ORIGINAL RESEARCH article
Front. Vet. Sci.
Sec. Zoological Medicine
This article is part of the Research TopicSurveillance and Control of Wildlife Diseases: Integrating Ecology, Pathology, and Public HealthView all 13 articles
'Segregate, Test, Observe and Persevere' (STOP): Strengthening ex situ breeding programmes for biodiversity in zoos amid highly pathogenic avian influenza threats – a case approach
Provisionally accepted
Anne Günther1
Marco Roller2
Lukas Reese2Ulrike Foldenauer3Judith Tyczka4
Anne Pohlmann1
Martin Beer1Dominik Fischer5
Timm Harder1*- 1Friedrich-Loeffler-Institut, Greifswald - Insel Riems, Germany
- 2Zoological Garden Karlsruhe, Karlsruhe, Germany
- 3Public Order Office of the City of Karlsruhe, Karlsruhe, Germany
- 4State Institute for Chemical Analysis and Veterinary Diagnostics Karlsruhe, Karlsruhe, Germany
- 5Der Grune Zoo Wuppertal, Wuppertal, Germany
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Zoos with avian populations are vulnerable to incursions of the high pathogenicity avian influenza (HPAI) H5Nx virus due to the free-range husbandry, bird population density and shared open water areas between zoo birds and wild waterfowl. An outbreak of HPAIV H5N1, genotype 2.3.4.4b EA AB, at the Zoological Garden Karlsruhe, Germany, in 2022, was managed applying legal restriction measures but exceptionally exempting culling orders for RT-qPCR-positive but healthy birds. A critical factor in the zoo's response was the rapid implementation of a segregation concept approved in advance. The entire bird population could be rapidly separated into epidemiological housing units (epUs) cared for by separate staff. A total of 79 birds initially tested RT-qPCR-positive, but only 21 (26.6%) clinically diseased birds had to be euthanized or succumbed. Seroconversion amounted to 94.8% of the remaining 58 birds. Extensive RT-qPCR investigations of 3,634 samples confirmed infections remained confined to three initially infected epUs out of a total of 25. Spread of virus in the infected epUs was limited to three weeks after segregation. In the cohort of infected pelicans, surviving individuals remained seropositive with elevated levels of H5-specific antibody titers for the following two years suggesting ongoing protection. The described science-based control measures based on a legally binding yet interpretive statement regarding the pertinent animal health legislation are exemplary for managing an outbreak of HPAI in zoos. Preventing unnecessary culling in zoos aids in conserving endangered avian species and individual birds in ex-situ conservation programs.
Keywords: wild birds, ex-situ breeding program, Zoological institution, wildlife-zoo interface, disease prevention
Received: 18 Sep 2025; Accepted: 15 Jan 2026.
Copyright: © 2026 Günther, Roller, Reese, Foldenauer, Tyczka, Pohlmann, Beer, Fischer and Harder. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Timm Harder
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