1. Investigación

Oestrus ovis is an obligate parasite that causes myiasis in domestic ruminants, being commonly found in the Mediterranean area. From 2009 to 2019 a total of 3476 heads of culling sheep and goats from the Mediterranean coast of Spain were examined for the presence of O. ovis. The total prevalence was 56.3%, significantly higher in sheep than in goats (61.2% and 43%, respectively). Differences were found in the mean annual prevalence, with the highest value being registered in 2018 (61.7%) and the lowest in 2012 (50.3%). Autumn, for sheep, and winter, for goats, were the seasons with the highest number of infested specimens. Temperature, but not rainfall, was found to be associated with prevalence (p < 0.05). Most L1 were found in the anatomic region I (septum, meatus, and ventral conchae), while L2 and L3 were mainly located in regions II (nasopharynx, ethmoid labyrinth, and dorsal conchae), and III (sinuses). The overall intensity was 12.8 larvae per head, significantly higher in sheep (13.3) than in goats (3.5). Our results confirm the high prevalence of O. ovis in sheep and goats in this geographic area over the last decade, with the trend increasing in recent years in association with higher mean temperatures.

Visceral leishmaniosis is the one of the most important protozoal zoonoses in Europe, and it is caused by Leishmania infantum, an intracellular protozoan parasite. The disease is endemic in dogs in the Mediterranean area. The main goal of this work is to correlate the levels of several cytokines linked to immune response against L. infantum infection in two canine breeds. Thirty-one Boxer and twenty-eight Ibizan Hound dogs living in the Valencian Community (East coast of Spain) were analyzed for the presence of anti-Leishmania antibodies in serum by IFAT test. Cytokines IFN-γ, TNF-α, IL-2, IL-6, IL-8, and IL-18 were determined by ELISA commercial tests. The levels of IFN-γ, IL-2, and IL-18 in our study, cytokines linked to a cellular immune response, were higher (p < 0.05) in the Ibizan Hound breed; IL-6 levels were higher, although not significant, and only levels of IL-8 were higher in Boxer than in Ibizan Hound. No expression of TNF-α was found. These results corroborate that Ibizan Hound can develop a protective response against canine leishmaniosis, while Boxer is a susceptible breed. The study of immunological aspects in the different canine breeds may represent a useful tool in the prediction of the disease.

Honeybee populations have locally and temporally declined in the last few years because of both biotic and abiotic factors. Among the latter, one of the most important reasons is infection by the microsporidia Nosema ceranae, which is the etiological agent of type C nosemosis. This species was first described in Asian honeybees (Apis cerana). Nowadays, domestic honeybees (Apis mellifera) worldwide are also becoming infected due to globalization. Type C nosemosis can be asymptomatic or can cause important damage to bees, such as changes in temporal polyethism, energy and oxidative stress, immunity loss, and decreased average life expectancy. It causes drastic reductions in workers, numbers of broods, and honey production, finally leading to colony loss. Common treatment is based on fumagillin, an antibiotic with side effects and relatively poor efficiency, which is banned in the European Union. Natural products, probiotics, food supplements, nutraceuticals, and other veterinary drugs are currently under study and might represent alternative treatments. Prophylaxis and management of affected colonies are essential to control the disease. While N. ceranae is one potential cause of bee losses in a colony, other factors must also be considered, especially synergies between microsporidia and the use of insecticides.

Leishmaniosis is the third most important vector-borne disease in humans, preceded by malaria and lymphatic filariasis, and it is considered endemic in tropical and subtropical areas, where higher temperatures favor development of its vector, sandflies. This zoonotic disease is caused by infection of protozoa Leishmania spp. and the most serious mucocutaneous and visceral form is produced by Leishmania infantum, which predominates in the Mediterranean region. The usual hosts for this parasite are dogs and humans, but an increment in cases of L. infantum infection has been observed in cats in the last years. This increase could be due to the use of sandflies repellents in dogs, obligating the parasite to looking for other hosts. The role of cats in the epidemiology of this disease is unknown, although increase of prevalence of feline leishmaniosis has been observed in endemic areas in the last years. Diagnostic techniques and treatments in cats are not standardized, which makes it difficult to establish prevalence and epidemiology of feline leishmaniosis. Furthermore, the clinical signs and immune response against Leishmania in cats are different to those in dogs, with an observed increment of drug resistance. It is necessary to increase our knowledge about L. infantum infection in cats, including clinical signs, transmission, treatments, and the role of cats in the increasing of zoonoses. Finally, new alternative treatments are required for controlling the spread of this disease in all species of mammals.

More than 50 years after anthelmintic resistance was first identified, its prevalence and impact on the animal production industry continues to increase across the world. The term “anthelmintic resistance” (AR) can be briefly defined as the reduction in efficacy of a certain dose of anthelmintic drugs (AH) in eliminating the presence of a parasite population that was previously susceptible. The main aim of this study is to examine anthelmintic resistance in domestic herbivores. There are numerous factors playing a role in the development of AR, but the most important is livestock management. The price of AH and the need to treat a high number of animals mean that farmers face significant costs in this regard, yet, since 1981, little progress has been made in the discovery of new molecules and the time and cost required to bring a new AH to market has increased dramatically in recent decades. Furthermore, resistance has also emerged for new AH, such as monepantel or derquantel. Consequently, ruminant parasitism cannot be controlled solely by using synthetic chemicals. A change in approach is needed, using a range of preventive measures in order to achieve a sustainable control programme. The use of nematophagous fungi or of plant extracts rich in compounds with anthelmintic properties, such as terpenes, condensed tannins, or flavonoids, represent potential alternatives. Nevertheless, although new approaches are showing promising results, there is still much to do. More research focused on the control of AR is needed.

Anisakidosis is a parasitic zoonotic disease which can cause gastroallergic reactions in humans. In 2010, the European Food Safety Agency estimated that approximately 20,000 cases of anisakiasis had been reported across the world, with Spain having the highest number of infections in Europe. The blue whiting (Micromesistius poutassou, Risso, 1827) is one of the most widely fished species worldwide and represents around 25% of the white fish eaten in Spain. The Spanish Food Safety Authority requires obligatory evisceration of certain fish species before commercialization, but not for blue whiting. Nevertheless, some supermarkets carry this out themselves to prevent human infections and negative customer reactions deriving from the presence of ascaridoid larvae. To assess the effectiveness of eviscerations at supermarkets, a total of 320 blue whiting specimens were examined. The risk of larval migration from the visceral cavity to the musculature in gutted and ungutted fish was also assessed. Our results showed a total prevalence (25%) of ascaridoids in fish gutted at the supermarket, and a direct relationship was found between the presence of larvae in the muscle and time until evisceration. In ungutted fish, the standard length and weight were higher for infected than for non-infected fish. Also, massive infections had a higher prevalence in these larger specimens, in which the viability of larvae was also high. Larval viability was not found to be affected by a 24-h refrigeration period. Anisakis was the most prevalent genus identified in the fish examined. The results indicate that gutting at the supermarket is not an effective method for the total removal of ascaridoid larvae and that additional safety measures are advisable.

En el presente capítulo se comenta la importancia del uso de los parásitos en diferentes áreas de investigación, destacando los trabajos relativos a las especies parásitas de los peces marinos. En esta sección veremos que los parásitos no son tan malos como los pintan ya que pueden ayudarnos a conocer el origen de las capturas pesqueras y a diferenciar entre poblaciones de peces. Tambiés es importante su conocimiento en las especies acuícolas que se producen en todo el mundo y son indicadores de las alteraciones medioambientales y del cambio climático global. Además, se desarrollarán ejemplos de cómo la actuación del ser humano puede provocar algunas de las connotaciones negativas que se atribuyen, a través de ejemplos con especies invasoras-introducidas y del problema de la anisakiosis.