Cholera and related vibroses

Overview


The infection is often mild or without symptoms, but sometimes it can be severe. Approximately one in 20 infected persons has severe disease characterized by profuse watery diarrhea, vomiting, and leg cramps. In these persons, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.

Epidemiology and Demographics
There are 0-5 cases per year in the United States. A major cause of epidemic diarrhea throughout the developing world. Ongoing global pandemic in Asia, Africa and Latin America for the last four decades.


 * 25-50% of typical cases are fatal if untreated.

In January 1991, epidemic cholera appeared in South America and quickly spread to several countries. A few cases have occurred in the United States among persons who traveled to South America or ate contaminated food brought back by travelers.

Cholera has been very rare in industrialized nations for the last 100 years; however, the disease is still common today in other parts of the world, including the Indian subcontinent and sub-Saharan Africa.

Predicting how long a Cholera epidemic will last is difficult. The cholera epidemic in Africa has lasted more than 30 years. In areas with inadequate sanitation, a cholera epidemic cannot be stopped immediately, and, although far fewer cases have been reported from Latin America and Asia in recent years, there are no signs that the global Cholera pandemic will end soon. Major improvements in sewage and water treatment systems are needed in many countries to prevent future epidemic cholera.

In the United States, cholera was prevalent in the 1800s but has been virtually eliminated by modern sewage and water treatment systems. However, as a result of improved transportation, more persons from the United States travel to parts of Africa, Asia, or Latin America where epidemic cholera is occurring. U.S. travelers to areas with epidemic cholera may be exposed to the cholera bacterium.

Risk Factors
Virtually none in the United States. Risk extremely low (1 per million) even in travelers. Persons living in poverty in the developing world.

Pathophysiology & Etiology
Vibrio cholerae serogroup O1 or O139 that produces cholera toxin.

A person may get cholera by drinking water or eating food contaminated with the cholera bacterium. In an epidemic, the source of the contamination is usually the feces of an infected person. The disease can spread rapidly in areas with inadequate treatment of sewage and drinking water. Occasionally transmitted through eating raw or undercooked shellfish that are naturally contaminated.

The cholera bacterium may also live in the environment in brackish rivers and coastal waters. Shellfish eaten raw have been a source of cholera, and a few persons in the United States have contracted cholera after eating raw or undercooked shellfish from the Gulf of Mexico. The disease is not likely to spread directly from one person to another; therefore, casual contact with an infected person is not a risk for becoming ill.

Treatment
Cholera can be simply and successfully treated by immediate replacement of the fluid and salts lost through diarrhea. Patients can be treated with oral rehydration solution, a prepackaged mixture of sugar and salts to be mixed with water and drunk in large amounts. This solution is used throughout the world to treat diarrhea. Severe cases also require intravenous fluid replacement. With prompt rehydration, fewer than 1% of cholera patients die.

Antibiotics shorten the course and diminish the severity of the illness, but they are not as important as rehydration. Persons who develop severe diarrhea and vomiting in countries where cholera occurs should seek medical attention promptly.

Is a vaccine available to prevent cholera?

A recently developed oral vaccine for cholera is licensed and available in other countries (Dukoral from SBL Vaccines). The vaccine appears to provide somewhat better immunity and have fewer adverse effects than the previously available vaccine. However, CDC does not recommend cholera vaccines for most travelers, nor is the vaccine available in the United States.

Primary Prevention
The risk for cholera is very low for U.S. travelers visiting areas with epidemic cholera. When simple precautions are observed, contracting the disease is unlikely.

All travelers to areas where cholera has occured should observe the following recommendations:


 * Drink only water that you have boiled or treated with chlorine or iodine. Other safe beverages include tea and coffee made with boiled water and carbonated, bottled beverages with no ice.
 * Eat only foods that have been thoroughly cooked and are still hot, or fruit that you have peeled yourself.
 * Avoid undercooked or raw fish or shellfish, including ceviche.
 * Make sure all vegetables are cooked avoid salads.
 * Avoid foods and beverages from street vendors.
 * Do not bring perishable seafood back to the United States.

A simple rule of thumb is "Boil it, cook it, peel it, or forget it. "

Acknowledgements
The content on this page was first contributed by: C. Michael Gibson, M.S., M.D.

List of contributors: