Besides just living in your hair, lice can also find ways to inhabit the clothing you wear.
If the clothing is worn repeatedly without washing, it might be the ideal place for nits to hatch and the louse larvae to mature. If a living human, ready to furnish blood, is putting on the same clothes day after day, the louse has a built-in life of ease.
So dealing with body lice is really just an issue of hygiene. Simply washing your clothing and bedding regularly you can completely avoid the problem.