Emergence of Echinococcus multilocularis among Red Foxes in northern Germany, 1991--2005

The parasite Echinococcus multilocularis is currently of great concern in Europe because of its spreading behavior, which has public health implications. This study investigates the spatiotemporal distribution of Echinococcus multilocularis in Red Foxes. The infection status of 8459 foxes was sampled from 43 regions in the north German province of Lower Saxony over three investigation periods 1991--1994, 1994--1997 and 2003--2005. Linear empirical Bayesian smoothing within the binomial model was used to produce smoothed choropleth maps. Geostatistical kriging was applied to generate prevalence risk maps. Further geostatistical modeling of the prevalence difference between study periods facilitated spatiotemporal trend investigations. The spatial scan statistic was used for cluster detection analysis. The average prevalence risk for Lower Saxony increased from about 12 to 20% during 1991--2005. Specifically the increases from first to second and to third study periods were estimated by 3.3% (CI 95%: 0.6%-5.9%) and 8.5% (CI 95%: 5.2%-11.8%), respectively. Infections in foxes were clustering and a location stable disease cluster was detected in the south of the province. This study is the first showing evidence for steady emergence of Echinococcus multilocularis in Red Foxes. First cases of human Alveolar Echinococcosis were recorded recently.     

Increase in the prevalence of Echinococcus multilocularis infection in red foxes in Lower Saxony.]

Echinococcus multilocularis is a tapeworm having carnivores as final hosts, the red fox in particular, dog and cat less frequent. Its two host life cycle consists of a larval cycle which predominantly takes place in the liver of rodents such as mice but it can also develop in musk rats as intermediate hosts. Man can also be infected and serves as a wrong intermediate host. He develops an alveolar echinococcosis which usually ends lethal without medical treatment. The prevalence of E. multilocularis among 5.365 red foxes in Lower Saxony was monitored from 1991 to 1997. The data were analysed using spatial epidemiological methods. This evaluation is based on a significance test which was applied to the parameters of spatial autoregressive regression models (CAR) fitting to the data of two successive sampling periods from 1991-1994 and 1994-1997. The mean prevalence (spatial median) increased from 6% to 11%. The results of this epidemiological study which was restricted to Lower Saxony support for the first time the earlier reported assumption that the prevalence of foxes infected with E. multilocularis has risen in Europe in the last decade. The reasons for this development are still unknown.     

Epidemiological study of pasture-associated laminitis and concurrent risk factors in the South of England

A retrospective study of laminitis was carried out to identify risk factors associated with this disease on an East Anglian farm with approximately 1000 animals living in an area of 1000 acres. Medical records between January 1997 and May 2000 and between April 2005 and March 2008 were reviewed, and the age, sex, weight (kg), height (inches [in] and hands [H]) and weight-to-height ratio (kg/in) was recorded. The prevalence, incidence and seasonality of laminitis were determined and their relationship to the monthly temperature, rainfall and hours of sunshine was evaluated. Averaged over the six years, the highest prevalence (2.6 per cent) and incidence (16 cases/1000 animals) of laminitis occurred in May. The findings of a multivariate analysis revealed that females (P=0.007, odds ratio [OR] 1.46, 95 per cent confidence interval [CI] 1.1053 to 1.9646) and light animals (P ≤ 0.001, OR=0.995, 95 per cent CI =0.9932 to 0.9963) had the greatest risk of developing laminitis. A positive association was found between hours of sunshine and incidence (P=0.007, relative risk [RR] 1.009, 95 per cent CI 1.001 to 1.012) and prevalence (P=0.002, RR 1.008, 95 per cent CI 1.003 to 1.012) of laminitis. The data suggest that there is a relationship between season, sex of the animal and the development of laminitis.     

Echinococcus multilocularis in Austrian foxes from 1991 until 2004

The prevalence rates of Echinococcus multilocularis in foxes (n=5600) evaluated in several Austrian surveys conducted between 1991 and 2004 were analysed for spatial and temporal differences. Data from early studies (1993-1997) in which the intestinal scraping technique (IST) was utilized were compared with data from recent (1999-2004) investigations, which made use of the shaking in a vessel technique (SVT), and it was assessed whether or not the infection rates of Austrian foxes had increased between the investigated intervals. In total, data from 85 districts are presented and both the retrospective and recent data are available from 39 of these districts. A Bayesian hierarchical model of parasite prevalences is presented which (i) accounts for differences in the sensitivity of IST and SVT, (ii) incorporates spatial auto-correlation between neighbouring districts, (iii) investigates the possibility of a temporal shift in the infection status of foxes, and (iv) quantifies uncertainty at each level of the model. The national average prevalence rates in the mid-1990s and at the turn of the millennium were 2.4% (95% confidence intervals 1.1-4.8) and 3.9% (95% confidence intervals 1.5-8.4) respectively. Above average prevalence rates were observed in the western and the northern parts of the country. Evidence is also presented for a temporal augmentation of the prevalence rates in some districts in the northern and eastern parts of the country. These findings are in concordance with several investigations in other European states where both newly emerged areas and elevated levels of transmission in existing endemic areas have been found. None of the districts investigated here showed significant evidence of a drop in prevalence.     

Base line prevalence and spatial distribution of Echinococcus multilocularis in a newly recognized endemic area in the Netherlands

The base line prevalence of Echinococcus multilocularis in foxes was determined in the eastern part of the province of Groningen in the Netherlands adjacent to the German border. This region has been identified in a previous study in 1998 as one of the westernmost border areas of E. multilocularis. Base line prevalence data are important for a better insight in the possible spread of the parasite and its changes in time. As fox feces containing E. multilocularis eggs are an important source for human exposure this base line prevalence is also an indicator for the potential risk for public health. The base line prevalence was estimated at 9.4% (95% CI: 5.2-16.5%). These results confirm previous findings of E. multilocularis in the same region. The spatial distribution of the infected foxes has been analyzed as a spatial gradient using a logistic model. The prevalence appeared to change strongest in east-western direction and was highest near the German border, adjacent to a German endemic area. These results suggest that the border areas in the Netherlands are the most margin of E. multilocularis territory.     

Use of the scan statistic on disaggregated province-based data: foot-and-mouth disease in Iran

The spatial scan statistic was applied to density-smoothed data that approximated the spatial distribution within the area and reduced the potential bias produced when location data have been aggregated for large areas. The method is illustrated, using data on the location of foot-and-mouth disease (FMD) outbreaks in Iran. Data examined were 4477 FMD outbreaks reported on a per province basis between June 1996 and September 2003. A kernel density of the outbreak locations was estimated, using a fixed radius and the centroid of each province as the designated location of all cases reported for the province. The radius that produced a density map with the highest correlation with expert opinion was 4° (latitude/longitude). Livestock density was used as a proxy for the underlying population at risk of acquiring FMD. Livestock and outbreak density maps were overlain to obtain the number of outbreaks and livestock in each of 15,599 cells covering the mapped surface of the country. A spatial scan statistic was applied to the density-smoothed data assuming that the outbreaks had a Poisson distribution. Results were compared with those obtained using a spatial scan statistic on provincially aggregated data. Application of the spatial scan statistic on the density-smoothed data allowed identification of clusters (P < 0.01) related more to the actual geographic distribution of cases (expert opinion) and of animals at risk, than to the distribution of the provinces. Significant clusters of FMD were identified that coincided with roads, neighboring countries, and high-density population areas, suggesting that the region may represent a route for cross-continent transmission of FMD.     

Spatial distribution and genetic diversity of Echinococcus multilocularis in Hungary

Human alveolar echinococcosis, caused by the tapeworm Echinococcus multilocularis, is the most pathogenic helminthic zoonosis in the temperate and arctic region of Europe. Between November 2008 and February 2009, 840 red fox (Vulpes vulpes) carcasses, were randomly collected from the whole Hungarian territory. The intestinal mucosa from all the foxes was tested by sedimentation and counting technique. E. multilocularis adult worms were detected in foxes of 16 out of the 19 Hungarian counties and in the suburban areas of the capital, Budapest. The prevalence and abundance of infection was significantly (P<0.001) higher in the north-western half (16.2%, CI=14.5-17.9; m ± SE=165.5 ± 112.4) than in the south-eastern half of the country (4.2%, CI=3.2-5.2; m ± SE=3.6 ± 2.1). The highest prevalence (26.6%, CI=22.5-30.8%) and abundance (m ± SE=614.2 ± 469.3) was observed in the Northern Mountain Region bordering Slovakia. The multi-locus microsatellite analysis of 81 worms showed the presence of four out of the five main European profiles. The H profile was the most common profile (55.5%) with nine genotypes, followed by the G (18.5%) with two genotypes, E (13.6%) with one genotype and D (12.4%) with two genotypes. The genetic distance was not statistically correlated with the geographical distance of the samples, supporting the hypothesis that the geographical distance is only a minor factor among those involved in the genetic distribution of this parasite in Europe. These data indicate that Hungary should be considered as a peripheral area of a single European focus, where the dispersal movement of foxes resulted in the spreading of the parasite from one county to another within a time period short enough to avoid a substantial genetic drift.     

Spatial distribution of bluetongue surveillance and cases in Switzerland

Swiss Bluetongue surveillance from mid 2007 to mid 2008 was a combination of monthly bulk milk testing of 200 cattle herds in zones of higher risk for vector presence and intensification of passive clinical surveillance. The spatial scan statistic and Moran's I statistic were used to determine clustering of surveillance data. The results show a high level of surveillance intensity for BT in Switzerland in 2007. In the region encompassing the Cantons of Aargau, Basel-Landschaft, Basel-Stadt and Solothurn, where cases were detected in 2007, the surveillance was significantly higher than in the rest of Switzerland. Six cases of Bluetongue were detected within the surveillance system. The prevalence estimates 9.62% (95% CI = 3.25%-18.85% versus 0.98% (95% CI = 0.2%-2.22%) were also significantly higher in the area with higher surveillance intensity. Spatial variation in surveillance data should to be considered if a disease event is analysed on a national scale. The spatial variation of prevalence estimates should be considered in future Bluetongue surveillance in Switzerland.     

Red foxes (Vulpes vulpes) are a natural intermediate host of Neospora caninum

The present study was undertaken to determine if red foxes are natural intermediate and/or definitive host for Neospora caninum and to study the importance of infection of N. caninum in this species in North-eastern Spain. Faecal samples and brain tissues were obtained from 122 foxes from 21 rural areas of Catalonia. Faeces collected were examined for parasite eggs and coccidian oocysts using sucrose flotation. For PCR-based diagnosis of N. caninum in brain tissues, the specific genomic Nc5 region was selected as the target sequence for DNA amplification. To control for PCR failure and facilitate identification of truly negative samples, the competitor pNc5C molecule was added to all negative samples in a second round of PCR reactions. Of the 122 foxes analysed, 13 (10.7%) were positive by PCR for N. caninum. Signal intensities of all positive samples were relatively weak with the exception of one sample from a 3-month male animal, that also showed the highest repeatability. No differences were observed by sex, age or area of sampling analysis. Detection of stages of N. caninum in brain from naturally infected red foxes demonstrated that red foxes are a natural intermediate host for N. caninum. Faecal samples were analysed for the presence of N. caninum oocysts, however, no oocysts compatible with N. caninum were found. A widespread latent infection of red foxes in North-eastern Spain found in the present study indicates that red foxes could have a very important role in the epidemiology of neosporosis in our area.     

Echinococcus multilocularis in Grisons: distribution in foxes and presence of potential intermediate hosts

The southern border of the European endemic area of Echinococcus multilocularis runs along the alpine crest. This endemic transition area was analysed in the canton Grisons on a small spatial scale. A total of 543 foxes originating from 10 areas north and 4 areas south of the main alpine divide were investigated. Parasites were isolated using the sedimentation and counting technique on intestinal contents. The mean prevalence of E. multilocularis was 6.4% with significant differences between different areas. In the southern valleys, only foxes from the Val Müstair were infected (14.3%). On the northern side of the main alpine divide, prevalences varied between 0 and 40%. The predation habits of foxes on potential intermediate hosts was investigated by means of stomach content analyses (n=530). Rodents of the genera Microtus/Pitymys were found in 19.6% of fox stomachs, Clethrionomys glareolus in 8.0% and Arvicola terrestris in 0.4%. A small scale analysis based on a 10 x 10 km grid suggested that the predation rate on the genera Microtus/Pitymys significantly correlated with the prevalence of E. multilocularis in foxes (Spearman's r = 0.51). Hence, E. multilocularis appears to occur in the alpine study area on a very small spatial scale. These local sources of infection may persist for decades. This may partly explains why, during the last 34 years, some human cases of alveolar echinococcosis occurred in areas of the Canton Grisons where the parasite is presently endemic in foxes. No such human cases have been recorded in other areas free of E. multilocularis.     

Long-term study of Sarcoptes scabiei infection in Norwegian red foxes (Vulpes vulpes) indicating host/parasite adaptation

The red fox (Vulpes vulpes) population, in Norway, was na?ve to Sarcoptes scabiei prior to the late 1970s when this parasite was first recorded and a still ongoing epidemic started. During the course of this protracted epidemic some degree of host/parasite adaptation, with the occurrence of healthy antibody positive foxes, might be expected. In the present study the prevalence of sarcoptic mange and serologically identified S. scabiei exposure was investigated in 363 Norwegian red foxes, shot by hunters during two different study periods (1994-1995 and 2002-2005). The sarcoptic mange diagnosis was based upon the presence of clearly visible lesions in the skin of the cadaver with confirmatory demonstration of S. scabiei. The serodiagnosis was based on an indirect-ELISA. There was a significant decrease in prevalence of both mange cases and seropositive animals from the first to the second study period. Whilst the mange prevalence fell more than threefold, from 30.0% to 6.6%, the seroprevalence dropped less dramatically from 53.3% to 19.1%. The smaller decrease in seroprevalence compared to mange cases reflected a significantly higher ratio of seropositive-mange negative versus seropositive-mange positive foxes, during the second study period, 40:18, compared to the first, 14:18. These findings indicate that the red fox population is adapting to live with the parasite and that low-grade or sub-clinical infections, and even recoveries, occur amongst exposed foxes. Mange positive foxes had significantly poorer body condition than those without sarcoptic mange. No significant difference in body condition was seen between seropositive-mange negative versus seronegative-mange negative foxes. The ELISA sensitivity was found to be 95% and proved a useful tool for investigating the exposure to S. scabiei in wild foxes. This study is believed to be the first pointing to a long-term Sarcoptes/fox adaptation, combining long-term prevalence studies of clinical sarcoptic mange and serological evidence of exposure to the parasite in the general fox population.     

Prevalence of antibodies against Toxoplasma gondii and Neospora caninum in Hungarian red foxes (Vulpes vulpes)

In the present study we have investigated the seroprevalence to the protozoan parasites Toxoplasma gondii and Neospora caninum in 337 red foxes (Vulpes vulpes) from 16 out of 19 counties in Hungary. The foxes were originally collected within a National vaccination program against rabies. Antibodies to T. gondii were detected in as many as 228 (68%) of the foxes using a commercial direct agglutination test (DAT). In an indirect iscom ELISA, five foxes (1.5%) were positive for antibodies against N. caninum. The high prevalence of foxes positive for T. gondii might be explained by the widespread occurrence of the parasite in the diet of foxes. As a contrast, latent infections of N. caninum among red foxes in Hungary are much less common.     

Choropleth mapping of regional count data of Echinococcus multilocularis among red foxes in Lower Saxony, Germany.

In this paper, choropleth maps display the geographical distribution of Echinococcus multilocularis in red foxes in Lower Saxony. Areas of high prevalence of the infection in foxes and with high fox population density pose high risk for the human population for alveolar echinococcosis. Spatial statistical methods were used to analyse regional count data obtained from 5365 hunted or found-dead foxes. Spatial smoothing (of raw estimates of regional prevalences based on count data before mapping) was used because raw estimates can give an erratic impression of the spatial pattern of the infection. For smoothing, empirical Bayesian methods are used as an explorative spatial epidemiological tool. The resulting map showed the geographical variation of the estimated prevalences around a median at 9% and indicated the presence of spatial-trend effects. Based on this finding, conditional autoregressive spatial modelling for Freeman-Tukey transformed data was used as an inferential spatial epidemiological tool. There were significant additive linear and quadratic spatial-trend effects with elevated prevalences in the north and south and extreme values (prevalences>38%) for the south of Lower Saxony.     

Echinococcus multilocularis in Europe - state of the art

New information has become available on the epidemiological situation of Echinococcus multilocularis in Europe. Additional endemic areas have been identified, and, in some areas, prevalences in foxes have drastically increased. In addition, some neozootic mammals may by now be involved in the lifecycle. The parasite is now widespread in urban and suburban areas in central Europe. The number of human cases of alveolar echinococcosis is small, but still underreported, and is likely to increase in the near future. Trials to counteract the spread of this parasite have been performed by application of anthelmintics to foxes via baits, and gave encouraging results on different spatial scales.     

Spatial distribution of Trichinella britovi, T. pseudospiralis and T. spiralis in red foxes (Vulpes vulpes) in Hungary

The red fox (Vulpes vulpes) is considered one of the main reservoir of Trichinella spp. in Europe. As limited information on Trichinella infection in wildlife of Hungary is available, 2116 red foxes, representing more than 3% of the estimated fox population of the country, were screened to detect Trichinella larvae by a digestion method. Trichinella larvae from the 35 positive foxes were identified by a multiplex PCR as Trichinella britovi (30 isolates, 85.7%), Trichinella spiralis (4 isolates, 11.4%), and Trichinella pseudospiralis (1 isolate, 2.9%). The true mean intensity of T. britovi, T. spiralis and T. pseudospiralis larvae in lower forelimb muscles was 23.6, 3.5 and 13.5larvae/g, respectively. T. spiralis was detected only in the southern and eastern regions. The non-encapsulated T. pseudospiralis was recorded for the first time in Hungary. Although the overall true prevalence of Trichinella infection in foxes was only 1.8% (95% confidence interval, CI=1.5-2.1%), the spatial analysis reveals different risk regions. In the north-eastern counties bordering Slovakia and Ukraine (21% of the Hungarian territory), the true prevalence of Trichinella infection is significantly higher than that observed in other regions (6.0%, CI=4.8-7.1%). In the southern counties bordering Croatia, Serbia and Romania (41% of the Hungarian territory), the true prevalence of Trichinella infection is moderate (1.4%, CI=1.0-1.8%). In the north-western and central counties (38% of Hungarian territory), the prevalence of Trichinella infection is significantly lower (0.2%, CI=0.1-0.4%) than that of the other regions. Based on the statistical analysis and the evaluation of epidemiological data, none of the counties can be considered free of Trichinella infection. In the past decade, Trichinella infection has been detected only in few backyard pigs, and only few wild boar-related autochthonous infections in humans were described. Nevertheless, these results highlight the need of the maintenance of a strict monitoring and control programmes on Trichinella infection in farmed and hunted animals of Hungary.     

Echinococcus multilocularis in Europe - state of the art

New information has become available on the epidemiological situation of Echinococcus multilocularis in Europe. Additional endemic areas have been identified, and, in some areas, prevalences in foxes have drastically increased. In addition, some neozootic mammals may by now be involved in the lifecycle. The parasite is now widespread in urban and suburban areas in central Europe. The number of human cases of alveolar echinococcosis is small, but still underreported, and is likely to increase in the near future. Trials to counteract the spread of this parasite have been performed by application of anthelmintics to foxes via baits, and gave encouraging results on different spatial scales.     

Screening for infection of Trichinella in red fox (Vulpes vulpes) in Denmark

A total of 6141 foxes (Vulpes vulpes) were examined for infection with Trichinella. The foxes were killed in Denmark during the hunting season 1995-1996 and 1997-1998; 3133 and 3008, respectively. Foxes included in the investigation came from throughout the country with the exception of the island of Bornholm. The right foreleg from each fox was submitted for investigation. The legs were stored at -20 degrees C for 3-10 months prior to examination. Following thawing, muscle tissue (10 g) from each leg was examined by trichinoscopy and by a pepsin-HCl digestion technique. In 1995-1996, three foxes were found positive corresponding to a prevalence of 0.001. Each of the infected foxes harboured an extremely low infection, i.e. about one larva per 10 g muscle tissue. It was not possible to obtain sufficient larval material for species identification. All three foxes were shot in the vicinity of a small village in the north-western part of Denmark. In 1997-1998 no Trichinella cases were found. The results, compared with previous studies, indicate that the prevalence of infection of Trichinella sp. among wild living foxes in Denmark is very low. This is further supported by the fact, that no infection of Trichinella sp. has been found in slaughtered pigs in Denmark for more than 65 years, which suggests that the infection pressure is very low. Considering the facts above we conclude that the risk of Trichinella infections is negligible in intensive indoor pig production units in Denmark whereas high local prevalence of Trichinella infections in the wildlife might constitute a serious risk for the expanding outdoor pig production.     

Factors associated with spatial clustering of foot-and-mouth disease in Nepal

The purpose of this study was to quantify associations between hypothesized epidemiological factors and the spatial distribution of foot-and-mouth disease (FMD) in Nepal. Spatial clustering of reports of at least one FMD case by Village Development Committee (VDC) in 2004 was examined by use of the spatial scan statistic. A Bayesian Poisson multivariate regression model was used to quantify the association between the number of reports and 25 factors hypothesized to be associated with FMD risk. The spatial scan statistic identified (P < 0.01) two clusters of FMD reports. Large numbers of people, buffalo, and animal technicians in a district were associated with an elevated risk of a VDC reporting ≥1 FMD case. The knowledge of high-risk areas and factors associated with the risk of FMD in Nepal could be applied in future disease control programs.     

CAN SONOGRAPHIC FINDINGS PREDICT THE RESULTS OF LIVER ASPIRATES IN DOGS WITH SUSPECTED LIVER DISEASE?

While abdominal ultrasound and ultrasound-guided fine-needle aspiration cytology are often combined to help determine the type of liver disease in dogs, little is known about the relationship that may exist between the results of these tests. We hypothesized that specific sonographic findings, or combinations of findings, may predict results of liver ultrasound-guided fine-needle aspiration cytology. Hepatic and extrahepatic sonographic findings were recorded prospectively using a standardized form in 70 dogs with clinically suspected liver disease and in which liver ultrasound-guided fine-needle aspiration cytology was performed. The predictive value of sonographic findings in regard to the category of cytology results was assessed with stepwise logistic regression analysis. Sonographic detection of a hepatic mass (≥3 cm; risk ratio [RR] 3.83, 95% Wald confidence intervals [95% CI] 2.42–3.93, P =0.0036), ascites (RR 3.82, 95% CI 1.94–4.28, P =0.0044), abnormal hepatic lymph node(s) (RR 3.01, 95% CI 1.22–4.88, P =0.0262), and abnormal spleen (RR 3.26, 95% CI 1.20–3.85, P =0.0274) were the most predictive of liver neoplasia on cytology. Conversely, sonographic detection of hepatic nodules (<3 cm; RR 1.97, 95% CI 0.95–2.96, P =0.0666) was most predictive of vacuolar hepatopathy on cytology. In dogs with suspected liver disease, several sonographic findings, alone or combined, are thus predictive of liver ultrasound-guided fine-needle aspiration cytology results. In the light of the fact that ultrasound-guided fine-needle aspiration cytology of the liver has limitations, these predictabilities could influence the selection of diagnostic tests to reach a reliable diagnosis.     

Serological (Em2-ELISA) and parasitological examinations of fox populations for Echinococcus multilocularis infections

Serum or body fluid samples of 1,006 foxes were investigated in an ELISA for antibodies against a highly sensitive and specific antigen (Em2-antigen) of Echinococcus multilocularis. Parasitological examinations of the intestines and simultaneous serological examinations were carried out in 505 foxes: A group of 98 blue foxes (Alopex lagopus) from Norwegian fox farms did not contain intestinal stages of E. multilocularis and was clearly sero-negative in Em2-ELISA. On the other hand in red foxes (Vulpes vulpes) originating from European areas known to be endemic for E. multilocularis the following average prevalence rates were found: 244 foxes from Southern Germany, E. multilocularis prevalence 55% and sero-prevalence 60%; 139 foxes from Austria, E. multilocularis prevalence 4% and sero-prevalence 12%. Serological identification of individual foxes with or without intestinal E. multilocularis infection was not possible. Only serological (no parasitological) examination in 402 foxes originating from endemic areas in Switzerland resulted in a sero-prevalence rate of 37%. Sero-prevalence was only 6% and 4% in 54 and 26 other foxes, respectively, originating from Swiss and German areas where E. multilocularis has not yet been reported. Negative control Norwegian (farmed) silver foxes (n = 43) were all sero-negative. The specificity of the Em2-ELISA was confirmed by negative Em2-serologies with sera from dogs infected with intestinal and tissue dwelling helminth species (with the exception of two from 24 dogs infected with E. granulosus).(ABSTRACT TRUNCATED AT 250 WORDS)