Characteristics and Perspectives of Disease at the Wildlife-Livestock Interface in Oceania

Abstract

Oceania encompasses Australasia, New Zealand, Melanesia, Micronesia, and Polynesia. It spans the eastern and western hemispheres, is composed of more than 25,000 islands, has a land area of approximately 8.6 M square kilometers, and a human population of approximately 40 million. It is the smallest continent on earth, with the largest island on earth, and is surrounded by the Indian, Southern, and Pacific Oceans. Oceania features extensive geological, climatic, and ecosystem diversity that supports a large array of globally unique native species due to its existence as a multitude of islands (thousands) separated by bodies of water for millennia. Over the past 300–400 years, pigs, goats, sheep, and cattle have been deliberately introduced onto Oceania’s island ecosystems as a source of food for humans, initially as an insurance policy for marooned sea travelers. Livestock husbandry from these deliberate introductions has become well established across the continent, which has created an interface between native wildlife, domestic livestock, and feral livestock. These dynamics have led to bidirectional pathogen transmission, primarily through indirect contact via shared resources where pathogen-host-vector compatibility exists. Animal production across Oceania ranges from small subsistence producers throughout many of the smaller islands to vast, extensive enterprises in Australia and New Zealand. Across the range of production systems, biosecurity risks from uncontrolled direct and indirect wildlife-livestock interaction are ever present. On the larger islands where fodder production is established, intensive livestock production systems (dairy, pigs, poultry, aquaculture) are practiced that implement stringent and robust biosecurity measures to prevent disease transmission and production losses. Unsurprisingly, these production systems sometimes result in scenarios that attract wildlife species, thereby increasing the potential risk of pathogen transmission. Oceania’s long geographical separation and physiological differences between native wildlife and introduced domestic livestock has provided natural biosecurity advantages. Resultantly, many endemic (e.g., bovine tuberculosis, bovine brucellosis, rabies, pneumonia) and emerging/re-emerging (e.g., chronic wasting disease [CWD], West Nile virus, variants of highly pathogenic avian influenza) diseases on other continents are absent from the majority of Oceania. Despite these natural advantages to reduced risk of foreign disease incursions, such as foot and mouth disease and African swine fever, the potential for disease transmission events is rapidly increasing commensurate with increasing trade and human movements globally. This chapter details the history and current status of disease prevalence, eradication, and management at the wildlife-livestock interface across Oceania. Emphasis is given regarding how cooperation within and among Australia, New Zealand and island states/territories is leading to improvements in surveillance, efforts to eradicate diseases, and proving freedom from diseases.