Another thing to worry about oysters – Vibrio parahaemolyticus

What is Vibrio parahaemolyticus?

Vibrio parahaemolyticus is a Gram-negative, curved-rod-shaped mobile bacterium that inhabits marine and estuarine environments throughout the world. It is a major foodborne pathogen that causes life threatening diseases in humans after the consumption of raw or undercooked seafood.^[1]

Vibrio genus was first described by an Italian physician, Filippo Pacini in 1854.^[2] He discovered the first Vibriospecies, Vibrio cholera, the causative agent of cholera while studying outbreaks of cholera disease in Italy. Although Dr. Pacini pointed out that cholerae was contagious, his discovery was largely ignored by the world’s scientific community for the next 30 years. During an active Vibrio outbreak, in Calcutta, India, another scientist, Robert Koch, successfully isolated Vibrio from pure culture and was finally recognized as an important public health discovery.

Vibrio genus consist of 142 species that are marine originated, and new species continue to be identified. Vibrio sp. infects any living being including animals and humans. Recently, the worldwide ocean warming and climate changes have enabled the emergence of foodborne pathogenic strains with several virulence factors in marine environments. The geographic areas where V. parahaemolyticus infections were originally reported were related to areas with high seafood consumption, particularly in Asia, but are expanding worldwide.^[3]

As a member of the Vibrionaceace family and Vibrio genus, Vibrio parahaemolyticus has been in limelight for the rising vibriosis and foodborne cases worldwide. It was first identified in 1951 by Tsunesaburi Fujino from Research Institute of Microbial Diseases (RIMD), Osaka University from an acute gastroenteritis outbreak. The outbreak occurred in a southern suburb of Osaka, Japan due to consumption of “shirasu,” a type of dried sardine which resulted in 20 deaths and 272 infected patients at that time.

Where Does Vibrio parahaemolyticus Come From?

Vibrio parahaemolyticus is a human pathogen that is widely distributed in the marine environments. This organism is frequently isolated from a variety of raw seafoods, particularly shellfish. ^[4] Consumption of raw or undercooked seafood contaminated with V. parahaemolyticus may lead to development of acute gastroenteritis characterized by diarrhea, headache, vomiting, nausea, and abdominal cramps. This pathogen is a common cause of foodborne illnesses in many Asian countries, including China, Japan and Taiwan, and is recognized as the leading cause of human gastroenteritis associated with seafood consumption in the United States. 

Although the gastroenteritis caused by V. parahaemolyticus infection is often self-limited, the infection may cause septicemia that is life-threatening to people having underlying medical conditions such as liver disease or immune disorders. Two deaths were reported among three cases of wound infections caused by V. parahaemolyticus in Louisiana and Mississippi after Hurricane Katrina in 2005.

The degree of V. parahaemolyticus contamination in raw shellfish is also known to relate to the water temperatures. Therefore, it is more likely to detect V. parahaemolyticus in oysters harvested in the spring and the summer than in the winter.^[5]

What are the Symptoms of Vibriosis?

The food poisoning caused by V. parahaemolyticus (“vibriosis”) usually occurs in summer (from June to October), and is predominantly associated with different kinds of seafood, including crab, shrimp, shellfish, lobster, fish, and oysters.^[6] Once consumers eat undercooked, contaminated seafood, illness is inevitable. The typical clinical symptoms of V. parahaemolyticus poisoning are acute dysentery and abdominal pain, accompanied by nausea, vomiting, fever, chills, and watery diarrhea that may contain blood and/or mucous. Severely low blood pressure (hypotension) often develops progressively and can lead to shock. Some severely affected patients become unconscious, develop convulsions, become pale or cyanotic, and if untreated can die. The distinct pathologic changes that occur within the body include erosive gastritis and internal organ damage (liver, spleen lungs).

What is the Treatment of Vibriosis?

Early treatment of Vibrio parahaemolyticus poisoning (“vibriosis”) is vital and commonly includes antibiotics and oral rehydration.^[7] Volume repletion is the most important element of therapy in patients with Vibrio gastroenteritis. The gastroenteritis caused by V. parahaemolyticus tends to be mild and self-limited. Antimicrobial therapy is reasonable in more severe cases, since among patients with cholera, antibiotic therapy is known to decrease the duration of diarrhea and the excretion of infectious organisms.

Because of the potential severity of illness, it is recommended that some subpopulations, including patients suffering severe physical or immunodeficiency diseases should avoid eating seafood during high risk seasons.

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^[1]           Wang, R., Zhong, Y., Gu, X., Yuan, J., Saeed, A. F., & Wang, S. (2015). The pathogenesis, detection, and prevention of Vibrio parahaemolyticus. Frontiers in microbiology, 6, 144. https://www.frontiersin.org/articles/10.3389/fmicb.2015.00144/full

^[2]           Letchumanan, V., Loo, K. Y., Law, J. W. F., Wong, S. H., Goh, B. H., Ab Mutalib, N. S., & Lee, L. H. (2019). Vibrio parahaemolyticus: The protagonist of foodborne diseases. Progress In Microbes & Molecular Biology, 2(1). https://journals.hh-publisher.com/index.php/pmmb/article/view/59

^[3]           Matsuda, S., Hiyoshi, H., Tandhavanant, S., & Kodama, T. (2020). Advances on Vibrio parahaemolyticus research in the postgenomic era. Microbiology and Immunology, 64(3), 167-181.

^[4]           Su, Y. C., & Liu, C. (2007). Vibrio parahaemolyticus: a concern of seafood safety. Food microbiology, 24(6), 549-558.

^[5]           Id.

^[6]           Wang, R., Zhong, Y., Gu, X., Yuan, J., Saeed, A. F., & Wang, S. (2015). The pathogenesis, detection, and prevention of Vibrio parahaemolyticus. Frontiers in microbiology, 6, 144. https://www.frontiersin.org/articles/10.3389/fmicb.2015.00144/full

^[7]           Wang, R., Zhong, Y., Gu, X., Yuan, J., Saeed, A. F., & Wang, S. (2015). The pathogenesis, detection, and prevention of Vibrio parahaemolyticus. Frontiers in microbiology, 6, 144. https://www.frontiersin.org/articles/10.3389/fmicb.2015.00144/full

Republished with permission from Bill Marler and Marler Clark. Copyright (c) Marler Clark LLP, PS. All rights reserved.

Source: https://www.marlerblog.com/case-news/another-thing-to-worry-about-oysters-vibrio-parahaemolyticus/