バングラデシュの家畜に影響を与える重要な寄生虫の分子系統解析および形態学的解析

博士(獣医学)岐阜大学(Gifu University

Mammalian and Avian Larval Schistosomatids in Bangladesh: Molecular Characterization, Epidemiology, Molluscan Vectors, and Occurrence of Human Cercarial Dermatitis

Schistosomiasis is a neglected tropical disease (NTD) caused by blood flukes (Schistosoma spp.). Schistosomatids affect a wide array of vertebrate hosts, including humans. In the present study, multiple species of schistosomatids were identified by isolating schistosomatid cercariae (SC) from naturally infected snails. We also described different biotic and abiotic factors influencing SC infections in snails and reported human cercarial dermatitis (HCD) for the first time in Bangladesh. A total of 22,012 snails of seven species: Lymnaea auricularia, L. luteola, Indoplanorbis exustus, Physa acuta, Viviparus bengalensis, Brotia spp., and Thiara spp., were collected and examined. Among these snails, 581 (2.6%) belonging to five species: L. luteola, L. auricularia, P. acuta, I. exustus, and V. bengalensis, were infected with SC. The rate of infection was the highest for L. luteola (11.1%), followed by L. auricularia (5.3%), and was the lowest for V. bengalensis (0.4%). Prevalence in snails was the highest in September (16.8%), followed by October (9.5%) and November (8.8%), and was the lowest in colder months, such as January (1.8%) and February (2.1%). Infections with schistosomatids were more common in larger snails and snails collected from sunny areas. We confirmed the presence of Schistosoma indicum, S. incognitum, S. nasale, S. spindale, and Trichobilharzia szidati by PCR and sequencing. Through a questionnaire survey, we detected HCD in 214 (53.5%) individuals, and the infection rate was almost equally distributed across all professions. Collectively, the present results suggest that lymnaeid snails are the main vector for Schistosoma spp. prevalent in Bangladesh, and schistosomatids with zoonotic potential are also prevalent

Molecular Investigation of Tick-Borne Haemoparasites Isolated from Indigenous Zebu Cattle in the Tanga Region, Tanzania

Tick-borne diseases (TBDs) are a major hindrance to livestock production in pastoral communities of Africa. Although information on tick-borne infections is necessary for setting up control measures, this information is limited in the pastoral communities of Tanzania. Therefore, this study aimed to provide an overview of the tick-borne infections in the indigenous cattle of Tanzania. A total of 250 blood samples were collected from the indigenous zebu cattle in the Tanga region, Tanzania. Then, we conducted a molecular survey using the polymerase chain reaction (PCR) and gene sequencing to detect and identify the selected tick-borne pathogens. The PCR was conducted using assays, based on Theileria spp. (18S rRNA), Theileria parva (p104), Theileria mutans and T. taurotragi (V4 region of the 18S rRNA), Babesia bigemina (RAP-1a), B. bovis (SBP-2), Anaplasma marginale (heat shock protein groEL) and Ehrlichia ruminantium (pCS20). The PCR screening revealed an overall infection rate of (120/250, 48%) for T. mutans, (64/250, 25.6%) for T. parva, (52/250, 20.8%) for T. taurotragi, (33/250, 13.2%) for B. bigemina and (81/250, 32.4%) for A. marginale. Co-infections of up to four pathogens were revealed in 44.8% of the cattle samples. A sequence analysis indicated that T. parva p104 and A. marginale groEL genes were conserved among the sampled animals with sequence identity values of 98.92–100% and 99.88–100%, respectively. Moreover, the B. bigemina RAP-1a gene and the V4 region of the 18S rRNA of T. mutans genes were diverse among the sampled cattle, indicating the sequence identity values of 99.27–100% and 22.45–60.77%, respectively. The phylogenetic analyses revealed that the T. parva (p104) and A. marginale (groEL) gene sequences of this study were clustered in the same clade. In contrast, the B. bigemina (RAP-1a) and the T. mutans V4 region of the 18S rRNA gene sequences appeared in the different clades. This study provides important basement data for understanding the epidemiology of tick-borne diseases and will serve as a scientific basis for planning future control strategies in the study area