This study has shown an increase in the number of publications on leishmaniasis over the 1945-2010 period, which seems to be more pronounced than that observed in other neglected tropical diseases, such as American trypanosomiasis or leprosy [17
] and global tropical medicine [12
]. Moreover, scientific publications on leprosy have experienced a reduced trend since the turn of the century [17
]. This is probably related to different causes. First, the increase in estimating the prevalence of leishmaniasis seen in recent years [1
]. Secondly, greater social awareness, including by the pharmaceutical industry and philanthropic world that has opened to these diseases, including the Bill & Melinda Gates Foundation and other non-governmental organizations. Thirdly, we do not doubt the important steps taken by the World Health Organization (WHO) for inclusion in its health agenda an initiative to control the disease in endemic countries [2
]. Fourthly, the therapeutic discoveries of drugs over the past 15 years (amphotericine B liposomic, miltefosine and paromomycin), or diagnosis procedures attract much attention on leishmaniasis [2
]. Therefore, the continuous interest in the field and the incorporation of new journals in PubMed may have contributed to this linear increase. In this sense, two outstanding open access journals devoted to the study of Tropical Diseases have been launched in recent years: PLoS Neglected Tropical Diseases
, started in 2007; and Parasites & Vectors
, established in 2008. Even though they do not appear in long-term bibliometric analyses, they are playing a major role in the area with a strong research activity.
Although the main language of leishmaniasis research output is English (82.8%), this language is less common than other bibliometric studies based on PubMed, where 85-90% of its documents are in English [8
]. The other more important languages were French and Portuguese. Leishmaniasis is endemic in North Africa, France and Brazil [1
], which might explain the prevalence of these languages with respect to others. For instance, the geographic distribution of the disease is important with the publication language about the disease [26
]. For this, reviewing the journals in the original language of geographical distribution of the diseases is interesting.
were the most commonly retrieved document type (approximately 90%), similar to other bibliometric studies on NTDs and non-NTDs [8
]. Although controlled trials offer the best evidence for medical intervention efficacy [27
], in this study they represented only 0.3% of the documents, a figure lower than in other fields [8
] and similar to other NTDs [18
Nucleus journals usually contain articles with the highest impact in the area and thus, subscriptions to such journals in indexing and abstracting services would be justified scientifically [10
]. Most top journals publishing on leishmaniasis were from the parasitology
, and tropical medicine
subject categories. The top journal was Transactions of the Royal Society of Tropical Medicine and Hygiene
from the UK, while the American Journal of Tropical Medicine and Hygiene
from the USA was second. Both included the public, environmental and occupational health
and tropical medicine
subject categories. The fourth and seventh journals were Memórias do Instituto Oswaldo Cruz
and Annals of Tropical Medicine and Parasitology
including the parasitology
and tropical medicine
subject categories. The third and fifth journals were Molecular and Biochemical Parasitology
and Experimental Parasitology
; both journals publish basic aspects of parasitology. The sixth and eighth journals were the Journal of Immunology
and Infection and Immunology
, respectively, both related to immunology.
USA was the leading country in publication output on leishmaniasis, like that which has also been described in other biomedical fields [8
], although the number of leishmaniasis cases there is less than in South America. Brazil, a country with a high prevalence of leishmaniasis, led scientific production on leishmaniasis in Latin America. This can be attributed to the number of researchers and development of the country’s scientific system, which has become the principal scientific reference for South America [20
]. India, a country with a high prevalence of leishmaniasis, mainly in the state of Bihar [1
], was the third country, and it led scientific production on leishmaniasis in Asia.
Leishmaniasis research in small countries, after adjusting for population, was led by Israel and Switzerland. Swiss publications came mainly from the WHO, especially from the Programmes of Prevention and Control of Leishmaniasis
and Drugs for Neglected Diseases initiative
]. Although institutions of the United Nations are not attributed to any country, the WHO is physical located in Geneva, Switzerland. The leading countries after adjusting for GDP were low- or middle-income countries with a higher prevalence of leishmaniasis, like Nepal, Tunisia, Kenya, Ethiopia and Sudan. When adjusting economic and demographic aspects (GNI per capita), the leading countries were low- and middle-income countries with a higher prevalence of leishmaniasis and overpopulated, like India, Ethiopia, Pakistan and Brazil [24
In visceral leishmaniasis, the leading countries were India and Brazil, both with high prevalence. Spain was the third country, probably influenced by the association of visceral leishmaniasis and HIV infection [32
]. In cutaneous leishmaniasis, Brazil, USA and Germany topped the rankings.
Europe was the world’s leading area in scientific production on leishmaniasis. Although the disease load in Europe constitutes less than 0.2% of global cases of leishmaniasis, there are people with Leishmania
infections living there, especially along the Mediterranean Coast [1
]. Europe has a long tradition of agencies and institutions implementing research and health programmes in tropical medicine and parasitology [33
], in addition to networks of scientists operating in these countries with other countries where leishmaniasis is endemic. Latin America was the world’s second-leading area in scientific production on leishmaniasis. Its relative contribution increased to 26.8% in the last 5-year study period. This is because of a high prevalence of this disease on this continent, the long lasting interest in this field in the Latin American countries, especially Brazil [19
], and the incorporation of new Latin American journals in PubMed. North America was the world’s third area. However, its relative contribution decreased to 14.4% in the 2006-2010 period. A decreased contribution from North America also occurred in other biomedical fields such as tuberculosis [8
]. The absolute and relative contribution from Asia increased in our study from 105 (8.8%) in 1986-1990 to 899 (20.5%) in the 2006-2010 period. This increasing Asian contribution has been seen in other scientific fields because of their improving research, including many leishmaniasis clinical trials conducted on the Indian subcontinent, and increasing incorporation of new Asians journals in PubMed [38
]. The relative contribution from North Africa and the Middle East, Africa and Oceania was similar during all 5-year periods.
Europe and North America are at the vanguard of scientific excellence and development, and should increase their collaboration with scientific publications in developing countries, especially from North Africa and the Middle East and Africa in the field of leishmaniasis. Europe was the world leader in visceral leishmaniasis, followed by Asia. However, Latin America and the Caribbean ranked first in cutaneous, mucocutaneous and diffuse cutaneous leishmaniasis.
PubMed and the Science Citation Index
were found to be the most suitable databases for searching and retrieving references for bibliometric studies [8
]. We used the PubMed database because it is easily accessible and widely used, it uses a controlled vocabulary for indexing and recovering documents [8
], and the index journal in Medline has a certain criteria for quality [16
]. However, the method we used may have several limitations that have been explained in other publications [18
]. For example, the database mainly includes journals published in English, and journals in other languages are less likely to be found on PubMed. However, this database has more non-English journals than the Web of Science database [41
]. Another limitation is that in PubMed, only the address of the first author appears in the journal articles, whereas in letters
, the address field is not recorded, and the address has only been included since 1986 and systematically ever since. For instance, estimating the quantity of articles resulting from multinational collaborations was not possible. This may cause some problems when estimating research productivity from developing countries that work in collaboration with scientists from a developed country. Even though the bibliometric methodology used may present some limitations and the results could, in some way, be biased [9
], we believe that this study represents a useful tool for scientists and public health policy makers in planning and organizing research in the field of leishmaniasis. We should emphasize that other authors should employ the method we used to find research production, so that our results may be comparable to others in the future.