Mesa West Medical

William E. Gilli, M.D., F.A.C.P.

Physician

Dr. Gilli is a Bakersfield native. He attended West High School and graduated from the USC School of Medicine in 1983. Dr. Gilli is Board Certified in Internal Medicine. He is an Assistant Professor of Medicine at UCLA teaching at Kern Medical from 1993 until 2019. At Kern Medical, he has helped teach over 300 physicians for 26 years until retiring from Kern Medical in 2019. Since Retiring from Kern Medical, Dr. Gilli is working full time at Mesa West Medical. He is also a Fellow at the American College of Physicians. In early 2009, Dr. Gilli underwent a total hip replacement and has returned to running. He is an avid walker, runner, cyclist, and skier.

Tracy Simonsen ACNP-C

Nurse Practitioner

Tracy Simonsen received her Bachelor’s Degree from Cal State University Bakersfield in Nursing. She then worked in Intensive Care Medicine for the next 7 years at Kern Medical Center. She obtained her Master's Degree from UCLA in Nursing with a specialty as an Acute Care Nurse Practitioner. Tracy Simonsen has been at Mesa West Medical since 1996. Tracy enjoys tennis and golf.

Sarah Dowda AGNP-C

Nurse Practitioner

Sarah Dowda received her Bachelor’s Degree from Western Governor's University in Nursing in 2018. She then worked as an admission nurse and clinical manager for the next 5 years at a local hospice. She obtained her Master's Degree from Walden University in Nursing with a specialty as an Adult-Gerontology Primary Care Nurse Practitioner. Sarah Dowda has been at Mesa West Medical since 2023. Sarah is a huge Alabama Crimson Tide football fan.