Abstract
The growing popularity of reptiles has contributed to their reproduction in captivity. When subjected to stressful environments, such as the presence of a higher number of humans and animals, reptiles may become more susceptible to parasites. Endoparasites in captive animals may cause several clinical signs ranging from mild to severe: lethargy, anorexia, diarrhea, cloacal/penile prolapse, infertility, intestinal malabsorption syndrome, and weight loss, among others. This study aimed to assess the presence of gastrointestinal parasites in fecal samples of reptiles from a Portuguese zoo through two techniques: a fecal flotation test (using a saturated sodium chloride solution) and Mini-FLOTAC. Ninety-nine samples belonging to 22 different animal species were collected and analyzed. Parasites were identified in 53.5% of the samples. Chelonians had a higher frequency (100%), followed by lizards (56.8%) and snakes (47.4%). The eggs/oocysts found were oxyurids (36.4%), strongylids/Kalicephalus sp. (8.1%), Eimeria sp. (5.1%), Hymenolepis spp. (5.1%), ascarids (4.0%), and Isospora sp. (2.0%). Both techniques presented the same results for each sample. The high prevalence of oxyurids, as well as of other parasites, can be explained by possible environmental contamination as these reptiles are kept in captivity. This study indicated the importance of assessing parasitic infections in reptiles in zoos, where routine coprological examinations should always be considered, as well as adequate prophylaxis.
1. Introduction
The growing popularity of reptiles has contributed to their captive breeding. However, there are few studies regarding the prevalence of diseases, particularly parasitic ones, which affect these animals in zoos. Reptiles, when subjected to stressful environments (such as those with a high concentration of animals and humans in restricted habitats), can become more immunologically susceptible to parasites that are often pathogenic to them, including possibly to other animals, such as humans [1,2]. Therefore, this topic has to be investigated using a One Health perspective. Reptiles kept in captivity have shown a higher prevalence of parasites and more efficient transmission of various monoxenous parasites compared to wild reptiles [2,3]. Additionally, in captive animals that were captured from their natural habitats, the absence of intermediate hosts, dietary changes, and other factors have been demonstrated to promote the adaptation of parasites to new conditions, potentially threatening other zoo animals, since there are different susceptibilities among different reptiles [1].
Endoparasites can cause different clinical outcomes depending on the species and their life cycle, habitat conditions, infection severity, and the host (age, sex, and health) [3]. Although mild helminth infections are generally well tolerated by reptiles, severe infections can result in clinical pathology, especially in young or immunocompromised animals [4]. An oxyurid infection may lead to lethargy, anorexia, diarrhea, cloacal/penile prolapse, growth disturbances, infertility, and, in high burdens, it can cause intestinal malabsorption syndrome, which can result in severe clinical conditions [5,6]. Kalicephalus sp. is the most common nematode in snakes and may cause weight loss, enteritis, lethargy, and anorexia [7]. Like helminths, reptiles also host a variety of intestinal unicellular pathogens, such as Blastocystis spp., Cryptosporidium spp., Eimeria spp., Entamoeba spp., Giardia spp., and Isospora spp. [8]. An infection by Entamoeba invadens can cause anorexia, dehydration, bloody diarrhea, hepatitis, gastritis, and colitis. Conversely, an infection by Eimeria spp. can result in weight loss and enteritis [4,9]. In Table 1, some epidemiological studies from European countries (with special emphasis on Portugal), with the prevalence of different helminths and protozoa identified in fecal samples from reptiles, are presented.
Table 1.
Prevalence (%) of helminths and protozoa identified in fecal samples from reptiles.
There are several methods for quantitative parasitological analysis, such as McMaster, FLOTAC, and Mini-FLOTAC. The last method provides faster results with higher repeatability and sensitivity while requiring less labor work and no centrifugation [17,18]. Although techniques like Mini-FLOTAC can be applied to samples from any host, their use in reptiles is uncommon [3]. This study aims to assess the presence of gastrointestinal parasites in reptiles kept in a Portuguese zoo using two techniques: a flotation test (using a saturated sodium chloride—NaCl—solution) and Mini-FLOTAC.
2. Materials and Methods
Between February 2021 and February 2022, fecal samples were collected from reptiles in a Portuguese zoo. In zoos, the aim is to carry out minimal animal manipulation. To achieve this, most animals have never been dewormed or previously dewormed animals are not dewormed for at least a year. All the samples collected were from animals placed in individual enclosures. For this study, 99 reptile samples were collected from 22 species of reptiles kept at Zoo da Maia (Portugal) and analyzed for the presence of gastrointestinal parasites (Table 2).
Table 2.
Species (scientific and common name) and number of reptiles examined.
The samples were collected from the environment immediately after defecation, during the normal daily activities of animal management and facility hygiene. After collection, the samples were stored in identified plastic bags at 4 °C and processed within 48 h through coprological methods in the laboratory of the Escola Superior Agrária of the Instituto Politécnico de Viana do Castelo (ESA—IPVC), Portugal. Each fecal sample was macroscopically checked for tapeworm proglottids and adult roundworms and then analyzed through a flotation test (a saturated sodium chloride solution, specific gravity of 1.2) [4] and Mini-FLOTAC techniques. Concerning Mini-FLOTAC, two flotation solutions were used—NaCl (specific gravity of 1.2) and zinc sulphate (ZnSO4) (specific gravity of 1.35)—following the instructions reported in the original description by Cringoli et al. [19]. A dilution factor of 1:20 was used in Mini-FLOTAC (2 g of sample was added to 38 mL of solution). To the best of our knowledge, a Mini-FLOTAC protocol for reptiles has not yet been defined; therefore, only qualitative results were considered for both techniques: Mini-FLOTAC and the traditional flotation test. To detect the presence of eggs/oocysts, a conventional optical microscope was used with total magnifications of 100× and 400×. Eggs and oocysts were identified according to the descriptions of Zajac et al. [4].
3. Results
Of the 99 samples examined, we detected the presence of parasites (eggs/oocysts) in 53 (53.5%). All of the chelonians investigated presented parasites (100%, n = 5/5), while the prevalence of parasites decreased in lizards (56.8%, n = 21/37), followed by snakes (47.4%, n = 27/57) (Table 3 and Table 4). Both techniques showed the same parasites for each sample.
Table 3.
Species and number of lizards examined and frequency of parasites.
Table 4.
Species and number of snakes examined and frequency of parasites.
Overall, the most frequent parasites were oxyurids (36.4%, n = 36/99) and strongylid/Kalicephalus sp. (8.1%, n = 8/99) (Table 5 and Figure 1).
Table 5.
Frequency of parasites in examined chelonians, lizards, and snakes.
Figure 1.
Microphotographs of reptile gastrointestinal parasites. (a) Oxyurid egg (on the left) and Isospora sp. oocyst (on the right); (b) Eimeria sp. oocyst; (c) Hymenolepis nana eggs; (d) Ascarid egg. All images were taken using a total magnification of 400×.
Among the samples where parasites were identified (n = 53), mixed parasitic infections were found in six (11.3%) reptiles. Only one chelonian out of the five investigated presented mixed parasitic infections (20.0%), followed by 2 lizards out of 37 (5.4%) and 3 snakes out of 57 (5.3%) investigated.
4. Discussion
Gastrointestinal parasites, primarily protozoa and nematodes, are commonly found in reptiles in captivity, possibly due to the monoxenous life cycle of several species and the high resistance of oocysts, eggs, or larvae, allowing them to survive in captive habitats [3]. Furthermore, as stated by Panayotova-Pencheva et al. [1], the confined environment of zoo habitats promotes geo-helminth development and maintenance, leading to frequent re-infections of reptiles.
According to Jacobson [20], parasites from the superfamily Oxyuroidea are usually observed as intestinal parasites in chelonians and lizards, often developing a commensal relationship with the host. The high frequency of oxyurids in this study in lizards and snakes can be explained by the fact that these parasites do not require an intermediate host to complete their life cycle [21]. Moreover, animals with an herbivorous and insectivorous diet are frequently parasitized by oxyurids [20], with at least twelve different genera of oxyurids already reported in snakes, lizards, and chelonians [21]. Moreover, the eradication of oxyurids may not always be successful [22]. Several studies reported a high prevalence of these parasites [2,5,6,10,11,12,13,14,15].
In the present study, ascarids were only identified in chelonians; however, they can also be found in snakes and lizards [2]. Ascarids have a monoxenous life cycle but can be transmitted via feeding or cohabitation through a paratenic host, such as amphibians, small mammals, and other reptiles [22]. Although the number of chelonian samples in this study was small (n = 5), the frequency of these parasites was high (80.0%).
The prevalence of strongylids (8.1%) in this study was lower compared to previous studies that found a prevalence of 20.4% (11/55), mainly Kalicephalus spp. [2], or 19.7% (14/74) [23]. Both of these previous studies were carried out in pet reptiles, which may explain the higher prevalence of parasites. The zoo sanitary and medical prophylaxis measures are more efficient in preventing parasitic infections. Conversely, other studies reported a lower prevalence, such as Pasmans et al. [3]. Although the definite host of Kalicephalus spp. is snakes [20], a small percentage of chelonians and lizards could also be affected (possibly functioning as paratenic hosts). These parasites have a direct life cycle and an oral infection route, with the possibility of transcutaneous infection, although this has not been properly proven [24].
Coccidiosis is one of the main causes of morbidity and mortality in reptiles [25]. The most common coccidian genera in these animals are Eimeria and Isospora [26], as found in this study. These parasites have a direct life cycle and are transmitted via the fecal–oral route through food, fomites, and infected substrates present in the terrarium [20,22], thus increasing the likelihood of transmission.
In this study, only two bearded dragons (Pogona vitticeps) were parasitized by the genus Isospora. Although the number is small, this is considered by Heard et al. [9] to be the most commonly reported coccidiosis in this species. Despite the small number, the prevalence of this genus in lizards (5.4%, 2/37) was higher than in the study by Rataj et al. [2], who reported 0.9%. These differences could be explained by the sample size of the different studies, as Rataj et al. [2] analyzed 949 samples while we investigated 99 samples.
According to Jacobson [20], the genus Eimeria is usually found in snakes and lizards. In this study, Eimeria was not identified in lizards, and in snakes, it had a lower prevalence (5.1%) compared to other studies (27.0% and 6.2%, respectively) [6,16]. The differences found between the studies may be related to the origin of the samples (whether they were collected from pet reptiles or a zoo), the size of the sample, and also the enormous diversity of reptiles that exist, each with its physiology, management, and very particular microbiota.
Although Hymenolepis sp. was found in this study in boas (Boa constrictor), its definitive host is the field vole [27]. Rinaldi et al. [6] considered it a pseudoparasite. In the present study, as boas are carnivorous, this parasite may have been acquired through feeding on live voles. Although it does not harm reptiles, this parasite is zoonotic [27], which underlines the importance of maintaining good hygiene practices among zoo staff during feeding and cleaning activities.
Overall, parasites can infect reptiles in a zoo through the introduction of a new animal that has not been quarantined in the zoo, through intermediary and paratenic hosts, or, even more probably, through food contamination and human visitors or staff who might be infected with these parasites [1]. All these parameters can and should be as controlled as possible, aiming for minimal manipulation of these animals (for instance, to proceed to medical prophylaxis or treatment) to avoid stress and for animal well-being purposes. This could be achieved by promoting training of zoo staff on biosecurity measures, zoonoses, and the importance of good personal hygiene practices to reduce the cross-contamination between habitats and protect animals and human health using a One Health perspective. Frequent and regular cleaning of the environment must be practiced, which will undoubtedly reduce the number of infective stages of different parasites in the environment, hence controlling such parasites.
The Mini-FLOTAC technique used in this study proved to be sensitive, as described in the literature. In the future, it would be useful to define a Mini-FLOTAC protocol for reptiles, together with reference values of eggs/oocysts per gram of feces that would allow distinguishing parasitism from parasitosis.
5. Conclusions
This study highlights the importance of assessing the presence of gastrointestinal parasites in reptile enclosures in zoological gardens. The present study found that 53.3% of the reptiles were infected with gastrointestinal parasites, demonstrating that, even with the high management standards practiced at the zoo, along with regular fecal examinations, a non-negligible frequency of parasitic infections remains. It is considered that if the biosecurity measures were reduced, a higher frequency of infection would become evident. Routine coprological examinations should always be conducted, and if diagnosed, animals should be properly treated and their environment sanitized as soon as possible. Furthermore, it is crucial to promote training of zookeepers from a One Health perspective.
Author Contributions
Conceptualization, D.D., C.L.B. and T.L.M.; methodology, D.D., C.L.B., M.J.C., N.A. and T.L.M.; formal analysis, D.D. and T.L.M.; investigation, C.L.B., M.J.C., N.A. and T.L.M.; resources, T.L.M.; data curation, D.D., M.J.C., C.L.B. and T.L.M.; writing—original draft preparation, D.D. and T.L.M.; writing—review and editing, D.D., C.L.B. and T.L.M.; supervision, T.L.M.; funding acquisition, T.L.M. All authors have read and agreed to the published version of the manuscript.
Funding
The participation of Teresa Letra Mateus was funded by national funds through FCT—Fundação para a Ciência e Tecnologia, I.P., within the scope of the project UIDB/05937/2020 with the DOI identifier https://doi.org/10.54499/UIDB/05937/2020 and UIDP/05937/2020 with the DOI identifier https://doi.org/10.54499/UIDP/05937/2020.
Institutional Review Board Statement
Ethical review and approval were waived for this study due to the fact that the samples were collected non-invasively; therefore, this study does not include any experimentation on animals.
Data Availability Statement
The original contributions presented in the study are included in the article; further inquiries can be directed to the corresponding author.
Acknowledgments
We would like to acknowledge the zookeepers who helped with the sampling of this study. The authors wish to thank Carla Canedo Ribeiro for her constructive feedback on earlier drafts. David Dantas, Cláudia Luís Batista, and Maria João Castro participated in this study in the context of their bachelor/master’s degree in Veterinary Nursing at IPVC.
Conflicts of Interest
The authors declare no conflicts of interest.
References
- Panayotova-Pencheva, M.S. Parasites in Captive Animals: A Review of Studies in Some European Zoos. Zool. Gart. 2013, 82, 60–71. [Google Scholar] [CrossRef]
- Rataj, A.V.; Lindtner-Knific, R.; Vlahović, K.; Mavri, U.; Dovč, A. Parasites in pet reptiles. Acta Vet. Scand. 2011, 53, 33. [Google Scholar] [CrossRef] [PubMed]
- Pasmans, F.; Blahak, S.; Martel, A.; Pantchev, N. Introducing reptiles into a captive collection: The role of the veterinarian. Vet. J. 2008, 175, 53–68. [Google Scholar] [CrossRef] [PubMed]
- Zajac, A.M.; Conboy, G.A.; Little, S.E.; Reichard, M.V. Veterinary Clinical Parasitology, 9th ed.; Wiley-Blackwell: Hoboken, NJ, USA, 2021. [Google Scholar]
- Hallinger, M.J.; Taubert, A.; Hermosilla, C.; Mutschmann, F. Occurrence of health-compromising protozoan and helminth infections in tortoises kept as pet animals in Germany. Parasites Vectors 2018, 11, 1–12. [Google Scholar] [CrossRef] [PubMed]
- Rinaldi, L.; Mihalca, A.D.; Cirillo, R.; Maurelli, M.P.; Montesano, M.; Capasso, M.; Cringoli, G. FLOTAC can detect parasitic and pseudoparasitic elements in reptiles. Exp. Parasitol. 2012, 130, 282–284. [Google Scholar] [CrossRef] [PubMed]
- Raiti, P. Snakes. In BSAVA Manual of Exotic Pets, 4th ed.; Meredith, A., Redrobe, S., Eds.; British Small Animal Veterinary Association: Quedgeley, UK, 2002; pp. 241–256. [Google Scholar]
- Magnino, S.; Colin, P.; Dei-Cas, E.; Madsen, M.; McLauchlin, J.; Nöckler, K.; Prieto Maradona, M.; Tsigarida, E.; Vanopdenbosch, E.; Van Peteghem, C. Biological risks associated with consumption of reptile products. Int. J. Food Microbiol. 2009, 134, 163–175. [Google Scholar] [CrossRef] [PubMed]
- Heard, D.; Fleming, G.; Lock, B.; Jacobson, E. Lizards. In BSAVA Manual of Exotic Pets, 4th ed.; Meredith, A., Redrobe, S., Eds.; British Small Animal Veterinary Association: Quedgeley, UK, 2002; pp. 223–240. [Google Scholar]
- Nonnis, F.; Tamponi, C.; Pinna, S.; Diana, F.; Pudda, F.; Muzzeddu, M.; Cavallo, L.; Zeinoun, P.; Carta, C.; Varcasia, A.; et al. Epidemiological survey of gastrointestinal helminthes and protozoa in Testudines from Sardinia, Italy. Vet. Parasitol. Reg. Stud. Andreports 2024, 54, 101084. [Google Scholar] [CrossRef] [PubMed]
- Hallinger, M.J.; Taubert, A.; Hermosilla, C.; Mutschmann, F. Captive Agamid lizards in Germany: Prevalence, pathogenicity and therapy of gastrointestinal protozoan and helminth infections. Comp. Immunol. Microbiol. Infect. Dis. 2019, 63, 74–80. [Google Scholar] [CrossRef] [PubMed]
- Murnik, L.C.; Schmäschke, R.; Bernhard, A.; Thielebein, J.; Eulenberger, K.; Barownick, N.; Gawlowska, S.; Delling, C. Parasitological examination results of zoo animals in Germany between 2010 and 2022. Int. J. Parasitol. Parasites Wildl. 2024, 24, 100942. [Google Scholar] [CrossRef] [PubMed]
- Ruivo, M.G.V.V. Parasitas Gastrointestinais em Répteis de Estimação em Barcelona. Master’s Thesis, Universidade de Lisboa, Lisbon, Portugal, 2019. Available online: https://repositorio.ulisboa.pt/handle/10400.5/17612 (accessed on 3 February 2024).
- Vítor, B.A.B. Prevalência de Parasitas Gastrointestinais em Répteis Domésticos na Região de Lisboa. Master’s Thesis, Universidade Lusófona de Humanidades e Tecnologias, Lisbon, Portugal, 2018. [Google Scholar]
- Bernardino, M.S.N. Parasitas Gastrointestinais de uma Colecção Privada de Geckos-Leopardo (Eublepharis macularius) e de Répteis Tidos como Animais de Estimação no Norte de Portugal. Master’s Thesis, Universidade Lusófona de Humanidades e Tecnologias, Lisbon, Portugal, 2014. Available online: https://repositorio.ulisboa.pt/handle/10400.5/7616 (accessed on 3 February 2024).
- Carvalho, T.J.F. Parasitas Gastrointestinais em Répteis de uma Coleção Comercial. Master’s Thesis, Universidade de Lisboa, Lisbon, Portugal, 2018. Available online: https://repositorio.ulisboa.pt/handle/10400.5/16344 (accessed on 3 February 2024).
- Szatmári, V. Feline Lungworm Infection. In August’s Consultations in Feline Internal Medicine; Little, S., Ed.; Elsevier: St. Louis, MO, USA, 2015; Volume 7, pp. 379–386. [Google Scholar]
- Barda, B.D.; Rinaldi, L.; Ianniello, D.; Zepherine, H.; Salvo, F.; Sadutshang, T.; Cringoli, G.; Clementi, M.; Albonico, M. Mini-FLOTAC, an Innovative Direct Diagnostic Technique for Intestinal Parasitic Infections: Experience from the Field. PLoS Neglected Trop. Dis. 2013, 7, e2344. [Google Scholar] [CrossRef] [PubMed]
- Cringoli, G.; Maurelli, M.P.; Levecke, B.; Bosco, A.; Vercruysse, J.; Utzinger, J.; Rinaldi, L. The Mini-FLOTAC technique for the diagnosis of helminth and protozoan infections in humans and animals. Nat. Protoc. 2017, 12, 1723–1732. [Google Scholar] [CrossRef] [PubMed]
- Jacobson, E. Parasites and Parasitic Diseases of Reptiles. In Infectious Diseases and Pathology of Reptiles: Color Atlas and Text; Jacobson, E., Ed.; Taylor & Francis Group: Boca Raton, FL, USA, 2007; pp. 571–666. [Google Scholar]
- Taylor, M.; Coop, R.; Wall, R. Reptiles. In Veterinary Parasitology, 3rd ed.; Blackwell Publishing: Oxford, UK, 2007; pp. 1523–1543. [Google Scholar]
- Greiner, E.C.; Mader, D.R. Parasitology. In Reptile Medicine and Surgery, 2nd ed.; Greiner, E.C., Mader, D.R., Eds.; Elsevier: Boston, MA, USA, 2006; pp. 343–364. [Google Scholar]
- Papini, R.; Manetti, C.; Mancianti, F. Coprological survey in pet reptiles in Italy. Vet. Rec. 2011, 169, 207. [Google Scholar] [CrossRef] [PubMed]
- Anderson, R. The Superfamily Diaphanocephaloidea. In Nematode Parasites of Vertebrates, Their Development and Transmission; Anderson, R., Ed.; CABI Publishing: Wallinford, UK, 2000; pp. 43–44. [Google Scholar]
- Tully, J.T.; Mitchell, M. Reptiles and Amphibians. In A Veterinary Technician’s Guide to Exotic Animal Care, 2nd ed.; Tully, J., Mitchell, M., Eds.; AAHA Press: Lakewood, OH, USA, 2012; pp. 37–78. [Google Scholar]
- Greiner, E. Coccidiosis in reptiles. Semin. Avian Exot. Pet Med. 2003, 12, 49–56. [Google Scholar] [CrossRef]
- Tijjani, M.; Majid, R.A.; Abdullahi, S.A.; Unyah, N.Z. Detection of rodent-borne parasitic pathogens of wild rats in Serdang, Selangor, Malaysia: A potential threat to human health. Int. J. Parasitol. Parasites Wildl. 2020, 11, 174–182. [Google Scholar] [CrossRef] [PubMed]
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).