Can enlarged spleen as a child with rocky mountain tick fever and still enlarged spleen as an adult give problems? Blood test showed low neutrophils

Agree with Dr. F. An enlarged spleen can enhance destruction of blood cells including neutrophils. Depending on the cause of splenic enlargement of spleen, the treatment, if one is warranted, needs to be tailored to the cause.
Need more info. The big spleen from rocky mountain spotted fever as a kid has no effect, but i'm concerned about why your spleen's big now. Arthritis? Gaucher's? Liver disease -- the american lifestyle itself can be sufficient cause. Some folks run low neutrophils in cycles. If absolute count's under 1500, workup's mandatory, much less than that is a danger to life. Glad you're being proactive -- good luck.