At the bottom of careers.nielsen.com is this:
It has come to Nielsen’s attention that individuals misrepresenting themselves as Nielsen representatives have offered fraudulent employment opportunities. In some cases, job seekers are asked to pay a processing or work permit fee in order to secure an offer of employment. Nielsen and our external recruiting/placement partners will never request credit card information or charge candidates an up-front fee of any kind.
If you receive a fraudulent employment request, save the message and send it to your local law enforcement agency. You may also contact us.