Cases of mortality in little penguins (Eudyptula minor) in New Zealand associated with avian malaria

Abstract

CASE HISTORY

A little penguin (Eudyptula minor) of wild origin, in captivity at Wellington Zoo, became inappetent and lethargic in March 2013. Despite supportive care in the zoo’s wildlife hospital, the bird died within 24 hours.

CLINICAL FINDINGS

Weight loss, dehydration, pale mucous membranes, weakness, increased respiratory effort and biliverdinuria were apparent on physical examination. Microscopic evaluation of blood smears revealed intra-erythrocytic stages of Plasmodium spp. and a regenerative reticulocytosis in the absence of anaemia.

PATHOLOGICAL FINDINGS

Post-mortem findings included reduced body condition, dehydration, pulmonary congestion and oedema, hepatomegaly, splenomegaly, hydropericardium and subcutaneous oedema. Histopathological findings included protozoal organisms in sections of lung, liver and spleen. A marked, diffuse, sub-acute interstitial histiocytic pneumonia was present. Accumulation of haemosiderin was noted in the Kupffer cells of the liver and in histiocytic-type cells in the spleen.

MOLECULAR TESTING

DNA was extracted from frozen portions of the liver. Nested PCR results and DNA sequencing confirmed infection of the deceased little penguin with Plasmodium (Huffia) elongatum lineage GRW06.

DIAGNOSIS

Avian malaria due to Plasmodium (Huffia) elongatum GRW06

RETROSPECTIVE INVESTIGATION

A retrospective analysis of 294 little penguin cases in the Massey University post-mortem database revealed three other potential avian malaria cases. Analysis of archived tissues using a nested PCR for Plasmodium spp. followed by DNA sequencing revealed that a little penguin which died at Auckland Zoo was infected with P. elongatum GRW06 and two wild little penguins found dead on New Zealand beaches were infected with P. relictum SGS1 and Plasmodium. sp. lineage LINN1. Therefore, the overall frequency of deaths in little penguins associated with avian malaria was 4/295 (1.36%).

CLINICAL RELEVANCE

Our results suggest that avian malaria is associated with sporadic mortality in New Zealand’s little penguins both in the wild and in captivity, but there is no evidence of mass mortality events due to Plasmodium spp. infection.

KEY WORDS:

• Avian malaria
• little penguin
• New Zealand
• Plasmodium spp
• LINN1
• GRW06
• SGS1
• zoo

Acknowledgements

Clinical records of the captive little penguins with avian malaria were kindly made available by Wellington Zoo and Auckland Zoo. The authors would also like to acknowledge all the contributing Massey University wildlife pathologists, especially Dr. Maurice Alley, for their expertise in undertaking post-mortems and submissions to the post-mortem database used in this study. The authors would also like to thank Elizabeth Burrows for technical assistance with Plasmodium spp. PCR assays.

Notes

*Non-peer-reviewed

Additional information

Funding

This work was supported by the Pacivicvet Avian Health Research Fund of the Institute of Veterinary, Animal and Biomedical Sciences (IVABS); Wildbase, IVABS, Massey University, and Wellington Zoo.