V. cholerae causes cholera (an acute diarrheal disease), whichmay be rapidly fatal, if not treated immediately.
The incubation period is short and varies from 2 to 3 days after ingestion of the bacteria. The condition shows an abrupt onset of watery diarrhea and vomiting. Profuse watery diarrhea is the most important manifestation of cholera. The volume of diarrheic stool excreted in cholera is much more than that of diarrhea caused by any other infectious pathogen. In a severe condition, patients may excrete as high as 250 mL of stool per kg body weight in a day. The cholera stool:
· is profusely watery that is colorless and odorless, free of pro-teins and speckled with mucous and often is described as rice water stool (in color and consistency, stool resembles water that has been washed off from cooked rice);
· contains few leukocytes, but no erythrocytes because V.cholerae does not stimulate any inflammatory response inthe intestinal mucosa; and
· is a bicarbonate-rich electrolyte fluid, which contains little protein.
Severe abdominal cramp, possibly caused by distension of the small intestine due to excretion of larger volumes of intesti-nal fluid, is also seen in these patients. Vomiting is another important manifestation of cholera and occurs in early stage of the disease. This is caused by decreased gastric and intestinal motility.
Cholera if left untreated can lead to severe loss of fluid and electrolytes due to diarrhea and vomiting. This could lead to isotonic dehydration, metabolic acidosis, hypokalemia, and hypovolemic shock.
Dehydration in cholera characteristically develops very fast, within hours after the onset of symptoms. This rapid develop-ment of dehydration is not seen with diarrheal diseases caused by any other enteropathogen. In patients with severe disease, diarrhea leads to vascular prolapse and shock, and patients may die of cardiac arrhythmia and renal failure. Other compli-cations include electrolyte imbalance and hypoglycemia.
In untreated patients, case fatality rate has been estimated to vary from 25% to 50%. In patients treated well with replace-ment of lost fluid and electrolytes, the case fatality is usually less than 1%.
V. cholerae O139 causes cholera, which can be as severe as thatcaused by V. cholerae O1. V. cholerae O139 may occasionally cause invasive disease producing bacteremia.