Non-exchangeable hydrogen isotope ratios (δ²H) are an underused proxy for studying past human-animal relationships, offering insights into diets, water intake, and ecological ranges. This study examines 218 bone collagen samples for δ¹³C, δ¹⁵N, and δ²H values of wild and domestic terrestrial species, and marine fishes from Ottoman-period Aqaba Castle, Jordan (16th–19th century CE). In this hyperarid region, high δ¹⁵N values reflect the elevated δ¹⁵N baseline of plants, causing overlaps in taxa with varying trophic levels. δ²H helps mitigate this by acting as an additional trophic level indicator. Domesticated herbivores mostly possess δ²H values close to that of predicted local rainfall, while hypercarnivorous cats (Felis catus) exhibit the highest δ²H values, averaging +42.4‰ above herbivores. Fish also show high δ²H values, correlated with trophic level (r = 0.84, R² = 0.70) and estimated body size (r = 0.61, R² = 0.37). Cattle and chickens, have the lowest δ²H values of all terrestrial species, likely due to their significant water requirements and the consumption of ²H-depleted aquifer water. Mapping wild gazelle (Gazella sp.) and chukar (Alectoris chukar) δ²H values on rainwater δ²H isoscapes indicates limited home ranges in the surrounding hyperarid highlands, in line with their expected behaviours. We assess the utility of δ2H for determining fish consumption using Bayesian dietary models for cats and hyenas (Hyaena hyaena), revealing higher fish consumption by cats when δ²H is included alongside δ¹³C and δ¹⁵N. This study highlights the value for δ²H values to enhance interpretations of animal diets and behaviours in archaeological contexts.
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Introduction: Swimmer's itch (or cercarial dermatitis) is caused by avian and mammalian blood flukes, a parasitic infection affecting people worldwide. In particular, avian blood flukes of the genus Trichobilharzia, including Trichobilharzia regenti, are known for causing swimmer's itch. While these parasites typically infect waterfowl as final hosts, incidental infections in humans by cercariae can occur. Such infections trigger immune responses leading to painful, itchy skin lesions. In experimental animals, T. regenti has however shown the ability to evade immune responses, causing neuroinflammation. Recent decades have witnessed an increase in swimmer's itch cases across Europe, turning it into an emerging zoonosis. Methods: Following a swimmer's itch case in Kampenhout (Belgium) in 2022, a malacological and parasitological survey was conducted at the transmission site, consisting of a private pond and adjacent creek. Results: Six snail species were collected, including Ampullaceana balthica, a common intermediate host for Trichobilharzia parasites. Shedding experiments and DNA barcoding identified one snail specimen infected with T. regenti, a new species record for Belgium. This finding further strengthens the link between T. regenti and cercarial dermatitis. Additionally, Echinostomatidae sp. and Notocotylus sp. were isolated from other A. balthica specimens. However, the absence of reference DNA sequences hindered genus- and species-level identification for these parasites. Conclusions: The presence of T. regenti in Belgium may have significant clinical implications, emphasizing the need for heightened diagnostic awareness among medical professionals. The lack of species-level identification for other parasite species underscores the need for comprehensive DNA databases for trematodes. These findings reveal the necessity for a Belgian framework to promptly detect and monitor zoonotic outbreaks of trematode parasites within the One Health context.
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