High subtelomeric GC content in the genome of a zoonotic Cryptosporidium species

Cryptosporidium canis is a zoonotic species causing cryptosporidiosis in humans in addition to its natural hosts dogs and other fur animals. To understand the genetic basis for host adaptation, we sequenced the genomes of C. canis from dogs, minks, and foxes and conducted a comparative genomics analysis. While the genomes of C. canis have similar gene contents and organisations, they (~41.0 %) and C. felis (39.6 %) have GC content much higher than other Cryptosporidium spp. (24.3-32.9 %) sequenced to date. The high GC content is mostly restricted to subtelomeric regions of the eight chromosomes. Most of these GC-balanced genes encode Cryptosporidium-specific proteins that have intrinsically disordered regions and are involved in host-parasite interactions. Natural selection appears to play a more important role in the evolution of codon usage in GC-balanced C. canis, and most of the GC-balanced genes have undergone positive selection. While the identity in whole genome sequences between the mink- and dog-derived isolates is 99.9 % (9365 SNVs), it is only 96.0 % (362 894 SNVs) between them and the fox-derived isolate. In agreement with this, the fox-derived isolate possesses more subtelomeric genes encoding invasion-related protein families. Therefore, the change in subtelomeric GC content appears to be responsible for the more GC-balanced C. canis genomes, and the fox-derived isolate could represent a new Cryptosporidium species.

Divergent Cryptosporidium species and host-adapted Cryptosporidium canis subtypes in farmed minks, raccoon dogs and foxes in Shandong, China

Cryptosporidium spp. are common parasitic pathogens causing diarrhea in humans and various animals. Fur animals are widely farmed in Shandong Province, China, but the prevalence and genetic identity of Cryptosporidium spp. in them are unclear. In this study, 1,211 fecal samples were collected from 602 minks, 310 raccoon dogs and 299 foxes on two farms in Shandong and analyzed for Cryptosporidium spp. by nested PCR and sequence analyses of the small subunit rRNA gene. The overall infection rate of Cryptosporidium spp. was 31.5% (381/1,211), with a higher infection rate in raccoon dogs (37.7%, 117/310) than in foxes (32.4%, 97/299) and minks (27.7%, 167/602). By age, the highest infection rates of Cryptosporidium spp. were observed in raccoon dogs of 1-2 months, minks of 5-6 months, and foxes of > 12 months. Three Cryptosporidium species and genotypes were detected, including C. canis (n = 279), C. meleagridis (n = 65) and Cryptosporidium mink genotype (n = 37). Among the three major host species, raccoon dogs were infected with C. canis only (n = 117), while foxes were infected with both C. canis (n = 32) and C. meleagridis (n = 65), and minks with C. canis (n = 130) and Cryptosporidium mink genotype (n = 37). Subtyping of C. canis by sequence analysis of the 60 kDa glycoprotein gene identified eight subtypes. They belonged to two known subtype families, XXa and XXd, and two novel subtype families XXf and XXg, with host adaptation at the subtype family level. Notably, C. canis from foxes was genetically distant from those in other hosts. Further subtyping analysis identified three subtypes (IIIeA21G2R1, IIIeA19G2R1 and IIIeA17G2R1) of C. meleagridis and two novel subtype families Xf and Xg of the Cryptosporidium mink genotype. The presence of zoonotic C. canis subtypes in raccoon dogs and C. meleagridis subtypes in foxes suggests that these fur animals might be potential reservoirs for human-pathogenic Cryptosporidium spp.

Seroprevalence of Echinococcus spp. and Toxocara spp. in Invasive Non-native American Mink

Invasive non-native species can become reservoirs of zoonotic pathogens and cause their spread during colonization, increasing the risk of zoonoses transmission to both wild hosts and humans. American mink (Neovison vison) are considered an important invasive mammal species responsible for carrying endoparasites. The aim of our study was to evaluate the role of feral American mink as a possible transmission vector of Echinococcus spp. and Toxocara spp. in wildlife. We analysed the frequency of American mink exposure to both parasites, the spatial distribution in Poland, and the variability over time on the basis of specific antibody presence using ELISA and Western blot. Alimentary tract analyses revealed that American mink do not serve as definitive hosts for these parasites. Altogether, 1100 American mink were examined. The average seropositivity for American mink was 14.2% for echinococcosis and 21.7% for toxocarosis; dual-seropositivity was detected in only 6.0%. Seroprevalence of both parasites differed between study sites and significantly increased over time in Toxocara spp. Thus, our study revealed that free-living American mink are exposed to parasites and likely to be involved in the maintenance of both Echinococcus spp. and Toxocara spp. in the wild as paratenic hosts.

Toxoplasma gondii infection in selected species of free-living animals in Poland

INTRODUCTION AND OBJECTIVE

Free-living animals can play an important role as a reservoir of Toxoplasma gondi;, however, data concerning this issue in Poland are still limited.The aim of study was to assess the occurrence of T. gondii infection by using molecular methods in free-living animals in selected regions of Poland.

MATERIAL AND METHODS

Tissues samples of 396 animals (foxes, muskrats, birds, martens, badgers, polecats, raccoons, minks, raccoon dogs, otters, small rodents and insectivores, and grass snakes were collected from various regions of Poland. After samples digestion, DNA was isolated using QIAmp DNA Mini Kit (Qiagen). DNA extraction from small rodents and insectivores samples was performed without digestion. Next, nested PCR (B1 gene) and, for a part of nested PCR positive amplicons, RFLP PCR, were performed according to the method by Grigg and Boothroyd (2001). The other part of nested PCR positive DNA isolates were genotyped using 5 genetic markers: SAG1, SAG2 (5'- and 3'), SAG3, BTUB and GRA6, based on the method by Dubey et al. (2006). These PCR products were sequenced and compared with the NCBI database using Blast.

RESULTS

In total, in 50 of the 396 examined animals DNA of T. gondii was detected (12.6%). The highest percentages of positive results in PCR was obtained in martens (40.9%) and badgers (38.5%), lower in birds (27.3%) and the lowest in foxes (7.4%). The RFLP and multilocus PCR analysis showed the dominance of T. gondii clonal type II (or II/III).

CONCLUSIONS

The results of this study indicate the frequent T. gondii infection among free-living animals in Poland, especially martens and badgers, which may indirectly indicate that these animals contribute to the spread of the parasite in the sylvatic environment in Poland. The genotyping analysis showed the dominance of T. gondii clonal type II (or II/III).

Leishmania infection in lagomorphs and minks in Greece

Greece is an endemic country for human and canine leishmaniosis. Studies about the role of lagomorphs and minks in the epidemiology of the diseases are, so far, limited. The aim of the present study was to investigate the prevalence of Leishmania infection in these animals, in different areas of the country. Samples from 393 domestic and wild rabbits, 90 hares and 200 minks were collected and examined by cytology (spleen imprints) and serology (ELISA), while spleen samples of 116, 56 and 95 of the rabbits, hares and minks, respectively, were examined by a PCR assay targeting the ITS1 region. For every animal examined a form was created, recording information like date, area, animal species, sex, etc. All imprint smears examined were negative, while serology revealed infection in 7.6% (C.I. 5.0-10.3%) rabbits, 6.7% (C.I. 1.5-11.8%) hares and 20% (C.I. 14.5-25.5%) minks. Infection was confirmed by molecular methods in 2.6% (C.I. 0.0-5.5%), 3.6% (C.I. 0.0-8.4%) and 2.1% (C.I. 0.0-5.0%) of the animals, respectively. The statistical analysis showed that minks are most likely to be seropositive and that in rabbits, the breeding method (i.e. homestead reared animals) was associated with infection. Because of the proximity of lagomorphs and minks to humans and dogs it is necessary to further elucidate their role in the epidemiology of leishmaniosis.

Toxoplasma gondii infection in wild mustelids and cats across an urban-rural gradient

The increase in human population and domestic pets, such as cats, are generating important consequences in terms of habitat loss and pathogen pollution of coastal ecosystems with potential to generate negative impacts in marine biodiversity. Toxoplasma gondii is the etiological agent of zoonotic disease toxoplasmosis, and is associated with cat abundance and anthropogenic disturbance. The presence of T. gondii oocysts in the ocean has negatively affected the health status of the threatened Southern sea otter (Enhydra lutris nereis) populations. The present study analyzed seroprevalence and presence of T. gondii DNA in American mink (Neovison vison), Southern river otters (Lontra provocax) and domestic cats (Felis silvestris catus) in four different areas in Southern Chile comprising studies in rivers and lakes in Andean foothills and mountains, marine habitat and island coastal ecosystems. Mean seroprevalence of T. gondii in the study was 64% of 151 total animals sampled: 59% of 73 American mink, 77% of 13 Southern river otters, 68% of 65 domestic cats and in two of two kodkods (Leopardus guigna). Toxoplasma gondii DNA was detected in tissues from one American mink and one Southern river otter. The present study confirms the widespread distribution of T. gondii in Southern Chile, and shows a high exposure of semiaquatic mustelids and domestic cats to the parasite. Cats and anthropogenic disturbance have a role in the maintenance of T. gondii infection in ecosystems of southern Chile.

Efficacy of imidacloprid, imidacloprid/permethrin and phoxim for flea control in the Mustelidae (ferrets, mink)

Farmed mink (Mustela vison), a close relative of the domestic ferret (Mustela putorius furo), naturally infested with the squirrel flea (Ceratophyllus sciurorum) were included in a study to investigate three compounds for flea control. The test products were imidacloprid in a 10% (w/v) solution, an imidacloprid 10% (w/v)/permethrin 50% (w/v) solution, and phoxim; all three are well-known compounds for the control of different ectoparasites in a wide range of animals. Two groups of mink received 0.1 ml per animal of the imidacloprid or the imidacloprid/permethrin combination at days 0 and 28, respectively. Two groups of mink were sprayed with 25 ml of a 0.1% phoxim solution at day 0 and either 1x25 ml or 2x25 ml, respectively, of a 0.05% phoxim solution at day 28. One group of mink served as an untreated control. At assessment on day 56 the efficacy was 91.9% in the imidacloprid group, 89.3% in the imidacloprid/permethrin group, 92.2% in the phoxim 1x25-ml group and 99.3% in the phoxim 2x25 ml group, respectively. In the untreated control group an average of 757 fleas per mink nesting material was recorded.

[Animal corynosomosis is a potential human helminthiasis in the Republic of Belarus]

In the Republic of Belarus, one representative of the genus Corynosoma - C. strumosum (Rudolphi, 1802) that is a causative agent of corynosomosis and that is of medical value is parasitic on animals. In Belarus, this proboscis worm has been encountered only in European and American minks. The author of the paper found this helminth in 2 of the 50 examined American minks in Byelorussian Polesye in 1980-2001. In this region, there were no C. strumosum larvae in fishes (1394 fishes of 21 species were studied). It is noted that the American mink plays a dominant role in the circulation of invasion and the attention of medical workers ofBelarus is drawn to the existing risk of human infection with the pathogen of Corynosomosis.

First U.S. Record of the Hard Tick Ixodes (Pholeoixodes) gregsoni Lindquist, Wu, and Redner

Ixodes (Pholeoixodes) gregsoni Lindquist, Wu, and Redner, a species of hard tick described in 1999 in Canada, was recovered from a harvested fisher (Martes pennanti Erxleben) and a domestic cat (Felis silvestris catus Ragni and Randi) in Vermont in 2001 and from harvested mink (Mustela vison Schreber) in Maine in 2003. These samples are the first records of this species within the United States. Although knowledge of this tick's natural history and distribution are still preliminary, these records indicate a possible greater distribution for I. gregsoni than initially perceived. Although its status as a disease vector is presently unknown, natural resource professionals should be aware of the possibility of this tick's occurrence in the northeastern United States.

First report of Cryptosporidium parvum ‘ferret’ genotype in American mink (Mustela vison Shreber 1777)

A total of 51 faecal samples from wild and farmed mink were analysed by a direct immunofluorescence antibody test. Cryptosporidium oocysts were identified in eight, apparently healthy, farmed American mink (Mustela vison). The isolates were identified as Cryptosporidium parvum 'ferret' genotype by PCR-RFLP and sequencing analysis of a 341-base-pair fragment of the Cryptosporidium oocyst wall protein (COWP) gene. This is the first report of Cryptosporidium in American mink.

Toxoplasmosis in a Free-ranging Mink

A free-ranging mink (Mustela vison), estimated to be 3 mo old, was found on the campus of Michigan State University, East Lansing, Michigan; it exhibited clinical signs of left hind limb lameness, ataxia, head tremors, and bilateral blindness. Histologically, the animal had a mild, nonsuppurative meningoencephalitis and severe chorioretinitis with intralesional bradyzoites and tachyzoites. Protozoal organisms were identified as Toxoplasma gondii based on histology, immunohistochemistry, and polymerase chain reaction. To the authors' knowledge, this is the first report of clinical toxoplasmosis in a free-ranging mink.

Status of Corynosoma (Acanthocephala: Polymorphidae) based on anatomical, ecological, and phylogenetic evidence, with the erection of Pseudocorynosoma n. gen

The possession of genital spines has been considered as a key taxonomic trait to differentiate Corynosoma from other genera of the Polymorphidae. However, Corynosoma currently consists of 2 groups of species with clear ecological and morphological divergences: the "marine" group (with ca. 30 species) infects mammals and piscivorous birds in the marine realm, whereas the "freshwater" group (with ca. 7 species) infects waterfowl in continental waters. Species from these groups differ in shape of body and neck, trunk spination, lemnisci length and shape, testes arrangement, and number and shape of cement glands. We tested whether species from these 2 groups formed a monophyletic assemblage based on a phylogenetic analysis by using 15 morphological characters. We also included species of Andracantha, Polymorphus, and Hexaglandula with which potential taxonomic conflicts could most likely arise. We obtained 108 equally most parsimonious trees of 32 steps, with a consistency index (CI) = 0.59, and a retention index (RI) = 0.82. The strict consensus tree indicated that the "freshwater" species of Corynosoma form a monophyletic assemblage closely related to some species of Polymorphus, whereas the "marine" species of Corynosoma are grouped together with Andracantha. Accordingly, Corynosoma is not a monophyletic assemblage, and Pseudocorynosoma n. gen. is proposed for the "freshwater" species of Corynosoma. This decision was strongly supported by (1) a functional comparison of foretrunk muscles between species of Polymophus, Andracantha, and Corynosoma; (2) a multivariate morphometric study of proboscis characters and egg size; and (3) an analysis of ecological patterns of host-parasite relationships.

Epidemiological investigations on Trichinella infections in farmed fur animals of Estonia

Farming of fur animals represents an important income in Estonia. Even though Trichinella worms does not induce a symptomatic disease in carnivores, the carcasses of skinned animals can increase the biomass of the parasite in the environment, if they are not properly destroyed. The aim of the present survey was to study the prevalence of Trichinella worms in farmed fur animals of Estonia. Of 281 muscle samples from blue foxes (Alopex lagopus), silver foxes (Vulpes vulpes fulva), minks (Mustela vison) and raccoon dogs (Nyctereutes procyonoides), which were collected in eight farms, Trichinella larvae have been detected in 21 animals (8%) from two farms by HCl-pepsin digestion. The highest number of larvae per gram of muscle was found in the front limb muscles. Larvae of the 21 isolates have been identified as Trichinella britovi or Trichinella nativa by a multiplex-PCR analysis.

Cranial helminths of Mustela vison Schreber, 1777 in Spain

A survey was carried out to investigate the presence of cranial helminths in 337 American minks (Mustela vison) from Spain. This information was obtained partly in order to evaluate potential conservation problems and sanitary risks to the congeneric European mink (Mustela lutreola), one of the most endangered carnivores in the world. Skulls and rectal faeces of each specimen were simultaneously analysed. Troglotrema acutum and Skrjabingylus nasicola were found in 5.6% of the M. vison analysed. No cranial lesions were seen in any of the examined skulls. The finding of both helminths in Spanish free-living M. vison specimens enlarges their natural definitive host spectrum in Western Europe. One relatively important focus of T. acutum in M. vison was detected (30.4%) in the Spanish Alava province while S. nasicola was found to be very infrequent. The suitability of both analytical methods was assessed in order to know to what degree coprological analysis reflects the real prevalence of cranial helminths in this host. It is possible to conclude that coprological analysis can be used instead of necropsies to analyse the possible incidence of pathogenic cranial helminths in mustelids. This aspect is very important and useful when trying to analyse the helminthological status of endangered species such as the native mink (M. lutreola) particularly in areas where both congeneric species are present and strict competition occurs.

Paragonimus westermani and Some Rare Intestinal Trematodes Recovered from Raccoon Dogs (Nyctereutes procyonoides viverrinus) Introduced Recently on Yakushima Island, Japan

Helminth parasites were collected from 9 raccoon dogs (Nyctereutes procyonoides viverrinus) and 2 Japanese weasels (Mustela itatsi sho) on Yakushima Island, Japan. The former carnivore was introduced to this World Natural Heritage Area presumably within the last two decades, expanding its population thence, although detailed process(es) of the introduction is unknown. The collected trematodes from raccoon dogs included the triploid form of Paragonimus westermani, Brachylaima tokudai, Maritrema eroliae, and Pseudocryptotropa sp. Simultaneously, Paragonimus ohirai was found in one weasel killed by a traffic accident. Although the triploid form of P. westermani and P. ohirai are known to be distributed in some river-mouth areas of Yakushima Island based on previous surveys on crab hosts, natural infection was detected for the first time in wild final hosts. Particularly, the raccoon dog infected with P. westermani was caught in a mountainous area, distant from human residence or river-mouth areas. Although it is possible that the infected raccoon dog moved from a river-mouth area endemic with P. westermani after infection, the alternative scenario remains to be pursued; the endemic area of this zoonosis is expanding along with the recent expansion of raccoon dogs or feral cats (Felis catus), that became prevalent recently on this island including the mountainous areas. Maritrema eroliae taking a variety of shorebirds as its natural final hosts, and a minute trematode, Pseudocryptotropa sp., taking unknown natural final host(s) were recorded for the first time in raccoon dogs.

Cholecystitis in otters (Lutra lutra ) and mink (Mustela vison ) caused by the fluke Pseudamphistomum truncatum

Between 1988 and 2004, postmortem examinations were carried out on 445 otters found dead, mostly as a result of road traffic accidents, in southern and south-west England. Thickened, shrunken gall bladders were observed in 10 cases, the first in 2000 and the others between February 2002 and August 2004. A digenean fluke, Pseudamphistomum truncatum, was found in the gall bladders of three cases and also in three of seven American mink examined. Nine of the 10 otters and all the mink came from a localised area of Somerset, indicating that the fluke has become established in the local fish population. P. truncatum has not been recorded previously in Britain, and the results suggest that it has been introduced recently, possibly in imported fish.

Toxoplasma gondii infection in Polish farmed mink

The aim of this study was to determine the seroprevalence of Toxoplasma gondii antibodies in Polish farmed mink according to way of feeding as well as to confirm the role of toxoplasmosis in reproductive losses in mink farms. The serological examinations were carried out on 961 mink randomly selected from 12 Polish farms. Blood sera were examined for the presence of T. gondii antibodies with the use of the latex agglutination test. The examinations for the presence of T. gondii in organ tissues were performed on five neonatal mink kits with the use of immunofluorescence method. In total 133 (13.9%) out of 961 examined mink had T. gondii antibodies. In large farms the seropositivity was lower (2.9%), than in small farms (26.33%) (P < 0.001). Significant difference was found in seroprevalence according to way of feeding. In farms feeding fish, percentage of seropositivity was lower (2.2%), than in farms based on non-frozen slaughter offal (43.4%). Titres of T. gondii antibodies were usually lower than 120 IU/ml. Using the immunofluorescence method, T. gondii was detected in impression smears from liver and brain of two neonatal mink kits derived from one seropositive female.

Host associations and seasonal occurrence of Haemaphysalis leporispalustris, Ixodes brunneus, I. cookei, I. dentatus, and I. texanus (Acari: Ixodidae) in Southeastern Missouri

Hemaphysalis leporispalustris (Packard), Ixodes brunneus Koch, Ixodes cookei Packard, Ixodes dentatus Marx, and Ixodes texanus Banks were collected during a 3-yr study of pathogen-tick-host interactions in southeastern Missouri. H. leporispalustris was collected from the eastern cottontail rabbit, Northern bobwhite, and Carolina wren, and it was active all year. I. brunneus was collected by drag and from passerine birds during December, March, and April. I. cookei was collected from raccoons and mink during April, June, September, October, and November. I. dentatus was collected from the cottontail rabbit and Carolina wren throughout the year. I. texanus was collected from the eastern gray squirrel, Virginia opossum, and raccoon throughout the year.

Histological evidence of disease in wild stoats (Mustela erminea) in England

Forty-four free-living stoats were collected from five game estates in England and examined for evidence of disease. All the macroscopic lesions were attributable to the trauma associated with being trapped or shot. There were no significant microscopic lesions in 27 (61 per cent) of the stoats. There was evidence of nematode parasitism in the intestines of six stoats (14 per cent), and in the lungs of five stoats (11 per cent), and of pulmonary granulomatous inflammation or microgranulomas in five stoats. In two of the stoats, blood-filled cavities in the liver were suggestive of peliosis hepatis, possibly associated with infection by Bartonella species or with sublethal exposure to anticoagulant rodenticides.

A review of Sarcocystis neurona and equine protozoal myeloencephalitis (EPM)

Equine protozoal myeloencephalitis (EPM) is a serious neurological disease of horses in the Americas. The protozoan most commonly associated with EPM is Sarcocystis neurona. The complete life cycle of S. neurona is unknown, including its natural intermediate host that harbors its sarcocyst. Opossums (Didelphis virginiana, Didelphis albiventris) are its definitive hosts. Horses are considered its aberrant hosts because only schizonts and merozoites (no sarcocysts) are found in horses. EPM-like disease occurs in a variety of mammals including cats, mink, raccoons, skunks, Pacific harbor seals, ponies, and Southern sea otters. Cats can act as an experimental intermediate host harboring the sarcocyst stage after ingesting sporocysts. This paper reviews information on the history, structure, life cycle, biology, pathogenesis, induction of disease in animals, clinical signs, diagnosis, pathology, epidemiology, and treatment of EPM caused by S. neurona.

Immunohistochemical confirmation of Sarcocystis neurona infections in raccoons, mink, cat, skunk, and pony

In the central nervous system of 2 raccoons, 1 cat, 1 pony, 2 mink, and 1 skunk, protozoa previously thought to be Sarcocystis-like reacted positively to Sarcocystis neurona-specific antibodies in an immunohistochemical test. In addition, S. neurona was identified in the brain of another skunk. These observations indicate that S. neurona is not confined to opossums and horses.

Sarcocystosis in mink (Mustela vison)

This report describes the clinical, microscopic, and ultrastructural findings in mink with muscular sarcocystosis. Three 2-3-mo-old mink were killed because they were ill with signs of progressive neurological disease. One mink had variable numbers of sarcocysts in multiple skeletal muscles. Sarcocysts were up to 300 microm in long and 20 microm wide. Ultrastructurally, the sarcocyst wall had numerous elongated 1.7-2.0-microm x 250-nm villar protrusions (VP). The VP had microtubules and irregularly distanced minute undulations. Both metrocytes and bradyzoites were present in sarcocysts. The mink with sarcocysts in muscles also had nonsuppurative meningoencephalitis and meningomyelitis. Similar brain lesions were found in other 2 mink from the same farm, but sarcocysts were not observed in the skeletal muscle of these animals. This is the first report of muscular sarcocystosis in mink.

[The susceptibility of different animal species to synanthropic and natural populations of Trichinella]

Pigs have been found to be highly susceptible to the synanthropic (domestic) population of Trichinella [correction of Trachina] and weakly susceptible to the natural (native) one. Fur-bearing animals (polar foxes and foxes) are more susceptible to the natural population of Trichinella [correction of Trachina], but minks are equally sensible to the two variants of T. spiralis. In the host's body, synanthropic Trichinella [correction of Trachinas] form capsules of lemon-like, less frequently, oval shape, but the native population do round capsules. There is larval adaptation when Trichinella [correction of Trachina] larvae enter the nonspecific host's body after their prepassage through the organism of domestic carnivorous animals (cats, dogs). The pig is successfully infected with T. spiralis nativa via the cat or dog; the infection rate is approximately close to that observed during control infection of pigs with synanthropic Trichinella [correction of Trachina].

The occurrence of ixodid ticks on wild mink Mustela vision in England and Wales

Four species of ticks found to infest 1391 American mink (Mustela vison) in Britain in five years were, in declining order of frequency, Ixodes hexagonus, Ixodes canisuga, Ixodes ricinus and Ixodes acuminatus. Ixodes hexagonus and I. canisuga occurred on 40% and 2.5% of mink respectively. Infestation rates (the proportion of infested mink) of adult females, nymphs and larvae were similar and tended to be lower in summer. The distribution of infestation size (the number of ticks per host) for adult females describes a negative binomial. The mean infestation size of nymphs varied with the sex of the host was 5.2 for males and 4.2 for females. Mink are competent hosts for I.hexagonus.

Developmental study of Taenia mustelae in the intermediate and definitive hosts, with a note on the life cycle of T. mustelae in Hokkaido, Japan

The gray red-backed vole Clethrionomys rufocanus bedfordiae and laboratory mice were fed eggs of Taenia mustelae via a stomach tube. Fully developed metacestodes were recovered from the voles fed the eggs at 25 days postinfection; voles were considered to be more suitable intermediate hosts for T. mustelae than laboratory mice. The prepatent period for the metacestodes from voles was shorter (16 days) in the mink than previously reported. A field survey was performed on hepatic cestodes of small mammals in Hokkaido, Japan in August 1993. We found T. mustelae metacestodes from C. rufocanus bedfordiae, representing a new host record.

Seroprevalence of Toxoplasma gondii in Danish farmed mink (Mustela vison S.)

One hundred and ninety-five mink sera randomly selected from 17 Danish mink farms were evaluated for the presence of Toxoplasma gondii antibodies in the latex agglutination test. Six (3%) sera contained T. gondii antibodies in titres of 1:64 or more. The estimated 3% prevalence means that 300,000 mink out of a total mink population of ten million might be infected with Toxoplasma gondii. This large number of possible sero-positive mink in Denmark indicates that there exists a potential risk of acquiring toxoplasmosis by pelting mink.

Migration and development of the larvae of Gnathostoma nipponicum in the rat, second intermediate or paratenic host, and the weasel, definitive host

Migration and development of the larvae of Gnathostoma nipponicum in the rat as second intermediate or paratenic host and the weasel as definitive host were examined to clarify the pathogenesis in each animal. The advanced third-stage larvae (AdL3) given orally to rats remained in the stomach for 12 h post-infection (PI). After that, larvae transiently invaded various organs and finally moved into the muscle within 48 h. The percentage of eosinophils in the blood taken from the jugular vein of rats infected with AdL3 reached a maximum (about 6%) on day 20 PI and then decreased. IgG antibody titre for G. nipponicum measured by ELISA began to increase on day 5 PI and reached a plateau on day 20 PI. The AdL3 given orally to weasels moved from the stomach into the muscle and then increased in size. Half of them invaded the muscle within 5 days, whereas the majority of them invaded the muscles within 20 days PI. Morphology of worms which invaded the muscles indicated that they were still the larval form with three rows of hooklets on the head bulb. The larvae in the muscles developed to young adult worms with seven rows of hooklets on the head bulb within 40 days PI. These young adult worms invaded the oesophageal wall and formed a tumour within 60 days PI. It was presumed that worms invaded the oesophageal wall through the adventitia. Ferret and mink were shown to be potential final hosts of G. nipponicum.

Prevalence of Encephalitozoon cuniculi antibodies in terrestrial mammals in Iceland, 1986 to 1989

Antibodies to Encephalitozoon cuniculi were found in wild arctic foxes (Alopex lagopus), feral mink (Mustela vison), wood mice (Apodemus sylvaticus) and house mice (Mus musculus) in Iceland. Animals with antibodies were found throughout the country. No lesions attributable to encephalitozoonosis were found in adult animals necropsied. However, one arctic fox cub with a neurological disorder had pathological and serological evidence of encephalitozoonosis.

Blood-feeding host preferences of the isomorphic species Simulium venustum and S. truncatum

Animal-baited traps, using fox, mink, rabbits and ducks, were used in host preference experiments in two habitats (Beach and Woods). A generalized linear model of blood-feeding host preference is presented to test for significant differences between the isomorphic species Simulium venustum and Simulium truncatum. The S. truncatum population peaked before that of S. venustum. On any given day the two species divided their blood-feeding efforts among the different hosts in the same proportions. On the Beach, fox was the preferred host at the beginning of the season, but by the end of the season flies fed with equal frequency on the fox and the mink. In the Woods fox remained the preferred host throughout the season (late May to early July). Possible reasons for these feeding trends are discussed.

Experimental infection with Toxoplasma gondii in farmed mink (Mustela vison S.)

Live Toxoplasma gondii tissue cysts (Strain 119) were administered orally to five mink (Mustela vison S.) and five mink were inoculated with a suspension of ultrasonicated Toxoplasma gondii trophozoites (RH-strain). Seroconversion was observed in all animals administered live T. gondii cysts indicating that infection was established. Likewise seroconversion was observed in three out of four animals administered ultrasonicated T. gondii trophozoites. Faecal shedding of oocysts of T. gondii was not demonstrated in any of the infected animals. Histologically chronic meningitis with calcification was seen in all animals. Cerebral T. gondii tissue cysts were detected in four animals administered live tissue cysts. The study demonstrates that mink can be experimentally infected with T. gondii, thus representing a potential infection source for man, when considering the pelting procedure.

Experimental evaluation of mink and Apodemus speciosus in the Echinococcus multilocularis life-cycle in Hokkaido, Japan

The epizootiological status of mink (Mustela vison) as definitive hosts and Apodemus speciosus as intermediate hosts in the transmission of Echinococcus multilocularis in Hokkaido, Japan, were evaluated by orally inoculating mink with protoscoleces, and A. speciosus with eggs of the cestode, respectively. No tapeworms were recovered from the alimentary tract of the mink, and no hydatid cysts were recovered from the viscera of the egg-inoculated A. speciosus. We conclude that mink and A. speciosus cannot serve as definitive hosts and intermediate hosts of E. multilocularis, respectively, in Hokkaido.

Extraglomerular lesions in kidneys of mink with encephalitozoonosis

Extraglomerular renal lesions were studied by light and electron microscopy in 13 farmed mink which showed cataractous eyes associated with spontaneous encephalitozoonosis. The extraglomerular renal lesions consisted of multiple renal cysts, multifocal-to-coalescing interstitial nephritis and vasculitis. Tubular cysts of varying size were present in the corticomedullary junction and medulla. The inflammatory infiltrates were composed mostly of lymphocytes and plasma cells and usually accompanied an interstitial fibrosis. Vasculitis, perivasculitis and sclerotic arteries were frequently seen.

Brain and spinal cord lesions in encephalitozoonosis in mink

Central nervous system lesions were studied by light microscopy in 43 farmed mink, aged 5 months to 2 1/2 years, with spontaneous encephalitozoonosis and showing cataractous eye changes. Lesions were found in the brain and spinal cord of all animals examined but were generally mild and chronic. The lesions were consistent with those previously described in spontaneous encephalitozoonosis in other carnivores. Parasites in parasitophorous vacuoles and free or phagocytosed in necrotic and granulomatous lesions were demonstrated in animals aged 5 months to 1 year. The occurrence of arterial lesions of the polyarteritis nodosa type found in the youngest animals probably indicates fetal infection. In animals aged 1 1/2 and 2 1/2 years active lesions were usually lacking and the changes were characterized by arterial sclerosis, sometimes with aneurysmal formations, small perivascular lympho-plasmacytic cuffings and focal gliosis.

Distribution, prevalence and intensity of Trichinella spiralis infection in furbearing mammals of Pennsylvania

Tongues from 1,170 raccoons, 384 opossums, 201 muskrats, 168 foxes (red and grey), 51 skunks, and 17 mink from Pennsylvania were examined for Trichinella spiralis larvae by peptic digestion. The overall prevalence of T. spiralis infection was 3.2%, varying in the carnivores from 2.6% in raccoons to 15.1% in red foxes; no muskrats were infected. Prevalence varied regionally, being higher west of the Susquehanna River, where, in the Ridge and Valley Province, it reached 9%. The larval densities varied greatly as reflected by the overall geometric mean number of larvae per gram of muscle (LPG) of 18.5 and the comparable arithmetic mean LPG of 113.3. No geographic, sex, or species-related differences in the intensity of infection were demonstrated.

A Hammondia-like coccidian with a mink-muskrat life cycle

A tissue cyst-forming coccidian morphologically resembling the known species Hammondia has a mink-muskrat life cycle. Cysts are found in skeletal muscle of muskrats (Ondatra zibetheca). Mink (Mustela vison) fed infected muskrat carcasses shed oocysts for 4 to 6 days after a prepatent period of 6 to 8 days. The oocysts, 99% of which are unsporulated in mink feces, measure 11.5 to 12 microns X 10 to 11 microns. Sporulated oocysts have 2 sporocysts, each with 4 sporozoites. The present work was insufficient to establish whether this Hammondia-like parasite is identical to the known Hammondia spp. or is a new parasite, although the evidence gathered supports the hypothesis that this parasite is a new member of the genus Hammondia.

Coccidial infections in ranch mink

A field study was conducted from April through June of 1976 to determine whether coccidial infections adversely affect the growth and survivability of young mink. Two anticoccidials, lasalocid (62 mg/kg of feed) and an antibiotic-sulfonamide preparation (220 mg/kg of feed), were incorporated into a standard pelleted ration. Comparisons of weight gains, mortality, and oocyst numbers were made between control and treated groups. Treatment reduced mortality (P < 0.001) but did not significantly affect weight gains. The antibiotic-sulfonamide preparation and, to a lesser extent lasalocid, reduced oocyst discharge. Increased oocyst shedding was detected among adult female mink from parturition to weaning of their kits.

Occurrence of Dioctophyma renale (Goeze, 1782) in mink from North Dakota

A total of 1185 mink (Mustela vison) from North Dakota was examined for Dioctophyma renale. Two specimens of the nematode were found and represent the first report of this parasite in North Dakota.

Development of Physaloptera maxillaris (Nematoda: Physalopteroidea) in skunk (Mephitis mephitis) and the role of paratenic and other hosts in its life cycle

The development of Physaloptera maxillaris in skunk (Mephitis mephitis) was examined. The third moult was first observed at 5 days after infection and the fourth at 10 days. The prepatent period was determined as 41–45 days in skunk maintained under summer conditions. Various stages occurring in skunk are briefly described. Development of worms from the third stage to adulthood was consistently asynchronous in skunk.The striped skunk appears to be the only suitable definitive host of P. maxillaris. Experimentally it was not possible to produce patent infection in dogs (Canisfamiliaris), cats (Felis catus), mink (Mustela vison), ferrets (Mustela furo), rats (Rattus norvegicus), or raccoons (Procyon lotor) fed on the same diet as skunk. P. maxillaris is redescribed briefly.Leopard frogs (Rana pipiens) and garter snakes (Thamnophis sirtalis) may be potential paratenic hosts of P. maxillaris. Third-stage larvae did not penetrate tissues but remained in the gut for several days after infection and retained their infectivity. However, frogs and snakes are apparently not important components of the diet of skunk in the Guelph area.