1. Investigación

Fish not only harbor host-specific species/genotypes of Cryptosporidium, but also species like zoonotic C. parvum or anthroponotic C. hominis, which can pose a risk for fish consumers. This study aims to investigate fish cryptosporidiosis in an important aquaculture and fishery area of the Western Mediterranean (Comunidad Valenciana, Spain). We analyzed 404 specimens belonging to the following three groups: cultivated fish (N = 147), wild synanthropic fish (N = 147) and wild fish from extractive fisheries (N = 110). Nested PCR targeting the 18S rRNA gene, followed by sequencing and phylogenetic analysis, were performed. Positive isolates were also amplified at the actin gene locus. An overall prevalence of 4.2% was detected, with the highest prevalence in the synanthropic group (6.1%). C. molnari was identified in thirteen specimens from seven different host species. Zoonotic C. ubiquitum was detected in two European sea bass (Dicentrarchus labrax). One isolate similar to C. scophthalmi was detected in a cultivated meagre (Argyrosomus regius), and one isolate, highly divergent from all the Cryptosporidium species/genotypes described, was identified from a synanthropic round sardinella (Sardinella aurita). This study contributes to increasing the molecular data on fish cryptosporidiosis, expanding the range of known hosts for C. molnari and identifying, for the first time, zoonotic C. ubiquitum in edible marine fishes, pointing out a potential health risk.

Leishmaniasis is a neglected disease presenting cutaneous, mucosal and visceral forms and affecting an estimated 12 million mostly low-income people. Treatment of cutaneous leishmaniasis (CL) is recommended to expedite healing, reduce risk of scarring, prevent parasite dissemination to other mucocutaneous (common with New World species) or visceral forms and reduce the chance of relapse, but remains an unmet need. Available treatments are painful, prolonged (>20 days) and require hospitalisation, which increases the cost of therapy. Here we present the development of optimised topical self-nanoemulsifying drug delivery systems (SNEDDS) loaded with buparvaquone (BPQ, a hydroxynapthoquinone from the open Malaria Box) for the treatment of CL from New World species. The administration of topical BPQ-SNEDDS gels for 7 days resulted in a reduction of parasite load of 99.989 ± 0.019 % similar to the decrease achieved with intralesionally administered Glucantime® (99.873 ± 0.204 %) in a L. amazonensis BALB/c model. In vivo efficacy was supported by ex vivo permeability and in vivo tape stripping studies. BPQ-SNEDDS and their hydrogels demonstrated linear flux across non-infected CD-1 mouse skin ex vivo of 182.4 ± 63.0 μg cm-2 h-1 and 57.6 ± 10.8 μg cm-2 h-1 respectively localising BPQ within the skin in clinically effective concentrations (227.0 ± 45.9 μg and 103.8 ± 33.8 μg) respectively. These levels are therapeutic as BPQ-SNEDDS and their gels showed nanomolar in vitro efficacy against L. amazonensis and L. braziliensis amastigotes with excellent selectivity index toward parasites versus murine macrophages. In vivo tape stripping experiments indicated localisation of BPQ within the stratum corneum and dermis. Histology studies confirmed the reduction of parasitism and indicated healing in animals treated with BPQ-SNEDDS hydrogels. These results highlight the potential clinical capability of nano-enabled BPQ hydrogels towards a non-invasive treatment for CL.

Cutaneous fungal and parasitic diseases remain challenging to treat, as available therapies are unable to permeate the skin barrier. Thus, treatment options rely on systemic therapy, which fail to produce high drug local concentrations but can lead to significant systemic toxicity. Amphotericin B (AmB) is highly efficacious in the treatment of both fungal and parasitic diseases such as cutaneous leishmaniasis, but is only reserved for parenteral administration in patients with severe pathophysiology. Here, we have designed and optimised AmB-transfersomes [93.5 % encapsulation efficiency, size of 150 nm, and good colloidal stability (-35.02 mV)] that can remain physicochemically stable (>90 % drug content) at room temperature and 4 °C over 6 months when lyophilised and stored under desiccated conditions. AmBtransfersomes possessed good permeability across mouse skin (4.91 ± 0.41 μg/cm2/h) and 10-fold higher permeability across synthetic Strat-M® membranes. In vivo studies after a single topical application in mice showed permeability and accumulation within the dermis (>25 μg AmB /g skin at 6 h post-administration) indicating the delivery of therapeutic amounts of AmB for mycoses and cutaneous leishmaniasis, while a single daily administration in Leishmania (Leishmania) amazonensis infected mice over 10 days resulted in excellent efficacy (98 % reduction in Leishmania parasites). Combining the application of AmB-transfersomes with metallic microneedles in vivo increased levels in the SC and dermis but is unlikely to elicit transdermal levels. In conclusion, AmB-transfersomes are promising and stable topical nanomedicines that can be readily translated for parasitic and fungal infectious diseases.

The diversity and frequency of enteric parasites in dog populations in the Castellón province (Eastern Spain) was assessed by means of a prospective cross sectional epidemiological survey. A total of 263 canine faecal samples were collected between July 2014 and July 2016. Detection of intestinal parasites was conducted by routine coprological methods. In addition, identification of Giardia duodenalis and Cryptosporidium spp. was carried out by direct immunofluorescence microscopy, whereas the presence of Strongyloides spp. was assessed by real-time PCR in a selected number of specimens. Based on conventional and/or immunofluorescence microscopy examination, 65.8% (95% CI: 59.7%‒71.5%) of the investigated dogs were found infected by at least one gastrointestinal parasite. Giardia duodenalis (35.4%) and members of the family Ancylostomatidae (27.0%) were the most prevalent protozoan and helminth parasites found, respectively. Other pathogens potentially infective to human included Toxocara canis (8.0%), Cryptosporidium spp. (6.8%), and Strongyloides spp. (1.1%). Frequency of occurrence of helminthic, but not protozoan, enteroparasites was geographical origin-dependent (P = 0.02), with dogs living in coastal areas presenting higher infection rates than those living in inland regions. Similarly, rural dogs were significantly more infected than urban dogs (P < 0.001). Our results revealed that zoonotic agents were common in dogs from the Castellón province. Animals from rural areas and sheltered dogs were particularly at risk of these infections.

In recent decades, worldwide fish consumption has increased notably worldwide. Despite the health benefits of fish consumption, it also can suppose a risk because of fishborne diseases, including parasitic infections. Global changes are leading to the emergence of parasites in new locations and to the appearance of new sources of transmission. That is the case of the zoonotic protozoa Cryptosporidium spp., Giardia duodenalis, and Toxoplasma gondii; all of them reach aquatic environments and have been found in shellfish. Similarly, these protozoa can be present in other aquatic animals, such as fish. The present review gives an overview on these three zoonotic protozoa in order to understand their potential presence in fish and to comprehensively revise all the evidences of fish as a new potential source of Cryptosporidium spp., Giardia duodenalis, and Toxoplasma gondii transmission. All of them have been found in both marine and freshwater fishes. Until now, it has not been possible to demonstrate that fish are natural hosts for these protozoa; otherwise, they would merely act as mechanical transporters. Nevertheless, even if fish only accumulate and transport these protozoa, they could be a “new” source of infection for people.