30th Annual Meeting of the German Society for Parasitology

Prof. Dr.

Screening of gastrointestinal parasites of dogs from municipal kennels in Portugal

Abstract text Introduction: Gastrointestinal parasites (GIP) are frequently reported in dogs worldwide, some of which are potentially zoonotic. Stray and shelter dogs are more prone to carry and spread GIP, but their prophylactic or therapeutical control is generally unknown. In Portugal, municipal kennels are facilities that shelter stray animals, but routine coprological analyses are rarely performed upon animal admission. Objectives: We performed a nationwide screening of GIP in dogs at municipal kennels and investigated the underlying potential causal factors. Materials &amp; Methods: Between November 2021-October 2022, 355 dog stool samples were collected in several municipal kennels in Portugal, and then processed with the Mini-FLOTAC technique, using zinc sulphate flotation solution. The influence of animal- and kennel-related variables in parasite presence was assessed by Fisher's exact tests, with 95% significance. Results: Approximately 17% (59/355) of the samples were GIP-positive. Trichuris sp. (20/355), Toxocaridae (19/355), Ancylostomatidae (13/355), and Cystoisospora sp. (8/355) were the most frequently observed parasites. Most of the positive samples (53/59) had more than 10 eggs or oocysts per gram. The results revealed that the region and number of dogs housed in kennels were significantly associated with the presence of Ancylostomatidae (p&lt; 0.001 and p=0.013, respectively) and Trichuris sp. (p=0.04 and p=0.03, respectively). Also, season was significantly associated with the presence of Ancylostomatidae eggs (p=0.004), while stool consistency and dogs' age range were significantly associated with Toxocaridae eggs (p=0.008 and p=0.049, respectively). Conclusion: To the best of our knowledge, this is the first nationwide screening of GIP in shelter dogs. The low overall GIP prevalence suggests that the internal deworming protocols in the assessed kennels are generally effective, with all of them deworming dogs internally upon admission, contributing to explain these results. However, our study also highlights the importance of considering several factors when establishing internal deworming protocols, including the intervention region encompassed by the kennel, the number of dogs housed and their age. Funding: Strategic Funding from FCT to cE3c (UIDB/00329/2020), CHANGE (LA/P/0121/2020), CIISA/FMV (UIDB/00276/2020), AL4AnimalS (LA/P/0059/2020), and to PL (2021.09447.BD), JL (2020.09037.BD) and ML (UI/BD/152818/2022), is gratefully acknowledged.

One Health/NTD/Zoonoses

Veterinary Parasitology

Talk

Prof.

Heavy infection with Contracaecum rudolphii A larvae in the intestine of Anguilla anguilla: Pathobiology and inflammatory response

Abstract text Introduction The European eel, Anguilla anguilla, is a major warm water fish species and Contracaecum rudolphii uses eel and several other fish species as paratenic host. Fish response to extra-intestinal parasites induce the formation of granuloma and granulomas are chronic inflammatory lesions that appear as nodules in one or more organs. Larvae (L3) of C. rudolphii A were encapsulated within the thickness of the eel intestinal wall and within a granuloma on the external visceral peritoneum (serosa). Information on the status of the eel immune system is of importance to maintain good health throughout the grow out period in eel fisheries. Objectives There is limited knowledge in terms of both cellular and humoral immune responses of A. anguilla to helminths. Identification of the host immune cells only with histology appeared to be insufficient. The current investigation was undertaken to gain information on the presence and distribution of 5 antibodies in different types of immune cells of A. anguilla intestine against C. rudolphii A (L3) larvae. Materials &amp; Methods From January to October 2022, a subsample of 40 eels from the Comacchio lagoons were examined, several 15 x 15 mm pieces (from infected-uninfected intestine) were excised and fixed in 10% neutral buffered formalin for 24 h and were assessed by histology techniques. For immunohistochemistry following molecules were tested: antibodies against immunoglobulin E (IgE)-like receptor (FCεRIγ), histamine, serotonin, tryptase and inducible-nitric oxide synthase (i-NOS). Results Twenty-four eels (60%) out of 40 harboured larvae (L3) of the nematode C. rudolphii A, the intensity of infection ranged from 5 to 76 parasites per eel. Conspicuous granulomas were visible on outer surface of the intestine. The outer part of the granuloma contained macrophages, macrophage aggregates, and mast cells (MCs) scattered among fibroblasts. The middle layer was rich in MCs and fibroblasts and the inner layer consisted mainly of dark epithelioid cells. Within the granulomas cells of different types were positive to antibodies anti-FCεRIγ, -histamine, -serotonin, -tryptase and -i-NOS. Conclusion Immune evasive mechanisms render the parasites able to survive even years in tissue despite the high abundance of host immune cells in vicinity. This survey might suggest an evolutionary trade-off between eel tolerance and relatively inactive nematode larva within granuloma.

Wildlife Parasites

Evaluating the in vivo efficacy of using the predatory fungus Mucor circinelloides (FMV-FR1) in the reduction of coccidia shedding in a peacock collection

Abstract text Introduction: Since the late 1990&quot;s, it has been demonstrated that the use of predatory fungi is a sustainable approach for the integrated control of gastrointestinal (GI) parasites affecting domestic, exotic and wild captive animals. However, studies performed in birds are still scarce. Objectives: This pioneer research aimed to assess the in vivo efficacy of using the ovicidal fungus M. circinelloides for reducing coccidia shedding in a peacock collection. Materials &amp; methods: This trial was performed between October and December 2022, in the resident peacock collection (n=60 birds) of São Jorge Castle, at Lisbon, Portugal. A total of 33 fungal administrations were performed, P.O. and 3x/week, using supplements composed by 600 g of bird feed mixed with 60 mL of a M. circinelloides (FMV-FR1) suspension (106 spores/bird). Feces were collected every 15 days, and then processed and analysed using the Mini-FLOTAC technique, to calculate the coccidia shedding (Oocysts per Gram of Feces – OPG). This bird collection served simultaneously as control (t0 days) and test group (t15-t90 days). Parasite shedding for each test timeframe was compared with control, using the Mann-Whitney Test, while the appearance of samples (normal vs blood and/or diarrhoea) was assessed using the Fisher Exact Test (95% significancy). Results: Peacocks were initially positive for Eimeria sp. (20107 ± 8034 OPG), and 88% (15/17) of the samples had normal appearance. Afterwards, it was possible to observe an overall decrease in the coccidia shedding, with reduction efficacies of 62%, 78%, 78%, 92%, 70% e 59%, after 15, 30, 45, 60, 75 and 90 days of fungal feeding, respectively, and with the values for days 45 and 60 being significant (p=0.004 and p=0.012, respectively). Finally, feces appearance did not differ between each test timeframe and the control time point. Conclusion: This strain of M. circinelloides was effective in reducing coccidia parasitism in peacocks, being the first study of this kind in birds, worldwide. Results suggest that this fungal strain might be used in integrated programs for the GI parasite control. Funding: This research was funded by CIISA/FMV Project UIDB/00276/2020 and LA/P/0059/2020 - AL4AnimalS (both funded by FCT). Also, João Lozano owns a PhD research fellowship 2020.09037.BD (funded by FCT).

Drug Development/Target Identification

Echinococcus spp. Namibian wildlife

Abstract text Introduction: Cystic Echinococcosis is a worldwide occurring zoonotic disease and can be caused by five distinct species of the cestode genus Echinococcus. Only in Africa are all five species present. Whereas E. felidis was so far only be found in wildlife, the lifecycle of the four other species, E. granulosus sensu stricto (s.s.), E. ortleppi, E. canadensis (G6/7) and E. equinus, is clearly associated with various livestock species and domestic dogs. However, previous studies showed that some of those domestic Echinococcus species can also be found in wild animals, e.g. E. granulosus s.s. in Kenyan lions. There is, however, little known about the extent to which wild animals are involved in the different lifecycles and their maintenance. Objective: The present study was conducted to learn more about the situation of Echinococcus spp. in wildlife in Namibia. Material &amp; Methods: At various locations in Namibia, faecal samples were collected from 224 wild carnivores and examined for the presence of taeniid eggs, and 300 possible wild intermediate hosts were examined for the presence of cysts. For species identification, eggs and cysts were analysed by PCR and sequencing of the nad1 or cox1 gene. Results: Echinococcus spp. could be identified in 31 carnivorous and 39 intermediate hosts. As anticipated, the wildlife adapted E. felidis could be detected in lions (7) and warthogs (4). However, the livestock associated species were also present. Echinococcus granulosus s.s. was found in African wild dog (2), E. ortleppi in black-backed jackals (2) and oryx antelopes (6) and E. equinus in lions (9), black-backed jackals (2) and zebras (27). The Echinococcus species detected in the most wildlife species was E. canadensis G6/7, namely in lions (3), cheetahs (3), African wild dogs (1), black-backed jackals (2) and oryx antelopes (2). Conclusion: All five Echinococcus species have been detected in Namibian wildlife, although only E. ortleppiand E. canadensis G6/7 have been found so far in Namibian cattle and sheep, respectively. These results indicate that the presence of Echinococcus spp. in wildlife is not accidental, but wild animals are important links in the parasitic lifecycle, at lease in the study area.

Seal louse and heartworm: Time trends and impact on harbour seals in the North and Baltic Sea

Abstract text Pinnipeds provide a livelihood for numerous parasites, showing unique morphological and physical adaptions to the semiaquatic lifestyle of their host. Echinophthirius (E.) horridus, the seal louse and the heartworm Acanthocheilonema (A.) spirocauda outline a possible unique vector-parasite congregate transported to the marine environment. Commonly mild health effects are reported, yet they can cause anaemia, alopecia or arteritis and obstruction of vessels in severe cases. E.horridus is discussed to play an obligatory role as vector for heartworm filariae (A. spirocauda) of harbour seals (Phoca vitulina). In this study we examined the prevalence of A.spirocauda and E.horridus in harbour seals (n = 672) between 2014 and 2021 to analyse time trends and life history traits using a unique sample set collected within a stranding network along the North and Baltic Sea coast comprising necropsy results, histological data and tissue archive. Additional Confocal Laser Scanning Microscopy (CLSM), nanoCT and attachment force measurements were performed to characterise physical solutions for life on marine hosts.Infection of harbour seals with A.spirocauda was found in 11% (n = 76). The prevalence of A.spirocauda varied over the seven-year-study period, and showed a notable increase compared to previous decade. Seal lice were found in 4% (n = 26) of the examined harbour seals. Seal lice prevalence remained relatively low. For both parasites, there were no sex related differences in infection patterns but a higher prevalence in yearling and young–of-the-year seals. Histological screening of seal lice revealed larval nematode stages in the hemocoel supporting the hypothesis of seal lice functioning as intermediate host and vector of A.spirocauda. Additional histology showed lesions affecting the health status of their host. CLSM of E.horridus indicates sclerotized structures and nanoCT aided in 3D reconstruction of musculoskeletal system, providing first understandings of attachment mechanisms. Increased prevalence of A.spirocauda over the study period may reflect growing seal populations, higher densities on haul-outs, thereby facilitating transmission by lice vectors. Higher prevalence in younger age groups might reflect the social behaviour of harbour seals within the different age groups; it could also indicate a vertical transmission pattern. The results underline, parasites are useful indicators for host ecology and ecosystem changes in the North and Baltic Sea.

Plasmodium and beyond - haemosporidian parasites of a Malagasy bird population

Abstract text Haemosporida are important intracellular protozoan parasites. In addition to the genus Plasmodium, other genera also belong to this order: Haemoproteus and Leucocytozoon, among others. Whereas species of the order Plasmodium can be found in all vertebrate taxa, Haemoproteus and Leucocytozoon are specialized on birds. Basic knowledge of prevalence, diversity and impact of all avian haemosporidian parasites is still scarce. A long-term, large-scale molecular study of a bird population in Madagascar is providing new insights into the parasite population that exists there. An enormous number of unknown haemosporidian lineages were found, showing that Madagascar is not only a biodiversity hotspot for birds, but also for their parasites. Each haemosporidian parasite differs in its degree of host specialization and abundance. Understanding those parasite-host interactions is crucial to assess the impact of these parasites on the environment.

Session V
Veterinary Parasitology & Wildlife Parasites II

Termin

Vorsitzende

Programm

Session VVeterinary Parasitology & Wildlife Parasites II

Termin

Vorsitzende

Programm

Session V
Veterinary Parasitology & Wildlife Parasites II