Genetic surveillance of endemic bovine Salmonella Infantis infection

Background: Salmonella serovar Infantis is endemic in Finnish food-producing animals since the 1970s. The purpose of this study was to describe the molecular epidemiology of the infection in cattle during 1985–2005, to follow the persistence of the feed-related outbreak strain from 1995 in the cattle population, and to analyse the stability of XbaI-banding patterns in individual herds during long-lasting infections. Methods: Salmonella Infantis isolates from 478 cattle herds (n = 588), covering 73% of the subclinically or clinically infected herds, were typed by pulsed-field gel electrophoresis (PFGE) using XbaI. DNA fragments larger than 125 kb were counted in PFGE types because of high plasmid background. Ribotyping and IS200-typing with BanI-digested DNA were done on 57 selected isolates. Results: The isolates associated with the infection consisted of 51 PFGE types with genetic similarity (F value) between 0.58 and 0.95. From 1985 to 2003, the major type appeared on 68% of the farms. The three most common types, with F values of 0.90 to 0.95, accounted for 80% of the isolates. Only 17% of the isolates had F values below 0.80, and 1% below 0.70. Ribotyping and IS200-typing classified 89% of the analysed isolates into the major ribotype and IS200 type combination, and the rest fell into closely related types. Analysis of successive isolates from 142 herds revealed changes in XbaI-banding patterns in 21% of the herds with two analysed isolates and in 38% of the herds from which three or more isolates were analysed. The feed-related S. Infantis genotype from the 1995 outbreak had disappeared by 1999, at the time when the incidence of bovine salmonella, and S. Infantis in particular, strongly decreased. Conclusion: The study showed how genetic surveillance, as part of salmonella control, provides tools to follow the persistence of particular infections, and to assess the efficacy of control measures. Testing of several isolates from a herd in outbreak investigations is advisable, because minor changes in PFGE banding patterns frequently occur during long-lasting infections

Genetic surveillance of endemic bovine Salmonella Infantis infection

Background: Salmonella serovar Infantis is endemic in Finnish food-producing animals since the 1970s. The purpose of this study was to describe the molecular epidemiology of the infection in cattle during 1985–2005, to follow the persistence of the feed-related outbreak strain from 1995 in the cattle population, and to analyse the stability of XbaI-banding patterns in individual herds during long-lasting infections. Methods: Salmonella Infantis isolates from 478 cattle herds (n = 588), covering 73% of the subclinically or clinically infected herds, were typed by pulsed-field gel electrophoresis (PFGE) using XbaI. DNA fragments larger than 125 kb were counted in PFGE types because of high plasmid background. Ribotyping and IS200-typing with BanI-digested DNA were done on 57 selected isolates. Results: The isolates associated with the infection consisted of 51 PFGE types with genetic similarity (F value) between 0.58 and 0.95. From 1985 to 2003, the major type appeared on 68% of the farms. The three most common types, with F values of 0.90 to 0.95, accounted for 80% of the isolates. Only 17% of the isolates had F values below 0.80, and 1% below 0.70. Ribotyping and IS200-typing classified 89% of the analysed isolates into the major ribotype and IS200 type combination, and the rest fell into closely related types. Analysis of successive isolates from 142 herds revealed changes in XbaI-banding patterns in 21% of the herds with two analysed isolates and in 38% of the herds from which three or more isolates were analysed. The feed-related S. Infantis genotype from the 1995 outbreak had disappeared by 1999, at the time when the incidence of bovine salmonella, and S. Infantis in particular, strongly decreased. Conclusion: The study showed how genetic surveillance, as part of salmonella control, provides tools to follow the persistence of particular infections, and to assess the efficacy of control measures. Testing of several isolates from a herd in outbreak investigations is advisable, because minor changes in PFGE banding patterns frequently occur during long-lasting infections

Suitability of Nasal and Deep Nasopharyngeal Swab Sampling of Calves in the Mycoplasma bovis Control Program

Peer reviewe

Prevalence of subclinical mastitis in Finnish dairy cows : changes during recent decades and impact of cow and herd factors

Background: The dairy industry has undergone substantial structural changes as intensive farming has developed during recent decades. Mastitis continues to be the most common production disease of dairy cows. Nationwide surveys of mastitis prevalence are useful in monitoring udder health of dairy herds and to study the impact of structural changes on the dairy industry. This survey on bovine subclinical mastitis was the first based on cow composite milk somatic cell count (SCC) data from the Finnish national health monitoring and milk recording database. A cow with composite milk SCC = 200,000 cells/ml in at least one of the four test milkings during the year was considered to have subclinical mastitis and a cow with composite milk SCC = 200,000 cells/ml in three or in all four test milkings during the year to have chronic subclinical mastitis. The aim of the study was to determine the prevalence of subclinical mastitis and chronic subclinical mastitis in Finland in 1991, 2001 and 2010 and to investigate cow and herd factors associated with elevated SCC. Results: Prevalence of subclinical mastitis in Finland decreased over recent decades from 22.3% (1991) and 20.1% (2001) to 19.0% (2010). Prevalence of chronic subclinical mastitis was 20.4% in 1991, 15.5% in 2001 and 16.1% in 2010. The most significant cow and herd factors associated with subclinical mastitis or high milk SCC were increasing parity, Holstein breed, free- stalls with an automatic milking system and organic production. Milk SCC were highest from July to September. Main factors associated with chronic mastitis were increasing parity and Holstein breed. Conclusions: Prevalence of subclinical mastitis in Finland decreased over recent decades, the greatest change taking place during the first decade of the study. Prevalence of chronic subclinical mastitis significantly decreased from 1991. The most significant factors associated with both types of mastitis were increasing parity and Holstein breed, and for subclinical mastitis also free-stalls with automatic milking. National surveys on mastitis prevalence should be carried out at regular intervals to monitor udder health of dairy cows and to study the impact of the ongoing structural changes in the dairy industry to enable interventions related to udder health to be made when needed.Peer reviewe

Survey of interdigital phlegmon outbreaks and their risk factors in free stall dairy herds in Finland

Background: Severe outbreaks of interdigital phlegmon (IP) associated with a high morbidity and major economic losses have occurred in Finland in the past decade. A survey was performed to indicate the current occurrence of infectious hoof diseases and to identify herd level risk factors predisposing to an outbreak of IP. Results: Responses to a questionnaire revealed that an outbreak of IP defined as morbidity >= 5% within the 1st month of the outbreak, had occurred in 18.0% of the respondent study farms. Risk factors for an outbreak included animal transport between herds, i.e. either animal purchase or contract heifer rearing, enlargement or renovation of the barn, and if the fields of the farm had been organically cultivated. Having any kind of mechanical ventilation in comparison to natural ventilation seemed to lower the risk of IP. Additionally, the farms that had experienced an outbreak of IP often had other infectious hoof diseases. However, it was unclear which disease appeared first. Conclusions: More attention is needed before and during enlargement or renovation of the barn and substantial planning is crucial for every part of the enlargement process in dairy farms.Peer reviewe

A comparison of unheated loose housing with stables on the respiratory health of weaned-foals in cold winter conditions : an observational field-study

Background: Newly weaned horses in Finland are often moved to unheated loose housing systems in which the weanlings have free access to a paddock and a shelter. This practice is considered to be good for the development of young horses. The daily temperatures can stay below -20 degrees C in Finland for several consecutive weeks during the winter season. However, the effect of unheated housing in a cold climatic environment on the respiratory health of weanlings under field conditions has not been studied before. This investigation was an observational field-study comprising 60 weanlings among 11 different voluntary participant rearing farms in Finland. Weanlings were either kept in unheated loose housing systems (n = 36) or in stables (n = 24) and were clinically examined on two separate occasions 58 days apart in cold winter conditions. Results: The odds of clinical respiratory disease were lower in the older foals(log(e) days); OR = 0.009, P = 0.044). The plasma fibrinogen concentration was higher when the available space (m(2)/weanling) in the sleeping hall was smaller (P = 0.014) and it was lower when the sleeping hall was not insulated (P = 0.010). The plasma fibrinogen concentrations at the second examination were lower with a body condition score above 3 (P = 0.070). Standardbreds kept in loose housing systems had a lower body condition score than Finnhorses or Standardbreds kept in stables at both examinations (P = 0.026 and P = 0.007, respectively). Haemoglobin level was lower in weanlings in loose housing systems compared to their counterparts at the first examination (P = 0.037). Finnhorses had higher white blood cell count than Standardbreds at first (P = 0.002) and at the second examination (P = 0.001). Conclusions: Keeping weanling horses in cold loose housing systems does not seem to increase the occurrence of respiratory disease, but special attention should be focused on ventilation, air quality and feeding-practices. Our field study data suggest it might be advantageous to keep Standardbred foals born late in the season in a stable over the Finnish winter.Peer reviewe

Semen as a source of Mycoplasma bovis mastitis in dairy herds

Mycoplasma bovis infections are responsible for substantial economic losses in the cattle industry, have significant welfare effects and increase antibiotic use. The pathogen is often introduced into naive herds through healthy carrier animals. In countries with a low prevalence of M. bovis, transmission from less common sources can be better explored as the pathogen has limited circulation compared to high prevalence populations. In this study, we describe how M. bovis was introduced into two closed and adequately biosecure dairy herds through the use of contaminated semen during artificial insemination (AI), leading to mastitis outbreak in both herds. Epidemiological analysis did not reveal an infection source other than semen. In both farms the primary clinical cases were M. bovis mastitis in cows inseminated with the semen of the same bull four weeks before the onset of the disease. One semen straw derived from the semen tank on the farm and other semen lots of this bull were positive for M. bovis. In contrast, semen samples were negative from other bulls that had been used for insemination in previous or later oestrus to those cows with M. bovis mastitis. Furthermore, cgMLST of M. bovis isolates supported the epidemiological results. To our knowledge this is the first study describing the introduction of M. bovis infection into a naive dairy herd via processed semen. The antibiotics used in semen extenders should be re-evaluated in order to provide farms with M. bovis-free semen or tested M. bovis-free semen should be available.Peer reviewe

The Impact of the Use of Neonicotinoid Insecticides on Honey Bees in the Cultivation of Spring Oilseed Crops in Finland in 2013–2015

The Neomehi project studied how neonicotinoid-based plant protection products affected honey bee colonies in oilseed rape and turnip rape cultivations in Finland. The final report combines the results of the growing seasons of 2013 and 2014. The experimental protocol included four trial fields where spring turnip rape was cultivated. Each trial field was treated in a different manner with neonicotinoid insecticides: without neonicotinoids, foliar spraying with neonicotinoids (thiacloprid) against pollen beetles, and/or seed treatment with neonicotinoids (thiametoxam) against flea beetles. The plant density and crop growth were determined in the trial fields. Additionally, the number of honey bees and other pollinators was assessed with the applied line transect method during the growing season. Five test bee colonies were located at the edge of each trial field. The performance of the bee hives was examined and the amount of bees and brood was counted 4-5 times during the summer season. A census was also done in autumn and in spring in order to acquire overwintering data. The bees and bee hive products from the test bee colonies were analysed for residues of neonicotinoids. Moreover, in the epidemiological pilot study (also called survey study in the text) of 2013-2014, residues were also analysed from samples collected as a survey from bee hives from five different geographical areas in Finland. In 2013, the sampling was optimized so that half of the bee hives were located close to oilseed cultivation and the other half far from oilseed cultivation. The crop growth was normal in three of the trial fields during the growing season of 2013. In one trial field (seed treatment with neonicotinoids), the crop growth probably suffered because of the variation in drilling depth. In 2014, both trial fields with uncoated seed had to be redrilled after flea beetles severely attacked the young plants in the fields. Therefore, the blossoming of turnip rape in those trial fields was delayed from late July to the beginning of August. The yield was low as well. The number of honey bees in the trial fields was higher when crop growth was good and lower when crop growth was poor. In three of the four fields that were treated with foliar spraying with a neonicotinoid (thiacloprid), the number of honey bees decreased after the treatment. The number of honey bees did, however, clearly increase 2-3 days after the foliar treatment. Both the adult and brood population dynamic curves of the test bee colonies were compared between trial sites. The adult bee population curves illustrated possible minor damages caused to the bee colonies in the sprayed test sites. The test bee colonies recovered from these casualties in two weeks. The average range of food consumption for the bees during overwintering and the overwintering index (the relation of the number of adult bees in spring compared to the number of adult bees in the beginning of overwintering) demonstrated typical levels compared to normal bee colonies in South-West Finland and there were no difference between the trial fields. Two of the test bee colonies lost their queen during winter 2013-2014. In 2014, one of the test colonies died due to suffocation because the pollen collector at the flight entrance was blocked by drones. The second test colony was lost because of robbing by other bee colonies after harvesting. A third test colony lost its queen during winter 2014-2015 and a fourth became a drone layer in the early spring of 2015. The winter losses of the test bee colonies did not differ from the average winter losses (7% in 2014 and 10% in 2015) in the South-West of Finland. The results of the first and second growing season did not indicate that seed coating with neonicotinoids affected the success of the bee colonies, but spraying the flowering field can be detrimental to the bee colonies that are located at the edges of the trial fields. The results of the residue studies indicated, however, that residues of neonicotinoids migrate into bee hives with pollen and nectar and are very common residues in honey bee hives around Finland. In this case, interest is focused on the seed treatment neonicotinoids thiametoxam and clothianidin, which are the most toxic pesticides to bees. The total residue levels of thiametoxam and chlothianide, especially in nectar, resulted in an estimated exposure, which is close to the chronic and acute sublethal risk limits presented in literature. Therefore, such a risk cannot be fully excluded on the basis of these residue studies.ABSTRAKTI Neomehi-hankkeen tärkein tavoite oli selvittää vaikuttavatko neonikotinoideja sisältävät torjunta-aineet pölytyspalvelussa käytettyjen mehiläispesien menestykseen ja talvehtimiskykyyn. Hankkeessa tutkittiin kahden kasvukauden ajan minkälaisia vaikutuksia rypsinviljelyssä käytettävillä, neonikotinoideja sisältävillä torjunta-aineilla on mehiläisiin suomalaisessa öljykasvin viljelyssä. Nyt julkaistava hankeraportti kokoaa yhteen kaksivuotisen Neomehi-hankkeen keskeisimmät tulokset. Koejärjestely sisälsi neljä kenttäkoetta kumpanakin kasvukautena 2013–2014, joissa viljeltiin rypsiä. Neonikotinoideja sisältäviä insektisidejä käytettiin eri tavoin kullakin pellolla. Koepellolla joko ei käytetty neonikotinoideja tai ruiskutettiin neonikotinoidilla (tiaklopridi) kirppoja vastaan ja/tai käytettiin neonikotinoidilla peitattua (tiametoksaami) siementä rapsikuoriaisia vastaan. Kasvien kasvua ja kasvutiheyttä seurattiin, ja pelloilla vierailevien mehiläisten ja muiden pölyttäjäryhmien esiintyminen laskettiin kasvukauden aikana. Kunkin pellon laidalla pidettiin viittä mehiläispesää. Mehiläispesien kuntoa seurattiin ja mehiläisten ja niiden jälkeläisten lukumäärä laskettiin vähintään neljällä eri tarkastuskäynnillä kesän aikana. Vahvuuslaskentoja tehtiin myös syksyjen 2013 ja 2014 aikana sekä keväällä 2014 ja 2015. Tällöin saatiin tarkempaa tietoa molempien hoitovuosien talvehtimisesta. Mehiläisiin ja mehiläispesän tuotteisiin kerääntyviä neonikotinoidien jäämiä analysoitiin kaikista kenttäkokeen pesistä. Kenttäkokeen lisäksi molempina kesinä 2013–2014 kerättiin näytteitä mehiläispesistä otantana viideltä eri alueelta Suomessa (epidemiologinen pilottihanke, otantatutkimus). Vuonna 2013 otantatutkimuksen näytteet valittiin siten, että puolet pesistä sijaitsi lähellä rypsinviljelyä ja puolet kaukana. Kasvien kasvu ja kukintojen tiheys oli normaalia kolmella koepellolla vuonna 2013. Yhdellä pellolla kasvu ei ollut niin hyvää johtuen todennäköisesti väärästä kylvösyvyydestä. Vuonna 2014 peittaamattomalla rypsin siemenellä kylvetyt kentät jouduttiin kirppojen vioitusten takia kylvämään uudestaan, jonka seurauksena niiden kukinta oli vasta heinä-elokuun vaihteessa. Pölyttäjälaskennat osoittivat, että pääsääntöisesti mehiläisten lukumäärä pellolla oli korkea, kun kasvin kasvu oli hyvä ja kukintoja runsaasti ja toisaalta taas mehiläisten lukumäärä alhainen kun kasvin kasvu heikkoa. Tällöin esimerkiksi ympäristössä olevat luonnonkasvit houkuttelivat mehiläisiä merkittävästi puoleensa. Koekentillä, jotka käsiteltiin neonikotinoidi-ruiskutuksella, ei mehiläisiä juuri havaittu heti ruiskutuksen jälkeen. Muutama päivä käsittelystä mehiläisten lukumäärä pellolla oli kuitenkin palautunut ruiskutusta edeltäneeseen tilaan. Ensimmäisen ja toisen kauden tulosten perusteella havaittiin, että neonikotinoideilla kukkivaan kasvuston tehdyt ruiskutukset saattoivat alentaa hieman koepesien aikuisten mehiläisten määrää. Mehiläispesät kuitenkin toipuivat menetyksistä kahden viikon kuluessa. Myös talvenaikainen ruoankulutus sekä talvehtimisindeksi (mehiläisten lukumäärän suhde syksyllä ja keväällä) asettuvat tyypillisiin arvoihin, joita mehiläisyhdyskunnille on mitattu Lounais-Suomessa, eivätkä eri koekenttien mehiläispesät poikenneet toisistaan tässä suhteessa. Talven 2013–2014 aikana kaksi pesää menetti kuningattaren. Toinen pesä oli koekentällä, jota ei käsitelty neonikotinoideilla ja toinen kentällä, jossa neonikotinoideja oli käytetty siementen peittaukseen. Hoitokaudella 2014 yksi pesistä tukehtui, kun kuhnurit tukkivat siitepölykeräimen. Toinen pesistä menetettiin koekentällä 3, kun muiden pesien mehiläiset ryöstivät sen tyhjäksi sadonkorjuun jälkeen. Talvella 2014–2015 yksi pesä menetti emonsa ja yhden pesän emo alkoi munia kuhnureita aikaisin keväällä 2015. Talvehtimistappiot eivät eroa koko Suomen keskiarvosta (7% 2014 ja 10% 2015). Jäämätutkimusten perusteella neonikotinoidien jäämiä siirtyy siitepölyn ja meden mukana mehiläispesiin. Peittausaineiden jäämät (tiametoksaamin, klotianidiinin) ovat erittäin yleisiä mehiläispesissä ympäri Suomen. Mitatut jäämäpitoisuudet etenkin medessä johtavat arvioon altistumistasosta, joka on lähellä kirjallisuudessa esitettyjä kroonisia ja akuutteja subletaaleja riskirajoja. Jäämätulosten perusteella ei voida siis täysin pois sulkea tämäntyyppistä riskiä.201

Extraintestinal pathogenic Escherichia coli in poultry meat products on the Finnish retail market

Background: Extraintestinal pathogenic Escherichia coli bacteria (ExPEC) exist as commensals in the human intestines and can infect extraintestinal sites and cause septicemia. The transfer of ExPEC from poultry to humans and the role of poultry meat as a source of ExPEC in human disease have been discussed previously. The aim of the present study was to provide insight into the properties of ExPEC in poultry meat products on the Finnish retail market with special attention to their prevalence, virulence and phylogenetic profiles. Furthermore, the isolates were screened for possible ESBL producers and their resistance to nalidixic acid and ciprofloxacin was tested. Methods: The presence of ExPEC in 219 marinated and non-marinated raw poultry meat products from retail shops has been analyzed. One E. coli strain per product was analyzed further for phylogenetic groups and possession of ten virulence genes associated with ExPEC bacteria (kpsMT K1, ibeA, astA, iss, irp2, papC, iucD, tsh, vat and cva/cv) using PCR methods. The E. coli strains were also screened phenotypically for the production of extended-spectrum β-lactamase (ESBL) and the susceptibility of 48 potential ExPEC isolates for nalidixic acid and ciprofloxacin was tested. Results: E. coli was isolated from 207 (94.5%) of 219 poultry meat products. The most common phylogenetic groups were D (50.7%), A (37.7%), and B2 (7.7%). Based on virulence factor gene PCR, 23.2% of the strains were classified as ExPEC. Two ExPEC strains (1%) belonged to [O1] B2 svg+ (specific for virulent subgroup) group, which has been implicated in multiple forms of ExPEC disease. None of the ExPEC strains was resistant to ciprofloxacin or cephalosporins. One isolate (2.1%) showed resistance to nalidixic acid. Conclusions: Potential ExPEC bacteria were found in 22% of marinated and non-marinated poultry meat products on the Finnish retail market and 0.9% were contaminated with E. coli [O1] B2 svg+ group. Marinades did not have an effect on the survival of ExPEC as strains from marinated and non-marinated meat products were equally often classified as ExPEC. Poultry meat products on the Finnish retail market may have zoonotic potential