Actually there is a huge discrepancy between north and south US for Lyme. The north has on average a much higher quality of life, less comorbid diseases. For example obesity, smoking, diabetes, lower income are all more prevalent in the southern US and all are risk factors for T. STDs are higher in the south, the south has lower access to health care. It all adds up I think. And there is a cultural component too. I think northerners, atleast the ones I know, would never admit discomfort no matter how bad. Thus I think T is also under reported in the north.