Hosts, Parasites, and Pathogens: An Investigation into the Nuanced Relationship of Brucellosis and Respiratory Metazoan Parasitism in Small Cetaceans off the California Coast
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| Title: | Hosts, Parasites, and Pathogens: An Investigation into the Nuanced Relationship of Brucellosis and Respiratory Metazoan Parasitism in Small Cetaceans off the California Coast |
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| Authors: | Shields, Morgan M. |
| Advisors: | Pesapane, Risa |
| Summary: | Brucellosis, a zoonotic disease caused by Brucella spp., affects a wide range of mammals, including cetaceans, where it can cause severe conditions such as meningoencephalitis, reproductive failure, chronic osteoarthritis, and pneumonia; negatively impacting vulnerable cetacean populations. Curiously, previous studies have shown that respiratory metazoan parasites common in cetaceans, such as those from the Pseudaliidae family, can harbor marine mammal-specific Brucella species. Although Brucella, predominately Brucella ceti in cetaceans, is known to cause disease in marine mammals, the interaction between Brucella and respiratory metazoan parasites, as well as the possibility of those parasites to act as vectors remains poorly understood. In this study, The Ohio State University College of Veterinary Medicine collaborated with The Marine Mammal Center (TMMC) to analyze data of 127 stranded small cetaceans off the California coast (2017-2023) to explore the prevalence of Brucella in respiratory metazoan parasites from this population, as well as to analyze for any associations between Brucella-positive parasites, clinical brucellosis, and respiratory metazoan parasitism in the affected cetaceans. Demographics, pathological reports, serological, microbiological, and molecular test results for Brucella were analyzed from TMMC records. In cases with parasitism, parasites were collected, identified, pooled, and analyzed for Brucella spp. DNA via real-time PCR and Sanger sequencing. The study reports the novel detection of marine mammal Brucella within three different species of respiratory parasites collected from 5 different cetaceans with one case confirmed B. ceti via sequencing. The pooled prevalence of marine mammal Brucella within all parasites was 0.1825%. No significant associations were found between Brucella-positive parasites and host demographics, parasite characteristics, and clinical or “suspect” brucellosis in the hosts. Similarly, no significant associations between respiratory metazoan parasitism and clinical or "suspect" brucellosis were found in the hosts, although there were positive associations with other pathologies indicating a multitude of concurrent disease states. These results confirmed the presence of Brucella within respiratory metazoan parasites in small cetaceans off the coast of California. However, the potential for them to act as vectors of brucellosis in cetaceans is unlikely based on this study. Instead, Brucella infection and parasitism may co-occur in similar tissues within immune-compromised hosts, intensifying disease severity and leading to the consumption of Brucella bacteria by proximal parasites. While no definitive conclusions can be drawn, the presence of Brucella in respiratory parasites and the impact of disease on cetacean health underscores the need for further research into the complex interactions between host, parasite, and pathogen in this system, particularly concerning the public health risks of zoonotic diseases like brucellosis. In conclusion, it is hoped that this thesis serves as a foundation for future investigations into the impacts of cetacean brucellosis and parasitism, particularly in light of the challenges posed by climate change, on vulnerable cetacean populations in order to protect their health, our health, and the health of our environment. |
| URL: | http://rave.ohiolink.edu/etdc/view?acc_num=osu1744022884061066 |
| Database: | OpenDissertations |
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