Most people exposed to the bacteria that cause cholera don't become ill and don't know they've been infected. But they can still infect others if their stool contaminates water or food.

When cholera causes symptoms, most often it leads to mild or moderate loose stools, called diarrhea. This is often hard to tell apart from diarrhea caused by other conditions. Other people develop more-serious symptoms of cholera, most often within a few days of infection.

Symptoms of cholera infection can include:

• Diarrhea. Cholera-related diarrhea comes on suddenly and can quickly cause dangerous fluid loss. Some adults make as much as a quart, or about 1 liter, of stool an hour. Diarrhea due to cholera often has a pale, milky appearance. It may look like water in which rice has been rinsed. And often, it smells fishy.
• Upset stomach and vomiting. Vomiting often happens in the early stages of cholera. It can last for hours.

• Dehydration. Dehydration can develop within hours after cholera symptoms start. It can range from mild to serious. A loss of 10% or more of body weight suggests serious dehydration.

Symptoms of cholera dehydration include irritable behavior, fatigue, sunken eyes, a dry mouth, extreme thirst, and little or no urinating. Skin may become dry, shriveled and slow to bounce back when pinched into a fold. Low blood pressure and an irregular heartbeat also can be symptoms.

Dehydration can lead to a rapid loss of minerals in your blood called electrolytes. These minerals maintain the balance of fluids in your body. When you lose too many, it's called an electrolyte imbalance.

Electrolyte imbalance

An electrolyte imbalance can lead to serious symptoms such as:

• Muscle cramps. These result from the rapid loss of salts such as sodium, chloride and potassium.
• Shock. This is one of the most serious dangers of dehydration. It happens when rapid fluid loss causes a drop in blood pressure and a drop in the amount of oxygen in the body. Without treatment, severe shock can cause death in hours.

The risk of cholera is slight in developed nations. Even in areas where it exists, you're not likely to become infected if you follow food safety recommendations. Still, cases of cholera occur throughout the world. If you get serious diarrhea after you visit an area with active cholera, see your healthcare professional.

If you have diarrhea, especially bad diarrhea, and think you might have been exposed to cholera, seek treatment right away. Serious dehydration is a medical emergency that needs urgent care.

A type of bacteria called Vibrio cholerae causes cholera infection. The deadly effects of the disease are the result of a toxin the bacteria make in the small intestine. The toxin causes the body to purge huge amounts of water. This leads to diarrhea and a rapid loss of fluids and salts.

Cholera bacteria might not cause illness in all people who are exposed to them. But infected people still pass the bacteria in their stool, which can taint food and water supplies.

Tainted water supplies are the main source of cholera infection. The bacteria can be found in:

• Surface or well water. Tainted public wells are frequent sources of large-scale cholera outbreaks. People living in crowded conditions that lack sanitation are especially at risk.
• Seafood. Eating raw or undercooked seafood, especially shellfish, that comes from certain places can expose you to cholera bacteria. Rarely, people in the United States have gotten cholera after eating raw or undercooked seafood from the Gulf of Mexico.
• Raw fruits and vegetables. Raw, unpeeled fruits and vegetables are a frequent source of infection in areas where there is cholera. In developing countries, uncomposted manure fertilizers or irrigation water that contains raw sewage can taint produce in the field.
• Grains. In regions where cholera is widespread, moist grains such as rice and millet sometimes pose a risk. They can grow cholera bacteria if they're contaminated after cooking and kept at room temperature for hours.

Everyone is prone to cholera. But illness is not common before the age of 2. Babies might get protection from the disease when they breastfeed from mothers who've had cholera in the past.

Still, certain factors can make you more likely to get the disease or have serious symptoms. Risk factors for cholera include:

• Poor sanitary conditions. Cholera is more likely to grow in places where a clean environment — including a safe water supply — is hard to maintain. Such conditions are common to refugee camps, countries with limited resources and areas afflicted by famine, war or natural disasters.

• Less or no stomach acid. Cholera bacteria can't survive in an acidic environment. Ordinary stomach acid often serves as a defense against infection.

  But people with low levels of stomach acid lack this protection, so they're at greater risk of cholera. Those at risk include children, older adults and people who take medicine to lower stomach acid. These medicines include antacids, H-2 blockers or proton pump inhibitor medicines. People with a condition in which the body's digestive juices lack stomach acid also are at risk. This condition is called achlorhydria.

• Household exposure. Your risk of cholera is higher if you live with someone who has the disease.
• Type O blood. People with type O blood are more likely to get cholera compared with people with other blood types. It's not clear why.
• Raw or undercooked shellfish. Developed nations no longer have large-scale cholera outbreaks. But eating shellfish from waters known to harbor the bacteria greatly raises your risk.

Cholera can quickly become fatal. Sometimes, the rapid loss of large amounts of fluids and electrolytes can lead to death within hours. Even in less extreme situations, the illness can be life-threatening without treatment. People who don't receive treatment can die of dehydration and shock hours to days after cholera symptoms first appear.

Shock and serious dehydration are the worst complications of cholera. But other conditions can occur, such as:

• Low blood sugar. Another name for this is hypoglycemia. Blood sugar is the body's main energy source. Dangerously low levels of it can happen when people become too ill to eat. Children are at greatest risk. Blood sugar that's too low can cause seizures, unconsciousness and even death.
• Low potassium levels. People with cholera lose large amounts of minerals, including potassium, in their stools. Very low potassium levels interfere with heart and nerve function and are life-threatening.
• Kidney failure. When the kidneys lose their ability to filter blood, excess amounts of fluids, some electrolytes and wastes build up. This can be life-threatening. In people with cholera, kidney failure often happens along with shock.

Cholera is rare in the United States and other developed countries. In these places, the disease is sometimes linked with travel abroad. Or it can be linked with seafood from waters that harbor cholera bacteria, such as those off the Gulf Coast.

If you travel to areas known to have cholera, take the following safety measures. They can keep your risk of the disease very low:

• Wash your hands with soap and water often. Handwashing is key after you use the toilet and before you handle food. Rub soapy, wet hands together for at least 20 seconds before rinsing. If soap and water aren't available, use an alcohol-based hand sanitizer with at least 60% alcohol.

• Drink only safe water, including bottled water or water you've boiled or disinfected yourself. Use bottled water even to brush your teeth.

  Most often, hot drinks are safe. So are canned or bottled drinks, but wipe the outside before you open them. And check to see that the seal isn't broken. Don't add ice to your drinks unless you made it yourself using safe water.

• Eat food that's completely cooked and hot. Stay away from street vendor food if you can. If you do buy a meal from a street vendor, make sure it's cooked in your presence and served hot.
• Stay away from sushi, as well as raw or undercooked fish and seafood of any kind.
• Stick to fruits and vegetables that you can peel yourself. Some examples are bananas, oranges and avocados. Stay away from salads and fruits that can't be peeled, such as grapes and berries.

Cholera vaccine

People who travel from the United States to areas affected by cholera can get a cholera vaccine called Vaxchora. It's suggested for people ages 2 to 64 who plan to travel where cholera is being spread or regularly spreads. It is a liquid dose taken by mouth at least 10 days before travel.

Many other countries offer vaccines taken by mouth as well. Contact your healthcare professional or local office of public health for more information about these vaccines. Even with the vaccine, it's important to take the above safety measures to prevent cholera.

Symptoms of severe cholera might seem clear-cut in areas where it's common. But the only way to find out for sure if you have it is with a test of your stool.

Rapid cholera dipstick tests let healthcare professionals in remote areas quickly confirm whether someone has cholera. The speed of the test helps lower death rates at the start of cholera outbreaks. And it leads to earlier public health measures for outbreak control.

Cholera needs to be treated right away because the disease can cause death within hours. Treatments include:

• Rehydration. The goal is to replace lost fluids and electrolytes using a simple rehydration solution, oral rehydration salts (ORS). The ORS solution is available as a powder that can be made with boiled or bottled water.

  Without treatment, up to half of people with serious bouts of cholera could die. With treatment, deaths drop to less than 1%.

• Fluids through a vein. You might hear these called intravenous (IV) fluids. Most people with cholera can be helped by oral rehydration alone. But badly dehydrated people also might need IV fluids.
• Antibiotics. These are medicines that help clear up infections caused by bacteria. They're not a necessary part of cholera treatment. But some antibiotics can help treat cholera-related diarrhea and shorten how long it lasts in very ill people.
• Zinc supplements. Research has shown that zinc might lessen diarrhea and shorten how long it lasts in children with cholera.

If you are in or have very recently returned from a country where cholera occurs, be aware of the symptoms. Get medical care right away if you have serious diarrhea or vomiting.

If you think you've been exposed to cholera, but your symptoms are not serious, call your family healthcare professional. Be sure to say that you think your illness may be cholera.

Here's some information to help you get ready for your checkup.

When you make your appointment, ask if there are restrictions you need to follow before your visit.

Make a list of:

• Your symptoms. Include when they began and how serious they are.
• Any recent exposures to possible sources of infection. This is key if you've traveled abroad recently.
• Key medical information. Include any other conditions for which you're being treated.
• All medicines, vitamins or other supplements you take. Include the amounts you take, also called the doses.
• Questions to ask your healthcare professional.

Some questions to ask your healthcare professional about cholera include:

• Are there other conditions that might be the cause of my symptoms?
• What tests do I need?
• What treatment do you recommend?
• How soon after I start treatment will I begin to feel better?
• How long do you expect a full recovery to take?
• When can I return to work or school?
• Am I at risk of any long-term problems from cholera?
• Am I contagious? How can I lower my risk of passing my illness to others?

What to expect from your doctor

Your healthcare professional likely will ask questions such as:

• Have you had watery diarrhea? How bad is it?
• Is there anything else unusual about the way your stools look?
• Have you been vomiting?
• Have you had symptoms of dehydration, such as intense thirst, muscle cramps or fatigue?
• Have you been able to keep down any food or liquid?
• Have you recently eaten raw shellfish, such as oysters?
• Are you pregnant?
• What is your blood type, if you know?

What you can do in the meantime

Stay well hydrated. For diarrhea and vomiting that may be cholera-related, use an oral rehydration solution.

In most developing countries, you can buy powdered packets of oral rehydration salts (ORS). These originally were developed by the World Health Organization to treat diarrhea and dehydration in infants with cholera. Stir the powder into clean drinking or boiled water according to the package directions.

If no oral rehydration solutions are available, you can make your own. Combine the following:

• 1 quart (about 1 liter) of bottled or boiled water.
• 6 level teaspoons (about 30 milliliters) of table sugar.
• 1/2 level teaspoon (about 2.5 milliliters) of table salt.