Thursday, May 3, 2012

Cirrhosis - Risks of Eating Raw Oysters

There are three things this blogger is obsessed with - bed bugs, parasites and foodborne illness.

Today on the blog we have two resources with information on Vibrio vulnificus, an organism found in raw or poorly cooked seafood- (raw oysters,sushi).

A Warning For People With Liver Cirrhosis

According to data found at Medscape; "Among all foodborne diseases, V vulnificus infection is associated with the highest case fatality rate (39%).

Patients with cirrhosis who consumed raw oysters were 80 times more likely to develop V vulnificus infection and 200 times more likely to die of the infection than those without liver disease who consumed raw oysters"

In the first article from "text book of bacteriology" interesting details on Vibrio vulnificus, V. cholerae and V. parahaemolyticus are discussed.
You might remember the latter in the headlines last year when the FDA announced a recall on oysters affecting 23 states.  The agency issued a warning to consumers not to eat raw oysters harvested from an area of Hood Canal in Washington State following an outbreak of illness caused by Vibrio parahaemolyticus bacteria - scary stuff.

In the second article published @ "ACP," Thomas A. Moore, MD, offers this warning;

"There are many reasons not to eat them. Hepatitis A is one; another is toxoplasmosis. The biggest risk factor for acquiring this parasitic infection is the consumption of raw oysters," Dr. Moore said. "It's like Russian roulette. Eating [raw oysters] is OK now and then, but if you go on a bender, you're gonna get it," he said.      

Read more on toxoplasmosis here.

Risks of Eating Raw Oysters

Certain health conditions put people at high risk for serious illness or death from V. vulnificus infections. These conditions include:

Liver disease (from hepatitis, cirrhosis, alcoholism, or cancer)
Iron overload disease (hemochromatosis)
Cancer (including lymphomas, leukemia, Hodgkin's disease)
Stomach disorders-a high use of antacids
Any illness or medical treatment that weakens the body's immune system, including HIV infection

You can get sick from Vibrio vulnificus in two ways:

Eating raw or undercooked shellfish

You can also get infected by getting seawater on an open wound, cut, sore or puncture. The bacterium can enter through the break in the skin and cause infection. In some people the infection heals by itself, while in others it progresses to severe infection of the skin and underlying tissues.

Vibrio vulnificus 
(This article has 3 chapters)
Kenneth Todar, PhD

Vibrio vulnificus is scarcely recognized by many microbiologists, less so by the public. Yet, in this country, the bacterium causes a disease with over a 50 percent mortality rate, and it causes 95 percent of all seafood-related deaths.

Vibrio vulnificus is a Gram-negative, motile curved bacterium found in marine and estuarine environments. It has been isolated from seawater, sediments, plankton and shellfish (oysters, clams and crabs) located in the Gulf of Mexico, the Atlantic Coast as far north as Cape Cod, and the entire U.S. West Coast. The bacterium thrives in warm seawater and is part of a group of vibrios that are "moderate halophiles", meaning they require salt for growth. Vibrios are frequently isolated from oysters and other shellfish in warm coastal waters during the summer months. This correlates with the peak incidence of disease caused by the bacterium.

Vibrio vulnificus is a Gamma Proteobacterium in the Family Vibrionaceae, with two other human pathogens Vibrio cholerae, the agent of epidemic cholera, and Vibrio parahaemolyticus, which causes acute diarrhea. Vibrios are one of the most common organisms in surface waters of the world. They occur in both marine and freshwater habitats and in associations with aquatic animals. Some species are bioluminescent and live in mutualistic associations with fish and other marine life. Other species are pathogenic for fish, eels, and frogs, as well as other vertebrates and invertebrates.

V. cholerae and V. parahaemolyticus are pathogens of humans. Both produce diarrhea, but in ways that are entirely different. V. parahaemolyticus is an invasive organism affecting primarily the colon; V. cholerae is noninvasive, affecting the small intestine through secretion of an enterotoxin.

Vibrio vulnificus is an emerging pathogen of humans. It causes wound infections, gastroenteritis, or a syndrome known as primary septicemia. It was first recognized as an agent of disease in 1976. The first documented case of disease caused by the bacterium was in 1979.

Figure 1. Vibrio vulnificus is a typical marine vibrio - a slightly curved bacterium, motile by means of a single polar flagellum.


V. vulnificus causes disease in individuals who eat contaminated seafood (usually raw or undercooked oysters) or have an open wound that is exposed to seawater. Among healthy people, ingestion of V. vulnificus can cause vomiting, diarrhea, and abdominal pain. Most V. vulnificus infections are acute and have no long-term consequences.

In immunocompromised persons, particularly those with chronic liver disease, V. vulnificus can invade the bloodstream from either a wound or from the GI tract, causing a severe and life-threatening illness called primary septicemia, characterized by fever, chills, septic shock and death. Blistering skin lesions accompany the disease in about 70% of the cases. V. vulnificus bloodstream infections are fatal about 50% of the time.

Although V. vulnificus is a rare cause of disease, it is likely that it is unrecognized and underreported (one estimate of the total number of cases annually in the U.S. is as high as 45,000). Between 1988 and 1995, CDC received reports of over 300 V. vulnificus infections from the Gulf Coast states, where the majority of cases occur.

Update From Medscape;

United States
Between 1998 and 2010, the incidence of Vibrio infections increased by more than 115%. The CDC estimates that 80,000 Vibrio infections (200 V vulnificus, 45,000 V parahaemolyticus, and 35,000 Vibrio species.) and approximately 100 deaths related to Vibrio infections may occur annually in the United States.[2] Vibrio infections are acquired through consumption of contaminated raw or undercooked shellfish such as oysters, clams, mussels, or crabs. Exposure of wounds to contaminated seawater, injury caused by contaminated seashells, and shark and alligator bites are potential alternative sources of infection.

V parahaemolyticus is the leading cause of seafood-associated gastroenteritis in the United States. During a large outbreak of gastroenteritis in July 2004 in the Gulf of Alaska, V parahaemolyticus caused illness in almost one third of cruise ship passengers who consumed Vibrio -contaminated oysters. From May to July 2006, health departments of New York City, New York state, Oregon, and Washington state reported a total of 177 cases of V parahaemolyticus gastroenteritis. Of these reported cases, 113 (64%) involved residents of Washington state

Also see;
Visual Analytics of Surveillance Data on Foodborne Vibriosis, United States, 1973–2010
CDC - Annual Summaries of Vibrio Illnesses

We continue with the article from "text book of bacteriology"
Persons who are immunocompromised, especially those with chronic liver disease, are at risk for V. vulnificus when they eat raw seafood, particularly oysters. These individuals are 80-200 times more likely to develop V. vulnificus primary septicemia than are healthy people. For this particular risk group, the infection carries one of the highest mortality rates of all bacterial infections.

Health conditions that place a person at risk for serious illness or death from V. vulnificus infection include liver disease, hemochromatosis, diabetes, stomach problems, kidney disease, cancer, immune disorders (including HIV) and long-term steroid use. In these individuals, the bacterium enters the blood stream, resulting in septic shock, rapidly followed by death in many cases. Such individuals are strongly advised not to consume raw or inadequately cooked seafood.

 next chapter...........

Additonal information; Full Text

There is substantial evidence that Vibrio-associated diseases are increasing worldwide with climate warming

Long-term effects of ocean warming on the prokaryotic community: evidence from the vibrios
The long-term effects of ocean warming on prokaryotic communities are unknown because of lack of historical data. We overcame this gap by applying a retrospective molecular analysis to the bacterial community on formalin-fixed samples from the historical Continuous Plankton Recorder archive, which is one of the longest and most geographically extensive collections of marine biological samples in the world. We showed that during the last half century, ubiquitous marine bacteria of the Vibrio genus, including Vibrio cholerae, increased in dominance within the plankton-associated bacterial community of the North Sea, where an unprecedented increase in bathing infections related to these bacteria was recently reported. Among environmental variables, increased sea surface temperature explained 45% of the variance in Vibrio data, supporting the view that ocean warming is favouring the spread of vibrios and may be the cause of the globally increasing trend in their associated diseases.
Continue Reading...

Scientific Meeting News for April 19, 2012

Like gambling? Eat raw oysters

If you're considering sampling local seafood while in town, you might want to steer clear of raw oysters, said Thomas A. Moore, MD, FACP, chair of infectious diseases at Oschner Medical Center in New Orleans, at a talk during Wednesday's Hospital Medicine precourse.
"There are many reasons not to eat them. Hepatitis A is one; another is toxoplasmosis. The biggest risk factor for acquiring this parasitic infection is the consumption of raw oysters," Dr. Moore said. "It's like Russian roulette. Eating [raw oysters] is OK now and then, but if you go on a bender, you're gonna get it," he said.

Another risk—and the subject of a portion of his talk—is Vibrio vulnificus. The organism is part of the normal marine flora, especially oysters, and tends to cause disease in warmer months. With a mortality rate of 50%, it accounts for 90% of all seafood-related U.S. deaths. A few years ago, The Sunday Times (of London) food critic Michael Winner nearly lost his leg from contracting the illness after eating a bad oyster, Dr. Moore noted.

Cases related to V. vulnificus have been increasing along the Gulf Coast, "perhaps due to global warming," Dr. Moore said.

Refraining from eating the raw mollusks won't entirely protect you from the skin and soft tissue infection caused by the organism, though, as it can be contracted from nonfoodborne exposure too, he said. Still, 90% of patients who get ill from V. vulnificus report having eaten oysters within the previous seven days, he noted.

Typically, the illness starts with abrupt onset of rigors, then fever and prostration. This is followed by hypotension in a third of cases. In 75% of cases, metastatic skin lesions develop with 36 hours of initial symptom onset, usually on the extremities, with the legs being more common than the arms. Leukopenia and thrombocytopenia are also common, but not universal, he said.
"Vibrio vulnificus is primarily associated with severe, distinctive soft tissue infection and/or septicemia," Dr. Moore said. "What you usually don't see is diarrhea; it invades the bloodstream without causing [gastrointestinal] symptoms."

Patients typically develop sepsis within 16 hours of symptoms and cellulitis somewhere between four hours and four days (the mean time is 12 hours), he said.

Physicians should consider V. vulnificus when a patient has septicemia associated with necrotizing skin lesions; is immunocompromised, as with liver disease; and has ingested or was exposed to oysters and/or salt water in the past one to three days.

If you do suspect V. vulnificus, be sure to alert the lab that is performing tests, as it may otherwise be missed. Only 25% of labs in Gulf Coast states routinely culture for the bacteria, he said.
In treating complicated skin and soft tissue infection due to V. vulnificus, the best option is tetracycline. Other good options include ceftriaxone and ciprofloxacin.

Patients with cellulitis from V. vulnificus respond well to antibiotics, but early diagnosis is critical as the condition progresses rapidly, Dr. Moore added. Early surgical consultation is also advised. "These patients often need early and aggressive debridement," he said.

Patients who have developed bacteremia don't respond as well to treatment, though starting antibiotics within 24 hours of the onset of symptoms does help lower mortality for these folks, he said.
Those who still want to ingest raw oysters after learning the potential consequences can lower their chances of getting sick by using tabasco, noted Dr. Moore. Research suggests the vinegar in the condiment inhibits the growth of V. vulnificus, so the higher the vinegar content of your chosen brand, the better, he said.
Oh, and cooked oysters? Totally safe, he said.

In Case You Missed It

In the news a few months ago...

Deadly Bacteria Found In Gulf Coast Tar Balls
Farron Cousins
Since the very first tar balls began rolling onshore along the Gulf of Mexico following 2010’s Deepwater Horizon oilrig explosion and subsequent underwater oil geyser, the oil industry told us to relax because those tar balls were completely harmless. But as we approach the two year anniversary of the disaster, new studies have confirmed that the tar balls we’re seeing along our beaches contain bacteria that are capable of killing human beings.

The new study, conducted by scientists at Auburn University, confirmed the presence of a bacteria called Vibrio vulnificus. According to researchers, this is the same bacteria that is responsible for causing illness and death from eating bad oysters. The tar balls contained concentrations of this bacteria more than 100 times greater than the surrounding water. The Centers for Disease Control says the following regarding Vibrio vulnificus:
Wound infections may start as redness and swelling at the site of the wound that then can progress to affect the whole body. V. vulnificus typically causes a severe and life-threatening illness characterized by fever and chills, decreased blood pressure (septic shock), and blood-tinged blistering skin lesions (hemorrhagic bullae). Overall, V. vulnificus infections are fatal about 40% of the time. Wound infections with V. vulnificus are fatal about 20% of the time, and aggressive surgical treatment can prevent death.

Persons who have immunocompromising conditions and especially persons with chronic liver disease are particularly at risk for V. vulnificus infection when they eat raw or undercooked seafood, particularly shellfish harvested from the Gulf of Mexico, or if they bathe a cut or scrape in marine waters. About three-quarters of patients with V. vulnificus infections have known underlying hepatic disease or other immunocompromising illness. Otherwise healthy persons are at much lower risk of V. vulnificus infection.
It is important to remember that this isn’t a fleeting threat to those of us who live, work, and play along the Gulf Coast. National Geographic recently pointed out that tarballs are continuously washing up along the coasts of the Gulf of Mexico, meaning that the threat of bacterial infection is not only real, but it is persistent. And with Spring Break season in high gear, beaches along the Gulf Coast are currently inundated with out of state families playing and relaxing on top of these toxic bacteria balls.
Source: Desmogblog (

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