The bacteria Vibrio grows in the Chesapeake Bay and its tributaries. (Katherine Frey/The Washington Post)

The bacteria, known as Vibrio, grows naturally in saltwater such as in the Chesapeake Bay and its tributaries, and increases significantly during the warmer months, according to Calvert County officials.

People can be exposed to the bacteria by consuming raw seafood or through contact via an open wound.

Symptoms caused by ingestion of the bacteria generally show up 24 to 48 hours after exposure and may include sudden chills, fever, nausea, vomiting or diarrhea.

Infections through physical exposure to contaminated water or seafood are signaled by redness, soreness and swelling of the skin or wound, officials said.

A combination of warm water temperatures, nutrient pollution, and the popularity of swimming, fishing and other summertime activities has allowed Vibrio to thrive in recent years.

According to officials, there were 168 cases of Vibrio infections in Maryland between 2006 and 2010. In 2010 alone, there were four reported cases of Vibrio infections in Calvert County; three of them were wound infections.

Virginia has also seen a recent uptick in infections, according to a report by the Chesapeake Bay Foundation in 2009.

Vibrio infections can be treated using antibiotics if caught in time, but could be fatal for those with weakened immune systems, health officials warn.

Tips from health officials for avoiding infection:

— Do not eat raw shellfish.

— Wash hands well with soap and water after touching raw seafood.

— Keep raw seafood and their juices away from other foods.

— Use gloves when touching raw shellfish.

— Eat cooked shellfish promptly and refrigerate leftovers right away.

— Protect open wounds or broken skin against contact with saltwater and shellfish.

— Immediately wash exposed wounds with soap and fresh water.

— Seek medical attention if signs of infection occur.