Scientific literature on neglected tropical diseases: a bibliometric analysis

Neglected tropical diseases (NTDs) are a group of diseases mainly affecting people in low- and middle-income Countries. The aim of this study was to perform a bibliometric analysis of the scientific literature on NTDs. Using the MeSH database, we quantified the number of publications on MEDLINE targeting each NTD, which were published from 1 January 1999 to 31 January 2019. In order to weight the number of publications targeting a given NTD according to the total number of publications/year, we calculated a Yearly Publication Index (YPI) for each NTD/year. Linear regression was used to determine if there was a significant increase or decrease of YPI over time. In order to weight the number of publications according to disease burden (expressed in Disability-adjusted life years - DALYs) we calculated a DALYs-weighted Publication Index (DWPI) for each NTD. The highest absolute number of publications focused on leishmaniasis, dengue and Chagas disease; the lowest on tungiasis, dracunculiasis, chromoblastomycosis and yaws. The number of publications significantly increased for chikungunya, chromoblastomycosis, dengue, leishmaniasis, snakebite envenoming, and yaws. It significantly decreased for ascariasis, cysticercosis, echinococcosis, leprosy, lymphatic filariasis, mycetoma, onchocerciasis. Leprosy had the highest DWPI (i.e. the highest number of publication considering the burden of disease), followed by Chagas disease; lymphatic filariasis had the lowest, followed by onchocerciasis. Overall, lymphatic filariasis, onchocerciasis and ascariasis presented the worst scenario, with both very few publications compared with their disease burden and a decreasing number of publications.