Under the laws of all states in this country (common law) the seller of an item is required to disclose to all potential buyers of the item all known matters that affect desirability or price paid.If you can prove that the sellers of the unit knew about bed bug issues with the unit you purchased and did not disclose this material fact to you before close of escrow, the sellers are responsible for all of your damages. Such damages would be costs of eradication of the bed bugs, lost rent, and possibly attorney's fees. I suggest that you consult with a real estate attorney about your matter.