Multi-pathogen serological survey of migratory caribou herds: A snapshot in time.

Pathogens can impact host survival, fecundity, and population dynamics even when no obvious disease is observed. Few baseline data on pathogen prevalence and diversity of caribou are available, which hampers our ability to track changes over time and evaluate impacts on caribou health. Archived blood samples collected from ten migratory caribou herds in Canada and two in Greenland were used to test for exposure to pathogens that have the potential to effect population productivity, are zoonotic or are emerging. Relationships between seroprevalence and individual, population, and other health parameters were also examined. For adult caribou, the highest overall seroprevalence was for alphaherpesvirus (49%, n = 722), pestivirus (49%, n = 572) and Neospora caninum (27%, n = 452). Lower seroprevalence was found for parainfluenza virus type 3 (9%, n = 708), Brucella suis (2%, n = 758), and Toxoplasma gondii (2%, n = 706). No animal tested positive for antibodies against West Nile virus (n = 418) or bovine respiratory syncytial virus (n = 417). This extensive multi-pathogen survey of migratory caribou herds provides evidence that caribou are exposed to pathogens that may have impacts on herd health and revealed potential interactions between pathogens as well as geographical differences in pathogen exposure that could be linked to the bio-geographical history of caribou. Caribou are a keystone species and the socio-economic cornerstone of many indigenous cultures across the North. The results from this study highlight the urgent need for a better understanding of pathogen diversity and the impact of pathogens on caribou health.

Human pathogens in marine mammal meat ­ a northern perspective.

Only a few countries worldwide hunt seals and whales commercially. In Norway, hooded and harp seals and minke whales are commercially harvested, and coastal seals (harbour and grey seals) are hunted as game. Marine mammal meat is sold to the public and thus included in general microbiological meat control regulations. Slaughtering and dressing of marine mammals are performed in the open air on deck, and many factors on board sealing or whaling vessels may affect meat quality, such as the ice used for cooling whale meat and the seawater used for cleaning, storage of whale meat in the open air until ambient temperature is reached, and the hygienic conditions of equipment, decks, and other surfaces. Based on existing reports, it appears that meat of seal and whale does not usually represent a microbiological hazard to consumers in Norway, because human disease has not been associated with consumption of such foods. However, as hygienic control on marine mammal meat is ad hoc, mainly based on spot-testing, and addresses very few human pathogens, this conclusion may be premature. Additionally, few data from surveys or systematic quality control screenings have been published. This review examines the occurrence of potential human pathogens in marine mammals, as well as critical points for contamination of meat during the slaughter, dressing, cooling, storage and processing of meat. Some zoonotic agents are of particular relevance as foodborne pathogens, such as Trichinella spp., Toxoplasma gondii, Salmonella and Leptospira spp. In addition, Mycoplasma spp. parapoxvirus and Mycobacterium spp. constitute occupational risks during handling of marine mammals and marine mammal products. Adequate training in hygienic procedures is necessary to minimize the risk of contamination on board, and acquiring further data is essential for obtaining a realistic assessment of the microbiological risk to humans from consuming marine mammal meat.

Brucella seroprevalence of the Kafue lechwe (Kobus leche kafuensis) and Black lechwe (Kobus leche smithemani): exposure associated to contact with cattle.

We investigated Brucella seroprevalence in Kafue (Kobus leche kafuensis) and Black (Kobus leche smithemani) lechwe antelopes to assess Brucella infections in relation to presence/absence of cattle interaction on the wetlands. Accordingly, two study populations based on cattle interaction were assesed: Kafue lechwe from Kafue flats which interact with cattle; and the Black lechwe with no known interaction with cattle from the Bangweulu swamps. Fourteen Kafue lechwe and thirty Black lechwe were slaughtered between October and December 2009 using special research licenses obtained from the Zambia wildlife authority to investigate diseases in lechwe antelope. For the purpose of this study, blood was collected and sera separated for Rose Bengal and indirect ELISA tests. Seroprevalence of Brucella in the Kafue lechwe was estimated at 42.9% [95% CI: 15.2-70.5] while that in Black lechwe was 0% [95% CI:0.0-11.6]. On the Kafue flats, cattle were spotted grazing in the same areas as lechwe while there was no evidence of cattle presence on the Bangweulu swamps. These differences in seroprevalence between Kafue lechwe and Black lechwe were assumed to be associated with interaction between Kafue lechwe and Brucella infected cattle, and no such contact existed between cattle and the Black lechwe. Our study suggests that brucellosis in the Kafue lechwe may have originated from cattle but has now established a reservoir in wild animals. It is also important to keep in mind that the Black lechwe can easily become infected with Brucella spp. once cattle are introduced in the surrounding areas.

Tuberculosis in Kafue lechwe antelopes (Kobus leche Kafuensis) of the Kafue Basin in Zambia.

Tuberculosis (TB) has been reported in the Kafue lechwe antelopes (Kobus leche Kafuensis) of Zambia. However, previous reports are restricted to the southern parts in Lochinvar, where only old male animals were investigated. This study was conducted to gather epidemiological information on TB in Lechwe antelopes across sexes and age groups in relation to other explanatory variables of disease occurrence in the Kafue Basin. Animals were hunted under a special licence to investigate diseases in the Kafue Basin during the 2004, 2005 and 2008 hunting seasons. Histopathology, acid-fast staining and mycobacterial culturing from tissue samples were conducted. A total of 119 animals were slaughtered with an estimated age range of 2.5-20 years. Of these, 29 (24.3% [95% CI: 16.5, 32.3%]) had necropsy lesions suggestive of tuberculosis, of which 21 (17.6% [95% CI: 10.7, 24.6%]) tested positive on acid-fast staining while 33 (27.7% [95% CI: 19.6, 35.9%]) showed culture and colony morphological characteristics suggestive of Mycobacterium species. On univariate analysis, animals with poor body condition were twice as likely to have tuberculosis associated lesions as those having good body conditions (OR=2.3, 95% CI: 0.6, 9.3%). Based on lesion distribution, a respiratory route of mycobacterial infection is intimated.

Prevalence of antibodies against Toxoplasma gondii in polar bears (Ursus maritimus) from Svalbard and East Greenland.

Serum samples from 419 polar bears (Ursus maritimus) from Svalbard and the Barents Sea (collected 1990-2000) and 108 polar bears from East Greenland (collected 1999-2004) were assayed for antibodies against Toxoplasma gondii using the modified agglutination test. Antibody prevalences were 3.6% among cubs dependent on their mothers and 21.4% among subadults and adults. Among subadults and adults there was an interaction between population and sex, with similar prevalences among females (Svalbard = 19.5%, Greenland = 18.0%), but a high frequency among Svalbard males (28.7%) as compared to Greenland males (5.8%). The pattern was also significant after correcting for differences in age distribution. The sex-population interaction term is believed to be connected to area- and sex-specific feeding ecology. The prevalences of antibodies against T. gondii in Svalbard and Greenland were high compared to previously reported findings in polar bears from Russian and Alaskan areas.

Prevalence of bovine tuberculosis and animal level risk factors for indigenous cattle under different grazing strategies in the livestock/wildlife interface areas of Zambia.

A cross-sectional study was conducted to investigate the prevalence and animal level risk factors for bovine tuberculosis (BTB) in indigenous cattle of the livestock/wildlife interface areas in Zambia. A total of 944 cattle from 111 herds were investigated. The comparative intradermal tuberculin test (CIDT) was used to identify reactor animals for BTB. Animal level data on sex, age, parity and body condition score were registered. The overall animal prevalence of BTB as determined by the CIDT was 6.8% (95% CI: 4.2, 9.5%). In Lochinvar and Blue Lagoon areas, animal level prevalence were observed at 5.2% (95% CI: 2.2, 8.2%) and 9.6% (95% CI: 6.1, 13.2%), respectively. Kazungula, an area outside the livestock/wildlife interface, had a prevalence of only 0.8% (95% CI: 0.0, 2.3%). The age of the animal, its body condition score and the type of management system, were predictive of its BTB status. The study revealed that BTB was relatively high in the livestock/wildlife interface areas of Lochinvar and Blue Lagoon compared to Kazungula. These findings should raise a serious public health concern considering the extent to which the communities of the study areas are in contact with their animals and the levels at which they use untreated milk.

Risk factors associated with bovine tuberculosis in traditional cattle of the livestock/wildlife interface areas in the Kafue basin of Zambia.

We conducted a cross-sectional study from August 2003 to February 2004 to identify risk factors for bovine tuberculosis (BTB) in the Kafue basin of Zambia. We investigated a total of 106 herds of cattle for presence of BTB using the comparative intradermal tuberculin test (CITT) while an interviewer-administered questionnaire was used to gather epidemiological data on herd structure, management and grazing strategies. BTB prevalence at herd level was estimated and possible risk factors were investigated using the multiple logistic regression model. The true herd level prevalence of BTB was estimated at 49.8% (95% CI: 37.9, 61.7%). The logistic regression model showed that cattle herd BTB status was highly associated with area and husbandry practices. When compared to Kazungula, cattle herds in Blue Lagoon were more likely to test positive for BTB when other factors such as management practices were controlled (OR=10.5). In terms of grazing strategies, transhumant herds (TH) had higher odds (OR=3.0) of being positive compared to sedentary herds (OR=1.0). The results in this study provide preliminary information about potential risk factors that were found to be associated with BTB status in cattle.

Phylogenetic comparison of rabies viruses from disease outbreaks on the Svalbard Islands.

Periodic wildlife rabies epizootics occur in Arctic regions. The original sources of these outbreaks are rarely identified. In 1980, a wildlife epizootic of rabies occurred on the previously rabies-free Svalbard Islands, Norway. After this outbreak of rabies in the arctic fox population (Alopex lagopus), only single cases have been reported from the Islands over the following two decades. Phylogenetic characterization of four viruses isolated from infected arctic foxes from Svalbard from three different time periods suggest that the source of these epizootics could have been migration of this species from the Russian mainland. Arctic fox migration has likely contributed to the establishment of another zoonotic disease, Echinococcus multilocularis, on Svalbard in recent years.

Isolation and partial characterization of a parapoxvirus isolated from a skin lesion of a Weddell seal.

A solitary skin lesion was found on the neck of a Weddell seal (Leptonychotes weddellii), chemically immobilized in Queen Maud Land (70 degrees 09'S, 05 degrees 22'E) Antarctica 2001. The lesion was elevated and 3cm in diameter, consisting of partly fresh and partly necrotic tissue, and proliferative papilloma-like structures were seen. Electron microscopy on a biopsy from the lesion revealed typical parapoxvirus particles. Polymerase chain reaction (PCR; B2L gene) generated amplicons of approximately 594 base pairs, comparable to Orf-virus, the prototype parapoxvirus. A comparison of these B2L PCR amplicon DNA sequences with corresponding sequences from other parapoxviruses, showed that the Weddell seal virus resembled isolates from grey seal (Halichoerus grypus) and harbour seal (Phoca vitulina) more than parapoxvirus from red deer (Cervus elaphus), sheep, cattle and Japanese serows (Capricornis crispus). It is thus concluded that the Weddell seal parapoxvirus belong to the tentative seal parapoxvirus species. Since parapox and orthopoxviruses may cause similar clinical diseases, we suggest that the term sealpox should be restricted to the clinical disease, whereas seal parapoxvirus should be used when caused by a parapoxvirus, rather than the general term "sealpox virus". This is the first verified case of parapoxvirus infection in a Weddell seal, and also the first report of any such infections in the Antarctic.

Analysis and comparison of the 4b core protein gene of avipoxviruses from wild birds: evidence for interspecies spatial phylogenetic variation.

Avipoxviruses have been isolated from a wide variety of avian hosts, and yet little is known regarding the host-virus species variation of the genus Avipoxvirus. We have investigated the variations in the viral 4b core protein gene from six different avipoxviruses based on PCR, Southern blot and nucleotide sequence analysis to evaluate the suitability of this region for differentiation between avipoxvirus isolates. Southern blot and nucleotide sequence analysis revealed considerable interspecies variation between the different virus isolates. In the deduced amino acid sequences (of 142 residues) of the 4b core protein gene, fowlpox virus vaccine strain (FPV-VR250) was found to be similar to the three poxvirus isolates from great tit (GTV-A310, GTV-A311 and GTV-A256), sparrowpox virus (SPV-A468), and pigeonpox virus (PPV-B7) with similarities of 79.6%, 81%, 81%, 64.8% and 84.5%, respectively. Furthermore, comparative phylogenetic analysis of the aligned DNA sequences revealed divergence among the different viruses that can be consistently correlated to the host.

Brucella sp. antibodies in polar bears from Svalbard and the Barents Sea.

A prevalence of 5.4% of anti-Brucella sp. antibodies was found in plasma samples from 297 polar bears (Ursus maritimus) from Svalbard and the Barents Sea. Plasma was tested by the classical brucellosis tests Slow Agglutination of Wright (SAW), EDTA modified SAW and Rose Bengal test, as well as by an indirect Protein A ELISA. Only samples classified as positive in all tests were regarded as containing anti-Brucella sp. antibodies. A significant west to east increase in the proportion of bears with anti-Brucella sp. antibodies was found, with 3.6% (n = 253) at Svalbard (Spitsbergen, Nordaustlandet, Edgeøya, Barentsøya and Hopen), and 15.9% (n = 44) in the central Barents Sea. Anti-Brucella sp. antibodies were previously found in ringed seals (Phoca hispida) and harp seals (Phoca groenlandica) from the same geographical areas. The ringed seal is an important prey species for the Svalbard polar bear population, and may thus be a source of brucellosis for the bears. There are no indications of reproductive disorders caused by Brucella sp. or other infectious agents in our study polar bear population. Potential impacts of Brucella sp. exposure on individuals or the population are unknown.

AhpC, AhpD, and a secreted 14-kilodalton antigen from Mycobacterium avium subsp. paratuberculosis distinguish between paratuberculosis and bovine tuberculosis in an enzyme-linked immunosorbent assay.

Sera from cattle naturally infected with Mycobacterium avium subsp. paratuberculosis (n = 56) and naturally (n = 4) and experimentally (n = 8) infected with Mycobacterium bovis were tested for the presence of antibodies against paratuberculosis antigens. An enzyme-linked immunosorbent assay (ELISA) was established based on absorption of M. avium subsp. paratuberculosis antigens on a hyperimmune antiserum against M. avium subsp. avium proteins in order to remove cross-reacting antigens. This absorbed-antigen ELISA recognized 66% of animals with paratuberculosis (37 of 56), while none of the animals with naturally occurring bovine tuberculosis (TB) had detectable antibodies. However, the animals with experimental bovine TB also responded in this ELISA. Similar results were found in a commercial ELISA, showing that neither of these tests was able to distinguish between paratuberculosis and bovine TB. The sera were further tested for antibody activities against purified AhpC and AhpD, which are proteins constitutively expressed by M. avium subsp. paratuberculosis, and against a secreted 14-kDa protein present in culture filtrates from the M. avium complex. Elevated antibody levels to AhpC, AhpD, and the 14-kDa antigen were found in 27% (13 of 48), 15% (7 of 48), and 27% (13 of 48), respectively, of the cattle with paratuberculosis. Together these ELISAs were positive with 35% (17 of 48) of the animals. None of the animals with bovine TB had detectable antibodies against any of the purified proteins despite their high levels of cross-reacting antibodies. These results show that purified specific antigens are needed to differentiate between paratuberculosis and bovine TB in ELISA.

Serum chemistry of the minke whale from the northeastern Atlantic.

Serum samples were collected from 42 harpooned minke whales (Balaenoptera acutorostrata) during commercial whaling off the coast of northern Norway (1997 and 1998) and analyzed for serum chemistry parameters in order to find clinical reference values for the northeastern Atlantic stock of this species. Mean and median values, as well as standard deviation and 90% central range, are presented for 28 different serum chemistry parameters. Lipemia is a common finding in marine mammals such as the minke whale, and chemical analysis of lipemic serum samples may produce artifacts. We found statistically significant elevated values of total protein, globulin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), sodium and chloride in strongly-lipemic compared to non-lipemic samples, all which may be artifacts due to interference of lipids with the methods used for analysis. In addition, we found significantly elevated levels of creatin kinase, lactate dehydrogenase (LDH), urea, uric acid and triglycerides, as well as a decrease in creatinine in the strongly lipemic samples. Reanalyzing serum samples after twelve mo storage at -20 C (n = 13) revealed reduction in the serum concentration of the enzymes ALT (42%), alkaline phosphatase (ALP; 10%), LDH (19%), gamma glutamyl transferase (17%) and amylase (11%), as well as for triglycerides (9%) and non-esterified fatty acids (16%). It is crucial that serum chemistry analysis is performed without delay after sampling. Possible changes in the values of some parameters due to the presence of high amounts of lipids or long term storage of samples must be considered when interpreting results from serum chemistry analysis in these animals.

[Smallpox and smallpox virus--200 years since the first vaccination in Norway]. / Kopper og koppevirus--200 år siden første vaksinasjon i Norge.

In December 1801, the first vaccination against smallpox in Norway took place. Vaccine material came from Denmark, England, Ireland, and other countries; it was also obtained from a few local cowpox cases. What mattered was the effect, not the origin. Several reports indicate that variola virus itself, the cause of smallpox, was also used for human vaccination after passages through cows and horses. A vaccine institute for production of vaccine in calves was established in Kristiania in 1891. Cowpox was once a rare disease in cattle, but a total of 70,985 bovine cases were reported between 1889 and 1928. The source of infection was thought to be humans vaccinated against smallpox. Pox-like diseases were also registered in horses, pigs, sheep, goats and dogs at that time. Compulsory vaccination continued in Norway until 1976; smallpox is now eradicated. During the last decades, however, cowpox virus infections have re-emerged among zoo animals, domestic cats and humans in Western Europe, with small wild rodents and shrews as wildlife reservoirs. Vaccinia virus is also met with new interest as a vector in recombinant vaccines. Given the fact that the human population no longer has immunity against orthopoxviruses and the new possible exposure through pets and wildlife, it may be appropriate to reflect on poxvirus history in Norway in the light of the present situation.

Comparison of thymidine kinase and A-type inclusion protein gene sequences from Norwegian and Swedish cowpox virus isolates.

During the last decades, cowpox virus, a member of the genus Orthopoxvirus within the Poxviridae family, has appeared as a pathogen in domestic cats, zoo animal species, and humans. At the same time, vaccinia virus, another orthopoxvirus, has been used as a recombinant vaccine vector with foreign genes inserted in the thymidine kinase (TK) gene. By PCR and cycle sequencing, we have determined the nucleotide sequences of the TK gene and the A-type inclusion protein (ATIP) gene of virus isolates from two human cowpox cases in Sweden, as well as a human and a feline case from Norway. We also obtained the corresponding sequences from ectromelia virus (strain Moscow), cowpox virus (strain Brighton) and vaccinia virus (strain Western Reserve). The new virus isolates differed from ectromelia virus and vaccinia virus, and were confirmed to be cowpox virus strains. Isolates originating from the same country had nearly identical TK sequences and fully identical ATIP sequences. They probably represent local geographical strains of cowpox virus.

Evidence of Brucella infection in marine mammals in the North Atlantic Ocean.

Between 1983 and 1996 a total of 1386 samples of serum were taken from four species of seal and three species of whale in the waters west of Iceland, the area of pack-ice north-west of Jan Mayen, the northern coast of Norway and the Kola Peninsula, the waters west of Svalbard, and the Barents Sea; they were tested for the presence of anti-Brucella antibodies with an indirect ELISA (protein G conjugate). The positive sera were re-tested with classical brucellosis serological tests, such as the serum agglutination test, the EDTA-modified serum agglutination test, the Rose Bengal test, and the complement fixation test, as well as an anti-complement ELISA. Anti-Brucella antibodies were detected in all the species investigated, except for the bearded seal (Erignathus barbatus), with the following prevalences: hooded seals (Cystophora cristata) 35 per cent; harp seals (Phoca groenlandica) 2 per cent; ringed seals (Phoca hispida) 10 per cent; minke whales (Balaenoptera acutorostrata) 8 per cent; fin whales (Balaenoptera physalus) 11 per cent; and sei whales (Balaenoptera borealis) 14 per cent. An isolate belonging to the genus Brucella was obtained from the liver and spleen of one of the seropositive minke whales. The findings suggest that antibodies against the surface lipopolysaccharide of Brucella species are widely distributed among marine mammals in the North Atlantic Ocean.

Clinical cowpox cases in Norway.

In 1994, a human and a feline case of cowpox virus infection appeared in the western part of Norway. Cowpox has not been diagnosed with certainty in Norway since the beginning of this century, when it was associated with the use of cowpox virus as a vaccine against smallpox. The human infection manifested as a spontaneously emerged, severe ulceration at the medial angle of the right eye in a 37-y-old woman, and developed into a relatively severe dermatitis. The ulcer healed slowly, leaving a scar. The feline infection was represented by a febrile, dehydrated and anorectic 6-months-old non-pedigree short-hair, with crater-like ulcers all over the body. After antibiotic and fluid therapy, revision of the skin lesions and amputation of a gangrenous toe, the cat recovered. Electron microscopy of the isolates and cultivation of virus on chorioallantoic membrane of chicken embryos confirmed the suspicion of cowpox virus infection.

Antibodies to orthopoxvirus in domestic cats in Norway.

The prevalence of antibodies to orthopoxvirus in 217 sera collected from domestic cats in the western part of Norway was 10.1 per cent as measured by a competitive ELISA. In one of the seropositive cats antibodies were also detected by an immunofluorescence assay. The average age of the cats sampled was 4.9 years, but the average age of the seropositive individuals was 7.3 years, higher than the average age of clinical cowpox virus cases in Britain (4.2 years), and in Germany (3.9 years). Antibodies against feline immunodeficiency virus (FIV) were detected in nine of 30 (30 per cent) of the seropositive cats, and in five of 30 (17 per cent) of the seronegative cats, which suggests that FIV infection may influence the susceptibility of domestic cats to orthopoxvirus, or vice versa. Orthopoxvirus infections, have recently been detected in rodent populations in several areas of Norway, and the infection may therefore be present in cats all over the country; cat owners and animal handlers should be aware of this (re)emerging zoonosis.

Characteristics of four cowpox virus isolates from Norway and Sweden.

We report the first isolation of cowpox virus from a domestic cat in Norway, and the first confirmed isolation of cowpox virus from a human case in Norway. These two Norwegian cowpox virus isolates, as well as two Swedish human isolates, were partially characterized and compared with each other and with cowpox virus Brighton and vaccinia virus strain Western Reserve. Restriction enzyme analysis of the genomes revealed differences between all six viruses examined, but suggested that the two Norwegian isolates are closely related, as are the two Swedish isolates. Restriction endonuclease digestion of genomic DNA demonstrated that one of the Swedish isolates and the two Norwegian isolates have larger genomes than vaccinia virus strain Western Reserve, but smaller than cowpox Brighton. All four Scandinavian isolates lacked a 72 base-pair region within the A-type inclusion body protein gene which is present in the prototype cowpox virus Brighton.