Browsing by Organization "Finnish Food Safety Authority Evira"

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  • Rikula, Ulla (Evira, 2008)
    Evira Research Reports
    Canine distemper (CD) is one of the longest-known infectious diseases of dogs and is still prevalent in many parts of the world. Vaccination combined with biosecurity measures is the most productive way to prevent and control infectious diseases. The beneficial effects of vaccination are realized not only on the individual but also on the population level, the latter in the form of herd immunity (HI). Control of CD among dogs relies heavily on vaccination, while in fur farms and zoos with several species or large numbers of CD-susceptible animals in close contact, biosecurity measures in some cases offer the only available means for CD control. Modified live CD virus vaccines have been successfully used to control CD among farmed mink, and since no licensed vaccines for other species kept for fur exist, mink CD vaccines have also been used for foxes and raccoon dogs in CD emergency situations. CD vaccines for dogs (Canis familiaris) and mink (Mustela vison) were studied in experimental settings for their ability to induce virus-neutralising (VN) antibodies in target species. Mink vaccines were also assessed in silver foxes (Vulpes vulpes), blue foxes (Alopex lagopus) and raccoon dogs (Nyctereutes procyonoides). Purpose-bred beagle dogs were vaccinated twice with one of three CD vaccines: Candur® SHP, Canlan®-3 or Dohyvac® DA2P, and the levels of VN antibodies were determined at the time of vaccination and one month after the second vaccination. Fur animals were vaccinated once with Distemink®, Distem®-R-TC or vaccine 3 (which was not licensed in Finland) and the levels of VN antibodies were determined at vaccination and 2-4 times 1-4 months afterwards. Significant differences among vaccine groups were found both in the proportion of animals with measurable levels of VN antibodies and in the mean titres of antibodies. The levels of VN antibodies were also determined from a large field sample (n = 4 627) of vaccinated dogs. In addition to the three CD vaccines in the seroconversion study above, additional two vaccines, Duramune®-4 and Nobivac® DHP, had been used in the field. Each dog with a known vaccination history, date of birth, sex and breed was sampled once. Based on the overall geometric mean titre of the dogs vaccinated with a single vaccine brand, vaccines were divided into high-take (Candur®, Nobivac® and Duramune®) and low-take (Dohyvac® and Canlan®) groups. The vaccine groups differed significantly among dogs less than two years of age both in the proportion of dogs with detectable VN antibodies and in the mean titres. Both the number of vaccinations and age were associated with the titre and vaccine usage. To control for possible confounding factors, the comparison 8 of titres among vaccine usage groups was adjusted by classifying them according to the number of vaccinations (one to four) and the age group (less than one, one to two, or over two years old). The same division into low- and high-take vaccines was observed, irrespective of the number of vaccinations the dogs had received. The observations of this seroprevalence study regarding Candur® , Canlan® and Dohyvac® were consistent with the results of the seroconversion study. CD was reintroduced into Finland in 1990 after 16 years of absence. The disease remained at a low endemic level in 1990-1994, reached epidemic proportions in 1994-1995 and disappeared during 1995. The epidemic also involved vaccinated dogs. Among the virologically-confirmed cases the proportion of Dohyvac®-vaccinated dogs was higher than expected from the market shares on the assumption that all the vaccines had an equal take. As a result of this observation, Dohyvac® was withdrawn from and Nobivac® and Duramune® introduced to the market during 1995. A drastic redistribution of the market shares between the low-take and high-take vaccines took place, and this coincided with the decline and dying out of the outbreak. The observed occurrence pattern of CD from 1990-1996 was largely attributed to the changes in the level of HI, although the possible contribution of other factors, such as developments in the dog demographics, was also recognized. It was concluded that an HI above 75% is needed to keep CD in check, i.e., only sporadic cases of CD, at most, can occur. With the currently used vaccines an HI of 80% corresponds to a vaccine coverage of some 94%. It was concluded that the development of vaccine-induced immunity is a multifactorial process depending on the properties of the vaccine, on the individual variation, age, species and other factors influencing the immunocompetence of the host. On the individual level the prevention of clinical signs is sufficient, but on the population level, halting the circulation of the virus is crucial for the definitive control of CD. The ultimate test and criterion for a vaccine is its contribution to herd immunity. Heterogeneity in the dog population contributes to the occurrence of CD.
  • Nuotio, Lasse Olavi (Evira, 2006)
    Evira Research Reports
    The monitoring and control of infectious animal diseases, limiting or prevention of their spread and efforts towards their eventual eradication are central tasks of the veterinary civil service. In addition to the cost-effectiveness of prophylaxis over disease and treatment, the animal welfare aspect is also involved. The purpose of this work is to review, describe and assess the available control measures against selected viral infections or diseases of domestic ruminants. The selected infections or diseases are bovine viral diarrhoea / mucosal disease (BVD), infectious bovine rhinotracheitis / infectious pustular vulvovaginitis (IBR), enzootic bovine leukosis (EBL) and maedi–visna (MV) of sheep. Each is recognized as a signifi cant disease of domestic animals. Decisive control and eradication measures are necessarily based on the biological, veterinary and diagnostic characteristics of the affl ictions, as well as on their epidemiology in terms of the intrinsic determinants of the hosts, host–agent relationships and sources and transmission of the infection, and occurrence of these infections or diseases. This information is compiled and presented in the fi rst part of the thesis with special reference to available or possible control and eradication measures. These measures and programmes against the four affl ictions employed in major cattle and sheep producing countries in individuals and herds and on national and international levels are outlined and assessed briefl y. In the descriptive part of the thesis the domestic and EU legislation that forms the offi cial framework for disease control and eradication are outlined. The development in the situation concerning these four infections or diseases is described from the early records to date. The fi rst recorded entries of the occurrence of BVD and EBL in Finland date back to the 1960s, those of IBR to the beginning of the 1970s and of MV to the beginning of the 1980s. Large-scale surveillance and health monitoring among dairy, suckler-cow and beef herds and sheep fl ocks, starting during the fi rst half of the 1990s, enabled the estimation of actual prevalences of these infections and diseases. A common feature of the occurrence of these infections or diseases is that none has had a prevalence of more than an estimated few percent before 1990, and a maximum of 1% since then. This has formed a very favourable starting point for the nation-wide control and eradication measures. The voluntary control programmes or schemes, as well as the offi cial control and eradication measures are described. The successful eradication of IBR and EBL in 1994 and 1996, respectively, and the signifi cant reduction in the occurrences of BVD and MV from 1990 to date, are reported in detail. The effi cacies of the offi cial control and eradication measures and of the actions of the voluntary control programmes or schemes are analyzed further, making use of a heuristic formulation for the infection reproduction number (R), i.e. the number of secondary cases produced by one infective animal. The infl uence of the measures is resolved into the three components of R: the probability of transmission, frequency of infectious contacts and length of the infectious period, and the impact of the measures on each component is graded on a three-step scale. 9 The conclusion is drawn that the offi cial measures complemented by voluntary actions for control and eradication have for the most part been adequate. The signifi cance of fi nancial compensation from the state for the costs incurred in the control of notifi able diseases is noted. In the case of BVD the decisive measures for fi nal eradication have only been available since 2004 and their impact will be seen in the next few years. The role of continued surveillance and health moni toring for both overseeing the situation with BVD and MV, and maintaining an IBR and EBLfree status is emphasized.
  • Hallikainen, Anja; Hirvonen, Tero; Liukkonen, Kirsi-Helena; Kartio, Mirja; Rautala, Taneli; Hietaniemi, Veli; Koivisto, Tauno; Rämö, Sari; Kronberg-Kippilä, Carina; Ovaskainen, Marja-Leena; Sinkko, Harri (Evira, 2008)
    Eviran tutkimuksia
    Yleisiä suomalaisissa viljoissa esiintyviä homeiden tuottamia Fusarium-toksiineja ovat deoksinivalenoli, zearalenoni, nivalenoli sekä T-2- ja HT-2-toksiinit. Fusarium-toksiineja esiintyy erityisesti kaurassa. EU:ssa on asetettu enimmäispitoisuusrajat deoksinivalenolille ja zearalenonille. T-2- ja HT-2- toksiinien lainsäädäntö on EU:ssa työn alla. Pitkäaikainen altistuminen Fusarium-toksiineille voi aiheuttaa terveydellisiä haittavaikutuksia, kuten immuunijärjestelmän heikkenemistä. Kaikkia pitkäaikaisen altistumisen vaikutuksia ei kuitenkaan toistaiseksi tunneta. Akuuteissa myrkytystapauksissa oireita ovat esimerkiksi pahoinvointi, oksentelu ja vatsakivut. Suomalaisten altistuminen Fusarium-toksiineille arvioitiin Evirassa yhteistyössä Maa- ja elintarviketalouden tutkimuskeskuksen ja Kansanterveyslaitoksen kanssa. Saannit ovat alle siedettävän päivittäisen enimmäissaantimäärän lukuun ottamatta T-2- ja HT-2-toksiineja, joita kauran suurkuluttajat voivat teoriassa saada raakaviljasta liikaa. Toksiinipitoisuudet vaihtelevat vuosittain erityisesti satokauden sään perusteella. Lisäksi viljan lajittelulla ja kuorinnalla voidaan vähentää toksiinien määrää merkittävästi. Viljoille asetettuja Fusarium-toksiinien enimmäispitoisuuksia on syytä valvoa jatkuvasti. Valvonnan kohdentamista suositellaan erityisesti kauralle ja kauravalmisteille, joissa esiintyy suurimmat pitoisuudet toksiineja.
  • Metlin, Artem (Evira, 2008)
    Evira Research Reports
    Rabies is a fatal disease that affects the central nervous system of all warmblooded mammals. The rabies virus belongs to the order Mononegavirales, family Rhabdoviridae, genus Lyssavirus. This virus has a negative single-stranded RNA genome and the virions are bullet-shaped. Rabies is reported in many countries throughout the world and has been registered in all continents except Australia, where only the bat Lyssaviruses have been found, and in Antarctica where the main vectors of rabies are absent. Russia and most of the bordering countries are affected by rabies. Finland was a rabies-free country from 1959 to 1988, when a sylvatic rabies epidemic appeared with raccoon dogs as the main host and vector of infection. That epidemic was eradicated by the oral vaccination of wild carnivores and the parenteral immunization of dogs and cats; and Finland has been rabies-free since 1991. However, this status is constantly under threat because rabies is endemic in Russia and Estonia. In June 2003, a horse imported to Finland from Estonia was clinically and laboratory diagnosed as rabies positive. The close relationship of the isolated equine virus strain with the current Estonian strains was verified during subsequent molecular epidemiological studies. Because the case was imported, it did not affect Finland’s rabies-free status. Also in 2007 another 2 imported cases of rabies were recorded: one in a human being from Philippines and the other in a dog from India. Five different antigenic variants of the rabies virus were identified among rabies positive field samples from Russia, Finland, and Estonia by using antinucleocapsid monoclonal antibodies. Two rabies virus field isolates showed a different reaction pattern that was similar to that of the vaccine strains of the SAD group, which might suggest a new antigen variant or reverted vaccine strain. Nevertheless, the sequence analysis showed that the vaccine strains RV-97 and SAD B19 included in the oral anti-rabies vaccine “Sinrab” (Russia) and “Fuchsoral” (Germany), respectively, differ considerably from all the field strains. Field rabies viruses collected in recent years from different regions of the Russian Federation were chosen on the basis of mAb studies and geographical origin for molecular epidemiological studies to characterize their genetic heterogeneity and to study their molecular epidemiology. In addition to the Russian viruses, archival samples from Estonia and Finland and Russian vaccine strains were also included in this study. Among the field viruses studied, two main phylogenetic groups were found, and designated as the Pan-Eurasian and Caucasian based on their geographical origin. The Pan-Eurasian 7 group including some reference viruses from Europe was further divided into four subgroups. All the vaccine strains were clearly different from the field strains. No recombination between the field and vaccine virus strains was observed. The critical roles of geographical isolation, the limitation of the genetic clustering, and the evolution of the rabies virus were shown during this study. The rabies virus vaccine strain RV-97 is widely used in Russia as a component of the oral anti-rabies vaccine “Sinrab”. To characterize the molecular properties of this strain, entire genome sequencing was conducted. A simple technique was developed to obtain this sequence, including the 3’- and 5’- ends. The entire genome sequence and deduced amino-acid sequences of the major viral proteins were compared with the sequences of other known fixed rabies viruses. The strain RV-97 formed a separate phylogenetic branch and seems to be more related to the group of Japanese strains. The field strains from the Caucasian group seem to be phylogenetically the nearest group to the RV-97 strain. The data shown herein makes it possible to develop molecular methods for distinguishing between the field rabies viruses from the vaccine strains for the rapid recognition of the vaccine strains that are unstable or have reverted back to their pathogenic form. The wide genetic heterogeneity verified in this study indicates that it is important to remain on permanent alert for the appearance of rabies.
  • Lindqvist, Nanna (Evira, 2008)
    Evira Research Reports
    Salmonellosis is one of the most significant zoonoses worldwide and also in Finland. The major serovars causing infections in humans are Salmonella Enteritidis and Salmonella Typhimurium. Salmonella Typhimurium definitive phage type (DT) 1 and Salmonella Infantis are considered endemic in Finland. These serovars have frequently caused outbreaks among humans, the source of which is often detected. For the sporadic cases they usually remain unknown. Salmonella Agona was not frequently encountered in Finland until a small outbreak among cattle farms occurred in 1994-1995. S. Agona became the third most common Salmonella serovar in cattle in Finland in 1995. The two more common serovars were S. Infantis and S. Typhimurium DT1. Bacterial typing methods are used for outbreak investigations and for surveillance, where the data can be used for risk assessment calculations in addition to the future prevention of outbreaks. In particular the identification of factors that contribute to the persistence and spread of infection in endemic situations, estimations of the effect of animal reservoirs on human cases, and the identification of other risk factors for human infections are among the important reasons for typing. Salmonella Infantis became more common in cattle in the 1980s, after it spread in the broiler chicken production in Finland in 1971. Subsequently it caused outbreaks among broilers and humans in the 1970s and 1980s. In the 1990s, S. Infantis became the predominant serovar among cattle in Finland. In 1995, a feedborne outbreak of S. Infantis in cattle occurred. We were able to identify the feedstuff-related genotype by XbaI-PFGE methodology. It belonged to the major endemic type, pf1, but differed from it by having a plasmid visible as an intensive band of 60 kb in XbaI-PFGE (plasmid subtype pf1/39). Farms infected with the feedstuff-related genotype pf1/39 or the related genotypes pf1/43, pf1/44, pf1/45, or pf1/46 containing the same 60 kb plasmid were also identified. The stability of the feedstuff-related genotype was followed on selected farms. The plasmid was stable on the farms during the follow-up period. The feedstuff-related genotype did not persist in the cattle population. Moreover, there was a general decline in bovine salmonella infections from 1997 onwards. The genetic diversity of the S. Infantis isolates taken from Finnish cattle was also assessed: the S. Infantis infection in cattle was highly clonal as 99 per cent of the isolates had XbaI-PFGE profiles clonally related to each other. The major genotype pf1 was predominant both at the starting year of our analysis in 1985 and as the infection seemed to fade out in 2003. Traditionally, only one isolate per farm is stored in the national collection. However, an infection may have existed subclinically for a long time in a herd until the first Salmonella isolates were obtained. In our analysis of successive isolates from the same herds, we frequently detected minor changes in banding patterns during long-lasting infections in individual herds. The sampling and testing of several isolates from a herd in outbreak investigations is therefore advisable. There is a trend towards less genetic diversity of the S. Infantis infection among domestic isolates from humans and poultry. Up to eight different ribo/IS200-types were detected in the 1980s isolates, whereas in the 1990s only two different ribo/IS200-types (1A, 1B) were seen. In cattle, 89 per cent of the analysed isolates possessed the ribo/IS200-type 1A, although four different ribo/IS200-types were recorded in the 1980s isolates, and two ribo/IS200-types in the 2000s isolates. The ribo/IS200-types and the most common XbaI-PFGE profiles determined amongst the analysed cattle isolates could also be detected among domestic isolates from poultry and humans. After the outbreak in cattle in the years 1994-1995, isolates of S. Agona taken from the 1984 to 1999 period were characterized by PFGE using XbaI, BlnI, SpeI, and NotI enzymes. Two outbreakrelated genotypes, which were not detected in the earlier isolates of S. Agona, were identified. Another small possibly genetically related outbreak among cattle farms occurred in 1997. In 1999, a large outbreak of S. Agona of domestic origin involving more than 50 human cases occurred. Despite epidemiological investigations carried out by the local authorities, the source of the outbreak remained unknown. Based on our typing data, this outbreak was unrelated to the cattle farm outbreaks, though it did occur in the same region of Finland. The outbreak profile for the 1999 outbreak could not be found in any of the other isolates. As no recent foreign isolates were available, a foreign source of the human infection cannot be disregarded. Salmonella Typhimurium DT1 has become the most common S. Typhimurium phage type among cattle farms in Finland, and has been detected annually since 1980. Domestic and foreign isolates of S. Typhimurium DT1 from 1981 to 1999 were characterised. Furthermore, two clusters formed by the effects of the combination of the XbaI-, BlnI-, and SpeI-PFGE profiles, IS200-profiles and possession of the serovar-specific virulence plasmid were analysed. The major cluster had no virulence plasmid and included the most common XbaI-PFGE profile 10 and IS200-profile D,typical of our endemic infection. The results of XbaI-, BlnI-, and SpeI-PFGE gave 54 different combination profiles, which can be applied in the analysis of outbreaks. In contrast, molecular subtyping by XbaI-PFGE alone is not discriminatory enough in analysing our endemic infection. The source of sporadic human infections is unknown in most cases, and molecular typing did not reveal any clear infection source. The most common XbaI-PFGE profile 10 was also seen in hedgehogs and wild birds. They might act as important reservoirs, maintaining a minimum baseline level of S. Typhimurium DT1 in the environment and consequently be possible sources of human infections.
  • Liukkonen, Kirsi-Helena; Lyytikäinen, Tapani; Hirvonen, Tero; Bäckman, Christina; Kronberg-Kippilä, Carina; Virtanen, Suvi (Evira, 2008)
    Eviran tutkimuksia
    Maksa sisältää runsaasti A-vitamiinia ja monia muita ravintoaineita. Vaikka maksa on monipuolinen ruoka-aine, sen käytössä on myös haittansa. A-vitamiini esiintyy maksassa retinoidimuodossa, mikä voi jatkuvina suurina annoksina aiheuttaa myrkytyksen. Liiallisen A-vitamiinin saannin ehkäisemiseksi maksaruokia ei vuodesta 1990 lähtien ole suositeltu alle 1-vuotiaille. Leikki-ikäisten lasten maksaruokien (jauhemaksa- ja maksapihvi, maksakastike, maksalaatikko), maksamakkaran ja –pasteijan käyttöä on neuvottu rajoittamaan pariin kertaan kuukaudessa. Suositusten tarpeellisuuden arvioimiseksi Elintarviketurvallisuusvirasto Evirassa tehtiin riskinarviointi suomalaislasten A-vitamiinin saannista maksaruokien välityksellä. Riskinarvioinnin tavoitteena oli arvioida 1-, 3- ja 6-vuotiaiden lasten altistumista maksaruokien retinoidimuotoiselle A-vitamiinille sekä samalla selvittää, tuleeko lasten maksaruokien käyttöä edelleen rajoittaa. Riskinarvioinnissa käytettiin maksaruokien kulutustietoja (DIPP-ravintotutkimus) sekä resepti- ja retinoidipitoisuustietoja. Monte Carlo -simulaatiolla arvioitiin A-vitamiinin ja retinoidien saantia maksaruoista sekä ilman maksaruokien käyttöä. Altistusta arvioitiin pitkäaikaissaantina sekä altistuksena kerta-annoksesta. Simulointituloksia verrattiin saantisuosituksiin ja saannin ylärajoihin. Simulointimallin avulla arvioitiin myös maksaruokien turvallista annoskokoa ja syöntitiheyttä. Riskinarvioinnissa tehtiin seuraavat johtopäätökset: 1. Vaikka maksansyönti auttaa joitain lapsia A-vitamiinin saantisuositusten täyttymisessä, se voi altistaa toisia lapsia liian suurille retinoidipitoisuuksille. 2. Todellisten maksansyöjien osuus on hyvin todennäköisesti suurempi kuin kolmen päivän ruoankäyttötietojen perusteella voidaan olettaa. 3. Tarkasteltaessa maksaruokien pitkäaikaiskäytön turvallisuutta todetaan, että annoskoon lisäksi syöntitiheydellä on keskeinen merkitys. Yksivuotias voi turvallisesti syödä maksamakkaraa tai –pasteijaa ja kolme- ja kuusivuotias kaikkia maksaruokia, kunhan syöntitiheys ei ole liian suuri. Turvallinen annoskoko ja syöntitiheys riippuvat lapsen iästä ja maksaruuasta. Yleisesti maksamakkaraa ja –pasteijaa voi käyttää useammin kuin maksalaatikkoa, maksakastiketta tai maksapihvejä.
  • Venäläinen, Eija-Riitta (Evira, 2007)
    Evira Research Reports
    Lead and cadmium are toxic elements, which are a natural part of earth crust. They are taken up from the soil and transferred upwards in the plant and animal food chain. Cadmium is widely distributed throughout the natural environment with human activities having an important role in its dispersion into the biosphere. The natural sources of cadmium are volcanic eruptions and old granite rocks, which are an important geochemical source. Anthropogenic sources of cadmium are related mainly to mining, fertilizers and atmospheric deposition. Leaded gasoline has been most important source of atmospheric lead. However, most countries have now prohibited the use of leaded gasoline. This action has greatly reduced emissions of lead into the atmosphere. Anthropogenic sources of lead other than traffic are typically fossil fuel combustion, non-ferrous metal production and iron and steel production. Zinc and copper are important constituents in a number of different enzyme functions in man and animals. Zinc and copper reach the environment via industrial releases involving production and refining of metals. In 1997 emissions of heavy metal particulates were only a third of their values in the early 1990s due to the installation of sulphur removal systems. In this study lead, cadmium, copper and zinc levels in Finnish game animals (moose, hares) and farmed game animal (reindeer) were studied during twenty years period. About 500 moose were collected between 1980 and 1999 from south western, southern, central and south eastern Finland. About the same number of Mountain and European hare samples were collected during the period 1980 and 1993 from south western, southern, south eastern and northern Finland. About 300 reindeer were collected in 1990–1992 from southern, eastern, western and northern Lapland. After these initial projects, it was decided to collect moose and reindeer samples every year as part of national residue control program; fifteen moose and ten reindeer per year. In this residue control program, also cattle samples have been collected regularly; muscle, liver and kidney from 30 animals in every year. The lead and cadmium levels in muscle tissue has decreased in all studied animals during the monitoring years being now near to the limit of quantification; 0.01 mg/kg w.w. for lead and 0.001 mg/kg w.w for cadmium. Also the lead levels in liver and kidney samples have decreased during the monitoring period but the moose cadmium levels have increased. The zinc levels had also increased in moose samples but there were no significant 5 correlation with increasing cadmium and zinc levels. The lead levels in liver and kidney in moose varied in 1999 from 0.04 to 0.07 mg/kg w.w. and 0.05-0.07 mg/kg w.w. The corresponding values for cadmium are 0.71-1.28 mg/kg w.w. and 4.95- 6.18 mg/kg w.w. The cadmium and lead levels in Mountain hares are higher than in European hares and the kidney cadmium levels in Mountain hares are statistically significantly higher than the kidney cadmium levels in moose. The lead levels in liver and kidney samples in both adult and calves of reindeer have been invariably below the recommended maximum level in the EU (0.5 mg/kg). However, the kidney cadmium level exceeds the maximum level (1.0 mg/kg) in almost all adult reindeer samples and also in some calves. The meat of Finnish moose, reindeer and hares does not contain residues of cadmium and lead and therefore consumers can be assured that consumption of the meat is not a health risk. The consumption of the organs of the animals studied may represent a health risk for human. However, the levels are far from the toxic levels to the animals themselves.