Cholera is an acute and potentially severe gastrointestinal disease (stomach and intestines) caused by the bacteria Vibrio cholerae. This agent has been investigated in the past as a biological weapon. Cholera does not spread easily from human to human, so it appears that major drinking water supplies would have to be profusely contaminated for this agent to be effective as a biological weapon.
Cholera normally can infect water or food that becomes contaminated by human bowel waste. The organism can survive for up to 24 hours in sewage and as long as 6 weeks in certain types of relatively impure water containing organic matter. It can withstand freezing for 3-4 days, but it is killed readily by dry heat, steam, boiling, short-term exposure to ordinary disinfectants, and chlorination of water.
The toxin causes a person’s intestines to create massive amounts of fluid that then produces thin, grayish brown diarrhea.
Signs and symptoms
Depending on how many organisms a person drinks or eats, the illness could begin within 12-72 hours. The symptoms start suddenly with intestinal cramps and painless (rice-water appearing) diarrhea. Vomiting, feeling ill, and headache often accompany the diarrhea, especially early in the illness.
Fever is rare. If untreated, the disease generally lasts 1-7 days. During the illness, the body loses great amounts of fluid, so it is important during recovery to replace fluids and balance electrolytes (such as sodium and potassium).
Children may experience seizures and cardiovascular imbalances severe enough to cause heart problems. The rapid loss of body fluids often leads to more severe illness. If not treated, up to half of children with cholera may die.
The doctor may examine a sample of the stool under a microscope to confirm the diagnosis. Symptoms alone are usually enough to identify cholera.
Fluids and electrolytes need to be replaced because the body has lost large amounts of fluids through the vomiting and diarrhea. Doctors may encourage the person to drink, but if someone continues to vomit or has frequent stools, an IV may be used to replace the fluid lost.
Antibiotics such as tetracycline or doxycycline shorten the duration of diarrhea and reduce fluid losses. The antibiotics ciprofloxacin or erythromycin also may be used for a few days.
A live vaccine is available for use in those considered to be at risk for exposure. The vaccine is protective for only about half of those immunized, and protection lasts for no more than 6 months. The vaccination schedule is an initial dose followed by another dose 4 weeks later, with booster doses every 6 months.
An inactivated oral vaccine is safe and provides rapid short-term protection. It requires 2 doses and has about 85% efficacy lasting 2-3 years for 2 different types of cholera.