Anaplasma platys beyond canines: a systematic review of host range, phylogenetic relatedness, and knowledge gaps in...

Anaplasma platys is a causative agent of canine cyclic thrombocytopenia, transmitted by Rhipicephalus sanguineus sensu lato. Reports of A. platys in Africa remain scarce and fragmented, with most detections occurring as co-infections in broader Anaplasmataceae surveys.

A systematic review was conducted from February to May 2025, analyzing all peer-reviewed journal articles, theses, and conference proceedings published in English in three databases-PubMed, Web of Science, and Scopus-from database inception up to and including December 2024. Following screening, 103 full-text peer-reviewed records were deemed eligible for data extraction. The outcome of interest was A. platys and A. platys-like detection by various methods and the corresponding sequences (16S ribosomal RNA (rRNA) and groEL genes) from GenBank for use in phylogenetic analyses.

Anaplasma platys and A. platys-like were detected in 80 studies in 25 of the 54 African countries across multiple host species, and there was no detection in the four semi-autonomous or autonomous territories. The pathogen was mostly detected in domestic dogs, with prevalence that ranged from 0.8% to 100%, followed by cattle, with prevalence of 0.2-84%, and sheep with 1.7-100%. Other domestic animals included goats (6.7-55.7%) and camels (0.7-61.1%), while wildlife included impala (9.5-58.3%), African buffalo (3.6-7.7%), sable antelope (4.3%), Grant's gazelle (32.4%), kudu (83.3%), zebra (16.7%), warthog (12.5%), elephant (50%), lion (16.7%), leopard (11.1%), bat-eared fox (88.9%), brown hyena (82.3%), and spotted hyena (100%). Additionally, A. platys DNA was detected in ticks, mainly R. sanguineus s.l. but also Rhipicephalus pulchellus, R. annulatus, R. pravus, R. evertsi evertsi, R. microplus, R. simus, R. humeralis, R. camicasi, Haemaphysalis leachi, and Hyalomma excavatum, as well as in fleas (Pulex irritans, Ctenocephalides felis felis, and Ctenocephalides felis canis). One documented human case involved a veterinarian who had traveled to South Africa, raising concerns about zoonotic potential, though the infection source remains unclear. The 16S rRNA phylogenetic tree demonstrated broad host and vector diversity, while the groEL-based analysis resolved distinct bovine- and canine-associated lineages.

These findings highlight a likely broad vertebrate host range of A. platys and possible association with multiple tick vectors. Critical knowledge gaps remain regarding host-specific genotypes and the role of tick species in transmission.