Mass hysteria rare, but more often seen in girls

A recent report has showed that teenage girls are high risk to suffer from mass hysteria or conversion disorder. There are numerous case reports of this condition that seems to be precipitated by stress, and stress-related conditions and presents with seizures, tics, and other neurological manifestations. On these reports no physical explanation was found after extensive investigation. Once the first person or “index case” starts with symptoms then it gets spread to other people who manifest “symptoms’ subconsciously. Further research is needed to establish the cause of this disorder.

http://www.nola.com/health/index.ssf/2012/02/mass_hysteria_rare_but_usually.html