Pinto, P. | Search bioRxiv

bioRxiv2021

Cross-border investigations on the prevalence and transmission dynamics of Cryptosporidium species in dairy cattle farms in western mainland Europe

Cryptosporidium is comprised an apicomplexan parasitic protist, which infects a wide range of hosts, causing cryptosporidiosis. In cattle farms, the incidence of cryptosporidiosis results in high mortality in calves leading to considerable economic loss in the livestock industry. Infected animals may also act as a major reservoir of Cryptosporidium spp., in particular C. parvum, the most common cause of cryptosporidiosis in calves. This poses a significant risk to other farms via breeding centres, to trading of livestock and to human health. This study, funded by the Interreg-2-seas programme, is a part of a global project aimed at strategies to tackle cryptosporidiosis. To reach this target, it was essential to determine whether prevalence was dependent on the studied countries or if the issue was borderless. Indeed, C. parvum occurrence was assessed across dairy farms in certain regions of Belgium, France and the Netherlands. At the same time, the animal-to-animal transmission of the circulating C. parvum subtypes was studied. To accomplish this, 1084 faecal samples, corresponding to 57 dairy-farms from all three countries, were analysed. Well-established protocols amplifying the 18S rDNA and gp60 genes fragments, followed by DNA sequencing, were used for the detection and subtyping C. parvum; the DNA sequences obtained were further characterised using a combination of bioinformatics and phylogenetics methods. Our results show 25.7%, 24.9% and 20.8% prevalence of Cryptosporidium spp. in Belgium, France and the Netherlands respectively. Overall, 93% of the farms were Cryptosporidium positive. The gp60 subtyping demonstrated a significant number of the C. parvum positives belonged to the IIa allelic family, which has been also detected in humans. Consequently, this study highlights how widespread is C. parvum in dairy farms and endorses cattle as a major carrier of zoonotic C. parvum subtypes, which subsequently pose a significant threat to human health.

microbiology↗

bioRxiv2020

Heavily burned wood from wildfires is less likely to provide substrate for stream biota

O_LIIncreasingly severe forest fires are recruiting more heavily burned wood into streams. Wood affects every ecological and physical process in streams differently throughout seasons. However, little is known about the seasonality of wood functions in fire-prone biomes and how it combines with wood burning level to guide future postfire restoration efforts. C_LIO_LIThrough an extensive three-year seasonal tracking of stream wood following forest fires in central Portugal, we examined for the first time the influence of burning level, season, and a large suite of driving factors on the likelihood of each of four functions with primary ecological consequences -- retention of organic matter, serving as substrate for aquatic biota, being key pieces forming wood jams, and deflecting flow including pool habitat formation. C_LIO_LIOur results strongly support that one of the main ecological functions of wood in rivers, i.e. to provide substrate for biological organisms -- namely for vegetation, periphyton, biofilms, and ovipositions -- can be negatively affected in heavily burned wood. C_LIO_LIExcept for jam formation, the probability of each stream wood function changed markedly with season and the probability of non-function was nearly twice as high in the Euro-Mediterranean dry as in the wet season. C_LIO_LIMore anchored and decayed wood increased the probability of all functions, whereas the effect of submergence depended on the function. Challenging the "size paradigm" assuming larger-sized pieces to provide more function, our data suggest the effect of size to be function-specific. C_LIO_LISynthesis and applications. We show how postfire restoration success can be maximized by selecting the most appropriate wood, taking advantage of attribute-function relationships and choosing the right timing for operations. We urge managers to refrain from removing wood or to selectively remove the most heavily carbonized only, allowing the persistence of great potential to provide substrate for stream biota. The non-attraction of heavily burned wood as substrate can be compensated for by other wood with attributes enhancing this function, such as wood deeper within the bankfull area, and with large diameters. These results help to inform successful management, as is increasingly asked from restoration ecology. C_LI

ecology↗