I think my maid is practicing black magic on my family. What things should I be looking out for? She is Filipino.

I think you should be more worried on WHY do you think she is doing this? What has happened that has warranted this kind of retribution? I agree with Jacq, find out the underlying cause for this because of there is a suspicion that she is up to no good then there is a reason why. Also, there is no scientific basis for black magic and voodoos. Purely psychological. 2 things to look out for though: 1) The person may be deranged. 2) Seeking revenge but tainting your food with saliva or human waste. This causes illness that is not related to any black magic. But I would advise to find out why she is acting like this.