Release of Lungworm Larvae from Snails in the Environment: Potential for Alternative Transmission Pathways

Background: Gastropod-borne parasites may cause debilitating clinical conditions in animals and humans following the consumption of infected intermediate or paratenic hosts. However, the ingestion of fresh vegetables contaminated by snail mucus and/or water has also been proposed as a source of the infection for some zoonotic metastrongyloids (e.g., Angiostrongylus cantonensis). In the meantime, the feline lungworms Aelurostrongylus abstrusus and Troglostrongylus brevior are increasingly spreading among cat populations, along with their gastropod intermediate hosts. The aim of this study was to assess the potential of alternative transmission pathways for A. abstrusus and T. brevior L3 via the mucus of infected Helix aspersa snails and the water where gastropods died. In addition, the histological examination of snail specimens provided information on the larval localization and inflammatory reactions in the intermediate host. Methodology/Principal Findings: Twenty-four specimens of H. aspersa received ~500 L1 of A. abstrusus and T. brevior, and were assigned to six study groups. Snails were subjected to different mechanical and chemical stimuli throughout 20 days in order to elicit the production of mucus. At the end of the study, gastropods were submerged in tap water and the sediment was observed for lungworm larvae for three consecutive days. Finally, snails were artificially digested and recovered larvae were counted and morphologically and molecularly identified. The anatomical localization of A. abstrusus and T. brevior larvae within snail tissues was investigated by histology. L3 were detected in the snail mucus (i.e., 37 A. abstrusus and 19 T. brevior) and in the sediment of submerged specimens (172 A. abstrusus and 39 T. brevior). Following the artificial digestion of H. aspersa snails, a mean number of 127.8 A. abstrusus and 60.3 T. brevior larvae were recovered. The number of snail sections positive for A. abstrusus was higher than those for T. brevior. Conclusions: Results of this study indicate that A. abstrusus and T. brevior infective L3 are shed in the mucus of H. aspersa or in water where infected gastropods had died submerged. Both elimination pathways may represent alternative route(s) of environmental contamination and source of the infection for these nematodes under field conditions and may significantly affect the epidemiology of feline lungworms. Considering that snails may act as intermediate hosts for other metastrongyloid species, the environmental contamination by mucus-released larvae is discussed in a broader context

Bovine besnoitiosis in a cattle herd in Sicily: an isolated outbreak or the acknowledgment of an endemicity?

Bovine besnoitiosis is a debilitating infectious disease caused by Besnoitia besnoiti (Apicomplexa; Sarcocystidae). The disease is mainly characterized by cutaneous and systemic signs, infertility in bulls, and abortion in cows. The current study describes an autochthonous outbreak of bovine besnoitiosis in Sicily, Southern Italy, being the first report of B. besnoiti infection in the island so far. In a cattle farm located in Syracuse province, a 4-year-old Belgian blue bull born in Sicily displayed typical clinical signs of the sub-acute/chronic disease phase with thickening of the skin of the scrotum and testicular degeneration. Histological examination of scrotal biopsies revealed the presence of several tissue cysts of B. besnoiti. The serological analysis of the herd using a commercial ELISA revealed a high seroprevalence (45 out of 55; 82%) of antibodies against B. besnoiti. Few seropositive animals (5 out of 45; 11%) showed clinical signs, cysts in vestibulum vaginae (1 out of 31; 3.2%), and testicular degeneration (4 out of 14; 28.6%) assessed by ultrasonographic investigations. The paucity of clinical signs associated with the high seroprevalence in the farm led to hypothesize that bovine besnoitiosis is endemic in the area though further studies are needed. Local practitioners should be more aware of the disease to facilitate the early detection of cases, prevent the spread of infection, and avoid economic losses and animal health problem

Vector-borne helminths of dogs and humans in Europe

Presently, 45% of the total human population of Europe, as well as their domestic and companion animals, are exposed to the risk of vector-borne helminths (VBH) causing diseases. A plethora of intrinsic biological and extrinsic factors affect the relationship among helminths, vectors and animal hosts, in a constantly changing environment. Although canine dirofilarioses by Dirofilaria immitis and Dirofilaria repens are key examples of the success of VBH spreading into non-endemic areas, another example is represented by Thelazia callipaeda eyeworm, an emergent pathogen of dogs, cats and humans in several regions of Europe. The recent finding of Onchocerca lupi causing canine and human infestation in Europe and overseas renders the picture of VBH even more complicated. Similarly, tick-transmitted filarioids of the genus Cercopithifilaria infesting the skin of dogs were recently shown to be widespread in Europe. Although for most of the VBH above there is an increasing accumulation of research data on their distribution at national level, the overall impact of the diseases they cause in dogs and humans is not fully recognised in many aspects. This review investigates the reasons underlying the increasing trend in distribution of VBH in Europe and discusses the diagnostic and control strategies currently available. In addition, this article provides the authors' opinion on some topics related to VBH that would deserve further scientific investigation

Effectiveness and safety of bimekizumab for the treatment of plaque psoriasis. a real-life multicenter study—IL PSO (Italian landscape psoriasis)

Introduction: Bimekizumab is a monoclonal antibody that targets Interleukin-17 A and F, approved for the treatment of moderate-to-severe plaque psoriasis. While bimekizumab has been evaluated in several phase-III clinical trials, real-world evidence is still very limited. Method: This multicenter retrospective study included patients affected by plaque psoriasis treated with bimekizumab from May 1, 2022 to April 30, 2023, at 19 Italian referral hospitals. Patients affected by moderate-to-severe plaque psoriasis eligible for systemic treatments were included. The effectiveness of bimekizumab was evaluated in terms of reduction in psoriasis area and severity index (PASI) compared with baseline at weeks 4 and 16. The main outcomes were the percentages of patients achieving an improvement of at least 75% (PASI75), 90% (PASI90) and 100% (PASI100) in PASI score. Results: The study included 237 patients who received at least one injection of bimekizumab. One hundred and seventy-one patients and 114 reached four and 16 weeks of follow-up, respectively. Complete skin clearance was achieved by 43.3% and 75.4% of patients at weeks 4 and 16, respectively. At week 16, 86.8% of patients reported no impact on their quality of life. At week 16, there were no significant differences between bio-naïve and bio-experienced patients in terms of PASI75, PASI90 and PASI100. The most commonly reported adverse events (AEs) were oral candidiasis (10.1%). No severe AEs or AEs leading to discontinuation were observed throughout the study. Conclusion: Our experience supports the effectiveness and tolerability of bimekizumab in a real-world setting with similar results compared with phase-III clinical trials

Lungworms and gastrointestinal parasites of domestic cats: a European perspective

With the exception of Aelurostrongylus abstrusus, feline lungworms have been poorly studied. Information on their distribution is patchy and mostly limited to case reports. In this study, the occurrence of feline lungworms and co-infecting gastrointestinal parasites has been investigated in 12 European countries (i.e. Austria, Belgium, Bulgaria, France, Greece, Hungary, Italy, Portugal, Romania, Spain, Switzerland and the United Kingdom). An average of 10 domestic cats, with regular outdoor access, was sampled each month for 12 months, and freshly passed faeces were collected. Stools were processed using a McMaster assay and a quantitative Baermann-Wetzel method. Animals positive for lungworms and/or gastrointestinal parasites were treated with a formulation containing fipronil, (S)-methoprene, eprinomectin, and praziquantel (Broadline®, Merial), and re-sampled 28 days post-treatment. The association between lungworm infection and risk factors was analysed using statistical medians/means and the efficacy of the treatment against each lungworm species was assessed. Of 1990 cats sampled, 613 (30.8%) were positive for at least one parasite, while 210 (10.6%) were infected by lungworms. The prevalence of lungworm infection varied between the sampled sites, with the highest recorded in Bulgaria (35.8%) and the lowest in Switzerland (0.8%). None of the cats from Austria or the United Kingdom were infected by lungworms. Aelurostrongylus abstrusus was the species most frequently detected (78.1%), followed by Troglostrongylus brevior (19.5%), Eucoleus aerophilus (14.8%) and Oslerus rostratus (3.8%). The overall efficacy of the treatment was 99% for A. abstrusus and 100% for T. brevior, O. rostratus and E. aerophilus. Data presented provide a comprehensive account of the diagnosis, epidemiology and treatment of feline lungworms in Europe, as well as of the occurrence of co-infections by gastrointestinal parasites.This work was funded by Merial SAS (Europe)