Review of: Acevedo-whitehouse, K. Rocha-Gosselin, A. Gendron, D. (2010) A novel non-invasive tool for disease surveillance of free ranging whales and its relevance to conservation programmes. Animal conservation, 13 (2) 217-225.
Pathogens are present in every ecosystem on the planet and their role in initiating infectious diseases and mass mortalities poses a serious threat to animal conservation. It therefore seems apparent that identifying the causative agents behind this threat to wildlife could enable the production of disease prevention strategies. However as easy as that sounds information on common pathogens in most wildlife species remains scarce. For cetaceans this is the reality of the case, as there are obvious problems retrieving samples from large, migratory, water bound mammals. As a result most information on cetacean parasites, pathogens and disease comes from captive based studies or stranded animals, which cannot be considered representative of the ‘normal’ population.
Reports of infectious diseases and mass mortalities in cetaceans have increased over recent years, with various pathogenic streptococci (some previously undescribed) and other microorganisms being increasingly found in stranded cetaceans. It therefore seems urgent that methods are created to monitor the health of free-ranging cetaceans, while limiting invasiveness so as not to cause stress. This study investigates the presence of potentially pathogenic bacteria in 8 cetaceans species (blue whales, gray whales, fin whales, Bryde’s whales, sperm whales, humpback whales, common dolphins and bottlenose dolphins), by examining exhaled breath condensate (EBC) or blow emitted from the cetaceans. This method is commonly used to diagnose respiratory conditions in humans; however it is the first time it has been used on free-ranging cetaceans.
The authors used two methods to collect EBC from the 8 species of cetaceans in the Gulf of California and in Baja California (Mexico). The first method involved an extendable pole to collect blow from nearby cetaceans, while the second method utilised a radio-controlled helicopter for those which kept a large distance away from the boat. In total 22 duplicate EBC samples were collected and analysed. Out of these samples, 11 consistently showed the presence of one or more of the following microorganisms: unidentified β haemolytic streptococci, Haemophilus species and Staphylococcus aureus. Environmental control samples were also taken, but none of these bacteria were detected in them, indicating their presence in the samples was not as a result of contamination. While the population-level relevance of these bacteria is unknown, and the possibility that they are present in the cetacean’s natural flora has been recognised, evidence has shown these bacterial strains to be pathogenic to these mammals. Staphylococcus aureus has previously been identified as a high-risk pathogen to cetacean health; streptococci have increasingly been associated with cetacean mortality events and although Haemophilus species have not been previously reported in stranded cetaceans this is possibly due to the fact that this species of bacteria is particularly hard to culture.
This study was limited by the restricted use of bacterial primers as a result of what limited knowledge is available on cetacean pathogens, however the authors suggest the construction of a 16S rRNA library of bacteria isolated from EBC and mention the possibility of its future use in evaluating the extent of cetacean exposure to antibiotic-resistant bacteria, as issue gaining relevance due to anthropogenic impacts on the environment. All in all I think the methods proposed by these authors seems practical and ethical, while causing minimal distress and having beneficial results. The authors mention that while writing this article they heard that their method was already being used to monitor resident killer whales elsewhere, indicating that the benefits of these methods have already been recognised by others.
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