A sharp rise in the number of people dabbling in Satanism and the occult is fueling a growing demand for more exorcists on both sides of the Atlantic.
Speaking in tongues, levitating and vomiting nails may seem far-fetched to most people, but experts from the Catholic Church in Italy and the US claim there is an urgent need to recruit more priests as exorcists in order to combat sorcery and black magic.
Valter Cascioli, a psychologist and scientific consultant to the International Association of Exorcists, which is endorsed by the Vatican, described as an "emergency" the lack of priests capable of fighting the forces of evil.
"The lack of exorcists is a real emergency. There is a pastoral emergency as a result of a significant increase in the number of diabolical possessions that exorcist priests are confronting," he told La Stampa newspaper.
"The number of people who take part in occult and satanic practices, which lead to serious physical, psychological and spiritual damages, is constantly rising."
Dr Cascioli teaches courses in exorcism at the Pontifical University of Regina Apostolorum, a Vatican-backed university in Rome. "The number of exorcists has increased in recent years, but there are still not enough to deal with a dramatic situation that affects, above all, young people who use the internet a lot.
"There is a broad spread of superstitious practices, and with that a growing number of requests for help from people who are directly or indirectly struck by evil.
"It is dangerous to underestimate a phenomenon that is caused by the direct actions of the devil, but also by a decline in faith and values."
He called for the establishment of a permanent training college or university where Catholic priests would be taught how to counter the malign influence of the Devil. "There doesn't exist a training institution at university level. We need an interdisciplinary approach in which science collaborates with religion, and psychiatrists work with demonologists and exorcists."
He said it was important not to confuse cases of diabolical possession with psychiatric illnesses. Only one per cent of people who claim to have problems with demons have real need of an exorcist, he said.
Father Ildebrando Di Fulvio, the exorcist for the diocese of Frosinone, a town south of Rome, said people possessed by the devil often vomited metal objects and chunks of undigested food and gibbered in archaic languages such as Aramaic, ancient Greek and Latin.
They demonstrated "violent reactions to prayers of liberation and to holy water," he said.
On the other side of the Atlantic, two of America's leading exorcists told The Telegraph that keeping up with demand for exorcisms is a constant struggle.
Father Gary Thomas, whose training in Rome was chronicled in the book The Rite: The Making of a Modern Exorcist, and Father Vincent Lampert, whose work has featured on the television show Paranormal Witness, said demonic possessions were the result of an increase in drug and pornography addiction.
They also pointed to a rise in the popularity of "pagan activities", such as using a Ouija board to summon the dead, the failure of the mental health care system, a spiritual void in the lives of Americans and the diminishing authority of the Church.
"We're gaining all sorts of knowledge, but there's still that emptiness within us that is being filled with addictive behaviour such as drugs and pornography," said Father Lampert, of the Archdiocese of Indianapolis. "The decline in faith goes hand in hand with the rise in evil."
Father Thomas, the official exorcist of the diocese of San Jose in northern California, trained in Rome in 2005 after being an ordained priest for 22 years. In the past 10 years, he says he has performed 50 to 60 exorcisms. "I am a full-time pastor and this is a very intense ministry. Almost every free night that I have is taken up with exorcisms," he said.