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, 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, 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), 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 (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 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 . 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 (Strigops or individuals working outside of MPI researchers. Figure 1 shows avian habroptilus), black , hihi/ 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 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 (N) on the plantar aspect of the rear digit. Scale identified in a variety of body tissues. graduations = 1mm. Photo by Stuart Hunter Given the large numbers of feral and domestic cats (Felis catus, the definitive and moderate soft tissue swelling over two kaka (Nestor meridionalis), two host of T. gondii) in New Zealand, it the second digit. The liver margins were kereru or wood pigeon (Hemiphaga would not be surprising to find that rounded and there were half a dozen novaeseelandiae novaeseelandiae), wild birds are important reservoirs for firm white foci 1–2 mm in diameter two brown kiwi (Apterynx mantelli), a the disease. The important role of cats on the surface of the liver. The lungs (Tadorna variegata), in infecting wildlife is supported by the were congested and contained multiple and a red-crowned parakeet or kakariki recent finding of a high prevalence of 1–3-mm firm dark green nodules. (Cyanoramphus novaezelandiae toxoplasmosis in Hector’s dolphins (Roe Similar nodules were attached to the novaezelandiae). The clinical signs have et al., 2013), which is assumed to be due serosa and mesentery of the intestines. ranged from depression, anorexia and to the contamination of freshwater runoff Histologically, this case showed multiple lethargy with separation from the flock, by cat faeces. early mycobacterial granulomas in to sudden death. Gross lesions seen Penguin mortalities in coastal numerous visceral organs, all of which were also non-specific and consisted contained large numbers of acid-fast of hepatosplenomegaly (which was Otago bacilli. However, the severe skin lesions marked in the kiwi but less severe in the During the 2014 yellow-eyed penguin and associated osteomyelitis were parakeet), while the kaka and kereru breeding season there was only one advanced and suggested that the foot was had swollen slightly firm deep-red lungs. reported death from diphtheritic the most likely route of Microscopically, there was extensive stomatitis, a disease that has previously mycobacterial infection. hepatocellular necrosis in the liver of the been a major cause of chick mortality in Otago. This was likely due to a DOC Toxoplasmosis in endemic birds kiwi while the kaka and kereru showed severe fibrinous bronchointerstitial field project involving extensive nest and dolphins pneumonia in which Toxoplasma tissue monitoring and treatment of chicks. Although avian toxoplasmosis has been cysts were visible in a direct-impression However, adult mortality increased recognised as a cause of death and smear of the cut surface. In the kiwi, earlier owing to a number of bacterial, blindness in caged birds, particularly protozoan organisms were present in fungal and protozoan infections. Many budgerigars and canaries (Vickers et al., both hepatocytes and Kupffer cells of of these cases were seen in birds that 1994; Alley, unpublished data), it has the liver, and in the epithelial cells and were in poor or emaciated condition. not been diagnosed in wild NZ birds macrophages of the interstitium of the Salmonella Saintpaul was isolated until recently. Over the last five years lungs in the kaka, kakariki and kereru. from the faeces of one bird and the disease has now been diagnosed The diagnosis in four of these cases was S. Typhimurium DT 135 was isolated in eight individual wild birds of a confirmed by immunohistochemistry, from another. In addition, at least 10 variety of endemic species. These were which identified both the toxoplasma- adult birds were found suffering from

24 Surveillance 42 (3) 2015 infected, sharp-edged wounds to the usually grasps the chick across its thorax, coli bacterial overgrowth. There was skin and subcutaneous tissues of the causing a quick death from asphyxiation a concurrent suppurative mesenteric flippers or feet. Although some of or pneumothorax. A hungry cat may lymphadenitis, from which E. coli was these wounds responded to treatment, then eat most of the carcase, leaving only cultured. It is hypothesised that intestinal others progressed to a septic arthritis or the feathers, the distal portions of the coccidiosis and possibly other unknown osteomyelitis requiring hospitalisation or legs, the feet, bill and skull available for factors predisposed this hare and possibly euthanasia. post-mortem examination. others of a similar age to colibacillosis. Exotic diseases were ruled out. In November, 29 adult little blue Wildlife cases notified via the MPI penguins were found dead at Doctor’s exotic pest and disease hotline References Point, north of Dunedin. All were in Exotic causes of disease were ruled out in Alley MR, Coomer AR, Gartrell BD (2004). good body condition with moderate all wildlife investigations conducted by Mycobacterial stomatitis and associated fat reserves, and many had recently- MPI in the past year. Avian investigations capillariasis in an Australasian harrier, Circus ingested fish in the proventriculus. All included but were not limited to tests approximans. Kokako 11(1) 3–5. showed evidence of recent trauma to for avian influenza, West Nile virus and Davis GB, Watson PR, Billing BE (1984). the head and neck, often consisting of Newcastle disease. Tuberculosis in a kiwi (Apteryx mantelli). New full-thickness skin puncture wounds Zealand Veterinary Journal 32(3), 30 Multiple outbreaks of mass mortality in on the ventrolateral neck, sometimes Howe L, Hunter, SA, Burrows E, Roe WD (2014). wild ducks were investigated, centred on paired and around 20 mm apart. Beneath Four cases of fatal toxoplasmosis in three species these wounds were variable areas of the Kapiti Coast and Auckland. These of endemic New Zealand birds. Avian Diseases haemorrhage and haematoma in the occurred during the summer months, 58(1), 171–175 which were unusually warm and dry. vertebral musculature and subcutaneous Hunter SA, Howard PA, Alley MR (2012). An tissues, consistent with (Mustela Outbreaks centred around stagnant outbreak of avian tuberculosis in captive blue putorius furo) attack. The fact that ponds. Potential causes including penguins, Eudyptula minor. Kokako 19(2), none of the carcases showed evidence highly pathogenic avian influenza and 30–31. of having been eaten supports this Newcastle disease (caused by avian McLennan JA, Potter MA, Robertson HA, Wake diagnosis, as are known to kill paramyxovirus-1) were ruled out. Given GC, Colbourne R, Dew L, Joyce L, McCann many prey without eating them. the environmental factors, avian botulism AJ, Miles J, Miller PJ, Reid J (1996). Role of was thought to be the most likely cause predation in the decline of kiwi, Apteryx spp. in Predation of kiwi chicks by cats of death. In a separate case reported from New Zealand. New Zealand Journal of Ecology Although (Mustela ermine) are a zoo, avian influenza was ruled out in 20(1), 27–35. widely recognised as the main predator an emu with bloody discharge from the Roe WD, Howe LJ, Hunter SA (2013). of brown kiwi chicks and older juveniles mouth, and the bird tested positive for Toxoplasmosis in Hector’s Dolphins, throughout New Zealand (McLennan et infectious laryngotracheitis virus. In Cephalorhynchus hectori. Kokako 20(2), 33. al., 1996), the notion that cats commonly another case, a viral cause was suspected Vickers MC, Hartley WJ, Mason RW, Dubery kill wild birds has recently received in cases of encephalitis in kaki/black stilt JP, Schollum L (1992). Blindness associated much media attention. Birds killed by chicks because previous bacterial and with toxoplasmosis in canaries. Journal of both urban and rural cats are mainly histological testing by Massey Wildbase the American Veterinary Medical Association, 200(11), 1723–1725. passerines (van Heezik et al., 2010) but indicated the cause was likely to be viral. a study of fledgling North Island brown West Nile Virus was ruled out by PCR of van Heezik Y, Smyth A, Adams A, Gordon kiwi in 1995 (McLennan et al., 1996) brain from three affected chicks. A novel J (2010). Do domestic cats impose an unsustainable harvest on urban bird populations? showed that feral cats killed just two of flavivirus, considered to be endemic, was Biological Conservation 143(1), 121–130. 49 kiwi chicks found dead. There have isolated by viral culture from one brain been few other reports of cats preying sample. Further testing is planned to Maurice Alley on kiwi since then, although Massey better characterise this virus. Wildbase Pathology University records note at least 15 cases Institute of Veterinary, Animal and over the past 10 years. A mortality event in feral hares (Lepus Biomedical Sciences europaeus) was investigated to rule out Massey University, Palmerston North The use of infra-red cameras (I.C. Castro, exotic diseases including tularemia, [email protected] pers. comm., 2015) has recently provided myxomatosis, and European brown Kelly Buckle good evidence of how vulnerable kiwi hare syndrome. A farmer called the Incursion Investigator chicks are to cat attacks. The affected MPI exotic pest and disease hotline to Surveillance and Incursion Investigation chicks show little or no awareness of report finding four dead juvenile hares (Animals and Marine) approaching cats, and make no attempt over a six-day period. Post-mortem Investigation and Diagnostic Centres and Response Directorate to escape or resist. Video records and examination of one hare revealed chronic Ministry for Primary Industries post-mortem evidence show that the cat parasitic enteritis and Escherichia [email protected]

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