State media reported that authorities shut down 46 blood-collection centers and arrested 23 dealers in a clampdown on illegal buying and selling of human blood. Blood centers face an uphill battle getting donations because of Chinese attitudes to blood giving. State employees are urged to give blood but many sidestep donations by turning to so-called "blood heads" to buy substitute blood from migrant workers and peasants. Such traders are blamed for causing devastating mass outbreaks of HIV in parts of rural China. On top of this, Ministry of Health officials said they uncovered irregular practices going on in government owned blood centers. In the meantime, Beijing had ordered tighter monitoring of blood-collection centers and manufacturers of blood products.