This marine bacterium could become a major threat to coastal populations in the future

This marine bacterium could become a major threat to coastal populations in the future

Subject: Environment

Section: Pollution

Source: DTE

Vibrio vulnificus:

• Vibrio vulnificus is a species of Gram-negative, motile, curved rod-shaped (vibrio), pathogenic bacteria of the genus Vibrio.
• Like humans have Escherichia coli in our gut, fish have Vibrios in their gut. But only a few harm them.
• Present in marine environments such as estuaries, brackish ponds, or coastal areas, V. vulnificus is related to V. cholerae, the causative agent of cholera.
• At least one strain of V. vulnificus is bioluminescent.
• These pathogens thrive in the tropics or subtropics, where sea or brackish water temperatures reach 20°C or higher. They also prefer waters with low salinity.
• Increasing seasonal ocean temperatures and low-salt marine environments like estuaries favor a greater concentration of Vibrio within filter-feeding shellfish; V. vulnificus infections in the Eastern United States have increased eightfold from 1988–2018.
• Infection with V. vulnificus leads to rapidly expanding skin infections by entering a wound causing cellulitis or even sepsis.
• V. vulnificus is also a source of foodborne illness. It was first isolated as a source of disease in 1976.
• People can get V vulnificus by eating infected raw shellfish (which results in diarrhoea, vomiting, fever) or by exposing wounds to waters where the bacteria live (which can cause life-threatening flesh-eating disease that kills about 20 per cent of the infected in one or two days).
• High phytoplankton blooms are associated with increased V vulnificus infections and deaths.
• Treatment becomes difficult when the bacteria enter the bloodstream. And when people are already immunocompromised. The risk is even higher among people with comorbidities such as chronic liver disease, cancer, chronic kidney disease and diabetes.

Northward move:

• The species has also been moving northwards at 48 km per year.
• Earlier till the 1980s, the bacteria was rare in the northern region of Europe and USA. Now they have a presence in the Northern part of the USA, Northern Europe, Baltic sea region, South Korea, Taiwan, Japan, and Mexico.
• The first case of pathogenic V vulnificus in marine organisms was documented in Japanese eel in 1975. The pathogen arrived in Spain through imported eels in 1985.
• It produces a toxin that is thought to interfere with the eel’s immune system. It also infects other organisms such as derbio (Trachinotus ovatus), tilapia (Oreochromis sp), trout (Oncorhynchus mykiss) and shrimp (Penaeus vannamei).
• Cases in India:
  • In 2018, India documented an outbreak of V vulnificus in a tilapia farm in Kerala. Originally from Africa and West Asia, tilapia is one of the most traded food fish globally.
• The European Centre for Disease Prevention and Control has developed Vibrio Map Viewer—a tracker for Vibrio species to calculate the infection risk index based on sea surface temperature and sea surface salinity.