Jorun Tharaldsen

ANTIBODIES TO RUMINANT ALPHA-HERPESVIRUSES AND PESTIVIRUSES IN NORWEGIAN CERVIDS

A serologic survey revealed that Norwegian populations of free-ranging reindeer (Rangifer tarandus tarandus), roe deer (Capreolus capreolus), red deer (Cervus elaphus), and moose (Alces alces) have been exposed to alpha-herpesviruses and pestiviruses. A total of 3,796 serum samples collected during the period 1993–2000 were tested in a neutralization test for antibodies against bovine herpesvirus 1 (BHV-1) or cervid herpesvirus 2 (CerHV-2), and 3,897 samples were tested by a neutralization test and/or enzyme-linked immunosorbent assay for antibodies against bovine viral diarrhea virus (BVDV). Antibodies against alpha-herpesvirus were found in 28.5% of reindeer, 3.0% of roe deer, and 0.5% of red deer, while all moose samples were negative. In reindeer, the prevalence of seropositive animals increased with age and was higher in males than females. Antibodies against BVDV were detected in 12.3% of roe deer, 4.2% of reindeer, 2.0% of moose and 1.1% of red deer. The results indicate that both alpha-herpesvirus and pestivirus are endemic in reindeer and pestivirus is endemic in roe deer in Norway. The viruses may be specific cervid strains. Seropositive red deer and moose may have become exposed as a result of contact with other ruminant species.

Screening of Feral Pigeon (Colomba livia), Mallard (Anas platyrhynchos) and Graylag Goose (Anser anser) Populations for Campylobacter spp., Salmonella spp., Avian Influenza Virus and Avian Paramyxovirus

A total of 119 fresh faecal samples were collected from graylag geese migrating northwards in April. Also, cloacal swabs were taken from 100 carcasses of graylag geese shot during the hunting season in August. In addition, samples were taken from 200 feral pigeons and five mallards. The cultivation of bacteria detected Campylobacter jejuni jejuni in six of the pigeons, and in one of the mallards. Salmonella diarizona 14:k:z53 was detected in one graylag goose, while all pigeons and mallards were negative for salmonellae. No avian paramyxovirus was found in any of the samples tested. One mallard, from an Oslo river, was influenza A virus positive, confirmed by RT-PCR and by inoculation of embryonated eggs. The isolate termed A/Duck/Norway/1/03 was found to be of H3N8 type based on sequence analyses of the hemagglutinin and neuraminidase segments, and serological tests. This is the first time an avian influenza virus has been isolated in Norway. The study demonstrates that the wild bird species examined may constitute a reservoir for important bird pathogens and zoonotic agents in Norway.SammendragScreening av byduer (Colomba livia), stokkender (Anas platyrhynchos) og grågås (Anser anser) for Campylobacter spp., Salmonella spp., aviært influenza virus og aviært paramyxovirus.Til sammen 119 ferske avføringsprøver ble samlet fra grågås på trekk nordover i april, og kloakksvabere ble tatt fra 100 skrotter av samme fugleart som ble skutt under jakta i august. I tillegg ble det tatt prøver av 200 byduer og fem stokkender. Ved bakteriedyrking ble Campylobacter jejuni jejuni funnet hos seks av duene og hos en av stokkendene. Salmonella diarizona 14 : k : z53 ble funnet hos ei grågås, mens alle duene og stokkendene var negative for salmonella. Aviært paramyxovirus ble ikke påvist i noen av de undersøkte prøvene. Ei stokkand fra ei elv i Oslo ble funnet positiv for influensa A virus med RT-PCR og ved innokkulering i embryonerte egg. Isolatet som benevnes A/Duck/Norway/1/03, ble funnet å være av H3N8 type, basert på sekvensanalyser av hemagglutinin og neuraminidase genene, og ved serologiske undersøkelser. Dette er første gang aviært influensavirus har blitt isolert i Norge. Studien viser at de ville fugleartene som ble undersøkt kan utgjøre et reservoar for viktige fuglepatogene og zoonotiske agens i Norge.

SEROLOGIC SURVEY FOR ANTIBODIES AGAINST MYCOBACTERIUM AVIUM SUBSP. PARATUBERCULOSIS IN FREE-RANGING CERVIDS FROM NORWAY

Affinity between protein-G and immunoglobulins from red deer (Cervus elaphus), moose (Alces alces), roe deer (Capreolus capreolus), and reindeer (Rangifer tarandus tarandus) was tested in a competition binding assay. Sera from red deer, reindeer, and moose inhibited the assay less than sera from cattle (less affinity), whereas sera from roe deer showed a slightly higher affinity to protein-G than did sera from cattle. The conclusion was made that protein-G could be used instead of anti-species antibodies for these cervid species, where the aim of the screening was to look for exposure or lack of exposure to mycobacteria in the tested populations. Serologic screening of 1,373 free-ranging cervids for antibodies against Mycobacterium avium subsp. paratuberculosis was conducted. All sera were tested by a protein-G–based antigen-absorbed enzymelinked immunosorbent assay (ELISA). Seropositive moose (10/537; 1.9%), red deer (14/371; 3.8%), roe deer (6/49; 12.2%), and semidomesticated reindeer (11/325; 3.4%) were found, whereas wild reindeer (n=91) were seronegative. In addition, the red deer sera were tested with a commercial ELISA, by which two animals tested positive and nine were suspicious of having M. avium subsp. paratuberculosis antibodies. Tissue samples and feces from 10 moose originating from a population with a clustering of seropositive animals were investigated by histology and bacteriology with negative results. Paratuberculosis has never been diagnosed in free-ranging or farmed cervid species in Norway. Thus, further studies are indicated to prove that the present findings reflect an infection with M. avium subsp. paratuberculosis.

A retrospective analysis of the infectious bovine rhinotracheitis (bovine herpes virus-1) surveillance program in Norway using Monte Carlo simulation models

Serological surveillance for antibodies against bovine herpes virus type I (BHV-1) which causes infectious bovine rhinotracheitis and infectious pustular vulvovaginitis has been carried out since 1992 in Norway. Since 1993 (when a single infected herd was detected) all bulk-milk and pooled-serum samples have been negative for BHV-1 antibodies. This paper describes the use of Monte Carlo simulation models for the analysis and interpretation of the results of the surveillance and provides support for the contention that the Norwegian cattle population is not infected by BHV-1.

A simulated surveillance program for bovine paratuberculosis in dairy herds in Norway.

Monte Carlo simulation models were used to evaluate the feasibility and potential results of a proposed national survey of the prevalence of bovine paratuberculosis (PTB) in dairy herds in Norway. The expected herd prevalence was assumed to be 0.2% in the simulations. The low sensitivity of the ELISA test, the assumed low herd prevalence, the typical low within-herd prevalence of PTB and the small herd sizes all present problems in detection of the disease. Simulations with 500, 1000, 2500 and 6000 herds tested were done. Our results suggest that a national survey would not be feasible at present, due to the low probability of detecting infected herds and because of the high number of false-positive reactions that would be expected to occur.

No indication of Coxiella burnetii infection in Norwegian farmed ruminants

BackgroundInfection with Coxiella burnetii, the cause of Q-fever, has never been detected in Norwegian animals. Recognising the increasing prevalence of the infection in neighbouring countries, the aim of the study was to perform a survey of Norwegian farmed ruminants for the prevalence of C. burnetii infection.ResultsMilk and blood samples from more than 3450 Norwegian dairy cattle herds, 55 beef cattle herds, 348 dairy goat herds and 118 sheep flocks were serologically examined for antibodies against C. burnetii. All samples were negative for antibodies against C. burnetii. The estimated prevalences of infected herds were 0 (95% confidence interval: 0% - 0.12%), 0 (0% - 12%), 0 (0% - 1.2%) and 0 (0% - 10%) for dairy cattle herds, beef cattle herds, goat herds and sheep flocks, respectively.ConclusionsThe study indicates that the prevalence of C. burnetii infection in farmed Norwegian ruminants is low, and it cannot be excluded that Norway is free of the infection. It would be beneficial if Norway was able to maintain the current situation. Therefore, preventive measures should be continued.

Seroprevalence of Toxoplasma gondii infection in Norwegian dairy goats

BackgroundToxoplasma gondii is a major problem for the sheep industry as it may cause reproduction problems. The importance of T. gondii in Norwegian goat herds is uncertain, but outbreaks of toxoplasmosis in dairy goat farms have been recorded. The aim of this study was to describe the prevalence of T. gondii infection in Norwegian dairy goats by using serology.FindingsGoat serum originally collected as part of two nationwide surveillance and control programmes between 2002 and 2008 were examined for T. gondii antibodies by using direct agglutination test. In total, 55 of 73 herds (75%) had one or more serologically positive animals, while 377 of 2188 (17%) of the individual samples tested positive for T. gondii antibodies.ConclusionsThis is the first prevalence study of T. gondii infection in Norwegian goats. The results show that Norwegian goat herds are commonly exposed to T. gondii. Nevertheless, the majority of goat herds have a low prevalence of antibody positive animals, which make them vulnerable to infections with T. gondii during the gestation period.

The prevalence and spatial clustering of Neospora caninum in dairy herds in Norway

The aims of this study were to estimate the national herd prevalence and the general spatial distribution of Neospora caninum infection in Norwegian dairy cattle. Bulk milk samples from 1657 randomly selected dairy herds were analysed by iscom ELISA for the presence of N. caninum specific antibodies. The national herd prevalence was estimated to be 0.7% (95% CI: 0.3-1.2%), which is the lowest national herd prevalence reported in Europe. In addition, we included a subpopulation study in which all 400 herds in the Oslo, Akershus and Østfold counties were sampled, and we found a herd prevalence of 1.8%. In the national herd study, a significant cluster of N. caninum infected herds was identified in Jaeren, on the south west coast of Norway. Jaeren has the highest density of farm animals in the country as well as climatic conditions that favour parasite survival. Dairy herds in this region had a 52 times higher relative risk of being N. caninum positive than dairy herds in other parts of Norway. This indicates that even though N. caninum infection is of minor importance in Norway, infection might cause abortion problems in high risk areas.

Description of the Infection Status in a Norwegian Cattle Herd Naturally Infected by Mycobacterium avium subsp. paratuberculosis

AbstractThe Norwegian surveillance and control programme for paratuberculosis revealed 8 seroreactors in a single dairy cattle herd that had no clinical signs of Mycobacterium avium subsp. paratuberculosis (M. a. paratuberculosis) infection. Paratuberculosis had been a clinical problem in goats several years previously in this herd. All 45 cattle were culled and a thorough investigation of the infection status was conducted by the use of interferon-γ (IFN-γ) immunoassay, measurement of antibodies, and pathological and bacteriological examination.In the IFN-γ immunoassay, 9 animals gave positive results, and 13 were weakly positive, while 19 animals were negative. In the serological test,10 animals showed positive reactions, and 5 were doubtful, while 30 animals gave negative reactions. There appeared to be a weak trend toward younger animals having raised IFN-γ and older animals having raised serological tests. Histopathological lesions compatible with paratuberculosis were diagnosed in 4 animals aged between 4 and 9 years. Three of these animals had positive serological reaction and one animal gave also positive results in the IFN-γ immunoassay. Infection was confirmed by isolation of M. a. paratuberculosis from 2 of these 4 animals. One single bacterial isolate examined by restriction fragment length polymorphism (RFLP) had the same profile, B-C1, as a strain that had been isolated from a goat at the same farm several years previously.Despite many animals being positive in one or both of the immunological tests, indicative of a heavily infected herd, none of the animals showed clinical signs and only one cow was shown to be shedding bacteria. A cross-reaction with other mycobacteria might have caused some of the immunoreactions in these animals. It is also possible that the Norwegian red cattle breed is resistant to clinical infection with M. a. paratuberculosis.SammendragBeskrivelse av infeksjonsstatus i en Norsk storfebesetning smittet med Mycobacterium avium subsp. paratuberculosis. I regi av overvåkings- og kontrollprogrammet for paratuberkulose ble det oppdaget åtte seropositive dyr i en melkekubesetning uten klinisk sykdom. Klinisk paratuberkulose hadde vært et problem på geit noen år tidligere på den samme gården. Besetningen på 45 storfe ble slaktet og en grundig undersøkelse av infeksjonsstatus ble foretatt ved bruk av interferon-γ (IFN-γ) test, måling av antistoffnivå, samt patologisk og bakteriologisk undersøkelse. IFN-γ testen gav positivt resultat på 9 dyr, svakt positivt resultat på 13 dyr og negativt resultat på 19 dyr. Serologisk undersøkelse ga positivt resultat på 10 dyr, usikkert resultat på 5 dyr og negativt resultat på 30 dyr. Det var en svak tendens til forhøyet IFN-γ hos unge dyr og forhøyet antistoffnivå hos eldre dyr. Histopatologiske lesjoner forenlige med paratuberkulose ble påvist hos 4 dyr som var mellom 4 og 9 år. Tre av disse dyrene var positive på serologi og ett dyr ga også positivt resultat i IFN-γ testen. Infeksjonen ble bekreftet ved dyrking av Mycobacterium avium subsp. paratuberculose (M. a. paratuberculosis) fra 2 av disse 4 dyrene. Et bakterieisolat undersøkt ved hjelp av RFLP metoden hadde samme profil, B-C1, som en stamme isolert flere år tidligere fra en geit på denne gården. Til tross for at mange dyr var positive i en eller begge av disse immunologiske testene, et funn som antyder en gjennominfisert besetning, viste ingen av dyrene kliniske symptomer, og utskillelse av bakterier i feces ble påvist hos kun ett dyr. Kryssreaksjon med andre mykobakterier kan ha forårsaket noen av de immunologiske reaksjonene hos disse dyrene. Det er også mulig at NRF-rasen er motstandsdyktig mot klinisk M. a. paratuberculosis infeksjon.