Are there statistics on Sickle Cell Traits based on country of origin?
For "where does it come from and how does it spread?", why not read Wikipedia?  Short answers: (1) malarial regions of sub-Saharan Africa; (2) movement of people and genetic introgression.

Googling 'sickle cell "country of origin" turns up, for example:

"Sickle cell disease in areas of immigration of high-risk populations: a low cost and reproducible method of screening in northern Italy" Blood Transfus. 2014 Jul; 12(3): 346–351. doi:  10.2450/2013.0188-13 PMCID: PMC4111816

Country    Selected     Enrolled/   Enrolled/
                        negative    Hb variant
-----------------------------------------------
Ghana      241 (51.4%)  112 (47.1%) 53 (57.6%)
Nigeria    152 (32.4%)  77 (32.4%)  29 (31.5%)
Guinea      15 (3.2%)   8 (3.4%)    4 (4.3%)
Cameroon    13 (2.8%)   10 (4.2%)   1 (1.1%)
Senegal     12 (2.6%)   8 (3.4%)    1 (1.1%)
Ivory Coast 10 (2.1%)   9 (3.8%)    1 (1.1%)
Other       26 (5.5%)   14 (5.7%)   3 (3.3%)
Total      469 (100%)   238 (100%)  92 (100%)


"The burden of sickle cell disease in Cape Town", South African Medical Journal 102(9), 2012 Wonham et al. http://www.samj.org.za/index.php/samj/article/view/5886/4421



Distribution of sickle cell disease patients by country of origin. Up to 93.1% (n=54) of the patients were originally from other countries in Africa, mainly from the Democratic Republic of Congo (62.1%, n=36).