Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus

Abstract

Although cholera is considered an old-world disease, it continues to be a serious problem in developing and economically impoverished countries. The infections caused by other vibrios are also increasing worldwide especially in developed countries and are increasingly being recognized as emerging diseases. Vibrio cholerae is known for its epidemic and pandemic outbreaks, especially in countries throughout Asia, Africa, and South and Central America, where the fecal–oral transmission mode spreads the disease, often through the consumption of contaminated drinking water. Upon entry into the intestine, the bacterium produces several adhesion factors including toxin-coregulated pili (TCP), flagella, neuraminidase, and accessory colonization factor (ACF) for colonization. The bacterium produces cholera toxin (CT) and zona occludin toxin (ZOT), which affect the ion transport pumps for Na⁺, Cl⁻, HCO₃ ⁻, and K⁺ and junctional integrity and results in extensive fluid and ion losses. Diarrhea appears within 6 h–5 days and lasts for 2–12 days. Oral vaccination with killed bacteria together with a purified B subunit of cholera toxin is widely used and is recommended by the WHO. Vibrio parahaemolyticus and V. vulnificus infections are associated with seafood harvested from estuarine or freshwaters. They produce several heat-stable (TDH) and heat-labile TDH-related hemolysins (TRH) and phospholipases, which are responsible for membrane pore formation, apoptosis, and fluid loss resulting in diarrhea. Additionally, V. vulnificus causes septicemia and wound infections, which could be fatal. Vibrio vulnificus is the most invasive of all vibrios in immunocompromised high-risk population. In addition to hemolysin, it produces collagenase, metalloprotease, lipase, and phospholipases, which promote rapid tissue destruction resulting in death within 24 h. The mortality rate of septicemic infection is about 50%, and wound infection is 22%.