Bats are a significant reservoir for numerous pathogens, including Bartonella spp. It is one of the emerging zoonotic bacterial diseases that can be transmitted to humans and may cause various unspecific clinical manifestations. Thus, bartonellosis is rarely diagnosed and is regarded as a neglected vector-borne disease (VBD). Bat flies have been hypothesised to be a vector in the transmission of pathogens among bats. They are host-specific, which reduces the likelihood of pathogen transmission across bat species; however, they are likely to maintain high pathogen loads within their host species. To explore the presence of Bartonella spp. in bat flies from Peninsular Malaysia; bat fly samples collected from various sites at the east coast states were subjected to molecular detection for Bartonella spp. It was discovered that 38.7 % of bats from Terengganu and Kelantan were infested with bat flies; however, no bat fly was found in bats collected from Pahang. The collected bat flies belonged to the families Nycteribiidae (79.6 %) and Streblidae (20.4 %). The collected bat flies were pooled according to the locations and species into 39 pools. Out of these 39 pools, 66.7 % (n = 26) were positive for Bartonella spp. by PCR. Sequence analyses of five randomly selected PCR-positive pools revealed that pools from Kelantan (n = 3) have the closest sequence identities (99 %) to Bartonella spp. strain Lisso-Nig-922 from Nigeria. However, the other pools from Terengganu (n = 2) were closely related to Bartonella spp. strain KP277 from Thailand and Bartonella spp. strain Rhin-3 from the Republic of Georgia with 99 % and 100 % sequence identity, respectively. This suggests that the Bartonella spp. found in Malaysian bat flies are genetically diverse and can potentially serve as reservoirs for pathogenic Bartonella spp.
Chigger mites (larval Trombiculidae) are obligate ectoparasites, some species transmit Orientia tsutsugamushi, the causative agent of scrub typhus. Despite their public health significance in rural Southeast Asia, relationships between chiggers infesting wildlife, domestic animals and those present in the surrounding environment remain poorly characterised. We hypothesised that agricultural-forest ecotones would support higher chigger occurrence and that murid rodents would be the principal maintenance hosts of chigger communities. We conducted ecological observations of chigger communities associated with backyard chickens (n = 117), free-roaming dogs (n = 22), murid rodents (n = 96), insectivorous bats (n = 24) and environmental black-plate samples (n = 150) within a scrub typhus-endemic rural village in Nan Province, northern Thailand. Host-chigger associations were characterized using bipartite and unipartite network analyses. Twenty-one chigger species were identified, including four previously known to harbour O. tsutsugamushi: Ascoschoengastia indica, Leptotrombidium imphalum, Eutrombicula wichmanni and Walchia kritochaeta. Unfed questing chiggers occurred within the central residential area rather than being restricted to peripheral agricultural-forest interfaces as hypothesised. Murid rodents contributed the greatest chigger diversity, while backyard chickens exhibited unexpectedly high infestation prevalence (54.7%) and mean abundance. Environmental chigger detection rate was 11.3%. Eutrombicula wichmanni was recorded on free-roaming dogs, representing the first documented chigger infestation on dogs in Thailand, and a complete mitogenome was obtained from environmentally collected adults. Network analysis identified distinct rodent- and domestic animal-associated chigger communities, with the environmental chiggers linking both groups, whereas bat-associated chiggers were clearly isolated. These findings reveal complex chigger community structures with distinct ecological partitioning, highlighting the importance of domestic animals, particularly backyard chickens and free-roaming dogs (in addition to rodents) as critical components of peri-domestic transmission cycles. Future studies integrating host-chigger ecology with rickettsial pathogen screening would inform targeted disease surveillance and control programmes in rural endemic communities.