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Further research is needed to determine the cause of the avian diphtheria, which has hit yellow-eyed penguin chicks on Otago Peninsula recently.

Date:  16 December 2010

Further research is needed to determine the cause of the avian diphtheria, which has hit yellow-eyed penguin chicks on Otago Peninsula recently.

Five breeding sites have been affected by the outbreak, all at the southern end of the Otago Peninsula.

Wildlife vets from the New Zealand Wildlife Health Centre at Massey University today met Department of Conservation (DOC) staff, local vets, Yellow-eyed Penguin Trust members, and a scientist from Penguin Place to discuss the most recent disease outbreak.

David Agnew, DOC’s Programme Manager Biodiversity Assets for Coastal Otago, said the meeting heard that much information about the disease had been collected by DOC, Massey University, the Trust, and Penguin Place since the first outbreak in 2002, and staff had learned a lot about how to treat the diphtheria.

“We’ve made progress analysing this data but this has illustrated the complex nature of the issue and shown the benefit that more extensive research could bring to solve the mystery about what’s causing the disease,” Mr Agnew said.

A research project was needed to determine the cause of the diphtheria, he said. A FRST (Foundation for Research, Science and Technology) application for a PhD student to study the diphtheria outbreak was submitted in 2009 by Massey University, in conjunction with Otago University with input from DOC and the Trust. The application was unsuccessful but the agencies were investigating applying for funding through other avenues.

Massey vet Kerri Morgan said the wildlife centre was hoping a dedicated PhD student could undertake the study, with adequate funding to support it.

One aim of the study was to look at the wider influence of variables that are not being considered at the moment, such as weather and sea patterns.

The meeting shared information about treating sick chicks, such as supplementary feeding with a special sardine smoothie, correct use of antibiotics and rehydration fluids.

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Background information

Chicks were first noticed with diphtheritic mouth lesions in mid-November, and were also balding, breathing heavily and emaciated. At Boulder Beach over 61% of the chicks showed signs of infection, 33 chicks died and several more were missing, which is a loss of about 36%. Chicks were also affected by the disease at Sandfly Bay. Dead chicks were submitted to the New Zealand Wildlife Health Centre at Massey University for post-mortem. The remainder of the chicks that were treated have survived.

At other sites on the Otago coast the majority of chicks were unaffected by the disease.

Chicks with severe lesions were treated by antibiotics and rehydration fluids and responded well to supplementary feeding when food was offered. Samples of the mouth lesions and swabs for microbiology were sent to Massey University, and viral swabs were taken from the chicks for ESR in Wellington to determine if a viral agent is responsible.

Massey University wildlife pathologist Stuart Hunter said most of the chicks died from secondary starvation as a result of the disease. Others had died from pneumonia after inhaling the friable mouth lesions. Bacterial toxins may have also caused some of the deaths. Microbiologists at Massey University have isolated Corynebacterium amycolatum from the swabs taken, the same bacteria found to affect yellow-eyed penguin chicks in 2002, 2004 and 2006. At this stage, it is still unclear if a viral agent is responsible for the outbreak, but testing of lesion samples and viral swabs will confirm the presence of a virus.

At other sites on Otago Peninsula, there were a few early losses of chicks but most have survived the most critical period. Penguin Place owner Liz McGrouther said that chicks at the northern end of Otago Peninsula are “huge and doing really well”.

In the Catlins, DOC Biodiversity Ranger Cheryl Pullar has inspected penguin chicks at all of the major breeding sites and found no signs of the disease. In North Otago chicks appear to be doing well despite a few early losses. Chicks will begin to fledge from late February to early March, and their parents will then gain weight for their month-long moult ashore.

DOC Biodiversity Ranger Mel Young said the partnership with Massey and the information they have provided has been very helpful to DOC and to other monitoring parties.

Further diagnostic tests on the samples collected are pending and it is hoped that these results will assist with dealing with the disease should future outbreaks occur.

Yellow-eyed Penguin Trust General Manager Sue Murray said the Trust is delighted that chicks on its reserves are relatively unaffected compared to other coastal habitats, suggesting the spread of the disease is localised this year.

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