30 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 70: 30-39, January-December 2022 (Published Jan. 27, 2022)

Bibliometrics of Sudanese scientific publications:

Subjects, institutions, collaboration, citation and recommendations

Moawia Mohammed Ali Elhassan1; https://orcid.org/0000-0002-0595-5186

Julián Monge-Nájera2; https://orcid.org/0000-0001-7764-2966

Yuh-Shan Ho3*; https://orcid.org/0000-0002-2557-8736

1. University of Gezira, Department of Oncology, National Cancer Institute, PO Box 20, Wad Madani, Sudan;

moawia2@gmail.com

2. Universidad Estatal a Distancia, Laboratorio de Ecología Urbana, Vicerrectoría de Investigación, 2050 San José, Costa

Rica; julianmonge@gmail.com

3. Asia University, Trend Research Centre, No. 500 Lioufeng Road, Wufeng, Taichung 41354, Taiwan;

ysho@asia.edu.tw (*Correspondence)

Received 06-IX-2021. Corrected 01-XI-2021. Accepted 15-I-2022.

ABSTRACT

Introduction: Sudan is the third largest country in Africa and has rich reserves of petroleum and other ground

resources, but its per capita Gross Domestic Product is only $808 and researchers work in insufficient institu-

tional facilities and with little funding. Previous studies about its scientific productivity have been limited to

specific subjects and relatively short periods, with no large analyses until now.

Objective: To analyze the scientific output of Sudan in depth, considering all research areas and several decades

of scientific activity.

Methods: We retrieved the documents with “Sudan” in field country in the Science Citation Index Expanded

for the period 1900-2019.

Results: We retrieved over 9 000 publications and found that most were articles; that citation was higher for

review articles and book chapters, and that this index mostly covered articles in English. Beginning in 1972,

the number of publications in this database has increased rapidly. The citation lifespan indicates slow growth

in the Sudanese scientific literature, and collaboration is frequent both nationally and internationally, possibly

because the scarce resources make collaboration almost compulsory. Most external collaboration is done with

Saudi Arabia but citation is higher for articles resulting from international megaprojects, led by Europe and the

USA, in which Sudanese researchers play secondary roles. Research focusses on applied technological subjects

with little innovation value. Women play a smaller role in Sudanese science.

Conclusions: Our recommendations for Sudanese science include increasing the number of women in leading

research positions; providing funding directly to researchers (i.e., bypassing bureaucratic bodies); increasing

basic research to avoid stagnation; training Sudanese researchers for leading positions; and identifying specific

research areas where Sudan can lead in its region.

Key words: tropical science; scientific productivity; science in Sub-Saharan countries; role of science in

research and development.

https://doi.org/10.15517/rev.biol.trop..v70i1.47392

OTHERS / SPECIAL ARTICLE

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 70: 30-39, January-December 2022 (Published Jan. 27, 2022)

With 1 882 000 km2 and 45 million inhab-

itants, Sudan is the third largest country in

Africa. Despite its rich reserves of petroleum,

natural gas, gold and other ground resources,

Sudan has a per capita Gross Domestic Product

of only $ 808 and a low human development

index, with extended poverty and social insta-

bility (World Bank, 2021).

The oldest study of Sudanese science

seems to be one by Johann Mouton about social

science in sub-Saharan Africa; it found that

Sudanese scientists, like those in other coun-

tries in the region, suffered from little govern-

ment support and poor institutional facilities,

but it also reported that researchers continued

to work and publish despite those obstacles

(Mouton, 2010); this was the panorama a

decade ago.

A couple years later, other studies con-

cluded that insufficient financial and human

resources, weak cooperation between univer-

sities and the productive sector, lack of man-

agement and organization ability, and a poor

research and development culture, kept Sudan

behind other developing countries, prevent-

ing the development of local technologies,

the adaptation of imported technologies, and

economic development in general (Nour, 2012;

Nour, 2013).

Another study from the time, which cov-

ered the older period 1982-2009, considered

the impact of human capital on economic

growth, and found a need to upgrade technol-

ogy and improve the quality of education and

health, all factors affecting economic growth

and human development in Sudan (Arabi &

Abdalla, 2013).

In the field of gender equality in science,

it was recently found that, while Sudanese

women represent up to 80 % of undergraduates

in agriculture and medical fields, they still are

a minority in teaching and leading positions

(Elhag & Abdelmawla, 2020). Despite all these

problems, the number of educational institu-

tions and students has grown rapidly in recent

years and there is hope that new funds will

improve research and linkage with industry

(Beshir et al., 2020).

Despite the existence of previous studies

on isolated sections, there are no scientometrics

studies that consider all of Sudanese science in

depth and for a prolonged period of time, so the

present report is the first to consider over half

a century of scientific activity in the country,

including publication types, document char-

acteristics, journals, subjects, authors, institu-

tions, international collaboration and citation

trends over time. Our study, however, is only

valid for Sudanese research covered by a par-

ticular American database and this should be

borne in mind when applying our results to the

improvement of science in Sudan.

MATERIALS AND METHODS

We used the Science Citation Index

Expanded (“SCI-EXPANDED”), Web of Sci-

ence Core Collection (updated January 22,

2021). We have our analysis system built

around this database and for that reason we

do not use others, like Scopus. Additionally,

we feel that this database is highly selective

and prefer to leave other sources for additional

work from other teams. We did an advanced

search using the word “Sudan” in field country

(CU) limited to the period 1900-2019. Data

were manually reviewed by the first author,

who is familiar with Sudanese science, and

processed by Excel. The journal impact fac-

tors (IF2019) were extracted from the 2019

Journal Citation Reports (JCR). This study is

part of a series on the scientific output of tropi-

cal countries and all methodological details

have already been published in Calahorrano

et al. (2020). We chose journal articles (7 539

articles) for further analysis because they rep-

resented the majority of document types, as

well as whole research ideas and results (Ho et

al., 2010). We also searched for relationships

between article subject and number of journals

in Web of Science categories. The Web of

Science can classify a document in more than

one type, for example, 120 proceedings papers

were also classified as articles, and thus the

sum of percentages can be higher than 100

% (Usman & Ho, 2020). Note: South Sudan

32 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 70: 30-39, January-December 2022 (Published Jan. 27, 2022)

seceded from Sudan in 2011, and this study

does not include a small number of documents

formally published with “South Sudan” in the

country label.

RESULTS

We retrieved over 9 000 publications that

had at least one coauthor with an institutional

address in Sudan. Note: additional figures and

tables appear as appendices.

Document type, citation, authorship and

language: The database records 15 docu-

ment types and 9 230 publications from Sudan

for the period 1923-2019. The majority were

articles (82 %), followed distantly by meeting

abstracts (8.9 %) (Table 1). The maximal total

citations per publication value (CPP2019) was

for reviews, with 25, which was 1.5 times the

citation rate of articles. The mean number of

authors per publication (APP) was 25 in cor-

rections, 18 in data papers, and 11 in reprints.

The mean number of coauthors was 18 in data

papers, 12 in book chapters, and 11 in reprints

(Table 1). Documents in this particular database

were published in a total of six languages but

99.7 % were in English, followed distantly by

German (0.17 %), French (0.08 %), and others

(Appendix 1).

Trends in time, output and citation lifes-

pan: This database has fewer publications from

Sudan before 1972 (probably these existed but

were not included in this database), but there is

a sharp increase after 2007 to reach 570 articles

in 2019 (Fig. 1; Appendix 2). Despite the fact

that probably many Sudanese publications are

missing from this database for first half of

the twentieth century, there were some small

citation picks in that period, but the highest

CPP2019 values were for articles published in

1955 and 2012 (79 and 72 citations, respec-

tively) (Fig. 1).

The CPP increased more rapidly in the

first two years after publication. The initial

value for citations per publication was 0.41 and

reached a peak with 2.22 citations per publica-

tion in the 3rd full year, for a total citation lifes-

pan of over sixty years (Fig. 2; Appendix 3).

Collaboration patterns, countries and

institutions: There were 5 015 internationally

TABLE 1

Characteristics of document type (percentage from a total of 9 230 publications)

Document type TP %AU APP Median TC2019 CPP2019

Article 7 539 82 53 897 7.1 4.0 120 666 16

Meeting abstract 817 8.9 4 290 5.3 4.0 112 0.14

Note 269 2.9 689 2.6 2.0 1 827 6.8

Review 267 2.9 2 332 8.7 4.0 6 598 25

Letter 186 2.0 651 3.5 2.0 769 4.1

Proceedings paper 120 1.3 649 5.4 5.0 2 207 18

Editorial material 105 1.1 583 5.6 3.0 619 5.9

Correction 21 0.23 520 25 6.0 4 0.19

News item 13 0.14 54 4.2 5 57 4.4

Book chapter 7 0.076 66 9.4 12 81 12

Discussion 7 0.076 24 3.4 1.0 6 0.86

Book review 5 0.054 5 1.0 1.0 0 0

Retracted publication 2 0.022 7 3.5 3.5 25 13

Data paper 1 0.011 18 18 18 0 0

Reprint 1 0.011 11 11 11 0 0

TP: number of publications; AU: number of authors; APP: number of authors per publication; TC2019: the total number of

citations from Web of Science Core Collection since publication year to the end of 2019; CPP2019: mean number of citations

(TC2019) per publication (TP).

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 70: 30-39, January-December 2022 (Published Jan. 27, 2022)

Fig. 1. Number of Sudan articles and citations per publication by year.

collaborative articles and 2 524 Sudan-indepen-

dent articles; of these 630 were collaborations

among Sudanese institutions (Appendix 4).

Sudanese researchers collaborated the most

with Saudi Arabia (898 publications) and col-

laboration is increasing rapidly (Appendix 5).

Nevertheless, China had the most first-author

and corresponding-author articles (6.4 % and

6.6 %, respectively). Articles with France,

Sweden, Japan, and Kenya had more citations

per publication (the lowest values were for

papers co-published with Saudi Arabia, Malay-

sia, and Egypt) (Appendix 4, Appendix 6).

A total of 5 645 were inter-institutionally

collaborative articles coproduced by Sudanese

institutions (CP), only 1 894 articles were

single-institution articles (IP) (Appendix 4).

The University of Khartoum ranked top

in all indicators, with TP of 3 687 articles,

IP of 1 079 articles (57 % of single institute

articles), CP of 2 608 articles (46 % of inter-

institutionally collaborative articles), FP of

1 896 articles (25 % of first-author articles),

RP of 1 755 articles (25 % of corresponding-

author articles), and SP of 396 articles (51 %

of single-author articles). The Federal Ministry

of Health published 281 articles, including 15

single-institute articles and 11 single-author

articles, and it had the highest CPP2019 of 68

(Appendix 7).

Institutionally, Sudan collaborated the

most with the King Saud University in Saudi

Arabia (257 articles) followed by the Univer-

sity of Putra Malaysia in Malaysia, the London

34 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 70: 30-39, January-December 2022 (Published Jan. 27, 2022)

School of Hygiene & Tropical Medicine in

the UK, and the University of Copenhagen in

Denmark. The King Saud University also pub-

lished the most first-author and corresponding-

author articles, with 112 and 139 articles,

respectively. The University of Edinburgh in

the UK and the University of Cape Town in

South Africa had high CPP2019 values (315

and 311, respectively).

Overall, the internationally collaborative

articles had a higher CPP2019 (20), while Sudan

independent articles had a CPP2019 of 8.6 (Fig.

3). Articles published with Sudanese research-

ers as first-authors, or corresponding-authors,

had lower CPP2019 values: 9.3 and 9.0, respec-

tively. There were no Sudanese researchers

among the first-authors, or the corresponding-

authors, of the most cited articles.

Journals and subjects (Web of Science

categories): Most studies were about tropical

medicine; public, environmental and occupa-

tional health; and veterinary sciences (Table 2;

Appendix 8).

The Sudanese articles were published in

2 185 journals among 173 categories. A total

of 132 articles were published in Transactions

of the Royal Society of Tropical Medicine and

Hygiene, followed by East African Medical

Journal and American Journal of Tropical

Medicine and Hygiene. Comparing the top ten

productive journals, articles published in Amer-

ican Journal of Tropical Medicine and Hygiene

had the highest CPP2019 (32). The journal with

the highest IF2019 of 60.390 was Lancet with 25

articles, followed by Nature (IF2019 = 42.779)

with six articles, and Science (IF2019 = 41.846)

with three articles (Table 3).

Top cited articles: Until 2019, a total

of 104 articles had received at least 100 cita-

tions in this database: 23 of them with first

Fig. 2. Citation life span for Sudan articles.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 70: 30-39, January-December 2022 (Published Jan. 27, 2022)

Fig. 3. Characteristics of publication type and their citations per publication. TP: total articles, NFR: both first and

corresponding-authors are not from Sudan, NR: corresponding-author is not from Sudan, NF: first author is not from Sudan,

IC: internationally collaborative articles, NC: nationally collaborative articles, II: institutional independent articles, CI:

Sudan independent articles, FP: first author is from Sudan, RP: corresponding-author is from Sudan, FR: both first and

corresponding-authors are from Sudan.

TABLE 2

Top 10 Web of Science categories

Web of Science category TP (%) APP CPP2019 No. J

Tropical medicine 806 (11) 6.7 18 23

Public, environmental and occupational health 775 (10) 8.2 18 193

Veterinary sciences 600 (8.0) 3.9 8.4 142

Parasitology 481 (6.4) 7.4 17 39

Infectious diseases 411 (5.5) 18 19 93

Food science and technology 362 (4.8) 4.1 13 139

Agronomy 347 (4.6) 3.5 9.0 91

Plant sciences 320 (4.2) 5.0 16 234

General and internal medicine 300 (4.0) 15 79 165

Pharmacology and pharmacy 295 (3.9) 5.0 14 270

TP: number of publications; APP: number of authors per publication; CPP2019: number of citations per publication (TC2019)/

(TP); No. J: number of journals in a Web of Science category.

36 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 70: 30-39, January-December 2022 (Published Jan. 27, 2022)

author from the USA, 17 from Sudan, and 12

from the UK (19 % with corresponding author

from the USA, 14 % from Sudan and 14 %

from the UK).

Five of the top cited articles were from

international mega-projects with 713 authors

(Naghavi et al., 2015), 679 authors (Vos et

al., 2015), 359 authors (Murray et al., 2012),

355 authors (Vos et al., 2012), and 207 authors

(Lim et al., 2012). Sudan’s article with the

highest TC2019 (191 citations) was “Effects

of algal grazing and aggressive-behavior of

fishes Pomacentrus lividus and Acanthurus

sohal on coral-reef ecology” (Vine, 1974),

whose author, P. J. Vine, had two affilia-

tions: Cambridge Marine Research Laborato-

ries and Suakin Marine Laboratory (Appendix

9). Citation histories of the top ten most cited

articles appear in Appendix 10 and Appendix 3.

Depending on the particular article, they follow

two citation curves, one flat and the other with

a rapid increase shape.

DISCUSSION

The document types published by African

countries have also been reported by other

workers (e.g. Confraria & Godinho, 2015;

Sooryamoorthy, 2018) who, like us, found a

clear domination of articles over other types

of documents, higher citation rates for reviews

and books; the appearance over time of more

complex articles with more coauthors and ref-

erences; as well as the limitation of the Web of

Science and its impact reports to only publica-

tions in English and in large journals (Bah et

al., 2019; Chiware & Becker, 2018; Ho et al.,

2018; Trang et al., 2020). This means that much

relevant information, published in smaller jour-

nals and other languages, is missing in most

scientometrics studies.

TABLE 3

Top ten most productive journals

Journals TP IF2019 Web of Science category APP CPP2019

Transactions of the Royal Society

of Tropical Medicine and Hygiene

132 1.868 Public, environmental and occupational health

Tropical medicine

5.8 26

East African Medical Journal 116 0.221 (IF2001)General and internal medicine 3.1 4.4

American Journal of Tropical

Medicine and Hygiene

102 2.126 Public, environmental and occupational health

Tropical medicine

9.4 32

Annals of Tropical Medicine and

Parasitology

84 1.203 (IF2013)Public, environmental and occupational health

Parasitology

Tropical medicine

4.4 17

PLoS Neglected Tropical Diseases 78 3.885 Infectious diseases

Parasitology

Tropical medicine

11 16

Saudi Medical Journal 76 1.195 General and internal medicine 3.0 4.6

PLoS One 74 2.740 Multidisciplinary sciences 7.8 12

Malaria Journal 73 2.631 Infectious diseases

Parasitology

Tropical medicine

11 18

Food Chemistry 70 6.306 Applied chemistry

Food science and technology

Nutrition and dietetics

3.6 29

Journal of Tropical Medicine and

Hygiene

66 0.916 (IF1997)Public, environmental and occupational health

Tropical medicine

3.3 10

TP (%): rank and the percentage of number of articles; IF2019: journal impact factor in 2019; TC2019: the total number of

citations from Web of Science Core Collection since publication year to the end of 2019; CPP2019: number of citations

(TC2019) per publication (TP).

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 70: 30-39, January-December 2022 (Published Jan. 27, 2022)

On the one hand, the near lack of coverage

of tropical science in the Web of Science before

1980, and the insufficient coverage after that

period, have been reported before (e.g., Monge-

Nájera et al., 2020) and Sudan is not an excep-

tion. On the other hand, a similar increase in

the number of scientific papers from Africa in

the 21st. century has been reported before, and,

interestingly, the African increase rate is faster

than the world average (Confraria & Godinho,

2015). The leading researchers in Africa are

South Africa, Egypt, and Tunisia: Sudan still

has a large gap to fill (Sooryamoorthy, 2018).

The long lifespan in citation of tropical

research reflects the slow pace at which science

advances in poorer countries, and also has been

widely reported before (Bah et al., 2019; Ho et

al., 2018; Trang et al., 2020).

While the central importance of collabo-

ration for productivity and visibility has been

reported for other African countries (Confraria

& Godinho, 2015; Trang et al., 2020), only

large emerging countries like China and Brazil

obtain leading roles for their researchers in

international collaborative projects; smaller

countries are normally excluded from the lead-

ing roles (González-Alcaide et al., 2017), and

this is the case with Sudan as well.

The geographic collaboration pattern, in

which the USA, ex-colonial powers, culturally

similar countries and geographic neighbors are

the main collaborators, has been reported pre-

viously by numerous studies about science in

tropical countries (Bah et al., 2019; Ho et al.,

2018; Sooryamoorthy, 2018; Trang et al., 2020).

The strong level of local collaboration

among Sudanese researchers is unusual for a

developing country: most studies of tropical

countries have found little collaboration among

local scientists (e.g., González-Alcaide et al.,

2017). A hypothetical explanation for our find-

ings is the poor facilities and small funding

that Sudanese researchers face; those condi-

tions make collaboration mandatory if any

significant research is to be done. Additionally,

our hypothesis is consistent with reports from

Ghana, a similar African country, where local

collaboration is important and focusses on basic

fieldwork (Chiware & Becker, 2018; Owusu-

Nimo & Boshoff, 2017; Trang et al., 2020).

As is typical of developing countries,

Ghana focuses research on applied subjects

meant to solve urgent local problems, like

health and food production (Sooryamoorthy,

2018; Trang et al., 2020), an option that also

favors stagnation and reduces innovation.

Interesting exceptions are South Africa and

Vietnam, where technological innovation plays

a larger role in research and leads to better

financial results in the long term (Confraria,

& Godinho 2015; Trang, et al., 2020). The

dispersion of publications among such a large

number of journals is also unusual and deserves

further study (Confraria & Godinho 2015;

Sooryamoorthy, 2018; Trang et al., 2020), we

have no hypothesis for this result.

While other studies of African science

found that well-funded international mega-

projects open the door to powerful journals

with high citation rates in the Web of Science

(Confraria & Godinho, 2015), there are few

that analyze citation trends over time. Those

that did, also found the two basic citation

curves that we report here, some with a surge

and quick fall, and some curves with a flatter

shape (e.g., Monge-Nájera et al., 2020). This

probably reflects fashionable subjects, in which

there are bubbles of production that collapse

when interest in those subjects suddenly falls,

against the rest of subjects that have a relatively

constant level of interest and output.

We have five recommendations for Suda-

nese science: increasing the number of women

in leading research positions (Elhag & Abdel-

mawla, 2020); providing direct funding to

researchers and not funneling it through bureau-

cratic bodies (Owusu-Nimo, & Boshoff, 2017);

increasing basic research to leave behind the

stagnation caused by the “applied research

only” model (Elliott et al., 2015; Owusu-

Nimo & Boshoff, 2017); educating Sudanese

researchers at the highest level, so that they

can occupy leading positions in international

projects (Arabi & Abdalla, 2013; Confraria

& Godinho, 2015; Elliott et al., 2015); and

38 Revista de Biología Tropical, ISSN: 2215-2075 Vol. 70: 30-39, January-December 2022 (Published Jan. 27, 2022)

identifying specific research areas where Sudan

can lead (Sooryamoorthy, 2018).

Ethical statement: the authors declare

that they all agree with this publication and

made significant contributions; that there is no

conflict of interest of any kind; and that we fol-

lowed all pertinent ethical and legal procedures

and requirements. All financial sources are

fully and clearly stated in the acknowledge-

ments section. A signed document has been

filed in the journal archives.

See Digital Appendix

ACKNOWLEDGMENTS

We thank Carolina Seas for her valuable

assistance with manuscript preparation.

RESUMEN

Bibliometría de publicaciones científicas sudanesas:

temas, instituciones, colaboración,

citas y recomendaciones

Introducción: Sudán es el tercer país más grande de África

y tiene ricas reservas de petróleo y otros recursos terrestres,

pero su Producto Interno Bruto per cápita es de solo $ 808 y

los investigadores trabajan en instalaciones institucionales

deficientes y con poca financiación. Los estudios previos

sobre su productividad científica se han limitado a temas

específicos y períodos relativamente cortos.

Objetivo: Analizar la producción científica de Sudán en

profundidad, considerando todas las áreas de investigación

y varias décadas.

Métodos: Recuperamos los documentos con “Sudán”

como país de origen en el Science Citation Index Expanded

para el período 1900-2019.

Resultados: Hallamos más de 9 000 publicaciones y

encontramos que la mayoría eran artículos; que fueron

más citados los artículos de revisión y capítulos de libros,

y que esta base de datos cubría principalmente artículos

en inglés; desde 1972, el número de publicaciones en ella

ha aumentado rápidamente. La vida útil de las citas indica

un crecimiento lento en la literatura científica sudanesa, y

la colaboración es frecuente tanto a nivel nacional como

internacional, posiblemente porque los escasos recursos

hacen que la colaboración sea casi obligatoria. La mayor

parte de la colaboración externa se realiza con Arabia

Saudita, pero hay más citas para los artículos resultantes

de megaproyectos internacionales, dirigidos por Europa y

Estados Unidos, en los cuales los investigadores sudaneses

desempeñan papeles secundarios. La investigación se

centra en temas de tecnología aplicada con poco valor de

innovación.

Conclusiones: Nuestras recomendaciones para la ciencia

sudanesa incluyen aumentar el número de mujeres en

altos puestos; proporcionar financiación directamente a los

investigadores (sin pasar por organismos burocráticos); ir

más allá de la investigación aplicada para evitar el estan-

camiento; capacitar al personal sudanés para puestos de

liderazgo; e identificar áreas de investigación específicas

donde Sudán puede liderar en su región.

Palabras clave: ciencia tropical; productividad científica;

ciencia en los países subsaharianos; papel de la ciencia en

la investigación y el desarrollo.

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