Journal Articles

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    Health impacts of poor water quality on an endangered shorebird breeding programme in Aotearoa New Zealand.
    (Taylor and Francis Group, 2024-02-04) Gartrell BD; Hunter S; Collen R; Jolly M; McInnes K; Richardson A; Reed C; Ward R; Pita A
    CASE HISTORY: Two clusters of mortality among endangered tūturuatu/tchūriwat'/shore plover (Thinornis novaeseelandiae) have occurred at captive breeding facilities around New Zealand in recent years. In the first, four chicks died at Pūkaha National Wildlife Centre (Mount Bruce, NZ) in February 2016, and in the second five adult birds at the Cape Sanctuary (Cape Kidnappers, NZ) died in 2022. CLINICAL FINDINGS: In 2016, four chicks were noted to become weak, have increased vocalisations and closed eyes prior to death. The remaining chicks were treated for 5 days with amoxycillin/clavulanate orally twice daily. Water containers and brooders were cleaned and disinfected with chlorhexidine. No further mortality was seen.In the 2022 cluster, three adult breeding birds died acutely and five others showed inappetence, weight loss and diarrhoea approximately 10 days after heavy rains flooded the local river. The five birds were treated with amoxycillin/clavulanate orally twice daily and oral fluids for 5 days. Two birds died and three survived. No breeding occurred in the aviaries in the following season. PATHOLOGICAL FINDINGS: In 2016, the chicks showed pulmonary changes ranging from congestion and oedema to heterophilic inflammation consistent with septicaemia.In 2022, the adult birds showed proliferation of bacteria in the distal small intestine associated with mucosal ulceration and heterophilic infiltration. Acid-fast staining of the caecal contents in one bird showed organisms consistent with Cryptosporidium spp. LABORATORY FINDINGS: Aerobic bacterial cultures of the lung and liver of two affected chicks carried out in 2016 showed heavy growth of Plesiomonas shigelloides. The same organism was cultured from water trays and holding tanks containing water boatmen (Sigara arguta) on which the chicks were fed.In 2022, cultures from the livers of three dead birds each showed a mixed bacterial growth with differing dominant organisms (Aeromonas sobria, Hafnia alvei, Citrobacter freundii and an Enterococcus sp.). PCR and sequencing confirmed Cryptosporidium parvum in the caecum of one bird. Fresh faeces from 24 breeding birds from the captive breeding facilities were negative by PCR for Cryptosporidium spp.The captive breeding facilities obtain water for the aviaries and aquatic invertebrates to feed to the chicks from local freshwater sources. Water quality testing at the Cape Sanctuary revealed concentrations of faecal indicator bacteria in excess of safe drinking water guidelines, with peaks following heavy rainfall. CLINICAL RELEVANCE: Fluctuations in water quality associated with mammalian faecal bacteria can adversely affect bird health and impact on captive rearing of endangered wildlife.
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    A novel gyrovirus is abundant in yellow-eyed penguin (Megadyptes antipodes) chicks with a fatal respiratory disease.
    (2023-02) Wierenga JR; Morgan KJ; Hunter S; Taylor HS; Argilla LS; Webster T; Dubrulle J; Jorge F; Bostina M; Burga L; Holmes EC; McInnes K; Geoghegan JL
    Yellow-eyed penguins (Megadyptes antipodes), or hoiho in te reo Māori, are predicted to become extinct on mainland Aotearoa New Zealand in the next few decades, with infectious disease a significant contributor to their decline. A recent disease phenomenon termed respiratory distress syndrome (RDS) causing lung pathology has been identified in very young chicks. To date, no causative pathogens for RDS have been identified. In 2020 and 2021, the number of chick deaths from suspected RDS increased four- and five-fold, respectively, causing mass mortality with an estimated mortality rate of >90%. We aimed to identify possible pathogens responsible for RDS disease impacting these critically endangered yellow-eyed penguins. Total RNA was extracted from tissue samples collected during post-mortem of 43 dead chicks and subject to metatranscriptomic sequencing and histological examination. From these data we identified a novel and highly abundant gyrovirus (Anelloviridae) in 80% of tissue samples. This virus was most closely related to Gyrovirus 8 discovered in a diseased seabird, while other members of the genus Gyrovirus include Chicken anaemia virus, which causes severe disease in juvenile chickens. No other exogenous viral transcripts were identified in these tissues. Due to the high relative abundance of viral reads and its high prevalence in diseased animals, it is likely that this novel gyrovirus is associated with RDS in yellow-eyed penguin chicks.