(CNN) The US Centers for Disease Control and Prevention has escalated its response to the polio-like illness that's struck children in 29 states, increasing the number of disease detectives in its Atlanta headquarters from two to 16, according to a CDC official close to the investigation.

The job of the detectives -- formally known as Epidemic Intelligence Service officers -- is to collect data on acute flaccid myelitis, known as AFM, and try to identify the cause of the outbreak. Currently, the cause is unknown, and there's no treatment and no vaccine.

AFM is a rare illness that affects the nervous system, especially the gray matter in the spinal cord, and causes muscle weakness and sudden onset of paralysis. There's a spectrum of how children can be affected: Some regain the use of their paralyzed limbs, while others are paralyzed from the neck down and can breathe only with the help of a ventilator.

The official said there was an "urgency" to the situation. "It was clear in October that we needed more staff to do the critical response," the official said. "We're pulling together the extra people, the extra minds, the extra resources, the extra activities."

In a CNN story last month, parents of children with AFM and some of the CDC's own medical advisers criticized the agency for being slow to respond to the outbreak.

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