The global distribution and risk prediction of Anaplasmataceae species: a systematic review and geospatial modelling...

The family Anaplasmataceae, reclassified under the order Rickettsiales, represents a highly complex group that poses an increasing global threat. However, their infection risk remains poorly understood. We aimed to map the diversity, distribution, and potential infection risk of Anaplasmataceae members.

We searched PubMed, Web of Science, bioRvix, and MedRvix for published articles to extract data on the detection of Anaplasmatacea species in vectors, animals, and humans from 1910 to 2022. We mapped the richness and global distribution of identified Anaplasmatacea species. Machine learning algorithms were applied to determine the ecological and vector-related factors contributing to the occurrence of major Anaplasmatacea members and project their potential risk distributions.

A total of 2605 studies meeting our inclusion criteria were used for data extraction. We identified 85 species of Anaplasmataceae family from 134 tick species, 312 wild animals, and 12 domestic animals. Anaplasma phagocytophilum had the widest range of vectors (97 species), followed by Anaplasma marginale (54 species), Anaplasma bovis (46 species), Anaplasma ovis (37 species), and Anaplasma platys (35 species). Aanaplasmaphagocytophilum was also detected in the widest range of wildlife (208 species), followed by Ehrlichia chaffeensis (46 species), Candidatus Neoehrlichia mikurensis (36 species), Ehrlichia canis (35 species), and A. bovis (32 species). In total, 52,315 human cases involving 15 Anaplasmataceae species were recorded, A. phagocytophilum and E. chaffeensis accounted for majority of human infections (66·5% and 32·4%, respectively). According to our modelling analysis, the geographic distribution of six major Anaplasmatacea species is primarily influenced by the projected habitat suitability index of tick vectors and climatic conditions. Among these, A. phagocytophilum presents the highest risk, with an estimated 3·97 billion individuals and 8·95 million km² area potentially affected.

The widespread distribution of Anaplasmataceae species emphasizes the need to enhance identification, surveillance, and diagnosis efforts in high-risk areas, particularly within low-income regions.

The National Key Research and Development Program of China (2023YFC2605603) and the Natural Science Foundation of China (82330103).