A California boy was “forced to lie in his own excrement” and left to die alone in “utter helplessness” at a boot camp-style school for problem teenagers, his parents said last week.

The allegations against the privately owned Thayer Learning Center Boot Camp and Boarding School, Missouri, sparked renewed calls for a crackdown on unlicensed “tough love” academies that have sprung up across America in recent years.

The academies are part of a booming industry peddling “shock therapy” solutions for problem teens but implicated in scores of student deaths.

Roberto Reyes, 15, was subjected to harrowing abuse and deprivation - including physical punishment, solitary confinement and not being allowed to go to the toilet - in the run-up to his death last November from an untreated venomous spider bite, the wrongful death lawsuit asserts.

Staff dismissed his pleas for help as “games and ploys”, despite an inability to walk, and “deteriorating respiratory and cognitive function”, it states. Other students were corralled “to wake up and drag and attempt to carry Reyes to the shower to be hosed down in a crude attempt to wash off human excrement and filth.”

A public tribunal ruled in December that Reyes’ death might have been avoided with timely medical attention. Missouri officials are investigating the abuse allegations.

Last May, three former staffers claimed the school forced a girl to sit for hours in a tub of her own urine, among other allegations.

Reyes’ parents sent him to 100-pupil, $50,000-a-year Thayer, which bills itself as a “military-based Christian boarding school for troubled teens”, after he ran away from home last summer, their lawyer said. A referral service that recommended Thayer to the Reyes and other parents turned out to be owned by the school’s proprietors.

School officials have declined to comment.

Lax regulations have made Missouri and several other US states magnets for private military academies.

Meanwhile, Mexican authorities recently closed four American boot camps that set up shop south of the border to cater for troubled US youngsters.

At least 37 students have reportedly died at private US boot camp-style programmes since 1980. Last month, an Arizona camp director was convicted of the reckless manslaughter for the 2001 death of a 14-year-old boy from dehydration and almost drowning.

Such camps aim to reform “delinquent” teenagers via a Spartan regime of bare dormitories, gruelling workouts and draconian discipline, including corporal punishment, presided over by staff modelled on drill sergeants.

Academic instruction is often minimal.

Though loved by some pop psychologists and talk-show hosts, such shock treatment is considered ineffective by most experts.

“Not only do these camps not work, they’re toxic,” said Robert Johnson, professor of psychiatry at the University of Medicine and Dentistry of New Jersey, who chaired a recent US government-sponsored summit on youth violence prevention.

Students are brutalised by the approach and contact with other miscreants, he added. “They get worse and some get physically harmed.

“There’s a belief someone dressed as a marine will make (trouble-makers) better, but there’s no evidence of that.”