We live in Houston, Texas in a two story home built in the 1960's. We purchased the home two years ago, and do not remember the smell that now owns us.

The second floor of our home smells like sewage/dirty diapers/raw eggs. It's a combination, really. And the intensity of the smell comes and goes. It is strongest in our master bath, stairwell, and now seems to be spreading into other upstair areas. In summer months it seems stronger, and when the air is not circulating it seems stronger.

There is no visible signs of mold in the house, and we recently had our HVAC systems cleaned out entirely. We had hoped that this would help the odor, but it has not.

Another possibility - we recently found rat droppings downstairs, and have heard rats running around at night, althoug most of the sounds are outside on a sky light. We are having a pest inspector come out to look around the house, but recent trips to the attic do not reveal anything of note. One suspicion is that something, somewhere, has died. The problem with this theory is that dead things ultimately decompose, and the smell goes with them. We have lived with this smell - and its ebbing intensity - since about last Fall when our first baby arrived. In fact, at first we thought it was her dirty diaper smell which had simply permeated everything we owned. But this, too, seems unlikely given the duration of the smell.

I'm looking for tips, thoughts, leads, anything you can do to help us. I am concerned this may be a health risk for my wife and baby. At this stage our suspicions regarding cause are:

1) some form of mold behind walls, despite fact that there is no visible evidence;

2) rats or some other pest that has nested and lived (possibly died) behind walls or elsewhere; and

3) some form of sewage issue the likes of which I Cannot and fear to articulate - but again, no stoppage, leaks, backflow, nothing to suspect this yet.

Anything you can do to help is appreciated. Heck, at this stage I will throw in a $100 reward to the person that helps me identify the right issue and a vendor that can help me solve the problem before I wake up with some rare skin cyst caused by deadly foreign fungi.

Hope to hear from you - thanks.

John Scott Black

Houston, Texas