While scouring the Internet, I came across an interesting study which compares the susceptibility of head lice, taken from the United States and Sabah, to permethrin.
Permethrin is a chemical substance used to threat lice infection or “peduculosis” in the US. Below is a photo of head lice, courtesy of Wikipedia.
The conclusion? The Sabah lice are more susceptible to permethrin than the US lice do. In other words, Sabah’s lice are lousy 
Here is a link to the study.
Link to this page