 10 most productive journals based on the number of publication at global level were analyzed ( Table 3)     The impact factor was reported according to the journal citation reports (JCR) 2014 field of dengue research at Arab level are shown in Table 6 [59][60][61][62][63][64][65][66][67]. Table 7

Discussion
In this study, I employed a bibliometric approach to analyse the research trends of dengue at global level and in the Arab world. The publications on dengue presented a solid growth with an increasing number of articles. This bibliometric analysis has demonstrated the leading role that the USA, India, Brazil, Thailand, the UK, and France play in dengue research. USA was the leading country in research output on dengue. Although the number of dengue outbreaks in the USA there is less than in other countries [3], these findings are in line with those of previous studies, especially those in other infectious fields [17,18,23,24]. Overall, Brazil, India, Thailand, Singapore, Malaysia, Japan, and Australia, accounted for most of the dengue research activity at global level. A possible explanation for these results may be due to high prevalence of dengue in these countries which faced many outbreaks [68][69][70][71][72][73][74]. Another possible explanation for these findings could be recognized to the number of researchers and development of scientific research system in these countries. However, only KSA and Egypt among Arab countries ranked among the first 50 countries in terms of worldwide contribution to research productivity in the dengue. Among the Arab countries, KSA and Egypt achieved the top rank. High national incomes and large populations and are the most probable reasons for this achievement. These results are consistent with data obtained from previous studies, especially those in medical fields [29,31,37,[75][76][77][78][79][80][81].
Publications from Arab world received lower citation rate than that from the world; because researchers from Arab world have published their work in scientific journals with slightly lower citation rates or without IF such as Dengue Bulletin, Eastern Mediterranean Health Journal, Journal of Infection and Public Health; and Biosciences Biotechnology Research Asia. These findings are in line with those of previous studies [75,77,78,82]. The current study designed to recognize scientific collaborations between Arab countries and non-Arab countries. The USA was Arab's most main cooperative partner. These results match those observed in earlier studies in the field of ophthalmology [77], and in the field of substance use disorders [83]. In addition, country with highest collaboration with researchers in India in dengue research was USA [84]. The investigation of publication output recognized several successful cases of researcher collaboration between Arab countries and Western Europe (France and Italy) and the Asiatic region (i.e. India and Malaysia). At the global level, the USA got a leadership position in dengue research with the largest publication followed by India [85]. Dengue disease has no borders and prevention; eradication and control of this disease requires worldwide efforts. Health-care systems in the Arab region are low priority in national spending plans and are perceived as being non-productive [86,87]. Arab region has been the source of most fatal infectious diseases (e.g. Middle East respiratory syndrome coronavirus, West Nile Virus, and leishmaniasis), and they should heavily participate and cooperate in research in order to combat them [75]. The Arab countries have cooperated with 87 countries in the field of dengue research.
The current study is the first to assess the quantity and quality of global research effort in the dengue field worldwide and from Arab world. The most important limitation  lies in the fact that the Scopus database only was used to extract data related to dengue. Articles published in non Scopus-cited journals were not studied, but it is interesting to note that the Scopus has several advantages more than others, as it is the largest abstract and citation database of peer-reviewed literature [42,43,88].

Conclusions
Based on 19,581 dengue-related documents from Scopus, this bibliometric analysis provided an overview of research in dengue and recognized some noteworthy issues in this field during the search period. The amount of literature related to dengue research has considerably increased over the last decade. This bibliometric analysis has demonstrated the leading role that the USA, India, Brazil, Thailand, the UK, and France play in dengue research. The Arab world produced fewer publications related to dengue with lower quality than other world countries. The result shows that KSA plays a leading role in dengue research through the number of publications with international collaboration in Arab world. The USA was Arab's leading internationally collaborative country, followed by India, France and Malaysia. Multinational collaboration can help dengue research get more international attention. More research is required to recognize what societal and individual level factors were involved in raising such a remarkable increase in quantity of dengue research in the last decade. Arab researchers especially in countries who at risk with dengue disease need to take the lead and promote research projects in this field of infection as an important public health concern.
Abbreviations IF: impact factor; IRB: institutional review board; JCR: Journal citation reports; KSA: Kingdom of Saudi Arabia; SCR: Standard competition ranking.

Competing interests
The author declares that he has no competing interests.
Authors' contributions SZ conceptualized, designed the methodology, and implemented the study, and did the analysis and write-up. Then read, and approved the final manuscript.

Funding sources
No funding was received for writing this study.