The three biggest killers of humans in the shark world are the Great White, the Tiger and the Bull Shark. The Great White, of course, is by far the most fearful and large, yet it rarely comes into shallow water. The same is largely true for the Tiger but the Bull Shark, well, he loves shallow murky water like that found along much of the Atlantic coast as the in close wave action froths up the water. That is one great reason to avoid swimming when the water is murky and stirred up.
The bull shark gets his name from his very stocky appearance, with a short and wide snout and heavy build. The average length is from six to eight feet with the females being larger. Seldom is one found over eleven feet in length, but he makes up for size by his strength and the power of his bite is as great as even a great white. He likes to hunt alone and is not afraid of humans swimming nearby and anything that aggravates him is likely to generate an attack. When doing so, he usually gives his bait a nudge, then goes in for a bite and he is not easily scared off once the attack has begun. He is determined and is hard to get him to give up his prey. It is why in a recent attack when a father saved his daughter from sure death, the shark didn't leave with a prize, her arm. With more and more people in the ocean these days, he is probably the most likely to have an encounter with someone unaware of their surroundings and his capabilities.
Bull sharks can also live for long periods of time in fresh water as well and for this reason he is found in rivers and even lakes which have an entry point from the ocean. Juveniles are born and nursed in shallow brackish or fresh bodies of water, thereby protected from other species of sharks that would otherwise destroy them. In crocodile or alligator infested inland waters, the role changes from predator to prey as bull sharks are a favorite meal.
As far as the Outer Banks and the Tidewater Virginia areas go, bull sharks are quite common, both in the shallow ocean near shore and in the Chesapeake Bay, the Pamlico and Albemarle sound regions as well as adjoining fresh water rivers. They have been seen in the Albemarle as far west as the Route 32 bridge on the south side of the sound between Columbia and Plymouth, as well as in the Chesapeake Bay and the Potomac and Patuxent Rivers. Very little evidence has been recorded of attacks in the rivers although many say a deadly assault on a Sunday school picnic river party in New Jersey back in 1916 was due to a bull shark.
So, what is the best advice to follow. It is caution. Stay away from murky water or schools of fish, don't wade into the surf to fish with bait attached to your body, avoid dawn and dusk swim sessions and use the buddy system. Anything is possible as the world becomes more crowded, but these steps will greatly lower your chance of having an encounter you will never forget. Just opt for being safe out there. Maintain respect for this powerful creature in the element he has inhabited for thousands and thousands of years and life will go on; fail to do so and things can turn ugly quick.