Tokarz, Rafal

Rafal Tokarz, PhD
Associate Research Scientist
Center for Infection & Immunity
Columbia University Mailman School of Public Health, New York, NY

“Virome Analysis in Ticks”

Dr. Tokarz’s research focuses on microbial discovery and the epidemiology of human infectious diseases. His primary interests center on investigating respiratory and tick-borne pathogens and understanding their roles in human disease.

Dr. Tokarz’s work in the field of tick-borne disease has been driven by two main hypotheses: 1) co-infections in human-biting ticks are common and can result in human poly-microbial infections; and 2) viral infections represent a proportion of undiagnosed tick-transmitted diseases. He designed and implemented one of the first multiplex PCR assays that targeted tick-borne agents and was one of the first scientists to document high rates of pathogen co-infections in ticks within New York State. His recent work has focused on exploring the diversity of the tick virome. He performed the first investigation of the virome of the three main human-biting ticks in New York State and thus far has discovered over 20 novel tick-associated viruses. He is now examining the potential for transmissibility and pathogenesis of these viruses.

In an effort to understand the etiology of respiratory diseases, Dr. Tokarz has participated in pathogen surveillance studies on specimens originating from Asia, Africa, Europe, South and North America. As part of this work, he used cutting edge molecular platforms to identify and characterize novel viral agents. Dr. Tokarz identified and characterized the first defined cluster of one such virus, enterovirus D68, an emerging agent implicated in a severe outbreak of pediatric respiratory disease in the US in 2014. He performed the first comprehensive phylogenetic characterization of this virus, identified the three main clades circulating worldwide and developed a classification system now employed by investigators in this field. In his current work, Dr. Tokarz is examining the pathogenesis of this virus and how its genetic variation influences the severity of disease.

Conference Lecture Summary

Tick-borne diseases are the most common vector-borne illnesses in the United States. In a proportion of presumed tick bite-associated infections, the etiologic agent is never identified, and the full range of tick- borne pathogens has not yet been explored. In contrast to bacterial pathogens, there is a limited understanding of the diversity of tick-borne viruses and their role in human infection. We are performing a virome analysis of the three main human-biting ticks endemic to the New York metropolitan area, with the goal of uncovering novel viral agents and determining their geographic distribution and prevalence. For novel viruses with homology to known pathogens, we will design serological assays to examine sera from subjects with history of tick bites for evidence of spillover of these viruses into the human population.