Trypanosoma lewisi infections in Rattus rattus from rural ecosystems in Gabon

Highlights: • Trypanosome infections were detected in all eight rural localities studied in Gabon, covering domestic, peri-domestic, and forest environments. • First documentation of Trypanosoma lewisi in Rattus in Gabon. • The black rat (Rattus) accounts for 89% of all infections, confirming its role as the primary reservoir and dispersal host for T. lewisi in Central Africa. Abstract: Rodents are important reservoirs for numerous zoonotic parasites. Among them, Trypanosoma lewisi (subgenus Herpetosoma) has been introduced into many regions worldwide through its primary reservoir, Rattus, which has spread globally along human commercial routes. Several other Herpetosoma species have been reported to infect native rodents in Africa, although their zoonotic potential remains unclear. In rural areas of Gabon, R. rattus is widely distributed within villages, being largely dominant in rodent communities. Based on sampling conducted across 11 localities, we screened 528 rodents. Using qPCR targeting the 18S rDNA gene. The overall prevalence for this subgenus was 56.6% (n = 299). Trypanosoma spp. were detected at all sampling sites, with prevalence in R. rattus ranging from 21.6% to 85.7% in domestic localities. Infections were also observed in Praomys jacksoni (100%), Lophuromys roseveari (72%), Lemniscomys striatus (25%), and Hybomys univittatus (71%). To formally identify the circulating species, a 2100 bp fragment of the 18S rDNA gene was successfully sequenced from a subset of 21 qPCR-positive samples, revealing that all these characterized isolates belonged to the subgenus Herpetosoma and clustered tightly within the T. lewisi subclade (genotype AF05b), recognized as T. lewisi sensu stricto. Our findings confirm the occurrence of T. lewisi AF05b within invasive R. rattus populations in rural Gabon. While T. lewisi DNA was also detected in a few native rodents, the low trypanosome diversity observed in this study is likely driven by the overwhelming dominance of R. rattus in our sampling. This study underscores the widespread presence of the T. lewisi clade in invasive rats in Gabon and emphasizes the importance of monitoring invasive rodent populations as potential amplifiers of zoonotic trypanosomes, though further targeted studies with balanced sampling are required to clarify the exact epidemiological role of native African rodents in these transmission cycles.