Urban prevalence and molecular confirmation of Trypanosoma lewisi in wild rats from Surabaya, Indonesia

Trypanosoma lewisi is a blood parasite of wild rodents increasingly recognised as an emerging zoonotic pathogen associated with atypical human trypanosomiasis. However, epidemiological and molecular data from major Indonesian metropolitan areas remain limited. This study investigated the prevalence and molecular identity of T. lewisi in urban wild rats from Surabaya, Indonesia’s second-largest city. A total of 100 wild rats, comprising Rattus norvegicus (n = 54) and Rattus tanezumi (n = 46), were captured across five geographic zones between February and August 2025. Infection was assessed by wet-mount examination and Dip Quick-stained blood smears, followed by PCR amplification of the ITS1 region of ribosomal DNA, Sanger sequencing, and Bayesian phylogenetic analysis. Overall microscopy-detectable T. lewisi clade prevalence was 13.0% (13/100; 95% CI: 7.1–21.2%), with infected rats detected in four of five sampling zones. All successfully sequenced samples were placed within the well-supported T. lewisi clade (PP = 1.0) in Bayesian phylogenetic analysis. These findings provide the first molecular evidence of T. lewisi circulating in urban wild rats in Surabaya and demonstrate that synanthropic rodents may serve as important reservoirs of this zoonotic parasite in densely populated Indonesian cities. The study highlights the need to incorporate rodent-borne trypanosomes into One Health surveillance frameworks in urban environments.