Rhipicephalus linnaei is a widespread tick species infesting dogs and capable of transmitting pathogens of veterinary and zoonotic concern. However, its associated bacterial communities remain poorly described in Malaysia. This study profiles the bacterial microbiome of R. linnaei collected from stray dogs in Kampar, Perak, using 16S rRNA gene amplicon sequencing targeting the V3-V4 region. A total of 360 ticks were collected from 13 dogs, of which 290 were pooled according to life stages and sex for microbial profiling. Shannon diversity indices indicated the mixed adult/nymph pool exhibited the highest richness and evenness (H’=5.4), whereas engorged adult females displayed the lowest diversity (H’=2.35), dominated by Gammaproteobacteria. Principal coordinate analysis revealed distinct microbial assemblages among pools, explaining 72% of total variance. Among 137 detected genera, Coxiella (0.6–34%), Staphylococcus (0.4–29%), Stenotrophomonas (0.3–5%), and Streptococcus (0.02–6%) were consistently found across all pools. Low-abundance but clinically relevant genera, including Ehrlichia (0.64%) and Nocardia (<0.01%), were detected in adult males. The consistent presence of Coxiella-like endosymbionts across all stages suggests a likely symbiotic role in nutrient provisioning and reproduction. To our knowledge, this is the first 16S rRNA gene-based profiling of the bacterial communities associated with R. linnaei collected from stray dogs in Malaysia. This study highlights variation across pooled tick categories and contributes to improved understanding of tick-borne pathogen ecology within a One Health framework.

Toxoplasma gondii, the etiologic agent of toxoplasmosis, infects about 30 – 50% of the world population. The currently available anti-Toxoplasma agents have serious limitations. The present study aimed to investigate the effects of two antimalarials; buparvaquone (BPQ) and chloroquine (CQ), on immunocompromised mice with chronic cerebral toxoplasmosis, using spiramycin as a reference drug. The assessed parameters included the estimation of mortality rates (MR) among mice of the different study groups, in addition to the examination of the ultrastructural changes in the brain tissues by transmission electron microscopy. The results showed that only CQ treatment could decrease the MR significantly with zero deaths, while both spiramycin and BPQ caused an insignificant reduction of MR compared to the infected non-treated group. All the used drugs decreased the number of mature ruptured cysts significantly compared to the infected non-treated group, while only CQ increased the number of atrophic and necrotic cysts significantly. Furthermore, both spiramycin and BPQ improved the microvasculopathy and neurodegeneration accompanying the infection with different degrees of reactive astrocytosis and neuronal damage with the best results regarding the repair of the microvascular damage with less active glial cells, and normal neurons in the CQ-treated group. In conclusion, this study sheds light on CQ and its excellent impact on treating chronic cerebral toxoplasmosis in an immunocompromised mouse model.