Novel Helicobacter Genotypes Identified in Pygmy Sperm Whales

Pygmy sperm whales (Kogia breviceps), a species rarely observed in their natural habitat, are primarily studied through individuals that strand, particularly along the southeastern United States coast. Stranding events have frequently revealed stomach ulcers in these whales, often associated with Helicobacter bacteria.

Researchers have now identified three previously unknown genotypes of Helicobacter bacteria within pygmy sperm whales.

Discovery of Novel Bacteria

Researchers from Florida Atlantic University's Harbor Branch Oceanographic Institute, in collaboration with other institutions, made a significant discovery. They identified three previously unknown genotypes of Helicobacter bacteria within pygmy sperm whales. These new genotypes are designated Kogia Helicobacter 1, 2, and 3, and their discovery was published in the Journal of Wildlife Diseases.

Research Findings: A Deeper Look

Stranding Response and Observations

Between 1999 and 2020, FAU Harbor Branch responded to 59 pygmy sperm whale strandings. Post-mortem examinations were conducted on 80% of these cases, providing crucial insights into the health of these elusive animals. Spiral-shaped bacteria were observed in stomach tissues in four instances during these examinations.

Unveiling New Genotypes

Utilizing a combination of histopathology, molecular diagnostics, and DNA sequencing, the research team retrospectively analyzed these tissues. This comprehensive analysis led directly to the identification of the novel Helicobacter genotypes.

• Kogia Helicobacter 1 and 2 exhibit genetic similarities to Helicobacter species previously identified in other cetaceans, such as dolphins and porpoises, and also in humans.
• Kogia Helicobacter 3 represents a more divergent lineage, suggesting a broader diversity of undiscovered bacteria in marine environments.
• Intriguingly, in one whale, both Kogia Helicobacter 1 and 3 were detected in forestomach tissues.

Associated Gastric Pathologies

All four whales that tested positive for Helicobacter presented with significant gastric pathologies. These included gastritis, gastric ulcers, fibrosis, and nematode infestations. Colitis was also observed in one case. While Helicobacter was not determined as the direct cause of death in these whales, its presence is consistently linked to these observed gastrointestinal lesions.

Broader Implications for Marine Mammal Health

Helicobacter species have been identified in multiple cetacean species globally since 2000. These infections are sometimes associated with a range of symptoms, including lethargy, appetite loss, regurgitation, gastric ulcers, and stomach inflammation.

Chronic Helicobacter infections in these animals could have significant implications for individual whale health and for broader populations, particularly for vulnerable species.

This critical research underscores the profound importance of long-term marine mammal stranding response programs. Such initiatives are vital for scientific discovery and for understanding the health challenges facing marine life.