[header] How to prevent hantavirus pulmonary syndrome (hps ) [title] Recognize signs of an infestation. [step] Look for small pellets of rodent droppings about ¼-½ " (0.5-1.0 cm) in size. You may also see signs of gnawing on your furniture or rodent tracks in dusty spaces. 
If you find small wads of soft materials or paper, you may have found rodent nests. You might even smell rodent urine or be able to hear them scurrying around.