Our Fellows

First Year

Idalis Cardona Ortiz, MD

I was born and raised in Puerto Rico, where I earned my medical degree from the University of Puerto Rico Medical Sciences Campus before pursuing a residency in Pediatrics at Yale University. I am excited to be joining the Allergy & Immunology program at Dartmouth and look forward to exploring all that the Upper Valley has to offer, especially New England’s beautiful fall foliage and the region’s unique charm. My professional interests include continuing research on health disparities and advancing efforts to improve healthcare access for patients and their families. Outside of medicine, I enjoy spending time in nature, hiking, traveling, practicing pilates, reading, watching TV shows, enjoying Puerto Rican coffee, and spending time with my family and two pet bunnies.

Jason Sanders, MD

I grew up in Southern Utah in Cedar City, Utah which is close to Zion National Park. I completed my undergraduate degree here at Southern Utah University in Human Nutrition. I moved to Meridian, Idaho for medical school and completed this at Idaho College of Osteopathic Medicine. I moved to New Hampshire in 2023 where I attended Pediatrics Residency here at Dartmouth Hitchcock Medical Center. I’m excited I have the opportunity to stay here to continue my training in Allergy and Immunology. I enjoy spending my free time with my wife and 2 children, being outdoors at parks or hiking, reading books, and playing/listening to music.

Second Year

Nathan Blaseg, MD

I grew up in Pierre, South Dakota and attended Montana State University for my undergraduate studies. I returned to South Dakota for medical school and then completed Pediatrics Residency at the University of Utah. I am excited to be joining the close-knit community of the Dartmouth Allergy and Clinical Immunology Program. I am particularly excited by our robust oral immunotherapy program, collaborative and unique research opportunities, and Dartmouth Hitchcock’s focus on improving rural healthcare. Outside of medicine, I love all things outdoors. My wife, 2 dogs, and I love camping, hiking, skiing, swimming, and visiting all of the beautiful small towns scattered throughout New England.

Alexander Zajack, MD

I grew up in Nevada, where I also attended medical school at the University of Nevada Las Vegas. I completed my pediatrics residency training at the University of Vermont. I am super excited to be completing my fellowship in Allergy and Immunology at Dartmouth Hitchcock Medical Center. Outside of medicine, I enjoy spending time outdoors with my spouse and child, watching all kinds of sports on television, or trying new restaurants.