SJGH Faculty & Staff

Asma Jafri, MD
Family medicine department chair / INTERIM PROGRAM DIRECTOR

Dr. Jafri completed her residency in our institution. Her areas of interest are chronic disease management, practice improvement and geriatrics care. Dr. Jafri is certified by ABFM - American Board of Family Medicine

BHanu Wunnava, MD
CLINICAL FACULTY

After finishing medical school in India,  Dr. Wunnava did his residency in Family Medicine at Louisiana State University, LSUHSC, in Shreveport, Louisiana (2004-2007).  He joined as an Assistant Professor in Family Medicine department in LSUHSC after his residency and provided full spectrum family medicine teaching.  He is board Certified by ABFM - American Board of Family Medicine. His areas of interest are infectious disease prevention, control, and pharmacology.  Healthy lifestyle, weight management, diabetes, and arthritis are some other areas of interest.  Dr. Wunnava enjoys a variety of sports and writing books on positive energy and the philosophy of life in his free time.  

Sabhrup biring, MD
Clinical Faculty

Dr. Biring graduated from Acharya Sri Chander college of Medical Sciences and Research in India. She completed her family medicine residency in our institution. After completing her residency she completed FM-OB fellowship at SJGH. Her areas of interest include Primary care, Women’s health, mental health and outpatient procedures including gynecological procedures. She also loves to teach! Outside medicine she likes cooking, dancing to Bollywood music and is a full time mom of 3 kids including twins!

Alicia romero
Program Coordinator

Alicia serves as the residency program coordinator for Family Medicine Residency at San Joaquin Hospital. She began her career here as a senior office assistant in the surgery department during the COVID-19 pandemic. She recently joined the graduate medical education team. Born and raised in Stockton, Alicia's deep roots in the community and experience, working directly with patients have helped ease her transition into this role. She now supports the residents who care for underserved populations, and is excited to go in this position. She's ensuring they have the support and resources needed to become well-rounded Family Medicine physicians. Outside of work, and Lisandra!! is traveling, attending concerts, and discovering new foods and local coffee shops.

Maggie Guerrero

Department Secretary

Magdalena "Maggie" has been at San Joaquin General Hospital since 2014. She started in the transitions of care unit and then transferred to the Family Medicine department in 2022. She really enjoys working with the residents and watching them girl from interns to fully fledged positions. It's a very rewarding process to experience! In her spare time she enjoys going to the beach, spending time with her family, and especially her six grandchildren. 

Felipe Chavez, MD
Clinical Faculty

Dr. Chavez graduated from Universidad de Guadalajara in Mexico. He completed an internal medicine residency in Mexico in 2020. He then completed a family medicine residency at San Joaquin General Hospital in 2025. He has a board certification from the American Board of Family Medicine. His professional interests include hospital, medicine, capital POCUS, chronic disease, management, geriatrics, substance, use disorders, and primary care. When he's in the hospital, Andrews, reading philosophy in history, and enjoy camping with his family.

Carol’s moNTES castellon, MD
Clinical Faculty / OB feLLOWSHIP co-Director

Dr. Montes Castellon completed her undergraduate studies at UCLA, and graduated from UC DAVIS School of Medicine. She developed her love for obstetrics during her rotation as a medical student at San Joaquin General Hospital. She completed her family medicine residency at Contra Costa Regional Medical Center, and obtained further training in surgical obstetric and care of high risk neonates through PCC Wellness/ West Suburban Parent Child Health Fellowship in Chicago, Illinois. She co-leads the OB Advanced Obstetrics fellowship, where she integrates her passion for whole person longitudinal health care, substance use disorders in pregnancy, and surgical obstetrics, all while promoting and practice full spectrum family medicine. Her interests outside of medicine include adventures with her dog, growing many plants, and advocating for immigrant rights.

Ramiro Zuniga, MD, MBA, FAAFP
Community Preceptor

Ramiro Zúñiga is the Vice President, Medical Director for Medi-Cal at Health Net. In this role, Dr. Zúñiga has leadership and oversight responsibilities for the contractual, compliance, and regulatory requirements for the Medi-Cal line of business. He also provides strategic and operational direction for quality, utilization management, and administrative/clinical policies, procedures, and programs. Prior to joining Health Net, Dr. Zúñiga was Chair of the Department of Family Medicine, Residency Program Director, and a member of the Board of Trustees at San Joaquin General Hospital in Stockton.

Ramiro is a Volunteer Clinical Professor at the Department of Family and Community Medicine of the University of California, Davis School of Medicine. He also serves on the Board of Directors of the Sacramento Latino Medical Association (SaLMA), co-leads the Northern California Chapter and serves in the Corporate Advisory Board of the National Hispanic Medical Association (NHMA), and is a member of the Board of Directors of the Archstone Foundation.

Ramiro earned his M.D. from the Pontificia Universidad Javeriana, in Bogotá, Colombia and completed his Family Medicine Residency at St. Mary of Nazareth Hospital Center in Chicago. He received an MBA degree from the UC Davis Graduate School of Management. He is board certified in family medicine and licensed in California, where he has practiced in underserved settings for over 25 years.

ERIC CHAPA, MD
COMMUNITY PRECEPTOR

 Dr Chapa graduated from medical school from University of California, Irvine. He completed residency at San Joaquin General Hospital in 1979. He was in private practice for over 40 years. He specialized in obstetrics, minor surgeries and ER medicine. Dr. Chapa worked for 18 years in the emergency room. He continues to keep his skills fresh as a surgical assistant within the community he grew up in. He also serves as a community preceptor in our continuity clinics. His professional interests include dive medicine. His hobbies include scuba diving, technical diving, an amateur radio.

Maureen Abaray, NP
Geriatric medicine

Maureen Abaray, FNP: Maureen was a pivotal team member of the Geriatrics Clinic at SJGH previously and has also been employed by the Health Plan of San Joaquin engaging in home visits for patients with chronic disease. She is a Certified Diabetes Educator. Her expertise in community resources stems from her residence in Stockton and Lodi for over 30 years. Maureen has language fluency in Spanish in integral to improving the quality of care our residency provides.