First their hands and feet feel cold. Then they go pale and cannot move. Some convulse and fall to the floor.

A mystery illness is plaguing girls in this town in northern Colombia, and locals say a vaccine against the sexually transmitted human papillomavirus, or HPV, is to blame.

In El Carmen de Bolivar, near the port of Cartagena, dozens of teenagers have experienced similar symptoms. Some have even lost consciousness.

"They vaccinated me in May and I started fainting in August. My legs became heavy and I couldn't feel my hands anymore. When I woke up, I was in the hospital," recalled 15-year-old Eva Mercado.

She passed out seven times in a month.

For most of the families affected in this town of 67,000, there is no doubt about what is causing the problem.

They place the blame squarely on a vaccination campaign against HPV, one of the most common sexually transmitted diseases, which can trigger cervical cancer.

The city's modest Nuestra Senora del Carmen hospital has been overwhelmed by a surge of unconscious teenage girls being wheeled through its doors.

Panicked fathers bring their daughters to the facility aboard their motorcycles, using the town's dirt roads.

Doctors search, in vain, for possible cases of hypoglycemia or drug abuse.

According to hospital official Augusto Agamez, about 370 minors have checked into the facility. There was also one boy among them.