Whip- and pinworm infections elicit contrasting effector and distinct regulatory responses in wild house mice

Infections with high doses of intestinal nematodes result in protective immunity based on robust type 2 responses in most mouse lines under laboratory conditions. Here, we report on cellular responses of wild house mice from northern Germany. We detected robust Th1 responses in wild house mice naturally infected with the whipworm Trichuris muris. In contrast, mice infected with pinworms (Syphacia, Aspiculuris) reported type-2 activity by elevated IgG1 levels and eosinophil counts, but also harbored high frequencies of Foxp3+ Treg cells, suggesting that natural whip- and pinworm infections induce distinct immunoregulatory as well as effector profiles.

PCR Testing of IVC Filter Tops as a Method for Detecting Murine Pinworms and Fur Mites

We evaluated PCR testing of filter tops from cages maintained on an IVC system through which exhaust air is filtered at the cage level as a method for detecting parasite-infected and -infested cages. Cages containing 4 naïve Swiss Webster mice received 360 mL of uncontaminated aspen chip or α-cellulose bedding (n = 18 cages each) and 60 mL of the same type of bedding weekly from each of the following 4 groups of cages housing mice infected or infested with Syphacia obvelata (SO), Aspiculuris tetraptera (AT), Myocoptes musculinus (MC), or Myobia musculi (MB) and Radfordia affinis (RA; 240 mL bedding total). Detection rates were compared at 30, 60, and 90 d after initiating bedding exposure, by using PCR analysis of filter tops (media extract and swabs) and testing of mouse samples (fur swab [direct] PCR testing, fecal flotation, anal tape test, direct examination of intestinal contents, and skin scrape). PCR testing of filter media extract detected 100% of all parasites at 30 d (both bedding types) except for AT (α-cellulose bedding, 67% detection rate); identified more cages with fur mites (MB and MC) than direct PCR when cellulose bedding was used; and was better at detecting parasites than all nonmolecular methods evaluated. PCR analysis of filter media extract was superior to swab and direct PCR for all parasites cumulatively for each bedding type. Direct PCR more effectively detected MC and all parasites combined for aspen chip compared with cellulose bedding. PCR analysis of filter media extract for IVC systems in which exhaust air is filtered at the cage level was shown to be a highly effective environmental testing method.

Evaluation of Traditional and Contemporary Methods for Detecting Syphacia obvelata and Aspiculuris tetraptera in Laboratory Mice

There is no consensus regarding the best practice for detecting murine pinworm infections. Initially, we evaluated 7 fecal concentration methods by using feces containing Aspiculuris tetraptera (AT) eggs (n = 20 samples per method). Sodium nitrate flotation, sodium nitrate centrifugation, Sheather sugar centrifugation, and zinc sulfate centrifugation detected eggs in 100% of samples; zinc sulfate flotation and water sedimentation detected eggs in 90%. All had better detection rates than Sheather sugar flotation (50%). To determine optimal detection methods, Swiss Webster mice were exposed to Syphacia obvelata (SO; n = 60) or AT (n = 60). We compared the following methods at days 0, 30, and 90, beginning 21 or 28 d after SO and AT exposure, respectively: fecal concentration (AT only), anal tape test (SO only), direct examination of intestinal contents (cecum and colon), Swiss roll histology (cecum and colon), and PCR analysis (pooled fur swab and feces). Detection rates for SO-exposed mice were: PCR analysis, 45%; Swiss roll histology, 30%; intestinal content exam, 27%; and tape test, 27%. The SO detection rate for PCR analysis was significantly greater than that for the tape test. Detection rates for AT-exposed mice were: intestinal content exam, 53%; PCR analysis, 33%; fecal flotation, 22%; and Swiss roll histology, 17%. The AT detection rate of PCR analysis combined with intestinal content examination was greater than for PCR analysis only and the AT detection rate of intestinal content examination was greater than for Swiss roll histology. Combining PCR analysis with intestinal content examination detected 100% of infected animals. No single test detected all positive animals. We recommend combining PCR analysis with intestinal content examination for optimal pinworm detection.

Interspecies Variation in the Susceptibility of a Wild-Derived Colony of Mice to Pinworms (Aspiculuris tetraptera)

Pinworms are common parasites in wild and laboratory rodents. Despite their relative nonpathogenicity in immunocompetent models, pinworm infections add an unwanted variable and may confound some types of research. For this reason, health monitoring programs and biosecurity measures aim to minimize the spread of pinworm infections into colonies free from the organisms. Wild-derived and laboratory strains of mice have shown varied susceptibility to infection with Aspiculuris tetraptera, the most commonly found murine pinworm. In particular, susceptibility is increased in wild-derived mice, young animals, and males. Routine surveillance at our institution revealed pinworm infection (A. tetraptera only) within a colony of multiple, wild-derived species of Mus, although only specific species showed positive results during initial sampling. To assess whether species-associated differences in susceptibility were present, we analyzed fecal egg counts of A. tetraptera in every cage of the colony. Our results revealed significant differences in susceptibility between various species and subspecies of Mus. Egg counts were significantly higher in Mus spicilegus than Mus m. domesticus (WSB/EiJ) and Mus macedonicus. Mus spretus had higher egg counts than M. m. domesticus (WSB/EiJ), M. m. musculus (PWK/PhJ), and M. macedonicus. Egg counts did not differ in regard to age, sex, or number of mice per cage. As wild-derived mouse models continue to compliment research largely based on laboratory strains, it will be important to understand host-parasite interactions and their effects on research, particularly studies evaluating immune responses, behavior, growth, and other physiologic parameters.

PREVALENCE AND ASSOCIATED RISK FACTORS OF INTESTINAL PARASITES IN HUMANS AND DOMESTIC ANIMALS ACROSS BORDERS OF THAILAND AND LAO PDR: FOCUS ON HOOKWORM AND THREADWORM

Hookworm and threadworm infections are major public health problems in developing countries. A cross sectional study comprising 843 participants (346 males and 497 females) was conducted in three populations: i) Thai residents (TR) of Ubon Ratchathani Province, Thailand; ii) Laotian immigrant workers (LI) in the same province; and iii) Laotian residents (LR) in Champasak Province, Lao PDR. Participants were interviewed based on a structured questionnaire regarding their health status. Stool samples from participants and 300 samples from domestic animals (277 dogs and 23 cats) living in the participants households were collected and examined for parasitic infection using a formalin-ether concentration and a Harada-Mori filter paper culture techniques. Approximately one-third of TR and LI populations and domestic animals in Thailand were positive for parasitic infections, while almost half of LR population and domestic animals were positive. We confirmed by PCR and DNA sequencing a case of Ancylostoma ceylanicum infection in a Thai man. We also observed infections of other parasites, such as Taenia spp and Opisthorchis viverrini. Multivariate analysis indicated that risk factors for hookworm infection were population group and walking barefoot. Factors associated with threadworm infection were population group, adult male, lack of previous antiparasitic treatment and of knowledge of parasitic infection, and failure to wash hands after contact with domestic animals. Our results highlight the high prevalence of both hookworm and threadworm infections especially among LI population and domestic animals in both countries. Our findings emphasize the need for public health intervention to control the spread of parasitic infections in Thailand and Lao PDR.

Phylogenetic relationships between pinworms (Nematoda: Enterobiinae) parasitising the critically endangered orang-utan, according to the characterisation of molecular genomic and mitochondrial markers

Pinworms (Nematoda: Enterobiinae) include 52 species parasitising primates throughout the world. In the present study, we performed the first ever molecular analysis to investigate the phylogenetic position of recently described pinworms parasitising the Sumatran orang-utan. The phylogenetic analysis of mitochondrial CO1 and chromosomal 18S rDNA and ITS1 regions could support the independent status of several Nematoda species. Our molecular data clearly suggest that Enterobius (Colobenterobius) buckleyi and Lemuricola (Protenterobius) pongoi together with Pongobius hugoti form separate clades among other studied species, which significantly supports the hypothesis of recently described new species parasitising the orang-utan (Pongo abelii and Pongo pygmaeus). The phylogenetic tree based on cytochrome oxidase 1 (CO1) gene variability showed possible close relationships between L. (Protenterobius) pongoi and P. hugoti; thus, we can assume that these species could have initially diverged in sympatry from a common ancestor.

Effect of fenbendazole on an autoimmune mouse model

Fenbendazole is an anthelmintic drug widely used to treat and prevent pinworm infection in laboratory rodents. Data regarding possible side effects of fenbendazole on the immune system are conflicting, potentially due to the design of treatment protocols. The purpose of the current study was to determine the effects of 2 fenbendazole therapeutic regimens (continuous for 5 wk and alternating weeks [that is, 1 wk on, 1 wk off] for 9 wk) on the development of autoimmune disease in (NZB × NZW)F1 mice. No significant differences in survival curves or weight were observed between the treatment groups and cohort mice receiving nonmedicated feed. At the termination of the experiment, there were no differences in tissue pathology. Hematocrit decreased and BUN increased over time in all groups, but no significant differences were present between groups. After the cessation of treatment, mice fed the medicated diet continuously for 5 wk showed an increase in antiDNA antibody. Although this difference was significant, it did not affect survival curves or disease-related tissue or blood changes. These data indicate that common protocols of fenbendazole treatment do not alter the progression of autoimmune disease in (NZB × NZW)F1 mice.

Age-associated variability in susceptibility of Swiss Webster mice to MPV and other excluded murine pathogens

Detection of mouse parvovirus (MPV) and other murine pathogens in research colonies is dependent on the transmissibility of the agents and the sensitivity of sentinels to those agents. Transmissibility is based on several agent-dependent properties including mode of transmission, infectivity, and environmental stability, whereas host susceptibility can vary according to mouse age, strain, and sex. In this study, 4-wk-old, 12-wk-old, and aged Swiss Webster female sentinel mice were compared for their ability to detect infectious agents by using a standardized health surveillance program, to determine whether sentinels should be replaced more frequently to improve the efficiency of detection of infectious agents within a murine colony. Both experimentally and naturally infected mice were used to transmit MPV and other infectious agents from index mice to sentinels. First, Swiss Webster mice were inoculated with MPV, and transmission to 4-, 12-, and 24-wk-old contact and soiled-bedding sentinels was determined. Second, mice naturally infected with 9 infectious agents were obtained from 2 local pet stores, and transmission to 4-wk-old contact sentinels and 4-, 12-, and 44-wk-old soiled-bedding sentinels was determined. For agents that were transmitted via soiled bedding (MPV, mouse hepatitis virus, murine norovirus, Theiler murine encephalomyelitis virus, and pinworms), transmission did not differ in regard to the age of the sentinels. In conclusion, susceptibility to several infectious agents did not differ according to sentinel age in a health-surveillance protocol that used mice older than 12 wk.

Sensitivity of perianal tape impressions to diagnose pinworm (Syphacia spp.) infections in rats (Rattus norvegicus) and mice (Mus musculus)

We determined the sensitivity of perianal tape impressions to detect Syphacia spp. in rats and mice. We evaluated 300 rat and 200 mouse perianal impressions over 9 wk. Pinworm-positive perianal tape impressions from animals with worm burdens at necropsy were considered as true positives. Conversely, pinworm-negative perianal tape impressions from animals with worm burdens were considered false negatives. The sensitivity of perianal tape impressions for detecting Syphacia muris infections in rats was 100%, and for detecting Syphacia obvelata in mice was 85.5%. Intermittent shedding of Syphacia obvelata ova is the most probable explanation for the decreased sensitivity rate we observed in mice. We urge caution in use of perianal tape impressions alone for Syphacia spp. screening in sentinel mice and rats.

Effects of fenbendazole on the murine humoral immune system

Pinworms are highly contagious parasites that have been effectively treated in laboratory rodents with fenbendazole (FBZ). Whether FBZ has any detrimental side effects that may compromise experimental results is unknown. Here we asked whether the immune systems from young and aged mice are altered under FBZ treatment. We compared control and FBZ-treated groups of young (age, 2 to 4 mo) and old (age, 22 to 24 mo) BALB/cN mice. The treated mice received a total of 4 wk (alternating-week treatment regimen) of FBZ-medicated feed. Spleen and bone marrow were collected for immunologic assays, and heart, stomach, intestines, kidneys, and liver were evaluated by histopathology. Our results indicate that FBZ treatment has significant effects on the immune systems of mice; these effects are greater in aged mice. FBZ treatment adversely affected mRNA and protein expression of E2A (a transcription factor crucial for B lymphocytes) in activated precursor B lymphocytes obtained from the bone marrow of young and old mice. These effects were reversed by 6 wk on regular feed after the end of treatment. Activated B lymphocytes from the spleens of young and old mice showed decreased function (cell proliferation, E2A mRNA and protein expression) through the last time point of FBZ treatment but recovered by 2 to 4 wk after treatment. Our findings suggest that FBZ treatment may alter sensitive immune and molecular measures as presented here, and postponing the experimental use of mice until at least 6 wk after treatment should be considered.

Characterization of rDNA sequences from Syphacia obvelata, Syphacia muris, and Aspiculuris tetraptera and development of a PCR-based method for identification

To differentiate the morphologically similar pinworms of the common laboratory rodents, such as Syphacia obvelata and Syphacia muris, we amplified and sequenced the region spanning the internal transcribed spacer 1 (ITS-1), 5.8S gene, and ITS-2 of the ribosomal DNA followed by designing of species-specific primers for future use in the identification of the worms. It was observed that S. obvelata, S. muris and Aspiculuris tetraptera can be differentiated from each other based on their rDNA sequences. This is the first report of the ITS-1, 5.8S, and ITS-2 of the rDNA of the three aforementioned rodent pinworm species. The use of restriction endonucleases, AluI or RsaI, further allowed the delineation of the three species. Moreover, we also constructed species-specific primers that were designed for unique regions of the ITS-2 of the three species. This approach allowed their specific identification with no amplicons being amplified from heterogenous DNA samples, and sequencing confirmed the identity of the sequences amplified. Thus, the use of these specific primers along with PCR-RFLP can serve as useful tools for the identification of pinworms in rats, mice, and wild rodents.

Molecular phylogeny of the pinworms of mice, rats and rabbits, and its use to develop molecular beacon assays for the detection of pinworms in mice

Though pinworm infestation has been prevalent since the early years of laboratory animal medicine, the genomes of these parasites have not yet been sequenced. The authors used high-fidelity polymerase chain reaction to amplify a large portion of the ribosomal gene complex of four pinworm species commonly found in lab rodents and rabbits (Aspiculuris tetraptera, Passalurus ambiguus, Syphacia muris and Syphacia obvelata). They determined DNA sequences for these complexes and carried out phylogenetic analysis. Using this information, the authors developed real-time molecular beacon assays for pinworm detection, comparing the new diagnostic approach with traditional methods such as perianal tape testing, fecal flotation and direct examination of intestinal content.

Evaluation of two fecal examination techniques for detection of Trypanoxyuris spp. infection in owl monkeys (Aotus nancymae)

Infections of Trypanoxyuris spp. pinworms in Aotus nancymae and other New World primates are typically subclinical, but infection during experimental use could confound interpretation of experimental data. Further, Trypanoxyuris species are highly infective, and rapid diagnosis is important to prevent an outbreak in the animal colony. This study sought to determine whether a fecal flotation technique was sensitive enough to replace the perianal tape test for diagnosis of Trypanoxyuris spp., thereby reducing stress to the animal and sample collection time. On days 0 and 3, we collected fecal samples from 45 animals confirmed to be infected with Trypanoxyuris spp. by perianal tape testing. Fecal samples were evaluated by both a commercial analysis system and by sucrose flotation with centrifugation. For both detection methods, no significant difference in sensitivity was detected between tests conducted on day 0 versus day 3. The sensitivity of repeated commercial tests was 80%, significantly higher than the 60% for sucrose flotation. The commercial test was significantly more sensitive than sucrose flotation, indicating that the commercial system was a better method for detecting Trypanoxyuris spp. However, sensitivity of only 80% confers a considerable risk of false negatives, thereby potentially delaying treatment and further contributing to environmental contamination. In our opinion, neither method of fecal analysis was a suitable replacement for the perianal tape test to diagnose Trypanoxyuris spp. in owl monkeys.

Echinococcosis granulosus in stray dogs and Echino-IHAT in the hunters in Cairo, Egypt

A total of fifty stray dogs of both sex and of different ages were examined for natural infection with Echinococcus granulosus after post-mortem. Three main intestinal helminthes were recovered. These were in descending order of abundance Dipylidium caninum, Toxocara canis and E. granulosus. The latter worm was demonstrated in eight of them (16%). The sera of three out of 21 dog-hunters (14.3%) showed positive Echino-IHAT. Two of the hunters suffered Enterobius vermicularis and one of them had Taenia saginata as well. But, the abdominal X-ray of the two hunters was more or less normal and did not show any hydatid cyst.

Passalurus ambiguus: new insights into copromicroscopic diagnosis and circadian rhythm of egg excretion

The present paper reports a study on the in vivo diagnosis and egg excretion rhythm of the pinworm Passalurus ambiguus in domesticated rabbits. Three copromicroscopic techniques were compared: the cellophane tape test, the McMaster technique, and the FLOTAC technique. Out of the 51 New Zealand White rabbit does examined, 42 (82.3%) resulted positive when examined with the FLOTAC technique, 39 (76.5%) with the cellophane tape test, and 29 (56.9%) with the McMaster technique. The agreement between the FLOTAC technique and the cellophane tape test was almost perfect (greater than 0.8); only moderate were the agreements (0.4) between the FLOTAC and the McMaster techniques and between the McMaster technique and the cellophane tape test. The results showed that the FLOTAC technique can be used for the quali-quantitative coprological diagnosis of P. ambiguus in rabbits due to its great sensitivity, as already shown for parasites of other animal species. The circadian rhythm of egg excretion by P. ambiguus was studied utilizing 42 individually caged rabbit does; fecal samples were collected from each cage every 6 h, i.e., at 6:00-12:00 hours, 12:00-18:00 hours, 18:00-24:00 hours, and 24:00-6:00 hours, and were analyzed by the FLOTAC technique. A circadian rhythm of P. ambiguus egg excretion was found, with significant lower values at 6:00-12:00 hours. In conclusion, the present study showed that the FLOTAC technique is the best copromicroscopic method for assessing P. ambiguus prevalence and intensity in rabbits and that the afternoon and evening hours are the best times for fecal sampling to perform the pinworm diagnosis.

Infection with Syphacia obvelata (pinworm) induces protective Th2 immune responses and influences ovalbumin-induced allergic reactions

Infections with pinworms are common in rodent animal facilities. In this study, we show the consequence of an outbreak in a transgenic barrier facility of infection by Syphacia obvelata, a murine pinworm gastrointestinal nematode. Immune responses were defined in experimental infection studies with BALB/c mice. Infection with S. obvelata induced a transient Th2-type immune response with elevated interleukin 4 (IL-4), IL-5, and IL-13 cytokine production and parasite-specific immunoglobulin G1 (IgG1). In contrast, BALB/c mice deficient in IL-13, IL-4/13, or the IL-4 receptor alpha chain showed chronic disease, with a >100-fold higher parasite burden, increased gamma interferon production, parasite-specific IgG2b, and a default Th2 response. Interestingly, infected IL-4-/- BALB/c mice showed only slightly elevated parasite burdens compared to the control mice, suggesting that IL-13 plays the dominant role in the control of S. obvelata. The influence that pinworm infection has on the allergic response to a dietary antigen was found to be important. Helminth-infected mice immunized against ovalbumin (Ova) elicited more severe anaphylactic shock with reduced Ova-specific IL-4 and IL-5 than did noninfected controls, demonstrating that S. obvelata infection is able to influence nonrelated laboratory experiments. The latter outcome highlights the importance of maintaining mice for use as experimental models under pinworm-free conditions.

Morphology of chimpanzee pinworms, Enterobius (Enterobius) anthropopitheci (Gedoelst, 1916) (Nematoda: Oxyuridae), collected from chimpanzees, Pan troglodytes, on Rubondo Island, Tanzania

The chimpanzee pinworm, Enterobius (Enterobius) anthropopitheci (Gedoelst, 1916) (Nematoda: Oxyuridae), is redescribed based on light and scanning electron microscopy of both sexes collected from the feces of chimpanzees, Pan troglodytes, of an introduced population on Rubondo Island, Tanzania. Enterobius (E.) anthropopitheci is characterized by having a small body (males 1.13-1.83 mm long, females 3.33-4.73 mm long), a rather straight spicule with a ventral membranous formation in males, double-crested lateral alae in females, small eggs (53-58 by 24-28 microm), and a smooth eggshell with 3 longitudinal thickenings. Morphological comparison is made between the present and previous descriptions.

Evaluation of a timed and repeated perianal tape test for the detection of pinworms (Trypanoxyuris microon) in owl monkeys (Aotus nancymae)

The purpose of this project was to determine if the detection of pinworm infections in owl monkeys (Aotus nancymae) could be improved by performing perianal tape testing at specific times of the day and/or by performing repeated sampling. Eight Aotus known to be infected with pinworms were sampled at four selected time points (06:00, 12:00, 18:00 and 24:00 hours) over the course of a 3-week period. Samples were examined microscopically and oxyurid eggs were quantified. Results revealed no significant differences in time points, but did indicate that repeated sampling significantly improved pinworm egg detection. Results also determined that Aotus housed with an infected cage mate are at an approximately 14-times greater risk of being infected than animals housed without an infected cage mate. Lastly, results indicated no significant difference between peripheral eosinophil and basophil numbers from infected and clean animals.

EFFECTS OF REPEATED ANTHELMINTIC TREATMENT ON ENTEROBIUS VERMICULARIS INFECTION IN CHIMPANZEES

Effects of repeated treatment with pyrantel pamoate on Enterobius vermicularis infection in chimpanzees were assessed by observing worms discharged in the feces after administration of anthelmintic treatment. Three of 9 chimpanzees reared in a zoological garden in Japan were subjected to fecal worm count and morphometric observation, and all were given oral pyrantel pamoate 6 times at 10-day intervals simultaneously. Following the first and second treatments, more than 30,000 pinworms were discharged from 1 chimpanzee. The number of discharged worms abruptly decreased after the third treatment, and only a few worms were recovered after the fifth treatment, indicating that repeated treatment at short intervals was very effective. Complete eradication was not achieved, however, presumably because of reinfection. The female proportion among discharged worms tended to increase as the treatment was repeated.

The lack of behavioral effects of fenbendazole: a medication for pinworm infection

Pinworm infection in rodent laboratories is common and often treated with fenbendazole, which is effective and has a low toxicity level. However, very little is known about the behavioral effects of the drug. The purpose of this study was to determine the behavioral effects of fenbendazole on rats tested by using various conditioning and timing procedures. These behavioral effects were examined both between animals (i.e., control versus medicated treatments) and within animals (baseline-treatment-baseline design). Fenbendazole reduced the detection of pinworm eggs, and it had no significant behavioral effects across multiple levels of analysis (e.g., from overall response rates to response patterns to interresponse intervals). All behavioral differences (e.g., discrimination ratios) were a result of task variables. These results suggest that behavioral studies are unlikely to be influenced by fenbendazole treatment given before or during a study.

Growth of Enterobius vermicularis in a chimpanzee after anthelmintic treatment

The growth of Enterobius vermicularis in a chimpanzee was investigated by observing worms discharged in feces after administration of pyrantel pamoate. Just after the final molting, immature adult male pinworms developed to a fully mature stage in 2 wk, after passing through a stage corresponding to the so-called Enterobius gregorii, which was surmised to be a younger adult form of E. vermicularis. The frequency distribution of body length forms 2 peaks in both male and female pinworms, with a depression in the transitional forms from the immature to the fully mature stage. This depression seems to be the result of more rapid growth or lower susceptibility to the drug in this transitional stage. Pyrantel pamoate effectively eradicated mature males, but gravid females were continuously observed in the feces after treatment. The complete eradication of pinworm infection by pyrantel pamoate could be achieved by repeated treatment at intervals shorter than 2 wk. This treatment would eradicate male worms first, resulting in females producing only unfertilized eggs, from which only males might hatch.

Fatal infection with human pinworm, Enterobius vermicularis, in a captive chimpanzee

A fatal infection with human pinworms, Enterobius vermicularis, was found in a 26-year-old chimpanzee kept in a zoo. Grossly, the animal was highly emaciated, and had severe enteritis with cecal multifocal nodules and severe cholelithiasis. Histopathologically, a large number of human pinworms were observed in the nodular lesions in the cecum and intestinal wall. These migrating worms were surrounded by an inflammatory cell infiltration which lacked eosinophils. There were areas of multifocal hyperemia and/or hemorrhages in various organs including the entire gastrointestinal tract. Pinworms were also observed in the portal venule and parenchyma of the liver. A light infection with Strongyloides cf. stercoralis was also observed.

Modification of the anal tape method for detection of pinworms in rodents

A modification of Graham's anal tape technique for detection of oxyurid worm eggs involves a coverslip or microscope slide covered with a thin layer of adhesive. The worm eggs stick to the adhesive and can be directly observed under the microscope.

Comparison of practical treatment methods to eradicate pinworm (Dentostomella translucida) infections from Mongolian gerbils (Meroines unguiculatus)

This study evaluates the efficacy of various treatment methods to eradicate Dentostomella translucida from Mongolian gerbil colonies. The following five treatment methods were instituted in naturally infected groups of 10 gerbils each: topical ivermectin misting, ivermectin-medicated drinking water, piperazine citrate-medicated drinking water, fenbendazole-medicated feed, and a combination of ivermectin-medicated drinking water and fenbendazole-medicated feed. Treatment success was assessed by using weekly fecal flotations, with necropsy examinations performed on fecal-negative gerbils (except those in the misted group) at 5 weeks after the last treatment. Topical ivermectin misting left 40% of gerbils fecal-positive. With piperazine citrate-medicated drinking water, 60% of the gerbils were fecal-positive; the remaining 40% had adult worms in their digestive tract at necropsy. Ivermectin-medicated drinking water caused 80% of the gerbils to be negative on fecal flotation. On necropsy, however, all but one of these gerbils harbored adult pinworms. Treatments with fenbendazole-supplemented feed alone or in combination with ivermectin-treated water resulted in no fecal shedding or evidence of adult pinworms on necropsy examination. Of the five treatments evaluated, only those using fenbendazole-medicated feed (150 ppm) provided a practical and reliable treatment method to eradicate pinworm infections in Mongolian gerbil colonies.

Susceptibility of natural hybrids between house mouse subspecies to Sarcocystis muris

A previous study showed that the susceptibility of hybrids between two Mus musculus musculus and Mus musculus domesticus did not apply to every parasite. The authors proposed that only parasites which exerted enough constraints would induce the selection of poorly compatible systems of resistance in the subspecies. This study completes the previous work. Experimental infections of mice of the two subspecies and their hybrids with the tissue-dwelling protozoan Sarcocystis muris show that hybrids are more susceptible to the coccidian than M. m. musculus and M. m. domesticus individuals. This result demonstrates that the hybrids are not only susceptible to intestinal helminths, and confirms the 'constraint hypothesis'.

Fenbendazole treatment without environmental decontamination eradicates Syphacia muris from all rats in a large, complex research institution

Syphacia muris parasitism was eliminated from rats and voles by feeding fenbendazole-medicated chow (150 ppm) for five 7-day periods; treatment periods were separated by 7-day periods of feeding non-medicated chow, yielding atotal treatment course of 9 weeks. No other manipulations to facilitate eradication, including the use of filter tops, autoclaved cages, environmental decontamination, colony depopulation, breeding cessation, and research restriction, were done. The examination of 3143 cellophane-tape impressions of the anus and 160 cecal examinations from euthanized rats and voles during the treatment period and for 7 months afterwards confirmed the efficacy of treatment. Treatment was rapidly effective in voles. In rats, pinworm eggs persisted at high levels for 2 weeks after the start of treatment, but no eggs were found after 22 days.

Toxicity evaluation of prophylactic treatments for mites and pinworms in mice

The detection of external and internal parasites in laboratory mice is a particularly problematic aspect of animal health evaluation. Because these organisms must be detected by direct examination of the feces or hair coat, low-level infestation or sporadic shedding can make them difficult to detect, thereby undermining confidence that negative reports are truly negative. Prophylactic treatment of suspect colonies with anthelminthics and/or insecticides may therefore be indicated under some circumstances. However, when considering the use of prophylactic treatments, the potential for toxicity is an important factor, especially in genetically modified strains of mice. To evaluate the potential toxicity of prophylactic anti- parasitic treatments on strains of mice that are commonly used as experimental models and in genetic engineering in our facility, we surveyed a number of strains and ages of mice for toxic reactions during treatment regimens that combine anthelminthic and anti-acaricidal agents. Three experimental protocols (ivermectin, piperazine, and dichlorvos in combination; ivermectin alone; and fenbendazole/permethrin or fenbendazole/dichlorvos) were evaluated. Our data suggest a potential for toxicity associated with these treatments and indicate to us that prophylactic treatment regimens should be initiated with caution.