The au pair insurance guidelines have changed starting from June 1st 2013:
http://www.johoinsurances.nl/images/pdf/isis/au_pair/isis_aupair__folder.pdf
instruction_apply_basic_health_insurance_for_au_pair-pdf
http://www.insurancesinthenetherlands.nl/health-insurance/temporary-stay-in-the-netherlands/au-pair-in-the-netherlands