Commissioned Corps of the U.S. Public Health Service

Scientist Professional Advisory Committee

Executive Board 2023–2024

Chair: CDR Zewditu Demissie

CDR Zewditu (Zewde) Demissie is the Health Equity Infrastructure and Capacity Building Team Lead for CDCs Office of Health Equity’s (OHE). Her team is responsible for activities related to improving and evaluating improvement of state, tribal, local, and territorial capacities and capabilities to effectively address minority health and health equity considerations and fostering growth of the health equity workforce. Before joining OHE, CDR Demissie served as the Associate Chief of Science for the Surveillance Branch in CDC’s Division of Violence Prevention. From 2010-2020, she worked in CDC’s Division of Adolescent and School Health as Supervisory Epidemiologist for the Scientific Support and Innovation Team, Senior Research Scientist, and Epidemic Intelligence Service Officer. CDR Demissie holds both PhD and MPH degrees in Epidemiology, from the University of North Carolina at Chapel Hill and the University of Minnesota – Twin Cities, respectively. She also has a Graduate Certificate in Global Health and Global Health Engagement from the Uniformed Services University of the Health Sciences. She is a behavioral epidemiologist qualified in occupational and environmental epidemiology, with expertise in youth populations, obesity-related factors, injury and violence, sexual health, and substance use. She has more than 50 scientific publications and has contributed to more than 60 scientific oral and poster presentations.

CDR Demissie commissioned into the U.S. Public Health Service Commissioned Corps in 2010. She is a former member of Rapid Deployment Force 3 and National Incident Support Team B, and has deployed for agency and service responses, including polio, Ebola, natural disasters, and COVID-19. She has served in several USPHS Commissioned Corps leadership roles, including as Atlanta Commissioned Officers Association President, Black Commissioned Officers Advisory Group Executive Secretary, Atlanta PACE Lead, and Editor-in-Chief of the PACE newsletter. She has contributed to more than 40 USPHS-related publications. Her previous major SciPAC roles have included Career Development Subcommittee Co-Chair and SciPAC Awards Subcommittee Chair, but her involvement has extended to the Category Day, Mentoring, Rules and Membership, Science, and Visibility Subcommittees. CDR Demissie is excited to serve as your Chair and welcomes any feedback on how we can best support our PAC and showcase the great accomplishments of Scientist Officers.

Chair-Elect: CDR Colleen Scott

LCDR Colleen Scott

CDR Colleen Scott is the Protocol Unit Lead for the Division of Global HIV and Tuberculosis (DGHT) at the Centers for Disease Control and Prevention’s Global Health Center. In this role, she serves as a subject matter expert in human subjects protections and research methods for the Division, and provides scientific guidance and support for research and non-research activities across 25 DGHT country and 3 DGHT regional offices. CDR Scott is a behavioral epidemiologist with expertise in infectious diseases, immunizations, and emergency response. During her time as an officer, she has responded to both CDC- (Ebola (2014 West Africa), Ebola (2019 DRC), COVID-19 (2020-2021), MPX (2022)) and HHS-directed emergency responses (Hurricanes Harvey/Maria/Irma 2018 & 2019), and NDMS/DMAT training (2019)). CDR Scott was commissioned into the U.S. Public Health service in 2012 as a Health Services Officer in the Jr Commissioned Officer Student Training Program and commissioned in the regular corps as a Scientist Officer in 2014 when she joined the CDC Epidemic Intelligence Service assigned to the Division of Tuberculosis Elimination. She earned a DrPH in Community and Behavioral Health from East Tennessee State University and an MPH in Behavioral Sciences and Health Education from Emory Rollins School of Public Health in Georgia. She previously served as SciPAC Executive Secretary and Chair and Co-Chair of the Visibility Subcommittee, among other SciPAC roles.

Executive Secretary: LCDR Jonathan Leshin


LCDR Jonathan Leshin is a Senior Regulatory Review Officer for the Division of Human Food Safety in the Center for Veterinary Medicine at the FDA. In this role, he serves as a subject matter expert on the food safety of veterinary drugs as well as a specialist in the human user safety of veterinary drugs. During his time as an officer, he has deployed for RDB as a Data and Information Section Chief across three deployments (COVID-19 2021, 2022, UAC 2021), an information management officer (Hurricane Ian 2022, COVID-19 2020, Typhoon Mangkhut/Hurricane Florence 2018), and a case manager (Hurricanes Harvey/Irma/Maria 2018). LCDR Leshin served his initial USPHS Commissioned Corps detail at the EPA as an antimicrobial pesticide toxicologist. He received his PhD from Georgetown University in Pharmacology with a focus on biological weapons defense. Prior to serving as the SciPAC Executive Secretary, he served for 3 years as the Executive Director of Prevention through Active Community Engagement (PACE) as well as 2 years as its Chief of Staff. Within SciPAC, he has served as Recruitment and Retention Subcommittee Chair, Policy Subcommittee Co-Chair, and Visibility Subcommittee Co-Chair, among other roles.


Executive Liaison: LCDR Shayne Gallaway 

LCDR Shayne Gallaway

LCDR Michael “Shayne” Gallaway commissioned as a Scientist Officer in 2016 after 12 years combined serving on active-duty in the Air Force and as a post-doctoral Civilian Scientist in the Army. He began his Commissioned Corps career at CDC with assignments in the Division of Health Informatics, Division of Cancer Prevention, and Division of Population Health. He is currently assigned to the Department of Defense, Defense Health Agency, Global Emerging Infections Surveillance Branch. Serving as the Respiratory Infections Focus Area Lead, LCDR Gallaway is responsible for enhancing global health security by coordinating global surveillance networks that promote rapid detection of respiratory pathogens with pandemic potential, including 15 partners laboratories and 25 projects across 40 countries. During his time as an officer, he has responded on several CDC-(Zika (2016), Hurricane Harvey (2017), Ebola (2019), COVID-19 Case Investigation (2020-21), Ebola (2022)) and HHS-directed emergency responses (Hurricane Maria (2017), Hurricane Florence (2018), COVID-19 Testing sites (2020), Unaccompanied Children (2021)). LCDR Gallaway earned a Ph.D. in Epidemiology and Biostatistics and an MPH in Behavioral Sciences from the University of Texas School of Public Health. He previously served as Chair and co-Chair of the Mentoring Subcommittee, among other SciPAC roles, and has also been very active in local COAs.


Immediate Past Chair: CDR Alice Shumate

CDR Alice Shumate

CDR Alice Shumate is the Director of the Center for Maritime Safety and Health Studies at the Centers for Disease Control and Prevention’s National Institute of Occupational Safety and Health. In this role she serves as a national subject matter expert on safety and health of maritime workers, and provides scientific guidance and fosters collaboration among researchers, industry, labor groups, and other partners. CDR Shumate is an epidemiologist with expertise in infectious diseases, environmental health, and occupational health. She has also served as a responder for natural disasters and outbreaks both nationally and internationally, including for Hurricane Sandy, MERS-CoV-2, Ebola, Hurricanes Irma and Maria, and in numerous roles as part of the COVID-19 emergency response.

CDR Shumate has previously served as a Voting Member and Financial Liaison for the Junior Officer Advisory Group. As an active member of the Scientist Category since her commissioning, she has served on several Subcommittees, including Rules and Membership, Category Day, Career Development, and the Recruitment, Retention, and Readiness Subcommittee, as well as having previously served as SciPAC Executive Secretary. CDR Shumate was commissioned into the U.S. Public Health Service as a Scientist Officer in 2012, where she began her career as a CDC Epidemic Intelligence Service (EIS) Officer assigned to the New Jersey Department of Health. She holds a Ph.D. in Evolutionary Biology from Dartmouth College and an MPH from the University of Washington.


SciPAC Chairs 1984–Present

Officer Agency Term                    
RADM Barry L. Johnson CDC 1984-1986
CDR Andrea A. Wargo FDA 1986-1988
CAPT Harry Milman EPA Sep 1988-Aug 1989
CAPT Jerry Johnson USCG Sep 1989-Aug 1990
CAPT John Bartko ADAMHA Sep 1990-Aug 1991
CAPT Derek Dunn CDC Sep 1991-Aug 1992
CDR Stephen Wilson FDA Sep 1992-Aug 1993
CAPT John Pennington FDA Sep 1993-Aug 1994
CDR Roland Garcia HRSA Sep 1994-Aug 1995
CAPT Joe Sun FDA Sep 1995-Aug 1996
CAPT Michael Alavanja NIH Sep 1996-Aug 1997
CDR S. Lori Brown FDA Sep 1997-Aug 1998
CDR Francois Lalonde NIH Sep 1998-Aug 1999
CDR Rebecca Sheets FDA Sep 1999-Aug 2000
CDR Richard Troiano NIH Sep 2000-Aug 2001
CDR Angela González Williams HRSA Sep 2001-Aug 2002
CDR Joe Despins FDA Sep 2002-Aug 2003
CDR Doug Thoroughman CDC Sep 2003-Mar 2004
LCDR Daphne Moffett CDC Apr 2004-Aug 2005
LCDR Ross Spears CDC Sep 2005-Aug 2006
CDR Martin Sanders CDC Sep 2006-Aug 2007
CDR Sara Newman NPS Sep 2007-Aug 2008
CDR Rachel Avchen CDC Sep 2008-Aug 2009
CDR Diana Bensyl CDC Sep 2009-Aug 2010
CDR Matthew Newland HRSA Sep 2010-Aug 2011
CDR Karon Abe CDC Sep 2011-Aug 2012
CDR Ryan Novak CDC Sep 2012-Aug 2013
CDR Nicole Frazer DOD Sep 2013-Aug 2014
CAPT Nisha Robbins DOD Sep 2014-Aug 2015
CDR Matthew Murphy CDC Sep 2015-Aug 2016
CDR Jennifer Adjemian NIH Sep 2016-Aug 2017
CDR Robin Toblin DOD Sep 2017-Aug 2018
CAPT Jennifer Thomas CDC Sep 2018-Aug 2019
CAPT Loren Rodgers CDC Sep 2019-Aug 2020
LCDR Jason Wilken CDC Sep 2020-Aug 2021
CDR Deborah Dee CDC Sep 2021-Aug 2022
CDR Alice Shumate CDC Sep 2022-Aug 2023
CDR Zewditu Demissie CDC Sep 2023-present

ADAMHA: Alcohol, Drug Abuse, and Mental Health Administration
CDC: Centers for Disease Control and Prevention
DOD: Department of Defense
EPA: Environmental Protection Agency
FDA: Food and Drug Administration
HRSA: Health Resources and Services Administration
NIH: National Institutes of Health
USCG: United States Coast Guard

Page Last Modified on 9/27/2023

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