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    An investigation of causes of disease among wild and captive New Zealand falcons (Falco novaeseelandiae), Australasian harriers (Circus approximans) and moreporks (Ninox novaseelandiae) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Veterinary Science at Massey University, Turitea, Palmerston North, New Zealand
    (Massey University, 2014) Mirza, Vaseem
    Infectious disease can play a role in the population dynamics of wildlife species. The introduction of exotic birds and mammals into New Zealand has led to the introduction of novel diseases into the New Zealand avifauna such as avian malaria and toxoplasmosis. However the role of disease in New Zealand’s raptor population has not been widely reported. This study aims at investigating the presence and prevalence of disease among wild and captive New Zealand falcons (Falco novaeseelandiae), Australasian harrier (Circus approximans) and moreporks (Ninox novaeseelandiae). A retrospective study of post-­‐mortem databases (the Huia database and the Massey University post-­‐mortem database) undertaken to determine the major causes of mortality in New Zealand’s raptors between 1990 and 2014 revealed that trauma and infectious agents were the most frequently encountered causes of death in these birds. However, except for a single case report of serratospiculosis in a New Zealand falcon observed by Green et al in 2006, no other infectious agents have been reported among the country’s raptors to date in the peer reviewed literature. During the review of post-­‐mortem records, organisms like Mycobacterium avium, Serratospiculum sp, Sarcocystis spp, Trichomonas galllinae and several unidentified helminths were identified as contributing or definite causes of mortality in all three species of raptors. But neither Plasmodium spp nor Toxoplasma gondii infections have been demonstrated in these birds so far. Therefore, a separate study was designed to determine the presence of these pathogens in New Zealand falcon, Australasian harrier and morepork tissues, using established molecular techniques. Molecular analysis of archived New Zealand raptor tissues confirmed the presence of both Plasmodium spp (10/117; 8.5%) and T. gondii (9/117; 7.7%) in all three species of raptors. Plasmodium strains identified were P. elongatum GRW6, P. sp AFTRU5, and P. relictum GRW4 and SGS1. Surprisingly, two Australasian harriers and one morepork tested for the presence of both Plasmodium spp and T. gondii as concomitant infections. However, it is unknown whether any of the positive tested birds suffered from clinical infections, since post-­‐mortem records had no record of clinical signs of disease associated with either infections in these birds. Once the presence of the aforementioned pathogens among New Zealand raptors was established, an attempt was made to investigate their presence among live raptor populations as well. Blood samples were collected from raptors being admitted to Wildbase Hospital, Massey University, Palmerston North and Wingspan-­‐ Birds of Prey Research Centre, Rotorua. Molecular analysis of these samples by PCR did not reveal the presence of Plasmodium spp in any of the ii tested birds, but one New Zealand falcon, Australasian harrier and morepork each tested positive for the presence of T. gondii. Interestingly, none of the positive birds showed any signs of clinical illness that may be associated with toxoplasmosis in raptors. We also analysed faecal samples and throat swabs from these birds to determine the presence of pathogens like Caryospora spp, Serratospiculum spp, Salmonella spp and T. gallinae, since many of these organisms have been detected in New Zealand and are also found affecting raptors in other parts of the world. However, apart from eggs resembling Capillaria spp, none of the other pathogens listed above were identified. My study has some limitations such as a small sample size and a geographic bias in terms of birds being submitted to Massey University, Palmerston North for post-­‐mortem analysis. But this research may be regarded as the first report of Plasmodium spp and T. gondii infections among New Zealand’s three well-­‐known raptor species and further research is required to determine the prevalence of these pathogens among the country’s total raptor population, pathogenicity of the organisms towards them and the role of these birds in the epidemiology of these diseases within New Zealand
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    Yersinia pseudotuberculosis, iron and disease in birds : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science, Massey University
    (Massey University, 1994) Cork, Susan Catherine
    An epidemiological study was conducted to determine the relative prevalence of yersiniae in different species of wild bird and in the environment. The prevalence of Y. pseudotuberculosis in wild birds, determined using bacteriological techniques, was low. Yersinia pseudotuberculosis was not isolated from environmental samples. The prevalence of other yersiniae isolated from birds was similar to those isolated from the environment in rural locations but not in urban locations. A concurrent serological survey was carried out on a proportion of the wild birds studied. A high number of serologically positive birds indicated frequent exposure to Y. pseudotuberculosis. Clinical cases of pseudotuberculosis in captive birds occurred in the winter and spring following a period of cold weather. Three outbreaks studied involved passeriforms and were associated with poor management. The sporadic cases studied involved individual columbiforms or psittaciforms with concurrent haemosidcrosis. To allow statistical comparisons of the amount and distribution of stainable iron in histological sections, an image analysis system was developed using an experimental model of haemosiderosis in the chicken. Using this technique for a retrospective study of 180 avian cases, it was found that birds which died from infectious diseases had significantly higher levels of iron in the Kupffer cells than did birds which died from non-infectious diseases. The total amount of hepatic iron was not significantly different between the two groups. An experimental model was developed in the chicken to examine the effect of parenteral iron on the pathogenesis of pseudotuberculosis. Challenged birds pre-treated with iron-dextran had higher serological titres to Yersinia lipopolysaccharide, the organism was more readily isolated from the faeces and there were more intestinal lesions than in challenged chickens pre-treated with dextran or desferrioxamine. However, chickens pre-treated with iron-dextran had fewer bacterial lesions in the liver and spleen. Intracellular survival of Y. pseudotuberculosis and Y. frederiksenii in vitro was enhanced in iron loaded macrophages. It was also determined that Y. pseudotuberculosis was able to acquire iron from normal chicken serum.
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    Avian influenza and avian paramyxoviruses in the New Zealand bird population : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Virology at Massey University, Palmerston North, New Zealand
    (Massey University, 2002) Stanislawek, Wlodzimierz Leonard
    A comprehensive study using virological and serological approaches was carried out to determine the occurrence of avian paramyxoviruses (APMVs) and avian influenza viruses (AIVs) in live healthy mallard ducks (Anas platyrhynchos) in addition to caged birds, wild birds (other than waterfowl), and poultry. Thirty-three viruses were isolated from 321 tracheal and cloacal swabs from mallard ducks and were characterised as: 6 AIV (two H5N2 and four H4N6), 10 APMV-1, and 17 APMV-4. Of 335 serum samples tested for AIV antibodies, 109 (32.5%) sera were positive by nucleoprotein-blocking ELISA (NP-B-ELISA). Serum samples (315) were examined for antibody to APMV-1, -2, -3, -4, -6, -7, -8, and -9 by the haemagglutination inhibition (HI) test. The largest number of reactions, with titres up to ≥1/64, was to APMV-1 (93.1%), followed by APMV-6 (85.1%), APMV-8 (56%), APMV-4 (51.7%), APMV-7 (47%), APMV-9 (15.9%), APMV-2 (13.3%), and APMV-3 (6.0%). All of the H5N2 isolates of AIV and the APMV-1 isolates from this and earlier New Zealand studies had low pathogenicity indices when assessed by the Intravenous Pathogenicity Index (IVPI) with the result 0.00 and Intracerebral Pathogenicity Index (ICPI) with results 0.00-0.16. Partial genomic and antigenic analyses were also consistent with the isolates being non-pathogenic. Phylogenetic analysis of the 10 APMV-1 isolates showed nine to be most similar to the reference APMV-1 strain D26/76 originally isolated in Japan and also to the Que/66 strain, which was isolated in Australia. The other isolate was very similar to a virus (MC 110/77) obtained from a shelduck in France. Antibodies to APMV-1, -2, and -3 were detected in 4.8, 1.7, and 2.6%, respectively, of caged bird samples. The majority of these caged birds were "exotic" or "fancy" poultry breeds. Amongst wild birds, 4.2% had titres to APMV-2 and over half of these were passerine birds; 1.7% of the samples had titres to APMV-1 and 0.8% to APMV-3 antigen. No APMVs or AIVs were isolated from any of the cloacal swabs collected from these birds. Of the 1778 poultry serum samples tested only five reacted with APMV-3 antigen and these were later found to be cross-reactions to APMV-1. No reactions were detected with APMV-2 antigen. Although, we can be confident that APMV-1 is present in caged birds, wild birds, and poultry of New Zealand, there is no conclusive evidence of the presence of APMV-2 and APMV-3 in poultry or APMV-3 in wild birds. The results also do not provide conclusive evidence for the presence of APMV-2 in wild birds. Despite New Zealand being free from ND and highly pathogenic avian influenza (HPAI) in commercial poultry and the lack of evidence of pathogenic APMV-1 and AIVs in other birds, a number of possibilities were suggested by which virulent strains of APMV-1 and HPAI viruses could emerge in New Zealand including: (1) introduction by migratory birds; (2) importation of live birds and avian products: and (3) mutation in endemic viruses of low virulence. The findings from this study and elsewhere emphasise the importance of good biosecurity measures on poultry farms, to prevent the introduction of viruses of low virulence, as well as monitoring for the presence and type of APMV-1 and AIV in wild and domestic birds. The situation is likely to be dynamic with new strains emerging and the occurrence of clinically important introductions is a real possibility.