Wildlife Disease Surveillance
Total Page：16
File Type：pdf, Size：1020Kb
Wildlife disease surveillance Surveillance of wildlife continues to be an Reports of particular interest are 2010–2014. Numbers of avian cases in important part of New Zealand’s national summarised in the Quarterly review of 2014 decreased slightly compared to 2013 surveillance system for exotic and diagnostic cases article in each edition and were fewer than in 2011 when more emerging pests and disease. The purpose of Surveillance. In addition, causes of than 300 oiled seabirds were examined of the Ministry for Primary Industries mortalities of threatened or critically after the container ship Rena was (MPI) wildlife surveillance endangered native species are monitored. wrecked in the Bay of Plenty. programme is to: As part of a DOC contract undertaken In 2014, birds comprised 87 percent of by Wildbase Pathology (part of the • facilitate early detection of exotic and submissions, with lizards 5.5 percent, Institute of Veterinary, Animal and emerging diseases; cetaceans (whales and Hector’s dolphins, Biomedical Sciences or IVABS, at Massey • support NZ’s statements of freedom Cephalorhynchus hectori) 4.4 percent and University, Palmerston North), animals from specific pests and diseases; pinnipeds 2.1 percent, while amphibians, found dead in the field or in captive fish, bats, tuatara (Sphenodon punctatus) • provide baseline information on facilities are sent to the laboratory for and other wild mammals totalled about 1 endemic disease occurrence in New post-mortem examination by veterinary percent. Mortalities of both adult yellow- Zealand wildlife; and wildlife pathologists. Since 2012, MPI eyed penguins or hōiho (Megadyptes • support fulfilment of NZ’s has provided ancillary laboratory testing antipodes) and adult little blue penguins international reporting obligations. to help determine the cause of death in (Eudyptula minor) were of concern in the The MPI national exotic pest and disease these cases. coastal Otago region, and mortalities of notification system provides for the black stilts (Himantopus novaezelandiae) reporting and investigation of unusual Wildlife cases processed by and whiteheads (Mohoua albicilla) disease events in all animals, including veterinary laboratories occurred following re-introduction wildlife. The MPI pest and disease Records of wildlife mortality are programmes in the South Canterbury emergency hotline (0800 80 99 66) helps held in the Huia database, which is and Auckland regions respectively. New Zealanders to meet their obligations jointly owned by DOC and Massey There was an increase in the number of under section 44 of the Biosecurity Act University and maintained by Wildbase marine mammal necropsies performed 1993, which requires every person to Pathology at IVABS. Most of the cases following the stranding of pygmy sperm report to MPI any suspect organisms involve mortalities in indigenous birds, whales (Kogia breviceps) and pilot whales not normally seen or otherwise detected particularly threatened species submitted (Globicephala melas) in Hawke Bay and in New Zealand. This enables the by DOC for diagnosis by Wildbase northern parts of the South Island. appropriate investigation of suspected Pathology. The database also holds some cases of exotic or emerging diseases case records from surveillance activities, Disease surveillance in highly identified in wildlife by organisations private veterinary laboratories and threatened species such kakapo (Strigops or individuals working outside of MPI researchers. Figure 1 shows avian habroptilus), black stilt, hihi/stitchbird surveillance programmes. cases compared to cases involving (Notiomystis cincta) and the endangered other types of wildlife over the period In addition to investigating reported events, MPI undertakes monitoring to detect changes in disease occurrence that may indicate an emerging disease that requires further investigation. As well as using MPI’s own data, this work also draws on disease occurrence information created by other organisations undertaking surveillance in, or working with wildlife, in particular the Department of Conservation (DOC). Routine disease diagnoses in wildlife by veterinary diagnostic laboratories are also monitored. Results from testing samples from feral, captive or wild native animals meeting a sick animal case criterion that are submitted to diagnostic laboratories by veterinary practitioners, DOC rangers, research workers or others, are provided Figure 1: Numbers of wildlife cases in birds and other taxonomic groups recorded in the Huia database, to MPI as anonymous summary data. 2010–2014 22 Surveillance 42 (3) 2015 species of kiwi (Apteryx spp.) continued Otago. The Canterbury region contains a heavy oral and pharyngeal Capillaria throughout the year. A small number of the Mt Cook National Park as well as infection (Alley et al., 2004). Other wild introduced birds were examined captive breeding centres for threatened native birds that have been infected because of the interest in preventing species at Willowbank and Peacock include captive kiwi (Apteryx mantelli) in transmission of diseases such as Springs, in Christchurch. Many cases Hawke’s Bay (Davis et al., 1984) and two malaria, beak-and-feather disease and submitted from the Auckland region little blue penguins kept in captivity in salmonellosis from introduced birds to were of threatened species on offshore Christchurch (Hunter et al., 2012). native species. islands such as Tiritiri Matangi, Rotoroa, A mature harrier from the Manawatu Great Barrier and Little Barrier. Locally The geographic distribution of avian region presented at Wildbase Hospital administered wildlife sanctuaries such as wildlife cases examined in 2014 with multiple nodular lesions on those at Bushy Park, Mangatautari, Cape is shown in Figure 2. The highest the ventral aspects of both feet. An Kidnappers and Zealandia-Karori also numbers of cases submitted were from incision biopsy showed that the bird contributed a significant number of cases. the Manawatu/Whanganui and Otago had a severe granulomatous dermatitis regions. The Manawatu/Whanganui Wildlife cases of special with subcutaneous cores of caseous cases included those from National interest in 2014 material bordered by heterophils and Wildlife Centre at Mt Bruce/Pukaha epithelioid macrophages (Figure 3, and from Tongariro National Park. Avian tuberculosis in harriers following page). Within the caseous The Otago submissions included those Tuberculosis in wild birds may enter the material were multiple small clusters from the highly endangered population skin or oral cavity following puncture of rod-shaped acid-fast organisms. A of yellow-eyed penguins in coastal wounds that can occur during predation diagnosis of mycobacterial dermatitis or scavenging of was made and the bird was euthanased. infected carcasses Histopathology confirmed the presence and coming in of a mycobacterial infection. In the contact with mid-dermis and extending into deeper sharp objects. In tissues was a large core of eosinophilic New Zealand, and pyknotic debris bordered by a tuberculosis in thick layer of epithelioid macrophages, raptors is less small numbers of multinucleated giant common than it is cells, scattered heterophils and fine in many northern bands of fibrous tissue, as well as small hemisphere perivascular aggregates of lymphocytes countries, and plasma cells. Clusters of acid-fast but because Gram-positive bacilli were scattered mycobacteria throughout peripheral areas of the may survive for necrotic core of these granulomas. There long periods in was no evidence of tuberculous lesions in the environment, the internal organs. infection of birds A second case of avian tuberculosis from contaminated was seen two months later in a harrier waste water, from the Horowhenua region. This bird sewerage and had a history of circling and falling soil should also over, and had a swelling on its left foot. be considered a It was radiographed after admission possibility. Avian to a rehabilitation centre and an old tuberculosis is proximal fracture was seen on the left present in some femur, together with three osteolytic backyard poultry lesions in the mid-diaphyseal area of flocks in NZ and the tibiotarsus. Radiographic lesions has been reported were also noted in the liver and lungs, so previously in the the bird was euthanased. Post-mortem oral cavity of a examination revealed severe soft tissue harrier (Circus swelling of the dorsolateral surface of Figure 2: Number of bird cases recorded in the Huia database for 2014 approximans) the left hock, extending to the first digit, by region associated with Surveillance 42 (3) 2015 23 positive tachyzoites and intact tissue cysts in the lungs and liver, or by PCR analysis of paraffin-embedded formalin-fixed liver and lung tissue, or by both methods. Genotyping of up to seven markers revealed that an atypical Type II isolate of Toxoplasma gondii was present in at least three of the cases (Howe et al., 2014). In the past, the differential diagnosis of toxoplasmosis has been fraught with difficulty as the clinical signs and pathology are non-specific, and differentiation of the organisms from other protozoa such as Plasmodium has relied on subtle differences in the morphology of the intracellular tachyzoites. Improved diagnostic tools such as PCR tests and immunohistochemistry now enable both cystic and individual organisms to be Figure 3: Longitudinal section of the foot of an affected harrier, showing a large subcutaneous granulomatous lesion (G) with a caseous necrotic core