Bloch, Evan

Evan M. Bloch, MD, MS
Assistant Professor
Associate Director, Transfusion Medicine
Johns Hopkins University, Baltimore, MD

“Babesia & the Blood Supply: Lessons Learned”

Evan M. Bloch, MBChB (M.D.), M.S. is an Assistant Professor in the Department of Pathology where he is an Associate Director in the Division of Transfusion Medicine. Dr. Evan Bloch is an Assistant Professor at Johns Hopkins University in the Department of Pathology and an Associate director in the Transfusion Medicine division at Johns Hopkins Hospital.

His major interests include both transfusion transmitted babesiosis and other neglected infectious diseases, particularly in the context of international blood safety. His interest in babesiosis was spurred by a case of transfusion-transmitted babesiosis during his transfusion medicine fellowship. He has since participated in studies of assay development and cost effectiveness related to transfusion screening in the United States.

Dr. Bloch is originally from South Africa where he completed his medical school (University of Cape Town) and clinical training, which first spurred an interest in infectious disease. Following completion of a combined residency in Anatomic and Clinical Pathology (Tufts Medical Center), post-graduate fellowship in Transfusion Medicine (University of California San Francisco [UCSF]) and Masters in Global Health (UCSF) he continued research at Blood Systems Research Institute, while continuing to teach at UCSF in Laboratory Medicine and Global Health Sciences. He joined the faculty of at Johns Hopkins University in the Department of Pathology in 2015.

Dr. Bloch has long been interested in babesiosis and other transfusion transmitted infections. Babesiosis is a tick-borne parasitic infection that is endemic to parts of the United States. Although infection is characterized by mild illness (e.g. flu-like symptoms) in immune competent adults, it poses significant risk to those patients at extremes of age, the immunocompromised and the asplenic. These high-risk groups are notably overrepresented among the transfused population accounting for complicated disease and even death in transfusion-transmitted babesiosis (TTB). Despite an increase in both naturally acquired- and TTB, there are currently no effective strategies to prevent TTB, nor any FDA licensed tests for blood product screening. Dr. Bloch has participated in studies to develop both antibody and molecular testis for detection of Babesia in blood donors. The studies have also been used to understand the biology of Babesia infection.

Dr. Bloch is also interested in blood safety in resource-constrained settings. He is an investigator on the Recipient Epidemiology and Donor Evaluation Study (REDS-III) in South Africa where he has helped lead a series of studies on transfusion practice and HIV in the obstetric population. Blood transfusion is a severity outcome measure for a variety of disease states; as such it can be used to highlight deficiencies in care, thereby informing rational intervention. Dr. Bloch also participated in an evaluation of transfusion infectious screening in twelve African countries; the findings highlighted the challenges surrounding extant testing methods and emphasized the need for proficiency testing for donor screening in Africa. He has been actively involved in education and operational outreach related to blood safety in Africa.

Dr. Bloch’s research has been funded through the National Heart, Lung and Blood Institute of the National Institutes of Health (NIH) through SBIR and R21 grant mechanisms.

The author of 27 peer-reviewed publications, Dr. Bloch is a member of the International Society of Blood Transfusion infectious disease working party (co-chair parasite sub-group) and has consulted on policy and development of clinical transfusion guidelines. He continues to be interested in rare and neglected infections and hopes to use blood transfusion as a platform for infectious surveillance so as to guide programmatic support, particularly in low-resource settings.

Conference Lecture Summary

Babesiosis is the clinical illness named for infection by Babesia, a genus of tick borne, intraerythrocytic protozoan parasites that are endemic to parts of the United States (US). Babesia is readily transfusion transmissible: following an increase in naturally acquired- (i.e. tick borne) and transfusion transmitted babesiosis (TTB) in the US, TTB, the overwhelming majority of which is caused by Babesia microti, has been recognized as the foremost infectious risk to the US blood supply for which licensed donor screening is still not available. Change is underway whereby new tools have been developed, including novel assays and pathogen reduction technology. The purpose of this talk is to discuss Babesia as a model for understanding the response to an emerging infectious disease in the context of blood safety. The talk will include lessons that were learned during the evolution from recognition of risk, to selection of a mitigation strategy, research and development through to implementation and policy. While nuanced challenges may be specific to babesia, the same principles apply to other pathogens, both known as well as emerging.