- Brief communication
- Open Access
Prevalence of Toxoplasma gondii in common moles (Talpa europaea)
© Krijger et al., licensee BioMed Central Ltd. 2014
- Received: 16 April 2014
- Accepted: 15 July 2014
- Published: 30 July 2014
The prevalence of Toxoplasma gondii in common moles, Talpa europaea, was investigated in order to determine whether moles can serve as an indicator species for T. gondii infections in livestock.
In total, 86 moles were caught from 25 different sites in the Netherlands. Five different trapping habitats were distinguished: pasture, garden, forest, roadside, and recreation area. No positive samples (brain cysts) were found during microscopic detection (n = 70). Using the Latex Agglutination Test (LAT), sera of 70 moles were examined, whereby no sample reacted with T. gondii antigen. Real Time-PCR tests on brain tissue showed 2 positive samples (2.3%).
Because of the low number of positives in our study, the use of the common mole as an indicator species for livestock infections is currently not recommended.
- Food safety
- Outdoor farming
Toxoplasma gondii is a zoonotic pathogen, which can infect a wide range of intermediate hosts –. The disease burden of clinical toxoplasmosis is high ,– and the risk for human infection is considered substantial . In farm environments , and especially in animal production systems with outdoor access for livestock a major risk emerges because of the coincidental uptake of oocysts or intermediate hosts . If cats (definitive parasite hosts) that were not previously exposed to T. gondii consume infected intermediate hosts tissue (e.g. birds or rodents), they can start shedding oocysts which may disperse into the soil by precipitation  and be taken up by earthworms . Earthworms carry infectious T. gondii–, although from these studies it is unclear whether the parasite originated from the earthworms or the soil associated with them. Here, we test whether the common mole (Talpa europea), whose staple food consists of earthworms , can be an indicator species for T. gondii. Use of an indicator species would be beneficial as this reduces the need to obtain blood samples from livestock to measure T. gondii prevalence. Moreover, moles are considered a pest and are regularly trapped because of their destructive behaviour. To our knowledge, only two studies have previously investigated T. gondii prevalence in common moles. In the first study, a case-report of a dead mole that carried T. gondii was presented . In the second study, 7 of 18 common moles examined were found to be positive using a Modified Agglutination Test (MAT) .
Half of the brain of each non-frozen mole (n = 70) was homogenised after dissection using a cell strainer (0.2 μM) and plunger with addition of 5 ml PBS (phosphate buffered saline, 8.2 g NaCl, 0.20 g KCL, 1.15 g Na2HPO4, 0.38 g KH2PO4 per litre). In order to enrich the T. gondii cysts, 5 ml Percoll (Sigma Aldrich, Zwijndrecht, the Netherlands) 30% gradient was added underneath the homogenised brain sample. After centrifuging this mixture (1200 g for 15 min at 4°C), resuspended in PBS, a 25 μl pellet was analysed using a light microscope (20 ×), (Floating Technique ), according a modified protocol . Frozen moles were not included in this analysis. DNA was extracted from homogenised brain tissue (the frozen samples were homogenised by using an ultra turrax) with the DNeasy Blood & Tissue kit (Qiagen GMBH, Hilden, Germany), using a slightly adjusted protocol: glass homogeniser beads were added to the sample mixed by a vortex during 60 s to facilitate lysis, after which lysis buffer was added. Samples were then incubated at 56°C for 2.5 h. Hereafter, the protocol of the test manufacturer was followed. The extracted DNA samples were stored at −20°C until tested by Real-Time PCR. For serologic detection of both T. gondii IgG and IgM antibodies by direct agglutination, blood obtained from non-frozen mole hearts (n = 70) was tested with Toxo-reagent kit RST701 (Mast Diagnostics Ltd, Bootle, UK), according to manufacturer’s instructions. The test was performed in microtiter plates with U-shaped wells (Greiner Bio-One GmbH, Frickenhausen, Germany). Control and diagnostic sera were diluted 1:8, and titrated on the plates to a dilution 1:1024. In addition to control sera from the Toxo-reagent kit, internal positive cat and pig samples were used. The plates were analysed at normal daylight against a dark background. A positive reaction was noted when T. gondii agglutinated in the well until a dilution of 1:64 (1:32 will be regarded as doubtfull, <32 as negative) while a negative reaction was noted by sunken latex on the bottom of the well.
DNA samples were tested for T. gondii by a Real-Time PCR, oriented at target AF146527 . Results were obtained using amplification primers Tox-9 and Tox-11  as forward and reverse primers, respectively. Reactions were set up to a final volume of 25 μl containing 1 μl of DNA sample, 4 μl H2O, and 20 μl SYBR Green PCR Master Mix (Applied Biosystems, Paisley, UK). The Real-Time SYBR Green PCR reaction products were analysed with an ABI 7500 Real-Time PCR system with SDS Software Version 2.0.1 (Applied Biosystems, Paisley, UK) by a first cycle of 10 min of activation at 95°C. The subsequent dissociation step consisted of: 95°C/15 s; 60°C/1 min; 95°C/15 s for 40 cycles and the dissociation was measured stepwise, every 0.5°C.
Overview of the trapping numbers and habitat types
#Trapped (positives between brackets)
Results of the LAT and real time-PCR detection
In this study, T. gondii presence in moles was studied by different tests. Our LAT showed no sample that reacted with T. gondii antigen. For the Real-Time PCR brain tissue was used as this is the target organ in mice and it is also used for human prenatal diagnostics. Ct-values were high for the two moles testing positive with Real-Time PCR (36.61 and 36.57, respectively), which means that little T. gondii DNA was present in the brain samples. Such high values could indicate false positives. However, in an earlier study, it was found that the Ct-values of experimentally infected mice were around 20, whereas in naturally infected mice it varied between 35 and38 ,. Therefore, we assume that the two samples found positive using Real-Time PCR were indeed positive. The positive samples from the Real Time-PCR were not positive using the LAT. A reason can be that it takes time for the animal to produce antibodies against T. gondii, whilst parasite DNA is already present.
In previous studies from France and Germany common moles were identified as possible intermediate hosts for T. gondii,. However, infection rates in our study (0–2.3%, depending on the testing method) were significantly lower than the prevalence in the French study, where 39% of the moles from North-Eastern France tested positive .
Generally, animal age is positively related to the risk of T. gondii infection. In our study, the average age of trapped moles may have been lower, as most of them originated from habitats where moles are trapped regularly and so mainly juveniles are present. However, the age of the trapped moles was not determined. Because of the low number of positive samples in our study, no relation could be found between the prevalence of T. gondii in common moles, their gender or habitat type of the trapping location. Consequently, it must be concluded that the use of common moles as an indicator species is not yet feasible. Concerning habitat, we assumed beforehand that in areas where generally more cats are present (gardens and pastures) the infection rate would be the highest. However, due to the low number of positive specimens, it was not possible to prove this hypothesis statistically. In order to acquire more insight into this relationship, it would be necessary to increase the number of trapping locations and to test larger numbers of common moles. A comparison of T. gondii incidence in moles between countries that apply mainly indoor animal production systems (such as The Netherlands) and countries that apply outdoor animal production systems might be useful as well, as the low infection incidence could also be related to the type of production system. In conclusion, the use of common moles as an indicator species for T. gondii should be the subject of further study, preferably linked to detection of this pathogen in its diet (earthworms) and in near-by livestock.
This study was supported by strategic research funds of Wageningen Livestock Research, Department of Livestock & Environment. We would like to thank the participating mole trappers and the laboratory technicians.
- Acha PN, Szyfres B: Zoonoses and communicable diseases common to man and animals. 2003, Washington, DC, Pan American Health OrganizationGoogle Scholar
- Newell DG, Koopmans M, Verhoef L, Duizer E, Aidara-Kane A, Sprong H, Opsteegh M, Langelaar M, Threfall J, Scheutz F, Van der Giessen J, Kruse H: Food-borne diseases - the challenges of 20 years ago still persist while new ones continue to emerge. Int J Food Microbiol. 2010, 139: S3-S15. 10.1016/j.ijfoodmicro.2010.01.021.View ArticlePubMedGoogle Scholar
- Opsteegh M:Toxoplasma gondii in animal reservoirs and the environment. PhD thesis. 2011, Utrecht University, Faculty of Veterinary Medicine, Utrecht,Google Scholar
- Dubey JP: Toxoplasmosis - a waterborne zoonosis. Vet Parasitol. 2004, 126: 57-72. 10.1016/j.vetpar.2004.09.005.View ArticlePubMedGoogle Scholar
- Montoya JG, Liesenfeld O: Toxoplasmosis. Lancet. 2004, 363: 1965-1976. 10.1016/S0140-6736(04)16412-X.View ArticlePubMedGoogle Scholar
- Petersen E: Toxoplasmosis. Sem Fetal Neonat Med. 2007, 12: 214-223. 10.1016/j.siny.2007.01.011.View ArticleGoogle Scholar
- Sroka J, Cencek T, Ziomko I, Karamon J, Zwolinski J: Preliminary assessment of ELISA, MAT, and LAT for detecting Toxoplasma gondii antibodies in pigs. Bull Vet Inst Pulawy. 2008, 52: 545-549.Google Scholar
- Tenter AM, Heckeroth AR, Weiss LM:Toxoplasma gondii: from animals to humans. Intl J Parasitol. 2000, 30: 1217-1258. 10.1016/S0020-7519(00)00124-7.View ArticleGoogle Scholar
- Havelaar AH, Rosse F, Bubura C, Toetenel MA, Haagsma JA, Kurowicka D, Heesterbeek JAP, Van der Giessen JWB: Prioritizing emerging zoonoses in the Netherlands. PLoS One. 2010, 5: E13965-10.1371/journal.pone.0013965.PubMed CentralView ArticlePubMedGoogle Scholar
- Kornalijnslijper JE, Rahamat-Langendoen JC, Van Duynhoven YTHP: Volksgezondheidsaspecten van veehouderijmegabedrijven in Nederland. Zoönosen en antibioticumresistentie. 2008, Bilthoven, RIVMGoogle Scholar
- Meerburg BG, De Craeye S, Dierick K, Kijlstra A:Neospora caninum and Toxoplasma gondii in brain tissue of feral rodents and insectivores caught on farms in the Netherlands. Vet Parasitol. 2012, 184: 317-320. 10.1016/j.vetpar.2011.09.001.View ArticlePubMedGoogle Scholar
- Kijlstra A, Meerburg BG, Bos AP: Food safety in free-range and organic livestock systems: risk management and responsibility. J Food Prot. 2009, 72: 2629-2637.PubMedGoogle Scholar
- Meerburg BG, Kijlstra A: Changing climate—changing pathogens: Toxoplasma gondii in North-Western Europe. Parasitol Res. 2009, 105: 17-24. 10.1007/s00436-009-1447-4.PubMed CentralView ArticlePubMedGoogle Scholar
- Du F, Zhang Q, Yu Q, Hu M, Zhou Y, Zhao J: Soil contamination of Toxoplasma gondii oocysts in pig farms in central China. Vet Parasitol. 2012, 187: 53-56. 10.1016/j.vetpar.2011.12.036.View ArticlePubMedGoogle Scholar
- Bettiol S, Obendorf D, Nowarkowski M, Milstein T, Goldsmid J: Earthworms as paratenic hosts of toxoplasmosis in eastern barred bandicoots in Tasmania. J Wildlife Dis. 2000, 36: 145-148. 10.7589/0090-3558-36.1.145.View ArticleGoogle Scholar
- Frenkel JK, Ruiz A, Chinchilla M: Soil survival of Toxoplasma oocysts in Kansas and Costa Rica. Am J Trop Med Hyg. 1975, 24: 439-443.PubMedGoogle Scholar
- Ruiz A, Frenkel JK: Intermediate and transport hosts of Toxoplasma Gondii in Costa Rica. The Am J Trop Med Hyg. 1980, 29: 1161-1166.PubMedGoogle Scholar
- Funmilayo O: Distribution and abundance of moles (Talpa europaea L.) in relation to physical habitat and food supply. Oecol. 1977, 30: 277-283. 10.1007/BF01833635.View ArticleGoogle Scholar
- Geisel O, Breuer W, Minkus G, Hermanns W: Toxoplasmosis causing death in a common mole (Talpa europaea). Berl Munch Tierarztl Wochenschr. 1995, 108: 241-243.PubMedGoogle Scholar
- Afonso E, Poulle ML, Lemoine M, Villena I, Aubert D, Gilot-Fromont E: Prevalence of Toxoplasma gondii in small mammals from the Ardennes region, France. Fol Parasitol. 2007, 54: 313-314. 10.14411/fp.2007.041.View ArticleGoogle Scholar
- Cornelissen AW, Overdulve JP, Hoenderboom JM: Separation of Isospora (Toxoplasma) gondii cysts and cystozoites from mouse brain tissue by continuous density-gradient centrifugation. Parasitol. 1981, 83: 103-108. 10.1017/S0031182000050071.View ArticleGoogle Scholar
- Fritz H, Bar B, Packham A, Melli A, Conrad PA: Methods to produce and safely work with large numbers of Toxoplasma gondii oocysts and bradyzoite cysts. J Microbiol Meth. 2012, 88: 47-52. 10.1016/j.mimet.2011.10.010.View ArticleGoogle Scholar
- Homan WL, Vercammen M, De Braekeleer J, Verschueren H: Identification of a 200- to 300-fold repetitive 529 bp DNA fragment in Toxoplasma gondii, and its use for diagnostic and quantitative PCR. Int J Parasitol. 2000, 30: 69-75. 10.1016/S0020-7519(99)00170-8.View ArticlePubMedGoogle Scholar
- Reischl U, Bretagne S, Kruger D, Ernault P, Costa J-M: Comparison of two DNA targets for the diagnosis of toxoplasmosis by real-time PCR using fluorescence resonance energy transfer hybridization probes. BMC Inf Dis. 2003, 3: 7-10.1186/1471-2334-3-7.View ArticleGoogle Scholar