The non-cholera vibrios do not cause cholera and include V. parahaemolyticus, Non-O1 V. cholerae, V. vulnificus, V. alginolyticus etc.

Mode of transmission of non-cholera vibrios:

The mode of transmission of non-cholera vibrios is usually by ingestion of seawater of ingestion of undercooked shellfish infested with non-cholera vibrios, because non-cholera vibrios can reach high concentrations in the tissues of shellfish.

Symptoms of non-cholera vibrios infection:

There are two major types of syndromes gastrointestinal illness and soft tissue infections. Very rarely V. vulnificus can lead to sepsis in immune compromised individuals.

• V. parahaemolyticus:

Commonly present in sea water. They can grow at salt concentration of 8-10% also. Eating raw or undercooked seafood is the major cause of infection. In the last twenty years (since 1990s) the incidence of infection and gastrointestinal illness as a result is increasing in many countries. Previously it was seen mostly in Japan.

In most countries infection of V. parahaemolyticus causes one of the two major symptoms, watery diarrhea (common type, with abdominal cramps, nausea, and vomiting and fever and chills in one fourth of such patients) and less common type, dysentery with severe abdominal cramps, nausea, vomiting and blood/mucous in stool.

Incubation period of V. parahaemolyticus infection is 4 hours to 4 days.

Treatment of V. parahaemolyticus infection:

All infections are self limiting and require neither hospitalization nor any antibiotics for treatment. Symptomatic treatment with fluid replacement for dehydration is generally sufficient. Death due to V. parahaemolyticus infection is extremely rare. If there is underlying serious disease (such as diabetes, liver disease, immunosuppression etc.) there may be some complications.

• Non-O1 V. cholerae:

They cause food borne outbreaks of gastroenteritis and sometimes sporadic cases of otitis media and wound infection. They are also present in marine environment like other non cholera vibrios. Mode of transmission is consumption of raw or undercooked oysters. Travel to some countries carries risk of infection.

Incubation period is generally less than 2 days and the symptoms last for 2-7 days. Symptoms include diarrhea (stool may be copious and watery, bloody or mucoid), dehydration, and sometimes abdominal cramps, nausea, vomiting, and fever. Frequent exposure to sea water can result in extra-intestinal infection such as otitis media.

Treatment of Non-O1 V. cholerae infection:

Dehydration should be treated with fluid replacement. The role of antibiotics is not clear. Extra-intestinal infection needs treatment with suitable antibiotics (most respond to tetracycline, ciprofloxacin, or third-generation cephalosporins).

• V. vulnificus:

This is the commonest cause of severe vibrio infections in the United States. They need saline environment for growth and seen in coastal areas during summer.

Symptoms:

Patients with underlying disease (such as liver disease hemochromatosis, hematopoietic disorders, chronic renal insufficiency, using immunosuppressive medications, alcohol abuse etc.) develop primary sepsis and without underlying disease generally develop wound infection. Patients with iron overload (hemochromatosis) develop more virulent disease.

Wound infection and other cutaneous manifestations develop in most patients and generally involve extremities (lower extremities more commonly than upper extremities). The common sequence is usually erythematous patches appear first which is followed by ecchymoses, vesicles, and bullae. Later on necrosis and sloughing occur.

Incubation period of V. vulnificus infection is 4 hours to 4 days with a mean of 12 hours. Infection most commonly occurs if fresh (or old) wound comes in contact with sea water.

Treatment of V. vulnificus infection:

Mortality rate is as high as 50%. Prompt treatment is vital for successful treatment. Treatment include empirical antibiotic administration (tetracycline, fluoroquinolones, and third-generation cephalosporins are usually effective), debridement of necrosed tissue in an aggressive way, and general supportive care.

• V. alginolyticus:

This can infect eye, ear and wound sometimes. V. alginolyticus is the most salt tolerant among all vibrios and can grow if salt concentration is more than 10%.

Most commonly people get infected in beaches.

Treatment:

This is less serious than other non cholera vibrios infection. Generally treatment with tetracycline and drainage of infected wound is curative.