Our leadership team

13SICK, National Home Doctor Service is Australia's largest network of home visiting doctors. Proudly Australian, our service has a 30 year history of providing urgent medical care after hours when GP Practices are closed. 13SICK combined the strengths of long term industry leaders: Family Care Medical Services; Melbourne Medical Deputising Service; and GPSolutions. More than 7,000 GPs trust 13SICK to look after their patients after hours.

Accredited to the standards of the Royal Australian College of General Practitioners, with Australian General Practice Accreditation Limited and GPAour reputation for quality care is built on the solid foundation of our Clinical Advisory Group.

Our Executive Management Team works collaboratively with our Clinical Advisory Group to ensure the business provides exceptional, accessible and sustainable healthcare.

Executive management team


  • John Pappalardo

    Chief Executive Officer

    John is an experienced executive who has worked across a number of major industries including healthcare, logistics and manufacturing. He has a track record in driving increased shareholder value through business growth and profit improvement programs.

    John has spent the last 12 years in healthcare, taking particular satisfaction from the higher social responsibility that is bestowed upon healthcare organisations. He is of a clear view that quality and patient-centricity is at the heart of our business purpose.


  • Dr Umberto Russo
    MBBS, FRACGP

    Chief Medical Officer

    Dr Russo has more than two decades’ experience both in General Practice and medical deputising. He established Adelaide’s leading medical deputising service prior to merging with 13SICK, National Home Doctor Service. Dr Russo works closely with the Board overseeing clinical governance, policies and procedures.

  • David Wiggins

    Chief Financial Officer

    David Wiggins is a Chartered Accountant and experienced Chief Financial Officer and Company Secretary, having held the financial leadership roles in a number of ASX listed and private equity owned companies over the past 20 years.

Clinical Advisory Group

Our Clinical Advisory Group is a team of distinguished Medical Directors from around the country who oversee medical governance, and set and review all clinical policies and procedures. The Group also advises Board and Management and offers valuable mentoring to our team of Doctors.

  • Dr Nicholas Demediuk

    Dr Nicholas Demediuk

    MBBS, BEd, FRACGP (LIFE MEMBER), DRANZCOG

    Medical Director - VIC

    • Medical Director: Parkmore Medical Centre
    • Medical Director: Dr Snip Vasectomy Clinics
    • Board member: AGPAL, AGPN, AAGP
  • Dr Bers Wenck

    Dr Beres Wenck
    MBBS, MAICD, FRACGP (HON) FAMA

    Medical Director - QLD

    • Rose-Hunt Award recipient (2012) for outstanding commitment to Australian General Practice
    • AMAQ President's Award (2007) for outstanding contributions to Queensland's health system
    • Past President, Brisbane North Division of General Practice
  • Dr Umberto Russo
    MBBS, FRACGP 

    Chief Medical Officer

    • Founding Partner, gpSolutions, Adelaide's leading medical deputising service prior to its merger with 13SICK. National Home Doctor Service
    • 23 years' experience in medical deputising
    • National Representative on various infection control and sterilization committees, including the National Infection Control Guidelines Steering Committee
  • Dr Spiro Doukakis

    Dr Spiro Doukakis

    MBBS, FRACGP 

    GM - Clinical Governance, SA

    • Founding Partner, gpSolutions, Adelaide's leading medical deputising service prior to its merger with National Home Doctor Service
    • Clinical Adviser for National Home Doctor Service
    • President of National Association of Medical Deputising (NAMDS)
  • Dr Bernd Lorenzen

    Dr Bernd Lorenzen

    MB,BS, DRANZCOG 

    Medical Director - SA

    • General Practitioner with small practice in Kensington Park, Adelaide, SA
    • Continuing interest in bariatric medicine and work with bariatric surgeons
    • Past Chairman of RACGP SA and NT faculty and past federal councillor RACGP, with subsequent involvement in development of Regional Training Programs
    • Previously served with hospital Clinical Privileges committees and  SA Health Clinical Privileges Committees 
  • Dr Paresh Dawda

    MBBS, DRCOG, DFRSH, FRCGP, FRACGP 

    Medical Director - ACT

    • GP and ACT Medical Director for multiple large integrated care clinics
    • Director, Prestantia Health
    • Adjunct Associate Professor, University of Canberra and Honorary Associate Professor, ANU
    • Board Member - Heart Foundation (ACT)
    • Advisory Services with membership of Committees at Australian Commission for Quality and Safety, Australian Digital health Agency, RACGP (Quality Care), Department of Health (Healthcare Homes)
  • Dr Jonathan Levy

    Dr Jonathan Levy

    MBBS, BSc (Medical Psychology), FRACGP, FARGP 

    Medical Director - VIC 

    • Trained in the UK, background in Emergency. Special interest in education
    • Teacher and mentor with National Home Doctor Service
    • Medical Director of SunDoctors Skin Cancer Clinics
    • Indigenous Healthcare for the NT
    • Ongoing role as a Senior Lecturer for the University of Queensland as well as practical surgical teaching and didactic lecturing 
  • Dr Rajendra Prakash

    DSM, Dip Sports Med, FRACGP 

    Medical Director - QLD 

    • Medical educator for AMC bridging programme 2006-2014. RACGP examiner since 2006
    • Visiting Medical Officer - Queensland Health. Member - Service Improvement Group for Kilcoy hospital and Woodford correctional health
    • Active role in induction of new deputising GPs, supervision of DGPs , promoting ongoing education, conducting CPD activities, clinical reviews and audits