House will Not Sell Because of Bat Infestation

[Geren Knight III]

I found a house that I can buy for 40% of the ARV. The ARV is over $200k. The house is in a great location (in regards to the neighborhood, low crime rate, and home values) with many of the houses in the area valued above $300k. There are some downsides to the neighborhood. The neighborhood is an old neighborhood with most of the homes built around the turn of the 20th century, late 1800s and early 1990s. The neighborhood is old and had already been established when the highway was built near it. The highway can be seen from the house. Furthermore, the backyard of this house slopes down into a ravine; however, that can be fixed with fill dirt, retaining walls and the proper drainage systems. The property has been for sale for over a year now and the owner has been unable to sell it. The house does need work on the inside, but nothing that should prevent it from selling. Through a little research I found out that the house used to be infested with bats. My agent has indicated that that is a reason the house will not sell.
If I were to purchase this house and rehab it, how can I overcome the bad sigma when I go to sell it?