OpenWHO: A Document-Level Parallel Corpus for Health Translation in Low-Resource Languages
Raphael Merx, Hanna Suominen, Trevor Cohn, Ekaterina Vylomova
Abstract
Health machine translation (MT) is a high-stakes domain characterised by widespread deployment and domain-specific vocabulary. However, there is a lack of MT evaluation datasets for low-resource languages in the health domain. To address this gap, we introduce OpenWHO, a document-level parallel corpus of 2,978 documents and 26,824 sentences from the World Health Organization’s e-learning platform. Sourced from expert-authored, professionally translated materials shielded from web-crawling, OpenWHO spans a diverse range of over 20 languages, of which nine are low-resource. Leveraging this new resource, we evaluate modern large language models (LLMs) against traditional MT models. Our findings reveal that LLMs consistently outperform traditional MT models, with Gemini 2.5 Flash achieving a +4.79 ChrF point improvement over NLLB-54B on our low-resource test set. Further, we investigate how LLM context utilisation affects accuracy, finding that the benefits of document-level translation are most pronounced in specialised domains like health. We release the OpenWHO corpus to encourage further research into low-resource MT in the health domain.- Anthology ID:
- 2025.wmt-1.8
- Volume:
- Proceedings of the Tenth Conference on Machine Translation
- Month:
- November
- Year:
- 2025
- Address:
- Suzhou, China
- Editors:
- Barry Haddow, Tom Kocmi, Philipp Koehn, Christof Monz
- Venue:
- WMT
- SIG:
- Publisher:
- Association for Computational Linguistics
- Note:
- Pages:
- 142–160
- Language:
- URL:
- https://preview.aclanthology.org/ingest-emnlp/2025.wmt-1.8/
- DOI:
- Cite (ACL):
- Raphael Merx, Hanna Suominen, Trevor Cohn, and Ekaterina Vylomova. 2025. OpenWHO: A Document-Level Parallel Corpus for Health Translation in Low-Resource Languages. In Proceedings of the Tenth Conference on Machine Translation, pages 142–160, Suzhou, China. Association for Computational Linguistics.
- Cite (Informal):
- OpenWHO: A Document-Level Parallel Corpus for Health Translation in Low-Resource Languages (Merx et al., WMT 2025)
- PDF:
- https://preview.aclanthology.org/ingest-emnlp/2025.wmt-1.8.pdf