[SciPy-User] How to read CSV with missing data in numpy array?

Trying to read this csv: 6;6;7;8;3; 8;10;8;;5; 3;5;6;7;; with this code: loadtxt('test.csv', delimiter=';', usecols=range(5)) yields "ValueError: could not convert string to float: " Is there any easy way numpy to read this CSV? Thanks