Ecological multiplex interactions determine the role of species for parasite spread amplification

Trypanosoma cruzi in wild mammals from an endemic area of Chagas disease on the coast of Ecuador

Trypanosoma cruzi is a protozoan parasite that causes Chagas disease, endemic in Ecuador. In the province of Los Ríos, where the vector Triatoma dimidiata is present, vector-borne transmission is considered the primary route of infection. Many mammalian are involved in the transmission cycle of T. cruzi. Nonetheless, significant gaps remain regarding mammalian reservoirs along the Ecuadorian coast, especially in ecologically altered areas. To investigate the role of wild and domestic mammals as hosts, we assessed the presence of T. cruzi in two localities of Quevedo canton. Sampling focused on wild, domestic, and peridomestic mammals using live capture techniques such as mist nets for bats and Sherman and Tomahawk traps for terrestrial mammals. Blood samples were collected from all individuals, and DNA was extracted using a commercial kit. PCR was performed targeting three regions of the T. cruzi genome. In total, 383 mammals were sampled: 66 domestic animals, 6 peridomestic, and 317 wild individuals. Of the wild mammals, 216 were captured in La Virginia 2 and 95 in the Jacome Forest. Four wild individuals tested positive for T. cruzi, including three Glossophaga soricina and one Marmosa simonsi, all collected from La Virginia 2, a peri-urban community. None of the domestic or peridomestic animals were infected. This study reports, for the first time, the infection of M. simonsi with T. cruzi. The presence of positive cases exclusively in an area close to human settlements raises concern about the risk of parasite transmission in transitional landscapes. Transmission cycles of the parasite are known to be influenced by land-use change, deforestation, and host community composition. These factors may alter ecological interactions between vectors and hosts, potentially favoring transmission. Further research is needed in Ecuador to understand how ecosystem alterations shape the sylvatic cycle of T. cruzi, particularly the role of bats in disease maintenance.

Tangled communities: links between predation and parasitism through trophically transmitted digeneans in aquatic communities

Many trophically transmitted digeneans (Platyhelminthes: Trematoda) benefit from prey-predator interactions to complete the last step of their life cycles. These parasites use prey as second intermediate hosts and predators as definitive hosts. We expect a relationship between predation and life-history and community aspects of trophically transmitted digeneans. We hypothesise at species level: (1) host ranges of metacercaria and adult digeneans are positively related; (2) second-intermediate-host range of a digenean relies on prey breadth of its definitive hosts. At community level: (3) digenean species that share second intermediate hosts share definitive hosts; (4) modularity (i.e., community composed of subsets of frequently interacting species) and module affiliation (i.e., tendency of species to share interacting partners across different ecological networks) is high between predator-prey, second intermediate host-metacercaria and definitive host-adult parasite networks. We used data from metacercaria and adult digeneans, their hosts and predation among hosts from nine aquatic locations or replicates. We tested hypotheses (1-3) with richness and Rao diversity dissimilarities (Spearman and Mantel correlations, respectively). For hypothesis (4), we combined the three types of networks to evaluate the multilayer network modularity and module affiliation of the species that participate in different ecological process (predation, metacercaria and/ or adult infection). We found: (1) significant positive correlations between host richness of metacercariae and adults in seven out of nine communities (Spearman correlations p < 0.05). (2) The relationship between the second-intermediate-host range of metacercariae and the diet breadth of their definitive hosts varied between communities and depended on the specialisation degree of the digeneans. (3) Metacercariae sharing second intermediate hosts also shared definitive hosts as adults in seven communities (Mantel correlations p ≤ 0.05). (4) Communities were modular. Module affiliation varied from high to intermediate. Trophic ecology of definitive hosts provides a mechanistic understanding for the second-intermediate-host range and transmission pathways of trophically transmitted parasites.

Integrating databases for spatial analysis of parasite-host associations and the novel Brazilian dataset

Incomplete information on parasites, their associated hosts, and their precise geographical location hampers the ability to predict disease emergence in Brazil, a continental-sized country characterised by significant regional disparities. Here, we demonstrate how the NCBI Nucleotide and GBIF databases can be used as complementary databases to study spatially georeferenced parasite-host associations. We also provide a comprehensive dataset of parasites associated with mammal species that occur in Brazil, the Brazilian Mammal Parasite Occurrence Data (BMPO). This dataset integrates wild mammal species' morphological and life-history traits, zoonotic parasite status, and zoonotic microparasite transmission modes. Through meta-networks, comprising interconnected host species linked by shared zoonotic microparasites, we elucidate patterns of zoonotic microparasite dissemination. This approach contributes to wild animal and zoonoses surveillance, identifying and targeting host species accountable for disproportionate levels of parasite sharing within distinct biomes. Moreover, our novel dataset contributes to the refinement of models concerning disease emergence and parasite distribution among host species.

Functional traits shape small mammal-helminth network: patterns and processes in species interactions

Understanding the role of species traits in mediating ecological interactions and shaping community structure is a key question in ecology. In this sense, parasite population parameters allow us to estimate the functional importance of traits in shaping the strength of interactions among hosts and parasites in a network. The aim of this study was to survey and analyse the small mammal-helminth network in a forest reserve of the Brazilian Atlantic Forest in order to understand (i) how functional traits (type of parasite life cycle, site of infection in their host, host and parasite body length, host diet, host locomotor habit and host activity period) and abundance influence host–parasite interactions, (ii) whether these traits explain species roles, and (iii) if this relationship is consistent across different parasite population parameters (presence and absence, mean abundance and prevalence). Networks were modular and their structural patterns did not vary among the population parameters. Functional traits and abundance shaped the interactions observed between parasites and hosts. Host species abundance, host diet and locomotor habit affected their centrality and/or vulnerability to parasites. For helminths, infection niche was the main trait determining their central roles in the networks.

The Structure of Ecological Networks Across Levels of Organization

Interactions connect the units of ecological systems, forming networks. Individual-based networks characterize variation in niches among individuals within populations. These individual-based networks merge with each other, forming species-based networks and food webs that describe the architecture of ecological communities. Networks at broader spatiotemporal scales portray the structure of ecological interactions across landscapes and over macroevolutionary time. Here, I review the patterns observed in ecological networks across multiple levels of biological organization. A fundamental challenge is to understand the amount of interdependence as we move from individual-based networks to species-based networks and beyond. Despite the uneven distribution of studies, regularities in network structure emerge across scales due to the fundamental architectural patterns shared by complex networks and the interplay between traits and numerical effects. I illustrate the integration of these organizational scales by exploring the consequences of the emergence of highly connected species for network structures across scales.

Forma mentis networks map how nursing and engineering students enhance their mindsets about innovation and health during professional growth

Reconstructing a "forma mentis", a mindset, and its changes, means capturing how individuals perceive topics, trends and experiences over time. To this aim we use forma mentis networks (FMNs), which enable direct, microscopic access to how individuals conceptually perceive knowledge and sentiment around a topic, providing richer contextual information than machine learning. FMNs build cognitive representations of stances through psycholinguistic tools like conceptual associations from semantic memory (free associations, i.e., one concept eliciting another) and affect norms (valence, i.e., how attractive a concept is). We test FMNs by investigating how Norwegian nursing and engineering students perceived innovation and health before and after a 2-month research project in e-health. We built and analysed FMNs by six individuals, based on 75 cues about innovation and health, and leading to 1,000 associations between 730 concepts. We repeated this procedure before and after the project. When investigating changes over time, individual FMNs highlighted drastic improvements in all students' stances towards "teamwork", "collaboration", "engineering" and "future", indicating the acquisition and strengthening of a positive belief about innovation. Nursing students improved their perception of 'robots" and "technology" and related them to the future of nursing. A group-level analysis related these changes to the emergence, during the project, of conceptual associations about openness towards multidisciplinary collaboration, and a positive, leadership-oriented group dynamics. The whole group identified "mathematics" and "coding" as highly relevant concepts after the project. When investigating persistent associations, characterising the core of students' mindsets, network distance entropy and closeness identified as pivotal in the students' mindsets concepts related to "personal well-being", "professional growth" and "teamwork". This result aligns with and extends previous studies reporting the relevance of teamwork and personal well-being for Norwegian healthcare professionals, also within the novel e-health sector. Our analysis indicates that forma mentis networks are powerful proxies for detecting individual- and group-level mindset changes due to professional growth. FMNs open new scenarios for data-informed, multidisciplinary interventions aimed at professional training in innovation.

An undescribed species of Sarcocystis associated with necrotizing meningoencephalitis in naturally infected backyard chickens in the Midwest of Brazil

Sarcocistys -associated menigoencephalitis is virtually an unrecognized cause of neurological disease in chickens. An undescribed species of Sarcocystis cause fatal infection in two backyard chickens in the Midwest of Brazil. Infected chickens presented anorexia, weight loss, incoordination, ataxia and opisthotonos. Yellow necrotic foci in the gray and white matter of the telencephalon were the main gross lesion. Microscopically, necrotizing granulomatous and heterophilic meningoencephalitis with intralesional Sarcocystis -like schizonts and mezoites were observed in the central nervous system. Molecular analysis of frozen brain samples of the two chickens was identical and the protozoan was named Sarcocystis sp. Chicken-2016-DF-BR. Complete nested PCR- sequence of Sarcocystis sp. Chicken-2016-DF-BR was equally similar to Sarcocystis anasi (EU553477) and Sarcocystis albifronsi (EU502868). This is the first report of Sarcocistys -associated meningoencephalitis with molecular characterization in backyard chickens.