Erik Ågren

Pathology of natural highly pathogenic avian influenza H5N1 infection in wild tufted ducks (Aythya fuligula)

Highly pathogenic avian influenza (HPAI) subtype H5N1 is an infectious systemic viral disease that results in high morbidity and mortality in poultry, and has been reported in a wide range of wild bird species during the last few years. An outbreak of HPAI H5N1 occurred in wild birds in Sweden in 2006 that affected several duck species, geese, swans, gulls, and raptors. Tufted ducks (Aythya fuligula) accounted for the largest number of positive cases and, therefore, were selected for more in-depth histologic and immunohistochemical evaluations. The main histologic lesions associated with the presence of avian influenza antigen were found in the brain, pancreas, and upper respiratory tract. Other tissues in which influenza antigen was variably found included liver, lung, adrenal glands, kidneys, and peripheral nerve ganglia. The current study describes the pathology and viral tissue targeting of H5N1 by using histology, polymerase chain reaction, and immunohistochemistry, and highlights the range and variation in the presentation of the natural disease in tufted ducks.

Evidence of Spread of the Emerging Infectious Disease, Finch Trichomonosis, by Migrating birds

Finch trichomonosis emerged in Great Britain in 2005 and led to epidemic mortality and a significant population decline of greenfinches, Carduelis chloris and chaffinches, Fringilla coelebs, in the central and western counties of England and Wales in the autumn of 2006. In this article, we show continued epidemic spread of the disease with a pronounced shift in geographical distribution towards eastern England in 2007. This was followed by international spread to southern Fennoscandia where cases were confirmed at multiple sites in the summer of 2008. Sequence data of the ITS1/5.8S/ITS2 ribosomal region and part of the small subunit (SSU) rRNA gene showed no variation between the British and Fennoscandian parasite strains of Trichomonas gallinae. Epidemiological and historical ring return data support bird migration as a plausible mechanism for the observed pattern of disease spread, and suggest the chaffinch as the most likely primary vector. This finding is novel since, although intuitive, confirmed disease spread by migratory birds is very rare and, when it has been recognised, this has generally been for diseases caused by viral pathogens. We believe this to be the first documented case of the spread of a protozoal emerging infectious disease by migrating birds.

DISEASES AND MORTALITY IN FREE-RANGING BROWN BEAR (URSUS ARCTOS), GRAY WOLF (CANIS LUPUS), AND WOLVERINE (GULO GULO) IN SWEDEN

Ninety-eight brown bears (Ursus arctos), 20 gray wolves (Canis lupus), and 27 wolverines (Gulo gulo), all free-ranging, were submitted to the National Veterinary Institute, Uppsala, Sweden, during 1987–2001 for investigation of diseases and causes of mortality. The most common cause of natural death in brown bears was infanticide. Infanticide also was observed in wolverines but not in wolves. Traumatic injuries, originating from road or railway accidents, were the most common cause of death in wolves and occurred occasionally in brown bears. Most wolverines were submitted as forensic cases in which illegal hunting/poaching was suspected. Sarcoptic mange was observed in several wolves but not in brown bears or wolverines. Sarcoptic mange most likely was acquired from infected red foxes (Vulpes vulpes) that were killed by wolves. Other parasites and infectious diseases were only found sporadically.

A semi-automated magnetic capture probe based DNA extraction and real-time PCR method applied in the Swedish surveillance of Echinococcus multilocularis in red fox (Vulpes vulpes) faecal samples

BackgroundFollowing the first finding of Echinococcus multilocularis in Sweden in 2011, 2985 red foxes (Vulpes vulpes) were analysed by the segmental sedimentation and counting technique. This is a labour intensive method and requires handling of the whole carcass of the fox, resulting in a costly analysis. In an effort to reduce the cost of labour and sample handling, an alternative method has been developed. The method is sensitive and partially automated for detection of E. multilocularis in faecal samples. The method has been used in the Swedish E. multilocularis monitoring program for 2012–2013 on more than 2000 faecal samples.MethodsWe describe a new semi-automated magnetic capture probe DNA extraction method and real time hydrolysis probe polymerase chain reaction assay (MC-PCR) for the detection of E. multilocularis DNA in faecal samples from red fox. The diagnostic sensitivity was determined by validating the new method against the sedimentation and counting technique in fox samples collected in Switzerland where E. multilocularis is highly endemic.ResultsOf 177 foxes analysed by the sedimentation and counting technique, E. multilocularis was detected in 93 animals. Eighty-two (88%, 95% C.I 79.8-93.9) of these were positive in the MC-PCR. In foxes with more than 100 worms, the MC-PCR was positive in 44 out of 46 (95.7%) cases. The two MC-PCR negative samples originated from foxes with only immature E. multilocularis worms. In foxes with 100 worms or less, (n = 47), 38 (80.9%) were positive in the MC-PCR.The diagnostic specificity of the MC-PCR was evaluated using fox scats collected within the Swedish screening. Of 2158 samples analysed, two were positive. This implies that the specificity is at least 99.9% (C.I. = 99.7 -100).ConclusionsThe MC-PCR proved to have a high sensitivity and a very high specificity. The test is partially automated but also possible to perform manually if desired. The test is well suited for nationwide E. multilocularis surveillance programs where sampling of fox scats is done to reduce the costs for sampling and where a test with a high sensitivity and a very high specificity is needed.

Behavioral and Physiological Responses of Trap-Induced Stress in European Badgers

Reasons for mammal trapping include removal of individuals for population management purposes, scientific purposes, pest control, and obtaining fur, skin, or meat for economic purposes. The type of trap used highly affects the responses of captured animals (Kreeger et al. 1990a, White et al. 1991). Research on captured red foxes (Vulpes vulpes) has shown that foothold traps inflict greater trauma compared with box traps even when the traps had padded jaws (i.e., the animal does not experience any obvious physical damage, Kreeger et al. 1990a). Also procedures, such as chemical immobilization, have been shown to affect the life history of mountain goats (Oreamnos americanus; Cote et al. 1998), moose (Alces alces; Ballard and Tobey 1981), and polar bears (Ursus maritimus; Ramsay and Stirling 1986). Thus, not only can entrapment cause physical trauma, such as limb, tissue, or tooth damage, but the overall response is likely to be affected by how the animal perceives the situation. White et al. (1991) demonstrated higher pathological responses in red foxes captured in box traps compared with untrapped individuals, which shows that even traps like box or cage traps that are likely to minimize physical injuries can have negative effects on animals. Stress-induced hyperthermia has been shown to be closely associated with activation of the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenalmedullary system, for example, in foxes (Moe 1996), thus, resulting in increased heart rate, body temperature, and cortisol levels. Cortisol levels have been used as indicators of stress during restraint of wildlife species (Morton et al. 1995), but although physiological responses often can be useful indicators of stress (Broom and Johnson 1993), it is not suitable to use them alone as stress indicators (Rushen 1991) because similar reactions can also be observed during nonstress situations (Kreeger et al. 1989, 1990b). It is well-known that psychological factors may cause or increase stress responses in animals. If an individual is in a threatening environment and is not able to cope with the situation it is likely to be stressed even without any physical injury (Jensen and Toates 1993, Toates 1995, Jensen 1996). An animal’s ability to predict or control its situation highly influences the response, with stress levels decreasing with increased ability to predict or control the situation (Weiss 1972, Jensen 1996). Therefore, besides potential physical trauma, a captured animal might also be exposed to psychological stress by experiencing lack of control because it is unable to escape from the trap. Furthermore, during long entrapment times there is also a risk of enhanced stress levels due to disruption of, or failure to perform, natural behaviors such as feeding. External factors, such as type of trap, entrapment duration, and time of day, most likely affect the stress response. Also species-specific factors, such as diurnal rhythms, general activity levels, and sociality, are likely to have an influence on how the animal responds to the situation. The European badger (Meles meles) is a nocturnal species that lives in social groups varying in size from 2–30 individuals (Rogers et al. 1997). A group uses a shared territory with one or several setts, but the individuals commonly feed independently from each other (Kruuk 1978a). Badgers are used in Sweden to train earth dogs (i.e., dogs that enter the sett when hunting [e.g., foxes and badgers]), and our study was a part of a project investigating stress coping in such badgers on commission of the Swedish Ministry of Agriculture, Food, and Consumer Affairs. Our aim was to examine some behavioral and physiological (heart rate, body temperature, and fecal cortisol) responses of semitame European badgers to restraint in cage traps for short and long capture periods during day and night time. We also studied behavior during 3 consecutive nights postrestraint (i.e., after the treatment period) and compared behavior to undisturbed conditions. We predicted that longer entrapment would affect the badgers more than short entrapment periods in terms of higher heart rate, body temperature, and fecal cortisol metabolites (FCM) levels and in terms of more long-term changes in behavior. We also predicted that entrapment during dark hours when badgers normally are active would be more stressful than during daylight.

SURGICAL IMPLANTATION OF RADIOTELEMETRY TRANSMITTERS IN EUROPEAN BADGERS (MELES MELES)

Abstract The suitabilities of two subcutaneous and two intraabdominal surgical approaches were evaluated for implantation of telemetry transmitters in the European badger (Meles meles). Two transmitters, one for heart rate and the other for body temperature, were needed in each badger. Five wild badgers were trapped, housed in an outdoor pen, anesthetized, and surgically implanted with one or two transmitters per procedure. A total of 16 transmitters were implanted, 10 subcutaneously and six intraabdominally, and each badger had up to three procedures performed. Six subcutaneous transmitters were placed over the chest wall and four on the dorsal aspect of the neck. Three intraabdominal transmitters were placed free in the abdomen and three were fixed to the abdominal wall. Eight of the subcutaneous transmitters were later damaged or dislodged, probably by mechanical friction, injuries from fighting, or wound licking. The intraabdominal implantation procedures were easier and faster to perform compared with subcutaneous procedures. Two of the free intraabdominal transmitters became thinly encapsulated, with some omental adhesions. The fixed intraabdominal approach for transmitter implantation is preferable in badgers.

Sublethal Lead Exposure Alters Movement Behavior in Free-Ranging Golden Eagles

Lead poisoning of animals due to ingestion of fragments from lead-based ammunition in carcasses and offal of shot wildlife is acknowledged globally and raises great concerns about potential behavioral effects leading to increased mortality risks. Lead levels in blood were correlated with progress of the moose hunting season. Based on analyses of tracking data, we found that even sublethal lead concentrations in blood (25 ppb, wet weight), can likely negatively affect movement behavior (flight height and movement rate) of free-ranging scavenging Golden Eagles (Aquila chrysaetos). Lead levels in liver of recovered post-mortem analyzed eagles suggested that sublethal exposure increases the risk of mortality in eagles. Such adverse effects on animals are probably common worldwide and across species, where game hunting with lead-based ammunition is widespread. Our study highlights lead exposure as a considerably more serious threat to wildlife conservation than previously realized and suggests implementation of bans of lead ammunition for hunting.

Fallot's Tetralogy in a European Brown Bear (Ursus arctos)

A congenital heart malformation was diagnosed in a free-ranging adult female European brown bear (Ursus arctos) found dead due to intraspecific violence. At necropsy, the heart had all four features of Fallots tetralogy. No further malformations were identified in the animal, which was of normal size and weight for its age, in normal body condition, and had probably borne young. The heart condition was considered to have contributed to death during an attack by another bear.

Necrotizing encephalitis of unknown cause in Fennoscandian Arctic foxes (Alopex lagopus).

A neurologic disease affected a colony of endangered Fennoscandian arctic foxes (Alopex lagopus) kept in captivity for breeding purposes. Several outbreaks of disease occurred between 1994 and 2004. The clinical signs included ataxia, indications of anosmia, blindness, and abnormal behavior. The disease was characterized by severe necrotizing encephalitis affecting mostly the cranial cerebrum, basal ganglia, and olfactory bulbs. Investigations to identify the etiology of the disease included testing for several infectious agents known to cause encephalitis in carnivores. Tests for Toxoplasma gondii, Encephalitozoon cuniculi, Neospora caninum, canine distemper virus, rabies, adenovirus type 1, Borna disease virus, and Listeria monocytogenes were negative. The colony was closed, and the cause of the disease remains undetermined.

Reproductive Maturation in the Male Eurasian Lynx (Lynx lynx): A Study on 55 Reproductive Organs Collected from Carcasses During 2002–2005

Data on reproductive physiology from the Eurasian lynx (Lynx lynx) are still scarce. The lynx is protected under Swedish hunting legislation. All lynx that are found dead or that are culled at hunting are to be sent to the Swedish National Veterinary Institute. In this study, we examined reproductive organs from 55 male lynx collected during the years 2002-2005. Age, body weight, testicular weight and volume, production of spermatozoa, and sperm viability were evaluated. The majority of the animals (39) had been killed in February and March, which is during the hunting season. The ages varied between 6 months and 17 years, body weight between 3.6 and 25.5 kg, and mean testes weight between 0.16 and 3.16 g. The gonadosomatic index was low compared with other species (approximately 0.02% in mature males). Mean testes weight differed significantly between males <12 months of age and all other age groups but did not differ between males of 18-23 months and older males. Spermatozoa could be collected but had lost most of their viability. Seven of 10 males of 18-23 months were fertile, as defined by the production of spermatozoa while no males < or =15 months of age were fertile. Adherence of the prepuce to the penis and absence of penile spines were associated with immaturity. The results indicate that most males are fertile during the reproductive season of their second year.