Community-wide versus school-based targeted deworming for soil-transmitted helminth control in school-aged children in Vietnam: the CoDe-STH cluster-randomised controlled trial.

Background: Soil-transmitted helminth (STH) infection control programs typically consist of school-based preventive chemotherapy (PC) targeted to school-aged children. STH reservoirs in untreated community members contribute to ongoing transmission in children. The CoDe-STH (Community Deworming against STH) trial, conducted in Dak Lak province, Vietnam, between October 2019 and November 2020, aimed to determine whether community-wide mass drug administration (MDA) is more effective than school-based targeted PC in reducing STH prevalence and intensity in children. Methods: In this two-arm cluster randomised controlled trial, 64 primary schools were randomly assigned 1:1 to receive either school-based targeted PC ("school arm") or community-wide MDA ("community arm"). A single dose of albendazole 400 mg was used for deworming. The primary outcome was hookworm prevalence in schoolchildren, measured using quantitative real-time PCR. We also measured infection intensity for Necator americanus only, using qPCR cycle threshold (Ct) values converted into eggs per gram of faeces (EPG). Analysis was by intention to treat. The trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12619000309189). Findings: The analysis included 4955 children in the school arm and 5093 children in the community arm. N. americanus was the dominant STH species. The relative reduction in hookworm prevalence was not significantly different between the school arm (30.1%, 95% confidence interval [CI] 20.5-36.9) and the community arm (34.6%, 95% CI 19.9-49.4). Due to lower baseline prevalence than expected, the study was underpowered to detect a difference in prevalence reduction between the study arms. The community arm showed significantly greater relative reduction in N. americanus infection intensity (56.0%, 95% CI 39.9-72.1) compared to the school arm (3.4%, 95% CI -24.7 to 31.4). The community arm also showed greater relative reduction in prevalence of moderate-to-heavy intensity (≥2000 EPG) N. americanus infections (81.1%; 95% CI 69.7-92.6) compared to the school arm (39.0%, 95% CI 13.7-64.2). Interpretation: Although no impact was seen on overall prevalence, community-wide MDA was more effective in lowering N. americanus infection intensity in schoolchildren compared to school-based targeted PC, measured 12 months after one round of albendazole deworming with high coverage. Funding: National Health and Medical Research Council, Australia (APP1139561).

Molecular detection of Rickettsia sp. genotype RF2125 from household dogs in the central highlands of Vietnam.

Rickettsia felis, a zoonotic vector-borne bacteria, is reported globally in humans, animals, and its invertebrate hosts. This study was designed to detect antibodies against R. felis and the DNA of R. felis in blood of domestic dogs in the Central Highlands of Vietnam using immunofluorescence antibody test (IFAT), and ompB- and gltA-PCRs, respectively. Using IFAT, 23 out of 338 plasma samples collected from household dogs were seropositive for R. felis, accounting for 6.80% (CI 95%: 4.45-10.1%). Of 171 buffy coat samples from household dogs, 50 were positive for spotted fever group rickettsioses using ompB-PCR assay, accounting for 29.2% (CI 95%: 22.6-36.7%). The gltA-PCR assay detected R. felis in 30% (15/50) of ompB-positive samples. DNA sequencing of ompB-PCR and gltA-PCR products confirmed the presence of R. felis and Rickettsia sp. genotype RF2125 / R. asembonensis. Our findings suggest a potential risk of R. felis infection in the communities in the Central Highlands of Vietnam, and the reservoir role of dogs to Rickettsia sp. genotype RF2125.

Rickettsia felis and species of fleas parasitizing on household dogs in the Central Highlands of Vietnam.

Rickettsia felis is an obligate intracellular gra m-negative bacterium that belongs to the family of Rickettsiaceae. Ctenocephalides felis, cat flea, is the primary vector of the bacteria. The flea is the most common ectoparasite in dogs and associated with flea-borne spotted fever in humans. Information on R. felis and flea species parasitizing on dogs in Vietnam is limited. This study aimed to identify the species of fleas collected from dogs in the Central Highlands of Vietnam and detected the existence of R. felis in these fleas utilizing molecular tools. Morphological identification of 1618 fleas and molecular confirmation revealed the predominance of C. felis orientis parasitizing on dogs in the Central Highlands of Vietnam. Sixty-eight out of 100 fleas collected from household dogs were positive for spotted fever group rickettsiae; whilst R. felis was detected in 97.06 % (66/68) of C. felis orientis and C. felis felis. The results of this study indicate the potentially high risk of R. felis infection to humans and animals.

Prevalence and risk factors of Taenia hydatigena in dogs, pigs, and cattle in the Central Highlands of Vietnam.

Taenia hydatigena is a globally distributed canine tapeworm. The canine tapeworm results in economic impacts for farmers owing to organ condemnation. T. hydatigena utilizes dogs and other carnivores as definitive hosts while swine and ruminants serve as intermediate hosts. T. hydatigena is endemic in Vietnam; however, information on the prevalence and risk factors associated with infection is scarce. This cross-sectional study aims to identify the prevalence of T. hydatigena taeniasis in dogs and T. hydatigena cysticercosis in pigs and cattle. The risk factors associated with taeniasis in dogs were identified using a fixed effects logistic regression model and quantified using population attributable fractions. The prevalence of T. hydatigena taeniasis in dogs and T. hydatigena cysticercosis in pigs and cattle was 10.31% (95% CI 8.21 to 12.84%), 7.60% (95% CI 6.34 to 9.08%), and 11.11% (95% CI 7.63 to 11.81%), respectively; these levels were lower than those reported in other regions of Vietnam. The population attributable fraction of risk factors associated with T. hydatigena taeniasis in dogs for dogs living in proximity of an abattoir, those having access to raw pork or beef viscera, and those living in multi-dog households were 80%, 19%, and 7%, respectively. This current study identified and quantified the risk factors for taeniasis in dogs thus advocating for targeted community intervention programs to break the lifecycle of T. hydatigena in Dak Lak province.