New York Infectious Disease & Public Health Medicine, P.C. Scarsdale, New York

About the physician

Mark N. Sayegh, MD

Board certified in Infectious Disease and Internal Medicine. Clinical Assistant Professor of Medicine at New York Medical College, with a clinical background in hospital-based infectious disease and outbreak response in New York City.

Practice

Portrait of Mark N. Sayegh, MD

Dr. Sayegh sees adults referred for infections that have not responded to first-line treatment, infections that keep returning, and illnesses where the organism has not yet been identified. He also provides general internal medicine care for adult patients.

He completed his infectious disease fellowship at Columbia University College of Physicians & Surgeons at Harlem, a New York City public hospital, where his work covered HIV care and the city’s 2022 mpox response. That experience shapes how the practice approaches communicable disease: identify it accurately, treat it, and account for the people around the patient.

His clinical interests include HIV treatment and pre-exposure prophylaxis, COVID-19, and malaria and other imported infections.

Credentials

Specialty
Infectious Disease
Board certification
Infectious Disease
Internal Medicine
Academic appointment
Clinical Assistant Professor of Medicine, New York Medical College
Fellowship
Infectious Diseases — Columbia University College of Physicians & Surgeons at Harlem, 2024
Residency
Internal Medicine — St. John’s Riverside Hospital (Montefiore Health System), Yonkers, 2022
NPI
1700374360
NY license no.
311603
Hospital affiliation
St. John’s Riverside Hospital
967 North Broadway, Yonkers, NY 10701
Professional memberships
Infectious Diseases Society of America (IDSA)
American Academy of HIV Medicine (AAHIVM)
Languages
English

Recognition

Named Fellow of the Year at Harlem Hospital Center in both his first and second years of infectious disease fellowship, selected from among fellows across all internal medicine subspecialties, and winner of the hospital’s 2024 Research Fair.

Research and publication

Dr. Sayegh has contributed to published work on the clinical management of mpox and on unusual bacterial and parasitic infections encountered in New York City hospitals.

Journal articles

  1. Leocadio C, Garcia E, Lash M, … Sayegh M, et al. Clinical Outcomes of Mpox Disease in Patients Treated with Tecovirimat. Clinical Infectious Diseases. 2025;ciaf520.
  2. Wuni G, Rodrigues P, Sayegh M, Barrington D-S, Sivapalan V. Streptococcus gordonii: an emerging pathogen as a cause of infective endocarditis? Dalhousie Medical Journal. 2025;50(1):10–12.
  3. Sandomirsky K, Sayegh M, Lopez P, Lwin Y, Mannheimer S. Ignatzschineria species Bacteremia: A Case Report and Review of the Literature. Marshall Journal of Medicine. 2025;11(1).
  4. Lopez P, Suleiman S, Valdez Imbert M, Sayegh MN, Schliep T. Plasmodium ovale: Exploring an Atypical Presentation. Cureus. 2024;16(11):e74508.
  5. Garcia EA, Foote MMK, McPherson TD, … Sayegh MN, et al. Severe Mpox Among People With Advanced Human Immunodeficiency Virus Receiving Prolonged Tecovirimat in New York City. Open Forum Infectious Diseases. 2024;11(6):ofae294.
  6. Mellacheruvu S, Sayegh MN, Sica RA, et al. Lymphomatous Meningitis From Anaplastic Lymphoma Kinase+ Anaplastic Large T-Cell Lymphoma Treated With Lorlatinib: A Case Report. JCO Precision Oncology. 2022;6:e2100250.
  7. Chan N, Pak K, Guo A, Singla P, Sayegh M. New-Onset Heart Failure in the Setting of T4-Conversion Disorder. Cureus. 2022;14(5):e25024.
  8. Whiting A, Reyes JVM, Ahmad S, Sayegh MN, Almas T, Song D. Thymic cancer: A not-so-indolent cause of pericardial effusion. Annals of Medicine and Surgery. 2021;71:102866.
  9. Corti MC, Thomas AD, Sayegh MN, Vernon K, Sherman C, Trainor R. Surgicel-Induced Anaphylaxis Post Permacath Placement. Cureus. 2021;13(8):e16938.
  10. Thomas AD, Sayegh M, Shah E, Joseph JJ, Samarneh M. A Rare Case of Idiopathic Adult Intussusception. Medical Case Reports. 2021;7(7):191.

Abstracts and presentations

  1. Mgbako O, Pelliccione AJ, McLean J, et al. Examining CD4, viral load and STI co-infection as predictors of severe mpox outcomes among a cohort of people with HIV in New York City. Poster 218, IDWeek 2025, Atlanta, GA.
  2. Leocadio C, Garcia EA, Lash M, … Sayegh MN, et al. Clinical Characteristics and Outcomes of Patients Treated with Tecovirimat for Mpox Disease: A Large Cohort in New York City. IDWeek 2024, Los Angeles, CA. Open Forum Infectious Diseases. 2025;12(Suppl 1):ofae631.072.
  3. Sandomirsky K, Sayegh M, Lopez P, Lwin Y, Mannheimer S. Ignatzschineria species Bacteremia: A Case Report and Review of the Literature. Harlem Hospital Research Fair, April 2024.
  4. Lopez P, Suleiman S, Valdez M, Sayegh M, Schliep T. Plasmodium ovale: Exploring an Atypical Presentation. Harlem Hospital Research Fair, April 2024.
  5. Shaw R, Schliep T, Sivapalan V, Bratu S, Mannheimer S, Dowie D, Sayegh MN, et al. Clinical features and management of a human monkeypox outbreak: a retrospective observational study in Harlem New York. IDWeek 2023, Boston, MA. Open Forum Infectious Diseases. 2023;10(Suppl 2):ofad500.954.

Make an appointment

New patients are seen by referral and by self-referral. Call the office at 914-222-1486 or see directions and hours.