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Schistosomiasis is a devastating parasitic disease in which the infectious stage to humans is released by intermediate host snails. The Senegal River Basin (SRB) is a high-risk area for both urogenital and fecal human schistosomiasis and has extensive rice cultivation. However, occupational risk of schistosomiasis to people working in irrigated rice fields is not well established. We performed intermediate host snail surveys from 2022-2023 in rice fields and irrigation canals throughout the SRB. We discovered human schistosome-shedding snails in rice fields and adjacent irrigation canals during the rice growing and non-growing seasons, establishing a clear occupational exposure risk to rice farmers. Relative to the non-growing season, this risk was higher in the rice growing and harvest season when more people are in the rice fields. Rice-fish co-culturing might reduce this occupational risk to rice farmers if local fish species consume enough snail intermediate hosts to reduceSchistosomatransmission. Our predation trials revealed that localHeterotis niloticusandHemichromisspp. fish consumed significant numbers ofBiomphalaria pfeifferiandBulinusspp. snails, and separate trials revealed that these same snail species exhibited only moderate avoidance and refuge use responses to fish chemical cues. These results indicate that there is exposure toSchistosomaparasites in rice fields in the SRB and introducing local fish to rice fields has promise for reducing this exposure as well as providing a protein source to rice farming families. We encourage future studies to more fully explore the benefits of rice-fish co-culturing in the West Africa. 

Abstract Ecological niche models (ENMs) have been used frequently to predict the distribution and future spread of the pathogenic chytrid fungusBatrachochytrium dendrobatidis(Bd). Based on the assumption that chytridiomycosis outbreaks are most likely to occur where the conditions are ideal for Bd, many studies have identified high‐risk areas for chytridiomycosis and its associated mortality risk using only known Bd occurrences. However, the presence of a pathogen does not necessarily indicate high infection, disease or associated mortality.We used the BIOMOD2 package implemented in R, 19 bioclimatic variables, and 267 locality records, covering three levels of infection progress (occurrence, high infection loads and disease‐associated mortality), to calculate the potential areas where: (1) Bd is likely to be present, (2) amphibians are prone to harbour high infections and (3) chytridiomycosis‐related mortalities are likely to occur. We evaluate discrepancies among the three potential areas projected by the models, encompassing their spatial extent and associated environmental conditions.When all the Bd occurrences were used, the predicted area subjected to Bd risk covered 17% of the study area. However, when just mortality records were used, the predicted area decreased three‐fold. Notably, the three predicted areas only overlapped in 3% of the total study area, suggesting that the region at risk of mortality plus high infections constituted only one‐fifth of the predicted area for Bd presence. Mean temperature during the wettest and warmest 3 months of the year together with isothermality emerged as the most robust negative predictors in each of the three models.Synthesis and applications. Ecological niche models (ENMs) based on the presence data ofBatrachochytrium dendrobatidis(Bd) can overestimate the mortality risk of chytridiomycosis because the environmental conditions suitable for Bd presence do not always correspond to those conducive to significant host mortality. Distribution modelling can be a powerful tool when used correctly, and this study highlights the significance of careful data selection to ensure alignment with intended objectives. Considering the widespread use of ENMs to inform policy, meticulous design and comprehensive evaluation are imperative. 

In Africa, many kids get sick from tiny worms called Schistosoma. These worms can slow children’s growth and development; damage the liver, intestines, and bladder; and sometimes lead to cancer or even death. Schistosoma can keep communities poor by reducing people’s ability to work. Over 800 million people are at risk of infection. People get infected when they play or wash in water filled with certain plants and snails. These plants grow fast because fertilizer from farmers’ fields washes into the water when it rains. We found that removing these plants can reduce Schistosoma. Plants that are removed can be turned into food for animals, compost for farms, or gas for cooking and electricity. This solution helps protect kids from getting sick and can even help to slow climate change. By working together, communities can clean their waterbodies and create a healthier, happier future, which is a win-win for people and nature. 

Extreme weather events (EWEs; for example, heatwaves, cold spells, storms, floods and droughts) and non-native species invasions are two major threats to global biodiversity and are increasing in both frequency and consequences. Here we synthesize 443 studies and apply multilevel mixed-effects metaregression analyses to compare the responses of 187 non-native and 1,852 native animal species across terrestrial, freshwater and marine ecosystems to different types of EWE. Our results show that marine animals, regardless of whether they are non-native or native, are overall insensitive to EWEs, except for negative effects of heatwaves on native mollusks, corals and anemone. By contrast, terrestrial and freshwater non-native animals are only adversely affected by heatwaves and storms, respectively, whereas native animals negatively respond to heatwaves, cold spells and droughts in terrestrial ecosystems and are vulnerable to most EWEs except cold spells in freshwater ecosystems. On average, non-native animals displayed low abundance in terrestrial ecosystems, and decreased body condition and life history traits in freshwater ecosystems, whereas native animals displayed declines in body condition, life history traits, abundance, distribution and recovery in terrestrial ecosystems, and community structure in freshwater ecosystems. By identifying areas with high overlap between EWEs and EWE-tolerant non-native species, we also provide locations where native biodiversity might be adversely affected by their joint effects and where EWEs might facilitate the establishment and/or spread of non-native species under continuing global change. 

Immunity changes through ontogeny and can mediate facilitative and inhibitory interactions among co-infecting parasite species. In amphibians, most immune memory is not carried through metamorphosis, leading to variation in the complexity of immune responses across life stages. To test if the ontogeny of host immunity might drive interactions among co-infecting parasites, we simultaneously exposed Cuban treefrogs ( Osteopilus septentrionalis ) to a fungus ( Batrachochytrium dendrobaditis , Bd) and a nematode ( Aplectana hamatospicula ) at tadpole, metamorphic and post-metamorphic life stages. We measured metrics of host immunity, host health and parasite abundance. We predicted facilitative interactions between co-infecting parasites as the different immune responses hosts mount to combat these infectious are energetically challenging to mount simultaneously. We found ontogenetic differences in IgY levels and cellular immunity but no evidence that metamorphic frogs were more immunosuppressed than tadpoles. There was also little evidence that these parasites facilitated one another and no evidence that A. hamatospicula infection altered host immunity or health. However, Bd, which is known to be immunosuppressive, decreased immunity in metamorphic frogs. This made metamorphic frogs both less resistant and less tolerant of Bd infection than the other life stages. These findings indicate that changes in immunity altered host responses to parasite exposures throughout ontogeny. This article is part of the theme issue ‘Amphibian immunity: stress, disease and ecoimmunology’.