Sarcoptes scabiei infestation does not alter the stability of ectoparasite communities

Antecedentes: La muestra representa un ecosistema heterogéneo donde varias especies de parásitos concurren e interactúan entre sí por el espacio y los recursos. Aunque estas interacciones pueden gobernar las características de una pequeña comunidad y pueden conformar la respuesta a perturbaciones externas, la resiliencia de las comunidades ectoparásitas a nuevas infestaciones sigue siendo poco explorada. Métodos: Se analizó la composición del ectoparásito en comunidades ubicadas en 214 individuos de íbices ibérica (Capra pyrenaica) que habita en el Espacio Natural de Sierra Nevada, en el sur de España. Se utilizaron los esquemas de clasificación y regresión, exploramos cómo la presencia de Sarcoptes scabiei (un ácaro muy contagioso), en la muestra exterior y la manada rigen la prevalencia y abundancia de los piojos y las garrapatas. Ningún modelo se ha aplicado en el análisis para evaluar el impacto de S. scabiei sobre la estructura de las comunidades de ectoparásitos. Resultados: Nuestros resultados sugieren que la infestación de S. scabiei actúa en tándem con muestras externas y en la manada para definir la prevalencia y abundancia de los piojos y las garrapatas. También hemos aportado pruebas de diferencias en la concurrencia de especies sólo en las primeras etapas de la infestación de S. scabiei. Con respecto a la diversidad de las especies, grabamos al ectoparásito en comunidades de íbices con S. scabiei, que alcanzó una proliferación más rápida que en individuos sanos. Conclusiones: aunque nos muestran que la carga del ectoparásito está correlacionada con la infestación de S. scabiei, el entorno exterior y la manada, la respuesta a la infestación de la especie S. scabiei y el clima parece ser muy variable y está influido por rasgos de la historia vital del ectoparásito. Las comunidades de ectoparásitos también parecen resistentes a las perturbaciones, lo que está de acuerdo con lo previamente reportado para los endoparásitos. El futuro perfeccionamiento de la recogida de la muestra y la incorporación de los sistemas ecológicos y las variables epidemiológicas pueden permitirnos establecer efectos causales y profundizar los conocimientos sobre los mecanismos y las consecuencias de las interacciones de los ectoparásitos.Background: The host represents a heterogeneous ecosystem where multiple parasite species co-occur and interact with each other for space and resources. Although these interactions may rule the features of an infracommunity and may shape the infracommunity response to external perturbations, the resilience of ectoparasite communities to new infestations remains poorly explored. Methods: We analysed the composition of the ectoparasite communities found on 214 individual Iberian ibexes (Capra pyrenaica) inhabiting the Sierra Nevada Natural Space, southern Spain. Using classification and regression trees, we explored how the presence of Sarcoptes scabiei (a highly contagious mite), the off-host environment and the host sex govern the prevalence and abundance of lice and ticks. Null model analysis was applied to assess the impact of S.scabiei on the structure of the ectoparasite communities. Results: Our results suggest that S. scabiei infestation acts in tandem with off-host environment and host sex to define the prevalence and abundance of lice and ticks. We also provided evidence for differences in species co-occurrence only at the early stages of S. scabiei infestation. Regarding species diversity, we recorded that ectoparasite communities in scabietic ibexes reached a high richness faster than those in healthy individuals. Conclusions: Even though we show that ectoparasite burden is correlated with S. scabiei infestation, off-host environment and host sex, the species response to S. scabiei infestation and climate seem to be highly variable and influenced by ectoparasite life-history traits. Ectoparasite communities also appear resilient to perturbations which is in agreement with what was previously reported for endoparasites. Future refinement of sample collection and the incorporation of ecological and epidemiological-related variables may allow us to establish causal effects and deepen the knowledge about the mechanisms and consequences of ectoparasite interactions.Trabajo patrocinado por: Ministerio de Economía y Competitividad. Proyecto CGL2012-40043-C02-01 Gobierno de Andalucía. Ayuda RNM-118 Fundação para a Ciência e a Tecnologia, European Social Fund y Ministério da Educação e Ciência, National Funds. Beca PhD SFRH/BD/98387/2013 para João Carvalho Fundação para a Ciência e a Tecnologia. Programa Postdoctoral SFRH/BPD/96637/2013 para Emmanuel Serrano Fundação para a Ciência e a Tecnologia y Ministério da Educação e Ciência, para CESAM RU (UID/AMB/50017)peerReviewe

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58\ub75%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31\ub72%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10\ub72%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12\ub73%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9\ub74%] of 7339 patients), middle (549 [14\ub70%] of 3918 patients), and low (298 [23\ub72%] of 1282) HDI (p<0\ub7001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17\ub78%] of 574 patients in high-HDI countries; 74 [31\ub74%] of 236 patients in middle-HDI countries; 72 [39\ub78%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1\ub760, 95% credible interval 1\ub705\u20132\ub737; p=0\ub7030). 132 (21\ub76%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16\ub76%) of 295 patients in high-HDI countries, in 37 (19\ub78%) of 187 patients in middle-HDI countries, and in 46 (35\ub79%) of 128 patients in low-HDI countries (p<0\ub7001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication. Funding: DFID-MRC-Wellcome Trust Joint Global Health Trial Development Grant, National Institute of Health Research Global Health Research Unit Grant