Francisella infections in fish and shellfish

Area of Science:

• Aquatic microbiology
• Fish and shellfish pathology

Background:

• Bacteria in the Francisellaceae family are increasingly identified as causative agents of disease in diverse aquatic animals.
• Previous under-reporting is likely due to specialized culture requirements for these bacteria.

Purpose of the Study:

• To highlight the growing threat of Francisellaceae infections in aquaculture.
• To summarize current knowledge on fish-pathogenic Francisella species, particularly in cod and tilapia.

Main Methods:

• Literature review of recent reports on Francisellaceae infections in aquatic species.
• Analysis of disease characteristics, including host range and pathological effects.

Main Results:

• Francisellaceae cause granulomatous inflammation in Atlantic cod (F. noatunensis) and tilapia (F. noatunensis subsp. orientalis).
• High mortalities are observed, with potential for disease spread through live fish movements.
• Affected species include cod, tilapia, salmon, grunt, cichlids, hybrid striped bass, and giant abalone.

Conclusions:

• Francisellaceae represent a significant and expanding threat to global aquaculture.
• Effective disease management strategies are crucial for cod and tilapia farming.
• The risk to human health from these aquatic Francisella species is considered minimal.