"If you use a chemical over and over, these little creatures will eventually develop resistance," said Dr. Kyong Yoon, who led the research.

Lice in the following states are said to have developed a high level of resistance to the most common treatments recommended by doctors:

  • Alabama
  • Arizona
  • Arkansas
  • California
  • Connecticut
  • Florida
  • Georgia
  • Illinois
  • Indiana
  • Kansas
  • Kentucky
  • Maine
  • Maryland
  • Massachusetts
  • Minnesota
  • Missouri
  • North Carolina
  • Ohio
  • Rhode Island
  • South Carolina
  • Tennessee
  • Texas
  • Virginia
  • Washington
  • Wisconsin