Epidemiological evaluation of the Nordic health registers for dairy cows : data transfer, validation and human influence on disease recordings

In Denmark, Finland, Norway and Sweden the National Dairy Disease Registers (NDDRs) collect and store disease information at the individual cow level. Because these registers are monitored nationally they offer access to data that cover most of the dairy population in each country. Data from these registers are used, for example, for herd health and animal welfare assessments, production management, genetic evaluations and epidemiologic research. Since the register data are not usually designed for research purposes their quality is unknown. Understanding the magnitude of data loss during data transfer and human influence in disease recording process is important. The knowledge will enhance the ability to improve register quality, which in turn will improve reliability of frequency measure calculations from the register data. This thesis investigated the quality (measured as completeness and correctness) of the Finnish NDDR and compared register qualities among the four countries. In Finland the quality of recorded information was excellent, but approximately 17% of disease information was lost during the data transfer steps. A large proportion of the data loss was due to artificial insemination (AI) technicians not transferring events. The majority of those events occurred close to culling of the cow, suggesting early removal of the cow health cards so that AI technician did not have access to those cards. Additionally, fewer diagnostic events were transferred from purchased cows compared to those born on farm suggesting problems with animal identification. An efficient way to improve completeness in the Finnish NDDR is to have veterinarians electronically transfer diagnostic information during farm visits. The Finnish system has already been modified accordingly. This thesis also showed how register quality for four reproductive disorders (metritis, retained placenta, assisted calving and oestrous disturbances) varied among the four countries. Metritis and oestrous disturbance events were well represented in the NDDRs. Farmer-observed completeness (the proportion of all farmer observations that were recorded in the NDDR) was around 0.80 and did not differ significantly among the countries. Assisted calving and retained placenta events showed more among-country variation. Farmer-observed completeness was highest in Denmark and lowest in Finland, ranging between 0.31 and 0.89. The comparison of completeness-adjusted incidences to incidences calculated from the registers showed that incidences were underestimated for assisted calving and retained placenta. Underestimation was highest in Finland. This thesis also demonstrated how both farmer and veterinary intentions toward starting veterinary treatment of mild clinical mastitis could explain the reasons for different mastitis incidence rates among the countries. The results suggest that when intentions towards veterinary treatment are greater, mild cases receive veterinary treatment more often than when intentions are reduced. Therefore, greater farmer and veterinarian intentions can increase the disease incidence calculated from the NDDR data. According to the study, intentions were greater in Denmark than in other countries.Tanskassa, Suomessa, Norjassa ja Ruotsissa kerätään lypsylehmien tautitietoja rekistereihin. Koska tiedot kerätään kaikissa maissa maanlaajuisesti, ne kattavat suurimman osan lypsylehmien tautitiedoista. Rekistereihin tallennettuja tietoja voidaan hyödyntää mm. karjan terveyden, tuotannon ja eläinten hyvinvoinnin tarkkailussa, jalostuksessa ja epidemiologisessa tutkimuksessa. Rekistereitä ei ole kuitenkaan yleensä suunniteltu tutkimustarkoituksiin, eikä niiden sisältämien tietojen luotettavuutta tunneta. Tieto siitä, kuinka tarkasti tautitietoja tallennetaan ja minkälaisia virheitä niiden tallennuksessa tapahtuu, mahdollistaa rekisterien luotettavuuden parantamisen. ----- Tässä väitöstyössä tutkittiin näiden neljän maan tautirekisterien laatua kattavuudella (eng. completeness) ja oikeellisuudella (eng. correctness) . Suomessa rekisterin oikeellisuuden havaittiin olevan erinomainen, vaikkakin noin 17 % tautitiedoista hävisi tiedonsiirtoprosessissa. Suurin yksittäinen syy tiedon häviämiseen oli se, että tietoja ei siirretty lainkaan ns. lehmäkortista tautirekisteriin. Tiedot puuttuivat, koska poistettujen lehmien lehmäkortit varastoitiin liian aikaisin, jolloin keinosiementäjä ei pystynyt siirtämään tietoja rekisteriin. Lisäksi tilalle ostetuista lehmistä päätyi vähemmän tietoa rekisteriin kuin tilalla syntyneistä, mikä viittaisi ongelmiin lehmien tunnistetiedoissa. Tiedon siirtymistä voidaan nopeuttaa ja rekisterin laatua parantaa, kun tiedot siirretään elektronisesti jo hoitohetkellä suoraan rekisteriin, mihin Suomessa ollaankin jo siirtymässä. Väitöstyössä havaittiin näiden neljän maan rekisterien kattavuuden vaihtelevan lisääntymishäiriöiden osalta vertailtaessa tuottajien havaitsemien tapausten määrää rekisterissä oleviin tapauksiin. Kohtutulehdukset ja kiimahäiriöt siirtyivät rekistereihin hyvin kaikissa maissa. Avustetun poikimisen ja jälkeisten kattavuudessa havaittiin merkitseviä eroja maiden välillä. Korkein kattavuus oli Tanskassa (0,89) ja alhaisin kattavuus Suomessa (0,31). Kun avustetulle poikimiselle ja jälkeisille korjattiin näiden lukujen avulla tautirekistereistä laskettuja ilmaantuvuuslukuja, havaittiin, että näitä häiriöitä esiintyi enemmän kuin pelkän tautirekisterin tiedoista laskettuna. Väitöstyössä osoitettiin myös, miten sekä tuottajien että eläinlääkäreiden asenteet lievän kliinisen utaretulehduksen hoidon aloittamista kohtaan voivat myös selittää utaretulehduksen ilmaantuvuuden eroja eri maiden kesken. Tulokset viittaavat siihen, että mitä myönteisempi oli suhtautuminen lääkehoidon aloittamiseen lisää tautitapauksen mahdollisuutta siirtyä rekisteriin. Tämä johtuu siitä, että tautirekisteriin tallennetaan pääosin lääkkein hoidettuja tautitapauksia Tanskassa lääkehoitomyönteisyys vaikutti olevan muita maita suurempi

Afrikkalaisen sikaruton taudinpurkauksen simuloidut taloudelliset vaikutukset Suomessa

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The effects of structural change in agriculture on the spread of animal disease in Finland

The structure of Finnish agricultural production has changed rapidly resulting in an increase in the average farm size and a reduction in the number of farms. Three animal diseases were used to illustrate the impacts of changing production structures and their consequences on the spread and control of disease: Foot-and-mouth disease (FMD), African Swine Fever (ASF) and Bluetongue (BT). The aim of this study was to assess how changes in the structure of animal production impact on animal disease risks and the economic consequences of diseases. The spread of diseases was simulated according to three predicted future production structure scenarios for 2033 and compared with reference simulations applying the production structure of the year 2009. FMD had the highest spread potential as the probability of spread and magnitude of an epidemic outbreak were the largest. ASF and BT had clearly lower spread potential and also structural change will affect them less. Spread potential is strongly dependent on how logistics will develop in relation with farm size increase. Economic losses due to FMD were similar in 2009 and 2033 simulations. Losses caused by ASF were smaller than those by FMD. In both cases distortions in the food exports were the main source of losses. Losses associated with BT were estimated to be smaller in the future.Kotieläintilojen keskikoko on kasvanut ja tilojen määrä on vähentynyt. Kehityksen voidaan arvioida jatkuvan myös tulevaisuudessa. Kolmea eläintautia, suu- ja sorkkatauti, afrikkalainen sikarutto ja sinikielitauti, käytettiin esimerkkinä siitä, kuinka muutokset kotieläintuotannon rakenteessa vaikuttavat taudin leviämiseen ja hallintaan. Tutkimuksen tarkoituksena oli arvioida kuinka kotieläintalouden rakennemuutos vaikuttaa eläintautiriskiin ja tautien taloudellisiin vaikutuksiin. Tautien leviämistä simuloitiin kolmen vuoteen 2033 ajoittuvan tulevaisuuskenaarion mukaan ja verrattiin simulointeihin, jotka pohjautuivat kotieläintalouden rakenteeseen vuonna 2009. Suu- ja sorkkataudilla oli suurin leviämispotentiaali, koska leviämisen todennäköisyys ja epidemian koko olivat suurimmat. Afrikkalaisella sikarutolla ja sinikielitaudilla oli selvästi matalampi potentiaali ja rakennemuutos vaikuttaa niihin vähemmän. Leviämispotentiaali on voimakkaasti riippuvainen logistiikan kehityksestä tilakoon kasvuun nähden. Suu- ja sorkkataudin aiheuttamat taloudelliset menetykset olivat samaa suuruusluokkaa nyt ja tulevaisuudessa. Afrikkalaisen sikaruton aiheuttamat tappiot jäivät maltillisemmiksi. Molemmilla taudeilla elintarvikeviennin häiriintyminen aiheutti eniten tappioita. Sinikielitaudin menetysten arvioitiin olevan nykyistä vähäisemmät tulevaisuudessa.En snabb strukturförändring inom lantbruket i Finland har resulterat i större men färre gårdar. Denna utveckling förväntas fortsätta även i framtiden. Tre sjukdomar; mul- och klövsjuka, afrikansk svinpest och blåtunga, har använts som exempel för att undersöka hur strukturförändringen påverkar smittspridningen och sjukdomskontrollen i framtiden. Syftet med arbetet var att utvärdera hur strukturomvandlingen i lantbruket påverkar djursjukdomsrisken och de ekonomiska konsekvenserna av sjukdomarna. Sjukdomsspridningen simulerades enligt tre tänkta framtida produktionsstrukturer för år 2033 och jämfördes sedan med simuleringar baserade på produktionen år 2009. Mul- och klövsjuka hade den största spridningspotentialen eftersom sannolikheten för spridning och storleken av ett epidemiskt utbrott var störst. Afrikansk svinpest och blåtunga hade klart lägre spridningspotential och även strukturförändringarna kommer att påverka dem mindre. Spridningspotentialen är starkt beroende av hur logistiken utvecklas i relation till gårdsstorleken. Ekonomiska förluster på grund av mul- och klövsjuka var lika stora i simuleringarna både för år 2009 och 2033. Förluster på grund av afrikansk svinpest var mindre än de orsakade av mul- och klövsjuka. I båda fallen var förlusterna orsakade av störd livsmedelsexport den huvudsakliga orsaken till ekonomiska förluster. Förluster orsakade av blåtunga verkade vara mindre i framtiden

Completeness of the disease recording systems for dairy cows in Denmark, Finland, Norway and Sweden with special reference to clinical mastitis

Abstract Background In the Nordic countries Denmark, Finland, Norway and Sweden, the majority of dairy herds are covered by disease recording systems, in general based on veterinary registration of diagnoses and treatments. Disease data are submitted to the national cattle databases where they are combined with, e.g., production data at cow level, and used for breeding programmes, advisory work and herd health management. Previous studies have raised questions about the quality of the disease data. The main aim of this study was to examine the country-specific completeness of the disease data, regarding clinical mastitis (CM) diagnosis, in each of the national cattle databases. A second aim was to estimate country-specific CM incidence rates (IRs). Results Over 4 months in 2008, farmers in the four Nordic countries recorded clinical diseases in their dairy cows. Their registrations were matched to registrations in the central cattle databases. The country-specific completeness of disease registrations was calculated as the proportion of farmer-recorded cases that could be found in the central database. The completeness (95% confidence interval) for veterinary-supervised cases of CM was 0.94 (0.92, 0.97), 0.56 (0.48, 0.64), 0.82 (0.75, 0.90) and 0.78 (0.70, 0.85) in Denmark, Finland, Norway and Sweden, respectively. The completeness of registration of all CM cases, which includes all cases noted by farmers, regardless of whether the cows were seen or treated by a veterinarian or not, was 0.90 (0.87, 0.93), 0.51 (0.43, 0.59), 0.75 (0.67, 0.83) and 0.67 (0.60, 0.75), respectively, in the same countries. The IRs, estimated by Poisson regression in cases per 100 cow-years, based on the farmers’ recordings, were 46.9 (41.7, 52.7), 38.6 (34.2, 43.5), 31.3 (27.2, 35.9) and 26.2 (23.2, 26.9), respectively, which was between 20% (DK) and 100% (FI) higher than the IRs based on recordings in the central cattle databases. Conclusions The completeness for veterinary-supervised cases of CM was considerably less than 100% in all four Nordic countries and differed between countries. Hence, the number of CM cases in dairy cows is underestimated. This has an impact on all areas where the disease data are used.</p

The association between farmers' participation in herd health programmes and their behaviour concerning treatment of mild clinical mastitis

BACKGROUND: In Denmark, it has recently become mandatory for all dairy farmers with more than 100 cows to sign up for a herd health programme. Three herd health programmes are available. These differ in a number of aspects, including the frequency of veterinary visits and the farmer’s access to prescription drugs. The objective of this study was to investigate whether dairy farmers’ behavioural intentions, i.e. to call a veterinarian or start medical treatment on the day that they detect a cow with mild clinical mastitis (MCM), are different depending on the type of herd health programme. METHODS: A questionnaire survey based on the Theory of Planned Behaviour (TPB) was conducted. TPB proposes that a person’s behavioural intention is strongly correlated with his or her actual behaviour. Three behavioural factors determine the behavioural intention: attitude, subjective norm and perceived behavioural control. Each of these factors is decided by a set of beliefs, each of which in turn is weighted by an evaluation: 1) the expected outcomes of performing the behaviour, 2) what a person believes that others think of the behaviour, and 3) the person’s perceived power to influence the behaviour. A set of statements about the treatment of MCM based on interviews with 38 dairy farmers were identified initially. The statements were rephrased as questions and the resulting questionnaire was distributed to 400 randomly selected Danish dairy farmers who use the two most restrictive herd health programmes, either Core or Module1, and to all 669 farmers with the least restrictive herd health programme, Module2. The association between intention and the herd health programme was modelled using logistic regression. RESULTS: The farmers with the Module2 herd health programme had a significantly higher behavioural intention to perform the behaviour, when compared to farmers with a more restrictive herd health programme (OR = 2.1, p < 0.0001). CONCLUSION: Danish dairy farmers who participate in Module2 herd health programme had a higher intention to treat cases of MCM, compared to farmers who participate in a more restrictive herd health programme in which the veterinarian initiates treatments

Completeness of the disease recording systems for dairy cows in Denmark, Finland, Norway and Sweden with special reference to clinical mastitis

BACKGROUND: In the Nordic countries Denmark, Finland, Norway and Sweden, the majority of dairy herds are covered by disease recording systems, in general based on veterinary registration of diagnoses and treatments. Disease data are submitted to the national cattle databases where they are combined with, e.g., production data at cow level, and used for breeding programmes, advisory work and herd health management. Previous studies have raised questions about the quality of the disease data. The main aim of this study was to examine the country-specific completeness of the disease data, regarding clinical mastitis (CM) diagnosis, in each of the national cattle databases. A second aim was to estimate country-specific CM incidence rates (IRs). RESULTS: Over 4 months in 2008, farmers in the four Nordic countries recorded clinical diseases in their dairy cows. Their registrations were matched to registrations in the central cattle databases. The country-specific completeness of disease registrations was calculated as the proportion of farmer-recorded cases that could be found in the central database. The completeness (95% confidence interval) for veterinary-supervised cases of CM was 0.94 (0.92, 0.97), 0.56 (0.48, 0.64), 0.82 (0.75, 0.90) and 0.78 (0.70, 0.85) in Denmark, Finland, Norway and Sweden, respectively. The completeness of registration of all CM cases, which includes all cases noted by farmers, regardless of whether the cows were seen or treated by a veterinarian or not, was 0.90 (0.87, 0.93), 0.51 (0.43, 0.59), 0.75 (0.67, 0.83) and 0.67 (0.60, 0.75), respectively, in the same countries. The IRs, estimated by Poisson regression in cases per 100 cow-years, based on the farmers’ recordings, were 46.9 (41.7, 52.7), 38.6 (34.2, 43.5), 31.3 (27.2, 35.9) and 26.2 (23.2, 26.9), respectively, which was between 20% (DK) and 100% (FI) higher than the IRs based on recordings in the central cattle databases. CONCLUSIONS: The completeness for veterinary-supervised cases of CM was considerably less than 100% in all four Nordic countries and differed between countries. Hence, the number of CM cases in dairy cows is underestimated. This has an impact on all areas where the disease data are used

Increases in the completeness of disease records in dairy databases following changes in the criteria determining whether a record counts as correct

BACKGROUND: The four Nordic countries: Denmark (DK), Finland (FIN), Norway (NO) and Sweden (SE), all have national databases in which mainly records of treated animals are maintained. Recently, the completeness of locomotor disorder records in these databases has been evaluated using farmers’ recordings as a reference level. The objective of the present study was to see how previous estimates of completeness figures are affected by the criteria determining whether a recording in the database is to be judged correct. These demands included date of diagnosis and disease classification. In contrast with the previous study, a period of time between the date of disease recording in the database and by the farmer was allowed. Further, the calculations were brought to bear on individual locomotor diagnoses instead of a common locomotor disease complex code. METHODS: Randomly selected dairy herds (≥ 15 cows) were invited to participate. During two 2-month periods in 2008 the farmers recorded the diseases they observed on the farm and their recordings constituted a farmer database (FD). These recordings were compared to disease recordings in the National Databases (ND). Earlier calculations of completeness for locomotor complex cases assuming an exact match on date were compared with ±7 day and ±30 day discrepancies calculated in this study. RESULTS: The farmers in DK, FIN, NO and SE recorded 426, 147, 97 and 193 locomotor disorders, respectively. When a window of ±7 days was allowed there was a relative increase in completeness figures lying in the range of 24–100%. Further increases were minor, or non-existent, when the window was expanded to ±30 days. The same trend was seen for individual diagnoses. CONCLUSION: In all four of the Nordic countries a common pattern can be observed: a further increase in completeness occurs when individual locomotor diagnoses recorded by the farmer are permitted to match any locomotor diagnosis recorded in the ND. Completeness increased when both time span and different diagnoses within the locomotor complex were allowed