The spread of Ebola from western Africa to suburban Texas has brought with it another strain of contagion: conspiracy theories.

The outbreak began in September when a Liberian newspaper published an article calling the virus a bioweapon designed by the U.S. military to depopulate the planet.

Not long after, accusations appeared online contending the federal Centers for Disease Control and Prevention had patented the virus and was poised to make a fortune from a new vaccine it had created with the pharmaceutical industry. There were even reports that the New World Order had engineered Ebola in order to impose quarantines, travel bans and martial law.

While most theories linger on the fringes of the Internet, a few have crept into the mainstream. Conservatives such as Rush Limbaugh and Laura Ingraham have floated the idea that President Obama had sent aid to Africa, risking U.S. lives, because of his guilt over slavery and colonialism. And hip-hop artist Chris Brown tweeted, "I don't know … but I think this Ebola epidemic is a form of population control."

Conspiracy theories always move in tandem with the news, offering shadow explanations.

"They're effective as expressions of anxiety," said Michael Barkun, author of "Culture of Conspiracy: Apocalyptic Visions in Contemporary America."

The notion that health officials are conspiring with Big Pharma to spread — and then cure — Ebola touches on a genuine aspect of our health care system, said Mark Fenster, author of "Conspiracy Theories: Secrecy and Power in American Culture."

"It's not so hard or paranoid to imagine private companies acting in their own best interests," he said.

It's also not surprising that populist and anti-government conspiracies are rampant at a moment when opinion polls suggest trust in government has reached a record low. In fact, most theories pit those who perceive themselves as powerless against elites.

That model certainly fits the allegation that the Pentagon created Ebola in a military lab to reduce the population.

Conspiracies "reinforce the idea that ordinary citizens are victims of the government," said James F. Broderick, co-author of "Web of Conspiracy: A Guide to Conspiracy Theory Sites on the Internet."

Some scholars find value in conspiracy theories because they give voice to hidden fears.

"I view these things as a way of framing the world," Fenster said. "And they're not necessarily a bad thing."