What is E. coli, what are the first signs you have it and other frequently asked questions

This 2006 colorized scanning electron micrograph image made available by the Centers for Disease Control and Prevention shows a strain of the Escherichia coli bacteria. Credit: AP/Janice Carr

Investigators continue to search for the source of the E. coli contamination in the Long Beach water system that Friday caused Nassau County health officials to issue a boil-water alert, as well as issue safety recommendations to visitors and residents. Officials said about 35,000 residents have been advised to boil water for at least a minute before drinking, brushing teeth, washing hands, preparing food and bathing infants. On Monday, officials ordered the closure of East, West and Lindell elementary schools out of an abundance of caution. Meanwhile, here's what you need to know about E. coli:

What is E. coli?

Scientifically speaking, Escherichia coli. A diverse group of bacteria which, according to the Centers for Disease Control and Prevention [CDC], "normally live in the intestines of people and animals." Most E.coli strains are harmless, the CDC said. Some "actually are an important part of a healthy human intestinal tract." Others, however, can cause illness, the most common being diarrhea. Six so-called pathotypes are associated with diarrhea and are referred to as diarrheagenic E. coli.

What are Escherichia coli?

Shiga toxin-producing E. coli — known as STEC — is the pathotype most-commonly heard about in the news associated with foodborne outbreaks. But, the CDC said, some STEC kinds of E. coli are used as markers for water contamination, which is why you hear about E. coli being found in drinking water. These markers are not themselves harmful, the CDC said, but indicated the water is contaminated. "It does get a bit confusing — even to microbiologists," the CDC said.

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Who gets STEC infections?

Anyone exposed to E. coli contamination become infected, the CDC said. However, very young children and the elderly are more likely to develop more severe illness than others — though even the most healthy can become seriously ill.

What are the first signs of E. coli?

The eight early signs and symptoms of E.coli illness are: Nausea; vomiting; stomach cramps or other abdominal pain; diarrhea, which often is bloody; a low-grade fever, usually no more than 100-101 degrees Fahrenheit; malaise; loss of appetite and mild dehydration.

How soon do symptoms appear after exposure?

The usual incubation period is 3-4 days after exposure, though the CDC said the time period could be as short as one day — or, as long as 10.

Where does STEC come from?

STEC comes from the guts of so-called "ruminant" animals. That is, animals that are cud-chewing, such as cattle, goats, sheep, deer and elk. As a result, most E. coli illnesses are the result of consuming unpasteurized milk, cider and soft milk-based cheese, while others are the result of improperly cooked meat or improperly washed vegetables. Authorities are required by law to notify the public when drinking water becomes contaminated.

How is water treated to protect from E. coli?

The usual processes involve chlorine, ultraviolet light or ozone, all of which kill or inactivate E. coli. Under the Safe Drinking Water Act, the U.S. Environmental Protection Agency requires all public water systems to monitor for coliform bacteria and then requires that any positive results be analyzed to determine the presence of fecal coliform or E. coli. Any positive result then triggers alerts to the public, as well as standardized decontamination and disinfection procedures.

What can you do to protect your household from E. coli exposure?

The CDC and other experts, such as those at the Mayo Clinic, said you must boil water for at least one minute at a rolling boil [longer, if you live at higher altitudes than here on Long Island] in order to kill any E. coli bacteria present.

Stomach acid and E. coli.

Decreased stomach acid levels can actually increase your risk of E. coli illness, the CDC said. So, if you take medications to reduce stomach acid it is even more important that you practice safe procedures to prevent any E. coli exposure or illness.

How do you treat illness caused by E. coli exposure?

The CDC said that if you have diarrhea that last for more than three days or is accompanied by a high fever, blood in your stool or "so much vomiting that you cannot keep liquids down," or if you pass very little urine, you should seek immediate medical treatment. For others, basic treatment includes constant hydration. The CDC warns that the use of antibiotics or antidiarrheal drugs actually can increase the risk of HUS or Hemolytic Uremic Syndrome, which is a type of kidney failure. In the case of infants or the elderly, authorities recommend you seek medical treatment at first sign of any potential E. coli-related illness or symptoms.

What is HUS — or Hemolytic Uremic Syndrome?

A potentially life-threatening complication of E. coli exposure, the CDC said HUS can develop about seven days after symptoms first appear — often when diarrhea appears to be improving. Clues to HUS include a decrease in urination, excessive tiredness, and the loss of color in cheeks and the inside of eyelids. If you develop HUS it is imperative you seek medical advice, which often results in hospitalization, because your kidneys can stop functioning. Most people who develop HUS recover, the CDC said. But some can suffer permanent damage or even die, making medical monitoring even more crucial once you believe you have been exposed to any serious E. coli illness.

Should an infected person avoid school, public gatherings or work?

Which exclusion policies differ by local jurisdiction, according to the CDC, but at the very least infected parties need to practice "good handwashing" after using the toilet, changing diapers or soiled linens, and, of course, before any food preparation.

Sources: Centers for Disease Control and Prevention, Mayo Clinic, Environmental Protection Agency

John Valenti, a reporter at Newsday since 1981, has been honored nationally by the Associated Press and Society of the Silurians for investigative, enterprise and breaking news reporting, as well as column writing, and is the author of "Swee'pea," a book about former New York playground basketball star Lloyd Daniels. Valenti is featured in the Emmy Award-winning ESPN 30-for-30 film "Big Shot."