Leadership Team










Dirk Zirbel, Ph.D.

Chief Executive Officer

Dirk Zirbel, Ph.D. has more than 25 years of healthcare operations experience, both in the for-profit and non-profit entities.  Dr. Zirbel has managed large scale clinic operations, with over 38 medical centers and 400,000 patient lives in his previous role as a Chief Operating Officer.  He has overseen various FQHCs (Federally Qualified Health Center) as Executive Director, and is currently the Chief Executive Officer for Operation Samahan.  He has a Ph.D. in Psychology, and a specialization in Industrial and Organizational Psychology from Alliant International University.











Federico Guerrero

Chief Operating Officer

With over 15 years of experience in Healthcare Operations, Federico is devoted to supporting the Mission of Operation Samahan. As an Operations Leader, he has experience with multiple service lines which include Primary Care, Women’s Health, Dental, Behavioral Health, Family Planning, HIV and Pharmacy. Additionally, Federico has been a key member for a Patient Centered Medical Home (PCMH) Level 3 Accreditation team for other FQHC health centers and has been a lead committee member of BCCQ (Building Clinic Capacity Quality) Grant, PCMH and Lean Six Sigma (LSS) teams.  Federico received a certification for Executive Management for Non-Profits from Brandman University and is a certified faculty member of the Institute of Healthcare Communications (IHC) and certified trainer of the programs “Treating patients with C.A.R.E. and Coaching for Impressive Care C.F.I.C.” The Institute for Healthcare Communication (IHC) advances the quality of healthcare by optimizing the experience and process of healthcare communication. He has taught CME eligible communication and development courses throughout the state of California.











Laura Rau

Chief Financial Officer

Laura has 25 years of financial, accounting management, and strategic planning experience in a variety of settings: profit, not for profit, and government. She has complimented her education and professional experience with active involvement and leadership in community service organizations. Laura has a BA in Economics from Whittier College, and a MBA in Finance, graduate studies in business law and strategic planning from University of Phoenix. She is certified as a Public Funds Investment Manager and as a Notary Public. Laura enjoys outside activities with her family, children and granddaughters, when she is not riding her motorcycle throughout the Northwest.











Tanushree Ghosh, DO

Chief Medical Officer

Dr. Ghosh is a board-certified Pediatrician who has been practicing since 2001. She attended the University of Medicine and Dentistry of New Jersey  and completed a residency in Pediatrics at Newark Beth Israel Medical Center in New Jersey. She sees patients from birth to age 18 years for the following services: newborn care, preventive health examinations, sport physicals, acute and chronic illnesses.  She loves educating and spending time with first time parents as they begin their journey into parenthood.  Dr. Ghosh is a mother to two beautiful girls and enjoys reading, trying out new recipes, and traveling with her family.











Mary Ann Sanvictores, DDS

Chief Dental Officer

Dr. Mary Ann V. Sanvictores has over 19 years of experience in the clinical and administrative setting of dentistry. She attended Loma Linda University School of Dentistry advanced pre-clinical and clinical courses. She is board certified and licensed in Oral Conscious Sedation, board certified and licensed dentist in the state of California since 1997.

She has worked in a Community Health Center for 11 years, and at a Federally Qualified Health Center for 3 years as an experienced provider in general dentistry. Dr. Sanvictores optimized the Electronic Dental Recording (EDR) system by providing smart note configuration-dental templates, conducted peer review of chart documentation, stream-lined the scope of dental services, and is currently the Chief Dental Officer at Operation Samahan, Inc.

She is an international graduate from the University of the East School of Dentistry, and a medical graduate at Perpetual Help College of Medicine. She completed her post graduate medical training at Rizal Medical Center and is board certified and licensed in both fields of dentistry and medicine in the Philippines.