Background: Malaria risk factors at household level are known to be complex, uncertain, stochastic, nonlinear, and multidimensional. The interplay among these factors, makes targeted interventions, and resource allocation for malaria control challenging. However, few studies have demonstrated malaria’s transmission complexity, control, and integrated modelling, with no available evidence on Uganda’s refugee settlements. Using the 2018–2019 Uganda’s Malaria Indicator Survey (UMIS) data, an alternative Bayesian belief network (BBN) modelling approach was used to analyse, predict, rank and illustrate the conceptual reasoning, and complex causal relationships among the risk factors for malaria infections among children under-five in refugee settlements of Uganda. Methods: In the UMIS, household level information was obtained using standardized questionnaires, and a total of 675 children under 5 years were tested for malaria. From the dataset, a casefile containing malaria test results, demographic, social-economic and environmental information was created. The casefile was divided into a training (80%, n = 540) and testing (20%, n = 135) datasets. The training dataset was used to develop the BBN model following well established guidelines. The testing dataset was used to evaluate model performance. Results: Model accuracy was 91.11% with an area under the receiver-operating characteristic curve of 0.95. The model’s spherical payoff was 0.91, with the logarithmic, and quadratic losses of 0.36, and 0.16 respectively, indicating a strong predictive, and classification ability of the model. The probability of refugee children testing positive, and negative for malaria was 48.1% and 51.9% respectively. The top ranked malaria risk factors based on the sensitivity analysis included: (1) age of child; (2) roof materials (i.e., thatch roofs); (3) wall materials (i.e., poles with mud and thatch walls); (4) whether children sleep under insecticide-treated nets; 5) type of toilet facility used (i.e., no toilet facility, and pit latrines with slabs); (6) walk time distance to water sources (between 0 and 10 min); (7) drinking water sources (i.e., open water sources, and piped water on premises). Conclusion: Ranking, rather than the statistical significance of the malaria risk factors, is crucial as an approach to applied research, as it helps stakeholders determine how to allocate resources for targeted malaria interventions within the constraints of limited funding in the refugee settlements.

Background: Biomphalaria and Physa (order Gastropoda) serve as vectors and reservoirs for infectious agents that affect both humans and animals. This study provides updated insights into the epidemiology, morphology, phylogeny, and haplotype diversity of Biomphalaria and Physa snails in Guangdong Province, southern China. Methods: Field surveys were conducted across Guangdong Province from 2016 to 2023. Morphological observations included assessment of snail shape, shell height, and aperture width. Molecular analysis targeted several genes, including Cytochrome c oxidase subunit 1 (COI), internal transcribed spacer (ITS), 18S rRNA, 16S rRNA, and 28S rRNA. Evolutionary trees were constructed with neighbor-joining and maximum likelihood methods. Haplotype networks were generated from COI sequences collected from multiple geographic locations. Results: Physa acuta was detected in 92% of surveyed sites, showing broad distribution and notable mitochondrial diversity (15 haplotypes). The dominant haplotype (Hap_3) was shared with sequences from Chile and the Netherlands. In contrast, Biomphalaria straminea was found at 62% of sites and displayed limited genetic variation (2 haplotypes), despite visible morphological dimorphism (red/black forms). Phylogenetic analysis exhibited minimal differences in 16S rRNA and COI gene sequences among turret snail strains, with B. straminea clustering closely to South American lineages. Morphometric analyses revealed significant size differences among strains, for example, Shuanglong B. straminea had a shell width of 8.74 ± 0.26 mm, whereas Zengcheng P. acuta exhibited 11.07 ± 0.90 mm. In contrast, analysis of 28S and 18S rRNA confirmed species boundaries but lacked at the intraspecific level. Conclusions: Our analysis of multiple target genes confirms that mitochondrial markers (COI and 16S rRNA) are effective for studying the evolutionary dynamics of freshwater invasive snails. Physa acuta exhibits a widespread distribution and notable genetic diversity across Guangdong, while B. straminea shows limited genetic variation, suggesting strong genetic conservation within the species.

In low- and middle-income countries (LMICs), enteric infections pose a significant threat to children’s health. However, understanding the specifics of when, where, and how young children in LMICs are exposed to enteric pathogens and the roles of animal reservoirs, environmental media, and human hosts play during exposure remains limited. This study systematically evaluates infants’ exposure to E. coli through various pathways in the rural Haramaya woreda of Ethiopia. Between June 2021 and June 2022, we conducted over 1300 hours of structured behavioral observations on 79 infants when aged 4–8 months (Timepoint 1) and 11–15 months (Timepoint 2). Enumerators recorded the infant’s behavior related to exposure, including when and where it occurred, using the Countee © application. Concurrently, we collected 1338 environmental samples from key contact interfaces between infants, other people, and the environment to test for E. coli . We used a competing hazard model for duration-based behaviors, an inhomogeneous Poisson point process model for frequency-based behaviors, and a left-censored lognormal distribution model for E. coli contamination levels. The behavioral and environmental information was then integrated into an agent-based exposure model framework to quantify the exposure to E. coli through different pathways. The infant behavior, which altered the relative importance of different exposure pathways, changed as children grew older. Notably, we observed increased rates of touching behavior (e.g., touching fomites) and soil-pica, increased consumption of solid food, and more time spent on the bare ground at Timepoint 2. The major sources of exposure to E. coli were food and breastfeeding at Timepoint 1 and food and soil at Timepoint 2. This study provides insights for interventions to minimize infants’ risk of exposure to fecal contamination and subsequent risk of enteric infections, including improved food handling practices, enhanced personal hygiene for breastfeeding caregivers, and education on the risk of soil-pica.

: Increasing attention has focused on health outcomes of Campylobacter infections among children younger than 5 years in low-resource settings. Recent evidence suggests that colonization by Campylobacter species contributes to environmental enteric dysfunction, malnutrition, and growth faltering in young children. Campylobacter species are zoonotic, and factors from humans, animals, and the environment are involved in transmission. Few studies have assessed geospatial effects of environmental factors along with human and animal factors on Campylobacter infections. Here, we leveraged Campylobacter Genomics and Environmental Enteric Dysfunction project data to model multiple socioenvironmental factors on Campylobacter burden among infants in eastern Ethiopia. Stool samples from 106 infants were collected monthly from birth through the first year of life (December 2020–June 2022). Genus-specific TaqMan real-time polymerase chain reaction was performed to detect and quantify Campylobacter spp. and calculate cumulative Campylobacter burden for each child as the outcome variable. Thirteen regional environmental covariates describing topography, climate, vegetation, soil, and human population density were combined with household demographics, livelihoods/wealth, livestock ownership, and child–animal interactions as explanatory variables. We dichotomized continuous outcome and explanatory variables and built logistic regression models for the first and second halves of the infant’s first year of life. Infants being female, living in households with cattle, reported to have physical contact with animals, or reported to have mouthed soil or animal feces had increased odds of higher cumulative Campylobacter burden. Future interventions should focus on infant-specific transmission pathways and create adequate separation of domestic animals from humans to prevent potential fecal exposures.

Biomphalaria straminea (Gastropoda: Planorbidae) and Physa acuta (Gastropoda: Physidae), both invasive species in southern China, are important vectors for zoonotic diseases. However, the lack of information on the infection dynamics of Angiostrongylus cantonensis in these snails leaves gaps in understanding the compatibility mechanisms between the snails and the parasite. This study aims to reveal differences in A. cantonensis infection between B. straminea and P. acuta from Guangdong, southern China, and to investigate the potential interaction mechanisms between A. cantonensis and P. acuta . We found that both phenotypic color variants of B. straminea snails were highly susceptible to A. cantonensis (100%). The load of the L3 larvae ranged from 243 to 765 per snail, and it was positively correlated with the infection dosage. Based on the comparison of third-stage larvae quantities, B. straminea is more suitable than P. acuta for establishing the life cycle of A. cantonensis in the laboratory. In contrast, geographic isolates of P. acuta exhibited variable susceptibility (13–91%) and markedly lower parasite loads, with 6–32 third-stage larvae per snail. Diverse strains of P. acuta exhibit distinct immune responses to A. cantonensis , characterized by varied expression patterns of immune-related genes such as TEP1, HSP70, FREP2, Cu-Zn_SOD1, Fe-Mn_SOD2, MIF and Galectin. Our findings establish B. straminea as both a high-risk vector and a laboratory model for studying the life cycle of A. cantonensis , while highlighting P. acuta as a model for investigating parasite-snail interactions, thereby enhancing our understanding of snail-parasite dynamics in southern China.

Zebra mussel invasion of North American lakes during the last century may play an important role in the occurrence of toxic cyanobacterial blooms. However, empirical evidence quantifying their influence on cyanobacterial community dynamics at broad spatial scales remains limited. Here, we analyzed data from the U.S. EPA National Lakes Assessment (>1000 lakes) to examine potential linkages among zebra mussels, cyanobacterial community composition, and cyanotoxin levels. The analysis results showed significant differences in cyanobacterial communities between lakes located in areas with and without established zebra mussel populations. The lakes with established zebra mussels exhibited significantly higher microcystin levels and cyanobacterial abundance, but lower phosphorus concentrations. Structural equation modeling was used to confirm and estimate the effect of zebra mussels on microcystin concentrations via different pathways. The results suggest three potential pathways whereby zebra mussels influence microcystin production: (1) altering phosphorus concentration; (2) increasing cyanobacterial abundance; and (3) shifting cyanobacteria community structure. The total effect of zebra mussel establishment resulted in an overall 1.40-fold net increase in microcystin level, which presumably resulted from three contributing factors: (1) a 1.06-fold increase through an increased cyanobacterial abundance; (2) a 1.53-fold increase through a selective force, resulting in increased cyanobacteria toxicity; and (3) a 0.86-fold decrease in microcystin level through total phosphorus decrease. The study highlights the potential role of zebra mussel invasion in altering cyanobacterial composition and influencing microcystin levels in U.S. lakes.