Plum Island is a small island in New York State, about two miles off the coast of Long Island and six from Connecticut. The US Federal government owns the Island, and some scary biological stuff goes on there.

The U.S. Department of Agriculture established a research facility there after acquiring the 840-acre island from the military at the end of World War II. The initial charter from Congress mandated the study of animal diseases, particularly foot-and-mouth disease, in an effort to remove such diseases from the nation’s livestock. The prevailing winds blow out to sea, making it an ideal location.

In 1954, scientists researched ways to inflict damage on Soviet livestock. The Cuban government alleges that in the 1960s and 70s, bioweapons developed at Plum Island were deployed against Cuban agriculture, targeting pork, tobacco and sugar cane. Back in 1999, Floyd P. Horn, administrator of the Agriculture Research Service, persuaded President Bill Clinton to include Plum Island in his expanded bioterrorism program based on the possibility of a biological attack on the nation’s agricultural base. In June 2003 the administration of the island’s research facilities was transferred from USDA to the Department of Homeland Security.

Plum Island is home to a Bio-Safety Level 4 (BSL-4) research facility. The only comparable government facilities in the country are the United States Army laboratory at Fort Detrick, MD, and the Centers for Disease Control and Prevention in Atlanta. Plum Island is specifically engaged in the study of zoonotic diseases. Those are diseases that can be transmitted from animals to humans, like West Nile, Lyme disease, and Ebola.

The island itself is mysterious, much about it is classified. The 200-odd employees do not live on the island; they commute from their homes in Connecticut and Long Island. The facility is only accessible by government ferry, and local sailors who have strayed too close have reported being warned off in no uncertain terms by armed military personnel. The diseases being researched do not live exclusively under glass—there are quite a number of infected live animals for study there. Some of these diseases have an incubation period extending for days.

Many Long Islanders are justifiably concerned about the facility, nicknaming it "Mystery Island." Some worry that a researcher will be infected and take the illness home with them, spreading it through the incubation period. The government claims that there has only been one outbreak on the island itself; a foot-and-mouth outbreak in 1978 which was contained by killing all the livestock. The US government maintains that there has never been a leak to the mainland. However, the first case of Lyme Disease appeared 13 miles northeast of the facility. Some paranoid people note that West Nile virus mysterously appeared in Long Island and New York City, for reasons still unknown.

There have also been a string of power and water outages on the island, due to strikes by Federal employees, though some reporters have accused that there was sabotage. Those outages temporarily shut down the decontamination systems on the island, and even disabled the air pressurized gaskets around the Bio Safety doors temporarily. Stephen King's horror novel, The Stand, centers around a scenario where an outbreak from a facility like this one kills 99% of the world's population.

In 2001, the New York Times revealed the existence of the Defense Department’s "Project Jefferson," an effort to develop a vaccine-resistant form of anthrax. The Pentagon responded to the story by asserting that the project would be completed and the results classified. I'm sure that didn't make anyone feel any better.

Plum Island is 136 miles from New York City, but some are still concerned. Long Islanders are concerned that the facility could come under attack by Terrorists. Nelson Demille wrote a novel Plum Island, a mystery thriller involving a murder near the Island. Dr. Hannibal Lecter was offered a "vacation" on Plum Island by the FBI in the novel "The Silence of the Lambs."

According to the USDA, Plum Island research has led to advances in the treatment of Foot-and-mouth disease, African horsesickness, African swine fever, Vaccines for foreign animal diseases, and import/export procedures for ham and other meat.

Sources:
http://www.ars.usda.gov/plum/
http://www.nypress.com/17/11/news&columns/feature.cfm