Endoparasite loads and the efficacy of conventional anthelmintics against gastrointestinal nematodes in captive European bison

Although little information exists on the efficacy of deworming in wild ruminants, gastrointestinal nematodes have been found to demonstrate increasing drug resistance. The spread of drug-resistant strains may be increased by transmission among livestock and susceptible wildlife species, thus posing a potential threat to endangered species, such as the European bison. The aim of the study was twofold: to identify the parasite loads in captive European bison with the use of coprological techniques, and to test the influence of other nearby ungulates on the richness of bison parasitofauna. Additionally, the efficacy of deworming procedures against gastrointestinal nematodes in bison was evaluated. The survey was based on a coprological investigation of 285 fecal samples from 156 European bison in 15 enclosures. The parasitofauna of the captive European bison was consistent with those of free-ranging populations. The highest prevalence was noted for Eimeria spp. oocysts (60.7%), strongyle eggs (50.9%), Fasciola hepatica eggs (13.1%), Dictyocaulus viviparus larvae (12.3%) and Trichuris sp. Eggs (9.47%). Moreover, the close proximity of other ungulate species resulted in a higher diversity of parasite species. In all cases, deworming with albendazole, fenbendazole and ivermectin proved to be ineffective against strongylids and Trichuris sp. The results of fecal egg count reduction test (FECRT) ranged from 37.2 to 99.6% (95% CI <90%) for albendazole; values >95% (95% CI = 41-100) were noted for fenbendazole, and FECRT ranged from 63.2 to 97.5 (95% CI = 0-99) for ivermectin. As the results of anthelmintic treatment are unsatisfactory, it seems justified to continue study in this area. Our study is the first large-scale attempt to evaluate the efficacy of anthelminthics in captive European bison. The potential sharing of parasite species between bison and other ungulates should also be further investigated from the perspective of minimizing the risk of the spread of drug-resistant parasite strains.

Coproscopical diagnosis of patent Fasciola hepatica infections in sheep - A comparison between standard sedimentation, FLUKEFINDER® and a combination of both

The liver fluke Fasciola hepatica is a highly pathogenic and zoonotic trematode with a cosmopolitan distribution. In livestock, infections may lead to significant economic losses if not diagnosed promptly and treated effectively. Particularly for small ruminants, the standard method for the detection of fluke infection is based on coproscopical methods such as the sedimentation method, which detects F. hepatica eggs in faecal samples. In this respect a recent innovative coproscopical approach to diagnose patent infections is the FLUKEFINDER® method, which relies on differential sieving before sedimentation. These two methods and a combination of both methods that allows larger amounts of faeces to be processed with the FLUKEFINDER® apparatus were compared, to assess which method is most appropriate to determine the prevalence and intensity of F. hepatica egg shedding. The methods were compared for their ability to recover eggs from ovine faecal samples containing different numbers of fluke eggs per gram (EPG) of faeces and diluting the samples further by mixing with faeces from uninfected sheep. To compare the specificity of the test procedures, positive and negative samples with a low EPG were analysed in parallel by an investigator blinded to the nature of the samples. Significant differences concerning the EPG outcome were found: The FLUKEFINDER® method demonstrated the highest EPG values (p < 0.001) in the undiluted samples as well as in all mixing levels, followed by the modified FLUKEFINDER® method. The standard sedimentation showed the lowest EPG values and the highest variability between technical replicates. The precision of the FLUKEFINDER® method and the modified FLUKEFINDER® method were significantly higher than the precision of the standard sedimentation as determined by comparison of variability between technical replicates. The highest raw egg counts were detected using the modified FLUKEFINDER® method. The FLUKEFINDER® method and the combined method showed a sensitivity of 100 % even at the lowest egg concentrations, whereas the sensitivity of the standard sedimentation was 98.1 % for the same set of samples (i.e. one false negative sample). In a separate investigation aiming to estimate the specificity no differences were found between the three methods: all protocols showed 100 % specificity and were able to correctly distinguish between truly positive and truly negative samples without any evidence of cross-contamination between positive and negative samples processed in parallel.

infection in dogs

Echinococcosis and taeniasis are important helminth diseases that carry considerable impact on human and animal health. Domestic dogs and other canids are definitive hosts for several parasites of this group, including Echinococcus granulosus, Taenia multiceps, T. ovis, T. hydatigena and E. multilocularis. Detection of infection in dog populations is imperative for estimating the risk to susceptible humans and animals, and for its mitigation through prevention measures in dogs, other animals and humans. To date, identification of taeniid eggs, antigens or DNA in fecal samples are the most practical diagnostic modalities available for canine definitive hosts. Although widely used for this purpose, there is limited information comparing copro PCR and combined coproscopy-PCR protocols for the detection of taeniids. In the current study, a widely used multiplex PCR was performed on a large number of dog fecal samples using DNA extracted directly from feces. The samples were also tested by fecal flotation and coproscopy, eggs were isolated from microscopically-positive samples and extracted DNA was tested using the same multiplex PCR. The total number of taeniid positive samples detected using both methods was 46/317 (14.5%), including 10/317 (3.2%) E. granulosus positive samples. Both copro PCR and coproscopy have identified an equal number of samples as taeniid positive (n = 32). However, for the purpose of identification to species level, the copro PCR was significantly more sensitive than coproscopy followed by PCR on isolated eggs (sensitivity 0.7 vs. 0.41, p = 0.012), with 32/317 (10.1%) and 19/317 (6%) positive samples identified, respectively. The difference in identification of E. granulosus was highly apparent, as the majority of the E. granulosus positive samples (8/10) were detected by the copro PCR only. Coproscopy and egg PCR have identified 5/317 (1.6%) positive samples not detected by the copro PCR, including only a single sample (0.3%) positive for E. granulosus. Adding these positive samples to those identified by the copro PCR did not significantly improve the overall sensitivity (p = 0.074). Therefore, using both copro PCR and coproscopy in parallel may not be advantageous for taeniid detection and identification, at least until the egg PCR is further optimized and performs better. These results should be weighed against the different advantages that coproscopy based approach may offer.

Gastrointestinal parasites in non-human primates in zoological institutions in France

Gastrointestinal parasites are frequently encountered in captive non-human primates and infestation may have severe consequences on the animal's health status. Most of these parasites are also transmissible to humans. Nevertheless, little is known about the prevalence and monitoring modalities of gastrointestinal parasitoses in non-human primates housed in zoological institutions and there are currently no guidelines available for their detection and identification. The objective of this study was to identify the main gastrointestinal parasites that may be observed in non-human primates in zoological institutions in France, as well as to develop a decision-making tree to ease their identification. Twenty-four zoological institutions were surveyed, most of which performed fecal examinations routinely on their non-human primates (91.7%). Most institutions used flotation enrichment protocols to detect gastrointestinal parasites (95.2%) and nematodes were the most frequently encountered parasites (73.0%). A total of 252 fecal samples corresponding to 68 different non-human primate species from these institutions were analyzed using sedimentation and flotation protocols. Protozoa (47.3%) were found to be more frequent than helminths (15.6%). Furthermore, old-world monkeys exhibited a higher parasite load (93.6%) than any other non-human primate species category. Compiled data from fecal examinations allowed the development of a decision-making tree and diagnostic atlas to facilitate parasite diagnosis in captive non-human primates.

Veterinary monitoring of gastrointestinal parasites in European bison, Bison bonasus designated for translocation: Comparison of two coprological methods

It is important to monitor the level of parasitic loads in herds of European bison and to identify threats early enough to prevent their spread to other populations or species. The aim of the present study was to compare the detection sensitivity of two fecal flotation techniques, viz. the modified Willis method (WM) with centrifugation and modified McMaster flotation technique (MM), in the diagnostics of gastrointestinal parasites of European bison before the translocation of animals.

Out of 166 feces samples, Eimeria spp. oocysts (84.3% in WM and 71.1% in MM) and Trichostrongylidae eggs (82.5% in WM and 53.6% in MM) predominated. These were accompanied by eggs from Capillaria spp. (prevalence: 13.9% in WM and 3.61% in MM), Nematodirus spp. (prevalence: 18.1% in WM and 4.8% in MM) and Trichuris spp. (prevalence: 12.7% in WM and MM) were identified. The lowest prevalence was noted for cestode eggs of Moniezia spp. (5.4% in WM and 3.0% in MM).

The Willis method yielded a higher prevalence of eggs and oocysts than the modified McMaster method, and hence has a higher probability of detecting parasitic structures than the modified McMaster method, especially in cases of very low levels of invasion.

As the two methods yield consistent results, it is recommended to use the Willis method for diagnosis of internal parasite infection in European bison. This test offers more sensitive method than McMaster technique of detecting the presence of low levels of a variety of parasite eggs and oocysts in feces, while also being inexpensive and adaptable to field work.

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Methods yield similar relative prevalence.

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Higher prevalence of eggs/oocysts in Willis than McMaster.

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Very low prevalence may not be detected by the McMaster method.

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Proposed formulas are provided for converting prevalence between methods.

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The Willis method is recommended over the McMaster method.

Evaluation of a spot-on imidacloprid-moxidectin formulation (Advocate®) for the treatment of naturally occurring esophageal spirocercosis in dogs: a double-blinded, placebo-controlled study

Background

Dogs are the definitive hosts of Spirocerca lupi. Spirocercosis is treated by prolonged avermectin administration by injection or daily oral doses. In this prospective, double-blinded, placebo-controlled, clinical trial, the efficacy of imidacloprid and moxidectin spot-on formulation (Advocate®) was compared to injectable doramectin (Dectomax®). Dogs diagnosed with benign esophageal spirocercosis were divided randomly into doramectin (400 μg/kg IM) or moxidectin and imidacloprid spot-on (2.5–6.25 mg/kg and 10–25 mg/kg, respectively) groups and treated weekly for 12 consecutive weeks. Dogs were followed for 20 weeks by physical examination, owners’ questionnaire, blood work, fecal floatation, PCR and endoscopy.

Results

All the doramectin group dogs (n = 10) completed the treatment and follow-up, and the disease had completely resolved in all by week 12. Of the Advocate® group (n = 10), four had complete resolution at week 12, four had partial resolution, one dog did not respond to treatment, and one dog was switched to the doramectin protocol on week 5 due to persistent severe clinical signs. PCR analysis was more sensitive in detecting S. lupi eggs compared to fecal floatation. Discrepancies were detected on 22 occasions, of which on 20 occasions, the PCR was positive while fecal floatation was negative, and only on two occasions the PCR results were negative while fecal flotation was positive.

Conclusions

The present results indicate that weekly Advocate® spot-on administration may be effective for treating benign esophageal spirocercosis, but is less effective than the currently used injectable doramectin therapy at the dose and duration used herein.

Detection and quantification of Spirocerca lupi by HRM qPCR in fecal samples from dogs with spirocercosis

Background

Spirocerca lupi, the dog oesophageal nematode, causes a potentially fatal disease in domestic dogs, and is currently clinically diagnosed by coproscopy and oesophagoscopy. To date, a single molecular method, a semi-nested PCR, targeting the cox1 gene, has been developed to aid in the diagnosis of spirocercosis. The present study describes three novel high-resolution melt (HRM) quantitative PCR (qPCR) assays targeting fragments of the ITS1, 18S and cytb loci of S. lupi. The performance of these molecular assays in feces was compared to fecal flotation and to the previously described cox1 gene semi-nested PCR in 18 fecal samples from dogs with clinical oesophageal spirocercosis diagnosed by oesophagoscopy.

Results

The HRM qPCR for ITS1 and 18S were both able to detect 0.2 S. lupi eggs per gram (epg), while the HRM qPCR for the cytb and the semi-nested PCR for the cox1 detected 6 epg and 526 epg, respectively. Spirocerca lupi was detected in 61.1%, 44.4%, 27.8%, 11.1% and 5.6% of the fecal samples of dogs diagnosed with spirocercosis by using the ITS1 and 18S HRM qPCR assays, fecal flotation, cytb HRM qPCR and cox1 semi-nested PCR, respectively. All dogs positive by fecal flotation were also positive by ITS1 and 18S HRM qPCRs. Quantification of S. lupi eggs was successfully achieved in the HRM qPCRs and compared to the fecal flotation with no significant difference in the calculated concentrations between the HRM qPCRs that detected the 18S and ITS1 loci and the fecal flotation. The HRM qPCR for the 18S cross-amplified DNA from Toxocara canis and Toxascaris leonina. In contrast, the HRM qPCR for ITS1 did not cross-amplify DNA from other canine gastrointestinal parasites.

Conclusions

This study presents two new molecular assays with significantly increased sensitivity for confirming and quantifying fecal S. lupi eggs. Of these, the HRM qPCR for ITS1 showed the best performance in terms of the limit of detection and absence of cross-amplification with other parasites. These assays will be useful in detecting infection and for follow-up during therapy.

Electronic supplementary material

The online version of this article (10.1186/s13071-017-2374-3) contains supplementary material, which is available to authorized users.

Coproscopy and molecular screening for detection of intestinal protozoa

Background

Intestinal parasitosis is one of several health concerns about immigrants who travel from endemic to non-endemic regions. Reliable rapid sensitive diagnostic tools, for use in non-endemic regions, are urgently required to enable frequent assessment of immigrant workers in jobs where risk of local transmission is a particular concern (e.g. food-handlers). We assessed the burden of intestinal protozoa in newly arrived immigrants and those applying for renewal of work permits in Qatar (n = 735), by both microscopic examination of stool samples and by Real Time PCR methodology.

Results

Prevalence was considerably higher using RT-PCR compared with coproscopy (Blastocystis hominis: 65.2 vs 7.6%; Giardia duodenalis: 14.3 vs 2.9%; Entamoeba histolytica: 1.6 vs 1.2%). Dientamoeba fragilis was sought only by RT-PCR (prevalence of 25.4%). Prevalence of G. duodenalis was significantly higher in male subjects, associated with blue collar workers and declined over time. Prevalence of B. hominis varied significantly with region of origin of subjects with highest values recorded among African immigrants. Prevalence of D. fragilis also varied with region of origin of subjects, and was lower in young female subjects and in renewal applicants compared with first-time applicants for work permits.

Conclusions

We strongly recommend that, henceforth, intestinal protozoa should be screened by RT-PCR, with a particular focus on frequent assessment of immigrant food-handlers.

American Association of Veterinary Parasitologists' review of veterinary fecal flotation methods and factors influencing their accuracy and use--is there really one best technique?

The principle of fecal flotation is based on the ability of a solution to allow less dense material (including parasite elements) to rise to the top. However, there are numerous factors that will influence the accuracy and use of such a theoretically simple technique. Whether or not centrifugation is used appears to have an impact on the ability to detect some parasites, but not others. Using a flotation solution with a relatively high specific gravity favors the simultaneous flotation of the diagnostic stages of many different parasites while, at the same time, making recognition of some more difficult because of distortion as well as the amount of debris in the preparation. Dilution methods tend to be less accurate because they require extrapolation; however, they are quicker to perform, in part, because of the cleaner preparation. Timing is a critical factor in the success of all flotation methods, as is technical ability of the personnel involved. Thus, simplicity, low costs and time savings have generally favored gravitational flotation techniques (including the McMaster technique and its modifications). How accurate the method needs to be is dependent upon the purpose of its use and choice of method requires an understanding of analytical sensitivity and expected levels of egg excretion. In some instances where the difference between, for example, 0 and 50 eggs per gram is insignificant with regards to management decisions, less accurate methods will suffice. In others, where the presence of a parasite means treatment of the animal regardless of the numbers of eggs present, methods with higher analytical sensitivities will be required, particularly for those parasites that pass few eggs. For other uses, such as the Fecal Egg Count Reduction Test, accuracy may become critical. Therefore, even though recommendations for standardized fecal flotation procedures have been promoted in the past, it is clear that the factors are too numerous to allow for the recommendation of one, or even a few, procedures for all purposes.