Mapping Scientific Research on Rare Diseases in African Portuguese-Speaking Countries and East Timor: A Bibliometric Study

Rare diseases represent a significant public health challenge worldwide. Yet, scientific production on this topic remains limited in many low- and middle-income countries. This study maps rare disease research involving authors affiliated with African Portuguese-speaking countries—Angola, Mozambique, Cape Verde, Guinea-Bissau, and São Tomé and Príncipe —as well as East Timor. A bibliometric review was conducted using PubMed, Scopus, Web of Science, LILACS, and SciELO, without language or publication year restrictions. Articles were included if they addressed rare diseases and featured at least one author affiliated with a PALOP country or Timor-Leste. Descriptive statistics, citation analysis, and co-authorship patterns were examined using manual extraction and data visualization tools. A total of 26 articles published between 2011 and 2024 were included. The majority were case reports, with limited use of multicenter or observational designs. Most articles involved international co-authorship (85%), with Portugal, Brazil, and the USA as the most frequent partners. Mozambique and Angola were the only PALOP countries represented. Only 38.5% of the articles listed a corresponding author from the region. Citation counts were highly skewed, with the most cited articles linked to international consortia. Few articles disclosed participation in formal research networks or national funding sources. This study reveals gaps and opportunities in rare disease research across Lusophone countries. Despite low publication volume and limited regional integration, the presence of PALOP-affiliated researchers in global initiatives highlights the potential for collaboration in Lusophone countries.