Epidemiological Factors Associated With Caligus rogercresseyi Infection, Abundance, and Spatial Distribution in Southern Chile.

Sea lice (Caligus rogercresseyi) are external parasites that affect farmed salmonids in Chile, and the scale of their sanitary and economic impact cannot be overstated. Even though space-time patterns suppose parasite aggregation, specific locations related to different infestation levels, as well as their associated factors across the geographic range involved, had not been investigated as of the writing of the present article. The understanding of the effects and factors entailed by the presence of C. rogercresseyi may be deemed a key element of Integrated Pest Management (IPM). In the present study, the multivariate spatial scan statistic was used to identify geographic areas and times of C. rogercresseyi infestation and to estimate the factors associated with such patterns. We used official C. rogercresseyi monitoring data at the farm level, with a set of 13 covariates, to provide adjustment within the analyses. The analyses were carried out for a period of 5 years (2012-2016), and they included three fish species (Salmo salar, Oncorhynchus mykiss, and Oncorhynchus kisutch) in order to assess the consistency of the identified clusters. A retrospective multinomial, spatial, and temporal scan test was implemented to identify farm clusters of either of the different categories of C. rogercresseyi infested farms: baseline, medium, and high, based on the control chemical threshold established by the health authority. The baseline represents adequate farm performance against C. rogercresseyi infestation. Then, production and environmental factors of the medium and high infestation farms were compared with the baseline using regression techniques. The results revealed a total of 26 clusters (p < 0.001), of which 12 correspond to baseline, 1 to medium, and the remaining 13 to high infestation clusters. In general, baseline clusters are detected in a latitudinal gradient on estuarine areas, with increasing relative risks to complex island water systems. There is a spatial structure in specific sites, north of Los Lagos Region and central Aysén Region, with high infestation clusters and epidemic peaks during 2013. In addition, average weight, salmon species, chemotherapeutants, latitude, temperature, salinity, and year category are factors associated with these C. rogercresseyi patterns. Recommendations for an IPM plan are provided, along with a discussion that considers the involvement of stock density thresholds by salmon species and the spatial structure of the efficacy of chemical control, both intended to avoid the advance of resistance and to minimize environmental residues.

Bioclimatic and anthropogenic variables shape the occurrence of Batrachochytrium dendrobatidis over a large latitudinal gradient.

Amphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has caused the greatest known loss of biodiversity due to an infectious disease. We used Bd infection data from quantitative real-time PCR (qPCR) assays of amphibian skin swabs collected across Chile during 2008-2018 to model Bd occurrence with the aim to determine bioclimatic and anthropogenic variables associated with Bd infection. Also, we used Bd presence/absence records to identify geographical Bd high-risk areas and compare Bd prevalence and infection loads between amphibian families, ecoregions, and host ecology. Data comprised 4155 Bd-specific qPCR assays from 162 locations across a latitudinal gradient of 3700 km (18º to 51ºS). Results showed a significant clustering of Bd associated with urban centres and anthropogenically highly disturbed ecosystems in central-south Chile. Both Bd prevalence and Bd infection loads were higher in aquatic than terrestrial amphibian species. Our model indicated positive associations of Bd prevalence with altitude, temperature, precipitation and human-modified landscapes. Also, we found that macroscale drivers, such as land use change and climate, shape the occurrence of Bd at the landscape level. Our study provides with new evidence that can improve the effectiveness of strategies to mitigate biodiversity loss due to amphibian chytridiomycosis.

Assessing the Present and Future Habitat Suitability of Caligus rogercresseyi (Boxshall and Bravo, 2000) for Salmon Farming in Southern Chile.

The sea louse (Caligus rogercresseyi) is the most relevant parasite for the farmed salmon industry in Chile, the second largest producer worldwide. Although spatial patterns of C. rogercresseyi have been addressed from data obtained from established monitoring and surveillance programs, studies on its spatial ecology are limited. A wide geographic distribution of C. rogercresseyi is presumed in Chile; however, how this species could potentially be distributed in space is unknown. Our study presents an analysis of the habitat suitability for C. rogercresseyi in the entire area occupied by marine sites of salmon farms in Chile. Habitat suitability modeling was used to explore the likelihood of species spatial occurrence based on environmental characteristics. Due to the expanding salmon industry in southern Chile, we studied C. rogercresseyi habitat suitability models for present (average of 2005-2010) and two future projections (2050 and 2100) under different climate change scenarios. Models were constructed with the maxent algorithm using a large database of spatial C. rogercresseyi occurrences from the Chilean fisheries health authority and included 23 environmental variables obtained from the Ocean Rasters for Analysis of Climate and Environment (Bio-ORACLE). Habitat suitability models indicated that water temperature, water salinity, and current velocity of waters were the most important characteristics limiting C. rogercresseyi distribution in southern Chile. Habitat suitability models for current climate indicated a heterogeneous pattern with C. rogercresseyi being present in waters with temperature range 12.12-7.08°C (sd = 0.65), salinity range 33.7-25.5 pss (sd = 1.73), and current water velocity range 0.23-0.01 m-1 (sd = 0.02). Predictions for future projections in year 2050 and year 2100 suggest new clumped dispersion of the environmental conditions for C. rogercresseyi establishment. Our results suggest complexity and a wide dispersion of the biogeographic distribution of the C. rogercresseyi habitat suitability with potential implications for control strategies and environmental issues for salmon farming in Chile. Further investigations are required into C. rogercresseyi distribution in southern Chile considering the possible effect of climate change.

Antibiotic-Resistant Salmonella, isolated from cloacal swab samples from turtles in Guatemala / Salmonella resistente a antibióticos, aislada de muestras de hisopados cloacales en tortugas de Guatemala

Salmonellosis is a relevant public health threat worldwide. Reptiles are commonly involved in human cases. A microbiological survey was conducted from August to October 2018 to isolate Salmonella bacteria and de-termine if they were resistant to regularly used antibiotics in eight species of pet turtles (Kinosternon acutum sp., K. leucostomum, K. scorpioides, Rhinoclemmys areolata sp., R. pulcherrima, Staurotypus salvinii sp., Trachemys scripta and T. venusta) in Guatemala city, San Lucas Sacatepéquez and Antigua Guatemala. Cloacal swabs were taken from 63 turtles and cultivated in the Microbiology Laboratory at the Veterinary Medicine and Animal Hus-bandry Faculty, University of San Carlos of Guatemala, in Guatemala City. Three samples were positive to the presence of Salmonella sp. One of these isolates (from Trachemys scripta) was resistant to gentamicin, penicillin and amikacin, other isolate (from T. scripta) was partially resistant to amoxicilin + clavulanic acid and penicillin, and other (from T. venusta) to penicillin. These findings highlight the need for better biosecurity practices and show the capacity of bacteria to develop survival strategies that involve resistance to harmful substances like antibiotics.

La salmonelosis es una importante enfermedad zoonótica considerada una amenaza a la salud pública a nivel mundial. Los reptiles están comúnmente involucrados en la transmisión animal-humano. Con el objetivo de determinar la presencia de Salmonella y determinar su resistencia a antibióticos de uso común, se realizó un estudio exploratorio en ocho especies de tortugas (Kinosternon acutum sp., K. leucostomum, K. scorpioides, Rhinoclem-mys areolata sp., R. pulcherrima, Staurotypus salvinii sp., Trachemys scripta y T. venusta) en Guatemala y en San Lucas Sacatepéquez. Se tomaron hisopados cloacales de 63 especímenes y se cultivaron en el Laboratorio de Microbiología de la Facultad de Medicina Veterinaria y Zootecnia de la Universidad de San Carlos de Guatemala. Tres muestras fueron positivas a la presencia de Salmonella sp. Uno de los aislados (de Trachemys scripta) fue resistente a gentamicina, penicilina y amikacina, otro aislado (de T. scripta) fue parcialmente resistente a amoxicilina + ácido clavulánico y a penicilina y un tercer aislado (de T. venusta) a penicilina. Estos hallazgos resaltan la necesidad de mejores prácticas de bioseguridad y muestran la capacidad de las bacterias para desarrollar estrategias de sobrevivencia que involucran la resistencia a sustancias que les son nocivas, como los antibióticos.

Declining Prevalence of Disease Vectors Under Climate Change.

More than half of the world population is at risk of vector-borne diseases including dengue fever, chikungunya, zika, yellow fever, leishmaniasis, chagas disease, and malaria, with highest incidences in tropical regions. In Ecuador, vector-borne diseases are present from coastal and Amazonian regions to the Andes Mountains; however, a detailed characterization of the distribution of their vectors has never been carried out. We estimate the distribution of 14 vectors of the above vector-borne diseases under present-day and future climates. Our results consistently suggest that climate warming is likely threatening some vector species with extinction, locally or completely. These results suggest that climate change could reduce the burden of specific vector species. Other vector species are likely to shift and constrain their geographic range to the highlands in Ecuador potentially affecting novel areas and populations. These forecasts show the need for development of early prevention strategies for vector species currently absent in areas projected as suitable under future climate conditions. Informed interventions could reduce the risk of human exposure to vector species with distributional shifts, in response to current and future climate changes. Based on the mixed effects of future climate on human exposure to disease vectors, we argue that research on vector-borne diseases should be cross-scale and include climatic, demographic, and landscape factors, as well as forces facilitating disease transmission at fine scales.