Anna-Maija Virtala

SYLVATIC TRICHINELLA SPP. INFECTION IN FINLAND

Abstract Although human infections caused by Trichinella sp. have not been reported in Finland for several decades and Trichinella sp. infection in pork has become virtually extinct in the last decade, sylvatic Trichinella spp. infection is still highly prevalent in Finland. Muscle digestion of 2,483 carnivorous wild animals from 9 host species during 1999–2005 showed 617 positive animals (24.8%). Molecular identification from 328 larval isolates revealed 4 different endemic Trichinella species, i.e., T. nativa, T. spiralis, T. britovi, and T. pseudospiralis. Seven percent of the infected animals carried mixed infections. Trichinella nativa was the most common species (74%), but T. spiralis was identified in 12%, T. britovi in 6%, and T. pseudospiralis in 1% of the animals. Host species showed different sample prevalence and Trichinella species distribution. Geographical distribution also varied, with the southern part of the country having significantly higher percentages than the northern part. Infection density was dependent on both the infecting Trichinella species and the host species. Trichinella spiralis was discovered in areas with no known domestic infection cases, indicating that it can also occur in the sylvatic cycle. Raccoon dogs and red foxes are the most important reservoir animals for T. spiralis, as well as for the sylvatic Trichinella species in Finland.

Approach to non-invasive sampling in dengue diagnostics: exploring virus and NS1 antigen detection in saliva and urine of travelers with dengue.

BACKGROUND Dengue diagnostics currently relies on serum and plasma tests. Although the proof of concept for detecting dengue virus (DENV) RNA and nonstructural protein 1 (NS1) antigen from urine and saliva has been demonstrated, few studies have explored their use in diagnostics. OBJECTIVES To investigate the occurrence, excretion kinetics, and diagnostic potential of DENV-RNA and NS1 antigen in the urine and saliva of dengue patients. STUDY DESIGN We examined serial serum, urine (n=50) and saliva (n=48) samples of 14 Finnish travelers with dengue. All samples were analyzed by NS1 ELISA and DENV RT-PCR, and the first and last serum specimens were tested for DENV IgG and IgM. In addition, biochemical parameters were studied from the urine and clinical and laboratory data of the patients were collected. RESULTS DENV-NS1 protein and RNA proved detectable from saliva and urine using tests developed for serum samples. RNA/NS1 detection showed a diagnostic sensitivity of 64%/54% and 60%/56% for urine and saliva, respectively. RNA analyses performed on days 7-13 after onset of symptoms revealed the sensitivity for urine (72%) to be greater than for serum (31%) or saliva (50%). The concentration of urine samples had no impact on RNA detection. CONCLUSIONS Noninvasive sampling enables an alternative approach to dengue diagnostics. The performance of the NS1 antigen assay may be improved by optimizing it for urine and saliva samples. The prolonged excretion of DENV-RNA in urine extends the sampling time window for molecular diagnostics and surveillance.

A 15-year survey of reproductive efficiency of Standardbred and Finnhorse trotters in Finland - descriptive results

BackgroundThe major horse breeds in Finland are the Finnhorse (FH) and the American Standardbred (SB). The foaling rates of the FH have consistently been lower than those of the SB. During the last years, a decreasing trend in foaling rates of both breeds has been observed. The purpose of this study was to describe and compare the structure of these two mare populations for age, reproductive history and mating type. In addition, changes over the years were studied that could explain the decline in foaling rates.MethodsIn Finland, the mating statistics and foaling rates per stallion are published yearly by Suomen Hippos, which is the Finnish trotting and breeding association authorized by the EU. The studied material was the electronic breeding data of Suomen Hippos in 1991-2005 which contained 69 180 cases (one mare bred in one year with one stallion), 20 168 mares, 2 230 stallions and 5 397 stud managers. The effect of mare age and type, mating type and changes during the study period were examined separately for FH and SB using SAS 9.1 for descriptive statistical analyses (frequencies, percentages, means, standard deviations and confidence intervals). The outcome of the last mating per season (foal or not) was used in the calculation of the foaling rates.ResultsThe FH mares were on average one year older and belonged to the older age groups more often than the SB mares. Ageing decreased foaling rates and even more in FH; the foaling rates were the following: young FH 68.6 and SB 72.1%, middle-aged FH 66.1 and SB 71.9%, ageing FH 61.2 and SB 68.4%, and very old FH 52.8 and SB 61.8%. The foaled mares were more frequent in the SB (45%) than in the FH (37%), but the barren and rested mares were more common in the FH. Natural mating was more commonly practiced in the FH as compared to the SB. The foaling rates decreased from 1991 to 2005 in SB from 75.1 to 65.9% and in FH from 66.5 to 60.8%. For both breeds, the proportion of young mares decreased and the proportion of very old mares increased over the years. Similarly, the proportion of foaled mares in both breeds decreased and the proportion of barren mares increased during the study period. In both breeds, insemination (AI) by transported cooled semen increased, diminishing the on-site AI in the SB and the natural mating in the FH.ConclusionsThe results of this study suggest that mare age and type and mating type all affect foaling rates and that the structural differences in the mare populations can explain differences in the foaling rates between the horse breeds and between the time periods.

Databases in veterinary medicine – validation, harmonisation and application: introduction

In order to use all the stored information on animal diseases in an optimal manner it is crucial that the purpose, circumstances and constrains for the data are known for the user. The objective with the NKVet symposium and ensuing special issue of Acta Vet Scand is to provide an overview of the most important databases on animal diseases in the Nordic countries. The possibility of using the databases for different purposes such as animal welfare, food safety and animal health economics will be in focus with the special question if we, in the future, can make databases more transparent by establishing database protocols to share among users of the databases. Finally, the possibilities of harmonisation of databases will be addressed. Large centralised data bases with information on animal diseases are becoming more and more common. The information can either be directly related to recording of the disease or pathogen, or it can be of indirect importance such as for example animal movements being a risk factor for disease transmission. The most detailed databases have been established for the production animals (cattle, pigs and poultry), but recently there has been increasing interest also for other species such as small animals and horses. Many databases have initially been established for different purposes such as, for example, calculation of breeding values in cattle or recording of specific pathogens to demonstrate disease freedom. The databases have been further elaborated over several years according to the specific circumstances, constraints and needs for the specific species. Therefore, the type of data on diseases varies from clinical observations, treatments pathological changes observed at meat inspection or laboratory diagnostic information on pathogens or their antibodies. Further, there is huge variation in events that trigger the collection of data being either a disease that needs treatment or a random sampling of animals. Obviously, this means that all the data on diseases have different validity in giving information on disease severity in terms of production loss or welfare or in terms of food safety.

Aleutian mink disease virus in free-ranging mustelids in Finland - a cross-sectional epidemiological and phylogenetic study.

Aleutian mink disease virus (AMDV) can cause severe immune-complex-mediated disease in American mink. AMDV has also been detected in several other mustelid species with potential negative impact on their health and population. A molecular and cross-sectional epidemiological study was conducted to obtain data on the prevalence, distribution, transmission and diversity of AMDV strains in Finnish free-ranging mustelids and risk factors associated with infection. The presence of anti-AMDV antibodies and/or AMDV DNA was tested from 308 samples representing eight mustelid species and 17 administrative regions. Positive samples were detected across Finland, and in 54 % (31/57) of feral American mink, 27 % (7/26) of European badgers and 7 % (1/14) of European polecats. Samples from Eurasian otters, European pine martens, least weasels, stoat and wolverine were negative. Major risk factors for infection were the species American mink with 335 and badger with 74 times higher odds than other species, and the years 2006-2009 with five times higher odds than the years 2010-2014. No clustering according to species, geographical origin or year was evident in phylogeny, except for four divergent sequences from Estonian badgers that formed a separate phylogroup distinct from other AMDV strains. This study showed that AMDV was prevalent in certain species of Finnish free-ranging mustelids and widely distributed across Finland. Furthermore, the free-ranging mustelids carried both strains similar to those found in farmed mink, but also distinct strains that may represent novel amdoparvoviruses.

Validation of an automated ELISA system for detection of antibodies to Aleutian mink disease virus using blood samples collected in filter paper strips

BackgroundAleutian mink disease virus (AMDV) is the cause of a chronic immune complex disease, Aleutian disease (AD), which is common in mink-producing countries. In 2005, implementation of an AMDV eradication programme in Finland created a need for an automated high-throughput assay. The aim of this study was to validate an AMDV-VP2 -recombinant antigen ELISA, which we developed earlier, in an automated assay format for the detection of anti-AMDV antibodies in mink blood and to determine the accuracy of this test compared with the reference standard (counter-current immunoelectrophoresis, CIEP).MethodsA blood sampling method based on filter paper 12-strips (blood combs) and a device to introduce these strips to an ELISA plate for elution of the samples were developed. Blood and serum samples were collected from 761 mink from two farms with low (2%) and high (81%) seroprevalences of AMDV infection in 2008. ELISA sensitivity and specificity were estimated with a Bayesian 2-test 2-population model that allowed for conditional dependence between CIEP and ELISA. Agreement between the two tests was assessed with kappa statistic and proportion agreement.ResultsThe sensitivity and specificity of the automated ELISA system were estimated to be 96.2% and 98.4%, respectively. Agreement between CIEP and ELISA was high, with a kappa value of 0.976 and overall proportion agreement of 98.8%.ConclusionsThe automated ELISA system combined with blood comb sampling is an accurate test format for the detection of anti-AMDV antibodies in mink blood and offers several advantages, including improved blood sampling and data handling, fast sample throughput time, and reductions in costs and labour inputs.

Nordic dairy farmers' threshold for contacting a veterinarian and consequences for disease recording: mild clinical mastitis as an example.

Previous studies have addressed the differences in registered disease incidence between the Nordic dairy disease recording systems. The main objective of this study was to investigate whether Nordic dairy farmers have varying intention to contact a veterinarian the same day as detecting signs of mild clinical mastitis (MCM) in a lactating dairy cow. This is the first, and necessary, step in the process leading to a disease event being recorded. The second objective was to study underlying behavioural components influencing this threshold for action. A questionnaire-based survey was carried out in Denmark, Finland, Norway and Sweden. The questionnaire was based on the Theory of Planned Behaviour from the field of social psychology. After performing qualitative face-to-face elicitation interviews a set of statements about treatment of MCM was identified. These were grouped into behavioural, normative and control beliefs. The most frequently mentioned beliefs were rephrased as questions. Behavioural intention, a proxy for the behaviour of interest, was assessed using case scenarios. The target and eligible herds were in milk recording and had an average herd size of at least 15 cows. The questionnaire was distributed to 400 randomly sampled dairy producers per included country. The response rate was around 50% in all four countries. The hypothesis of differences in behavioural intention between the countries was tested using Wilcoxons rank-sum tests. Multivariable linear regression was used to estimate the country-specific variability in behavioural intention as explained by attitude, subjective norm or perceived behavioural control alone, or in combination. The Spearman rank correlations between behavioural intention and each belief, weighted by its outcome evaluation or the motivation to comply, were estimated to find the most important drivers, constraints and social referents for the behaviour of interest. There were significant (p<0.01) differences in behavioural intention between all countries except Denmark and Norway. Swedish farmers had the weakest behavioural intention and Finnish farmers the strongest. Attitude explained most of the variability in behavioural intention in all four countries. The most important driver in all countries was to achieve a quick recovery for the cow. The varying behavioural intention partly explain the differences in completeness of disease data in the Nordic countries: if farmers have different thresholds for contacting a veterinarian the registered incidence of clinical mastitis will be affected. Knowledge about the importance of attitudes and specific drivers may be useful in any communication about mastitis management in the Nordic countries.

Nordic veterinarians' threshold for medical treatment of dairy cows, influence on disease recording and medicine use: Mild clinical mastitis as an example

National databases for dairy cows in the four Nordic countries, Denmark, Finland, Norway and Sweden, have been found to capture varying proportions of disease events on farm. A variation in the thresholds of veterinarians to initiate medical treatment may be a reason for this. Studying these thresholds may increase the understanding of prudent use of antibiotics. The primary objective of this study was to investigate whether Nordic veterinarians, on a between country-level, vary in their intention to start medical treatment of a dairy cow with mild clinical mastitis, on the same day as making the diagnosis. The threshold for initiating treatment was quantified as an intention score. Secondary, underlying behavioural components of the intention score was studied within each country. A social psychology model, the Theory of Planned Behaviour (TPB), was used to design a questionnaire that was distributed to 1047 veterinarians in cattle practice in the four countries during autumn 2010. The response rate was around 50% in all the countries, and 543 observations were retained for analysis. The between-country differences in intention were tested with one-way analysis of variance. Multivariable linear regression was used to estimate the proportion of variability in intention explained by the three behavioural components, attitude, subjective norm and perceived behavioural control. The Spearman rank correlations between specific beliefs about the behaviour and intention scores were estimated to find beliefs of high influence on the decision to treat or not. Intention scores differed between all countries (p<0.05) except between NO and SE (p=0.06). The mean intention scores were 0.71, 0.42, 0.58 and 0.50 in DK, FI, NO and SE, respectively. As measured by the adjusted R(2) in linear regression models, the underlying behavioural components of the TPB explained 0.37, 0.41, 0.40 and 0.48 of the variation in intention scores in DK, FI, NO and SE, respectively. Attitude was the most important predictor in DK, NO and SE, but perceived behavioural control was most important in FI. In all countries the specific attitude belief of highest influence was that starting treatment the same day as diagnosing a case of mild clinical mastitis gives the best result, compared to delaying treatment. The varying intentions of veterinarians to initiate medical treatment are likely to influence centrally registered mastitis incidence. This study has given an improved understanding of this behaviour, which may be useful in intervention studies or campaigns aiming at prudent use of antibiotics on dairy farms.

Enriched rearing environment and wild genetic background can enhance survival and disease resistance of salmonid fishes during parasite epidemics

Summary 1. The importance and volume of aquaculture is increasing world-wide. Rearing practices play a key role in determining growth rate, survival and disease resistance in aquaculture fishes. Recent evidence suggests that in comparison with a standard stimulus-poor rearing environment, an enriched or variable rearing environment has significant positive effects on several traits underlying growth and well-being of fish. However, the effect of enriched rearing on one of the most important threats for aquaculture development, occurrence of parasitic infections, remains unknown. 2. We used surveillance data of experimental salmonid populations of wild and hatchery origin under semi-natural parasite exposure to explore effects of enriched rearing on outbreaks of important aquaculture pathogens and associated fish mortalities in production-scale fish densities. We also conducted controlled parasite exposures to investigate if enriched rearing reduces susceptibility of fish to infection in comparison with standard rearing conditions. 3. We found evidence of enriched rearing influencing survival and disease resistance of aquaculture fish during parasite epidemics. Essentially, populations from enriched rearing had a higher survival rate, lower parasite occurrence and greater resistance to most infections compared to fish held in standard rearing conditions. Similarly, fish of wild genetic background had lower mortality during some of the epidemics compared to fish of hatchery origin. However, we also demonstrate significant variation in these patterns and in some cases a tendency for opposite effects of enriched rearing and genetic background depending on the fish species and nature of the epidemic. 4. Synthesis and applications. Our results suggest that parasitic infections and epidemics can be managed through enriched rearing conditions. This may have important implications for economically and ecologically sustainable parasite and disease prevention strategies in aquaculture.

Trichinella in the North

Background Endemic human trichinellosis has been rare in Norway, Sweden and Finland. In Norway the last outbreak involving five persons is from 1953 and before that there were reported six epidemics with 711 patients since 1881 (reference in [1]). In Sweden 10 outbreaks involving 504 patients were documented 1917-1969 (reference in [2]). In Finland only eight human cases have been reported since 1890, the latest being three hunters at 1977 who got the infection from bear meat (reference in [1]). Sporadic cases of trichinellosis in production animals have been detected in pig meat inspection in these countries. In Norway there was a peak of positive pigs in the 1950’s and 1960’s but since 1981 no positive finding in pigs has been reported. In Sweden, 127 positive pigs were reported 1970-1999 and no cases since 2000. The first infected Finnish pig was found 1954, and the total number of positive pigs in fifty years was up to 714 (1954-2003). There was a peak of cases in the 1980’s and 90’s when a total of 671 pigs were found positive. During 1981-2000, the positive animals originated from 0-19 farms yearly. Since 2004 no trichinella has been found in pigs. The decrease in Trichinella prevalence and incidence in domestic swine has been speculated to be due the change in Finnish swine industry since Finland joined the EU in 1995 [3]. During recent years, the industry has moved towards large-scale enterprises with corporative ownership with new facilities. These are better protected against the Trichinella infection commonly present in surrounding wildlife in Finland [3]. High sylvatic trichinellosis prevalence has been reflected to farmed wild boars in which condemnation due trichinelllosis has been relatively more common than in pig. To clarify the spatial variation of sylvatic trichinella prevalence suggested in earlier studies, a new Finnish sample set was analyzed.