Genetic diversity of the cestode Echinococcus multilocularis in red foxes at a continental scale in Europe

BACKGROUND

Alveolar echinococcosis (AE) is a severe helminth disease affecting humans, which is caused by the fox tapeworm Echinococcus multilocularis. AE represents a serious public health issue in larger regions of China, Siberia, and other regions in Asia. In Europe, a significant increase in prevalence since the 1990s is not only affecting the historically documented endemic area north of the Alps but more recently also neighbouring regions previously not known to be endemic. The genetic diversity of the parasite population and respective distribution in Europe have now been investigated in view of generating a fine-tuned map of parasite variants occurring in Europe. This approach may serve as a model to study the parasite at a worldwide level.

METHODOLOGY/PRINCIPAL FINDINGS

The genetic diversity of E. multilocularis was assessed based upon the tandemly repeated microsatellite marker EmsB in association with matching fox host geographical positions. Our study demonstrated a higher genetic diversity in the endemic areas north of the Alps when compared to other areas.

CONCLUSIONS/SIGNIFICANCE

The study of the spatial distribution of E. multilocularis in Europe, based on 32 genetic clusters, suggests that Europe can be considered as a unique global focus of E. multilocularis, which can be schematically drawn as a central core located in Switzerland and Jura Swabe flanked by neighbouring regions where the parasite exhibits a lower genetic diversity. The transmission of the parasite into peripheral regions is governed by a "mainland-island" system. Moreover, the presence of similar genetic profiles in both zones indicated a founder event.

[An attempt to determine intermediate hosts of the tapeworm Echinococcus multilocularis in Poland]

Echinococcus multilocularis, a tiny tapeworm (2-3 mm in length) occurs in the small intestine of red foxes and raccoon dogs in Poland. Small rodents, intermediate hosts of the tapeworm can ingest parasite eggs excreted in faeces by final host. Humans can become infected by accidental ingestion of the eggs. The resulting disease, alveolar echinococcosis, potentially lethal zoonosis, typically presents as an infiltrative tumor-like growth in the liver, which may invade neighbouring organs. The objective of the study was to determine intermediate host species for E. multilocularis in Poland. During the years 2004-2006, a total of 1425 animals, i.e. 1170 rodents (14 species), 238 insectivores (4 species) and 17 Mustelids (3 species) were trapped and autopsied for the presence of E. multilocularis protoscolices (larvae). Animals were captured in northern, north-eastern, central and southern Poland, areas where the high prevalence of the tapeworm was recorded in foxes. In 44 (3.1%) of examined animals were found cysts in the liver, however no typical lesions were affirmed. Infection was not confirmed using PCR technique with primers specific for E. multilocularis (EmCA90, EmTriple83).

Echinococcus multilocularis in the red fox Vulpes vulpes from the East Carpathian region of Poland and the Slovak Republic

The occurrence of Echinococcus multilocularis in the Poland-Slovak frontier zone of the East Carpathian region was assessed, for comparison with that in adjacent regions in both countries. A total of 392 red foxes from Poland and 427 red foxes from the Slovak Republic were examined from 2001 to 2004. Significant differences in prevalences were observed in foxes captured from the borderland and adjacent zones in both countries. The mean prevalence of E. multilocularis in the Polish borderland reached 45.7+/-18.6% and in the Slovak border 35.0+/-10.7%. In both countries, the prevalence of E. multilocularis in red foxes from adjacent districts, outside the frontier Carpathian region, was considerably lower (18.9+/-9.2% in Poland and 20.8+/-9.0% in Slovakia). These differences are probably due to geomorphological and ecological factors, which contribute to the survival of the tapeworm eggs and the subsequent spread of infection. The Carpathian regions of northeast Slovakia and southeast Poland are characterized by specific climatic conditions such as low mean annual air temperatures, low temperatures in active soil surfaces, high soil humidities and a high mean annual rainfall.

[Risk of alveococcosis for humans in Poland]

The paper presents data on occurrence, diagnosis and treatment of alveolar echinococcosis in humans as well as possible methods of its prevention. Studies done in 2001-2003 in Poland have shown the high prevalence of the tapeworm in red foxes in the north-east (34.5%) and south-east (39.3%) of Poland with foci of infection in some counties (up to 70% foxes infected). It makes the high potential risk for human infection in these areas.

The study of cell and tissue mechanisms of the homeostasis of "helminth-host" system at muscle trichinellosis before and after the administration of a herb biostimulator and anthelminthic

Results of micromorphological and histological studies of larvae of Trichinella spiralis and T. pseudospiralis, as well as, muscles, liver and small intestine of the rat-host before and after biostimulator administration of phytohemagglutinin and phytoanthelminthic were presented. It has been established that rats with Trichinella larvae of both species developed unspecific allergic angiomyositis, hepatitis, cholangitis, and erosio-haemorrhagic enterocolitis in the host's organism on the 35th day after infection. Furthermore, processes of compensatory hypertrophy, that support the host's (rats) homeostasis, on cell and tissue levels, were observed at histodestructional and morpho functional deficiency. It has been revealed that phytohemagglutinin, biostimulator injected into the host's organism before infection, is of immunostimulating nature and partially destroys the larvae of Trichinella. The phytoanthelminthic produces a significant trichinellocide effect: RNA synthesis and glycogen is intensified in the organs of the treated animals, their pathomicromorphogenesis weakened, and their compensatory and regenerative processes were observed. The combined use of the phytohemagglutinin and phytoanthelminthic fails to intensify the mentioned effect.

[The influence of different management systems on the infection level of some gastrointestinal parasites in sheep in southern Poland]

On the basis of the fecal egg counts, larval cultures and necropsies the infection of coccidia, tapeworms and gastrointestinal nematodes in dams and lambs under extensive and intensive management systems were estimated. During 1994 and 1995 total of 1740 coproscopic analyses were done. It was state, that in extensive farms the prevalence and EPG of gastrointestinal nematodes was higher in comparison with intensive management system (38.2-86% and 13.9-71.9% and 105-355 EPG and 33-131 EPG respectively). Similarly prevalence of tapeworms 0-18.2% and 1.3-8.3% respectively. Prevalence and intensity of coccidia was lower in extensive farms (20-78,5% and 83-482 OPG) comparing with intensive management system (38.2-88% and 139-2846 OPG). Predominant nematode species in both management systems were those from genes Haemonchus, Teladorsagia, Trichostrongylus, Cooperia and Nematodirus. One species--Nematodirus battus was found new for Poland.

[Studies on the incidence of echinococcus multilocularis in red foxes (Vulpes vulpes) in north-east, central and south of Poland]

During the year 1994-1997, a total number of 1042 red foxes orginating from the 33 provinces North-East, Central and South of Poland under special safety procautions for intestinal stages of Echinococcus multilocularis using the mucosal-smer technique were examined. An average of 5.09% (53 foxes) from 10 provinces was infected. In those provinces, the prevalance varied between 1.19% to 35.71%. The infection varied from low to very high but mostly harboured gravid E. multilocularis parasites with thick-shelled eggs. Our data indicate that E. multilocularis in foxes has a surprisingly wide distribution in Poland. These new epidemiological data indicate that a potential risk of infection for humans may exists in all areas where foxes infected with E. multilocularis have been identified. It has been assumed that E. multilocularis might also occur in other provinces in which foxes examination have not yet been undertaken or number examined of animals was low. This study was supported by a two grands from the Swiss National Foundation (projects No 7PLPJ038414 and 7PLPJ041302).

[Attempt of deworming of red and fallow deer in deer farm with rintal premix]

Rintal 2.4% premix (Bayer) in single dose 7.5 mg of active substance on kg body weight was given to the calves of red and fallow deer. Effectiveness of deworming against nematodes from family Trichostrongylidae was 85.2% in red and 97.8% in fallow deer. Against namatodes from genus Trichocephalus the effectiveness was higher extending in red deer 98.1%, and in fallow deer 99.5%. Anthelmintic was not effective against nematodes Varestrongylus sagittatus and Elaphostrongylus cervi.

Genetic resistance to gastrointestinal nematode parasites in Polish long-wool sheep

A study was undertaken from 1991 to 1994 on a farm in southern Poland to evaluate the genetic parameters of resistance to gastrointestinal nematodes. The predominant species were Teladorsagia circumcincta and Haemonchus contortus. A total of 32 sires were evaluated, around 15 per year. Faecal egg counts were measured twice during the 4-month grazing season for lambs (total 659 lambs) and three times for their mothers (total 327 ewes). Infection levels were high during the first 2 years and low during the last 2 years. Using an animal model, the heritability of log10(epg+25) increased from 0.20 in August to 0.33 in September for lambs, and from 0.18 in May to 0.25 in September for ewes. The repeatability of ewe faecal egg count between years was 0.25. A genetic correlation of 0.58 was found between faecal egg count in ewes and in 6-7-month-old lambs. A negative genetic correlation (-0.61) was estimated between faecal egg count in September and daily weight gain of lambs from 70 days of age to the end of grazing season (7 months of age). The results confirm the feasibility of genetic selection of sheep for resistance to nematode parasites in an environment where T. circumcincta and H. contortus are the dominant species.

Prevalence and epidemiology of trichostrongylids in Wyoming cattle with consideration of the inhibited development of Ostertagia ostertagi

During 1988, monthly collections of abomasa and the cranial portion of the small intestine of 208 native Wyoming cattle were examined for adult and larval helminth parasites. Egg counts were performed on colonic faecal specimens. The animals ranged from 7 months to 8 years of age and were sampled at slaughter houses or diagnostic laboratories from five different counties in the State. Most of the cattle had ranged for a long time on non-irrigated, high altitude grass plains from about 1250 to 2500 m above sea level. All animals examined were found infected. Nematode genera (and number of species) found included Ostertagia (4), Trichostrongylus (2), Haemonchus (1), Cooperia (4) and Nematodirus (2). One trematode, Fasciola hepatica, and a cestode, Moniezia benedeni, also were found. Trichostrongylus axei, Trichostrongylus longispicularis and Cooperia lyrata were found for the first time in Wyoming, Ostertagia circumcincta was found for the first time in cattle in Wyoming, and Haemonchus placei, tentatively identified in a previous survey, was definitively confirmed. Predominant species (and prevalence) were Ostertagia ostertagi (98%), Cooperia oncophora (60.6%), Ostertagia bisonis (41.8%), Cooperia bisonis (33.6%) and T. Axei (27.9%). One or more of the four species of Ostertagia were found in all animals. Inhibited O. ostertagi and O. bisonis larvae predominated from November to April and reached a peak in January to comprise 88% of the total nematode burden for that month. The adult population of abomasal nematodes peaked in April and predominated thereafter until October. Haemonchus placei also spent the autumn-winter period in an inhibited state of development. Faecal egg counts were lowest during winter months, when the highest number of worms were present as L4 larvae, as determined by luminal and mucosal counts. Nematode populations in the small intestine peaked in June and persisted until November. The results of this study showed the magnitude and species composition of nematode parasitism in cattle raised on high altitude grass plains, underscored the inaccuracy of faecal egg counts as an indicator of worm burden during fall and winter seasons, and provided information on which anthelmintic treatment timing would be most efficacious.

Echinococcus multilocularis (Cestoda), the causative agent of alveolar echinococcosis in humans: first record in Poland

Echinococcus multilocularis, the causative agent of human alveolar echinococcosis, was found for the first time in Poland in 2 of 20 red foxes (Vulpes vulpes), originating from the area of Gdansk (northern Poland). This finding supports the hypothesis that the endemic area of this parasite in central Europe (Belgium, France, Luxembourg, Switzerland, Liechtenstein, Germany, and Austria) is not an isolated focus as previously anticipated but is connected with the large endemic zone in Russia.

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines for evaluating the efficacy of equine anthelmintics

These guidelines have been designed to assist in the planning, operation and interpretation of studies which would serve to assess the efficacy of drugs against internal parasites of horses. Although the term anthelmintic is used in the title and text, these guidelines include studies on drug efficacy against larvae of horse bot flies, Gasterophilus spp, which are non-helminth parasites commonly occurring in the stomach of horses. The advantages, disadvantages and application of critical and controlled tests are presented. Information is also provided on selection of animals, housing, feed, dose titration, confirmatory and clinical trials, record keeping and necropsy procedures. These guidelines should assist both investigators and registration authorities in the evaluation of compounds using comparable and standard procedures with the minimum number of animals.

The influence of filter top caging on the transmission of pinworm infections in mice

The effectiveness of filter top cages in preventing infection of mice with pinworms, Aspiculuris tetraptera and Syphacia obvelata, was investigated by introducing mice from a pathogen-free colony into a colony in which both types of pinworms were enzootic. Half of the pathogen-free mice were maintained in filter top cages, while the remainder were held in similar cages without filters. All mice thus introduced were killed and examined after 3-8 week exposure periods. No pinworm were recovered from mice in 17 of 18 cages with filter tops while mice in 12 of 16 cages without filter tops were infected.

Internal parasites of Washington cattle

The occurrence of internal parasites in Washinton cattle was estimated. During the survey period in 1972 and 1973, more than 3,700 fecal samples from 29 herds and 4 feedlots, and viscera from 55 cattle were examined. The percentage of fecal samples with parasite eggs or oocysts from herds was as follows: oocysts, 77%; "strongyline" eggs, 44%; Nematodirus eggs, 3%; Moniezia eggs, 3%; Fasciola eggs, 2%; Trichuris eggs, 2%; and Dictyocaulus larvae, 1%. The fecal samples from feedlots contained principally strongyline eggs which varied markedly in numbers among groups of cattle in the lots. The predominant parasite in viscera was Ostertagia spp, which was recovered from all of the cattle examined. Other parasites identified in the survey were found less frequently in these examinations. Cattle in dairy and beef operations utilizing irrigated pastures were particularly prone to Fasciola infections, and more strongyline eggs were observed there than in fecal samples from other management systems. Seasonal fluctuations in numbers of strongyline and Fasciola eggs were pronounced.