Elissa A Hallem

Department Vice Chair, MIMG, University of California Los Angeles

Professor, MIMG, University of California Los Angeles

(310) 825-1778

Our research focuses on sensory circuit function in parasitic and free-living animals, and lies at the interface of neurobiology and parasitology. Nearly all organisms respond to sensory stimuli, but how sensory circuits specify behavior is poorly understood. We are investigating the neural basis of sensory behaviors in the context of human parasitism. We use parasitic nematodes and the free-living nematode C. elegans as models. The goals of our research are to understand how parasitic worms use sensory cues to locate and infect hosts, how sensory circuits of parasitic animals differ from those of free-living animals to enable parasitic behaviors, and how sensory microcircuits generate flexible outputs. Our research addresses fundamental questions of sensory circuit function and evolution. In addition, human-parasitic worms are a major cause of morbidity worldwide, and a better understanding of their behaviors may enable the development of novel strategies for preventing infections.


parasitology, host-seeking behavior, sensory neurobiology, skin-penetrating nematodes, neuroscience

Education and Training

Yale UniversityPhD05/2005Neuroscience
Williams CollegeBA06/1999Biology and Chemistry

Awards and Honors

  • Searle Scholar Award, 2012.
  • MacArthur Fellowship, 2012.
  • Burroughs-Wellcome Fund Investigators in the Pathogenesis of Disease Award, 2015.
  • UCLA Life Sciences Excellence in Research Award, 2023.
  • Rita Allen Foundation Fellowship, 2011.
  • UCLA DGSOM John H. Walsh Young Investigator Research Prize, 2015.
  • NIH Director's New Innovator Award, 2014.
  • McKnight Scholar Award, 2013.
  • Alfred P. Sloan Research Fellowship, 2011.
  • UCLA Faculty Mentor Award, 2020.
  • HHMI Faculty Scholar Award, 2016.
  • UCLA Dean's Recognition Award, 2013.


  1. Banerjee, N., Rojas Palato, E.J., Shih, P.Y., Sternberg, P.W., and Hallem, E.A.. Distinct neurogenetic mechanisms establish the same chemosensory valence state at different life stages in Caenorhabditis elegans. G3, 2024.
  2. Bryant AS, Akimori D, Stoltzfus JDC, Hallem EA. A standard workflow for community-driven manual curation of Strongyloides genome annotations. Phil Trans R Soc B, 2023.
  3. McClure CR, Patel R, Hallem EA . Invade or die: behaviors and biochemical mechanisms that drive skin penetration in Strongyloides and other skin-penetrating nematodes. Phil Trans R Soc B, 2023.
  4. Al-Jawabreh R, Anderson R, Atkinson LE, Bickford-Smith J, Bradbury RS, Breloer M, Bryant AS, Buonfrate D, Cadd LC, Crooks B, Deiana M, Grant W, Hallem E, Hedtke SM, Hunt V, Khieu V, Kikuchi T, Kounosu A, Lastik D, van Lieshout L, Liu Y, McSorley HJ, McVeigh P, Mousley A, Murcott B, Nevin WD, Nosková E, Pomari E, Reynolds K, Ross K, Streit A, Suleiman M, Tiberti N, Viney M.. Strongyloides questions-a research agenda for the future. Phil Trans R Soc B, 2023.
  5. Castelletto ML, Akimori D, Patel R, Schroeder NE, Hallem EA. Introduction to Strongyloides stercoralis Anatomy. WormAtlas, 2023.
  6. Banerjee N, Shih PY, Rojas Palato EJ, Sternberg PW, Hallem EA.. Differential processing of a chemosensory cue across life stages sharing the same valence state in Caenorhabditis elegans. Proc Natl Acad Sci USA, 2023.
  7. Atkinson LE, Hallem EA.. Editorial - Strongyloides research in the post-genomics era. Mol Biochem Parasitol, 2022.
  8. Wheeler NJ, Hallem EA, Zamanian M. Making sense of sensory behaviors in vector-borne helminths. Trends Parasitol, 2022.
  9. Mendez P, Walsh B, Hallem EA. Using newly optimized genetic tools to probe Strongyloides sensory behaviors. Mol Biochem Parasitol, 2022.
  10. Bryant AS, Ruiz F, Lee JH, Hallem EA. The neural basis of heat seeking in a human-infective parasitic worm. Curr Biol, 2022.
  11. Patel R, Hallem EA. Olfaction: One receptor drives opposite behaviors. Curr Biol, 2022.
  12. Castelletto ML, Hallem EA. Generating Transgenics and Knockouts in Strongyloides Species by Microinjection. J Vis Exp, 2021.
  13. Chavez IN, Brown TM, Assié A, Bryant AS, Samuel BS, Hallem EA. Skin-penetrating nematodes exhibit life-stage-specific interactions with host-associated and environmental bacteria. BMC Biol, 2021.
  14. Bryant AS, Hallem EA. The Wild Worm Codon Adapter: a web tool for automated codon adaptation of transgenes for expression in non-Caenorhabditis nematodes. G3, 2021.
  15. Carstensen HR, Villalon RM, Banerjee N, Hallem EA, Hong RL. Steroid hormone pathways coordinate developmental diapause and olfactory remodeling in Pristionchus pacificus. Genetics, 2021.
  16. Bryant AS, DeMarco SF, Hallem EA. Strongyloides RNA-seq Browser: a web-based software platform for on-demand bioinformatics analyses of Strongyloides species. G3, 2021.
  17. Gang SS, Castelletto ML, Yang E, Ruiz F, Brown TM, Bryant AS, Grant WN, Hallem EA. Chemosensory mechanisms of host seeking and infectivity in skin-penetrating nematodes. Proc Natl Acad Sci USA, 2020.
  18. Banerjee N, Hallem EA. The role of carbon dioxide in nematode behavior and physiology. Parasitol, 2020.
  19. Castelletto ML, Gang SS, Hallem EA. Recent advances in functional genomics for parasitic nematodes of mammals. J Exp Biol, 2020.
  20. Banerjee N, Hallem EA. Decoding Inter-individual Variability in Experience-Dependent Behavioral Plasticity. Neuron, 2020.
  21. Rengarajan S, Yankura KA, Guillermin ML, Fung W, Hallem EA. Feeding state sculpts a circuit for sensory valence in Caenorhabditis elegans. Proc Natl Acad Sci USA, 2019.
  22. Bryant AS, Hallem EA. Terror in the dirt: Sensory determinants of host seeking in soil-transmitted mammalian-parasitic nematodes. Int J Parasitol Drugs Drug Resist, 2018.
  23. Bryant AS, Hallem EA. Temperature-dependent behaviors of parasitic helminths. Neurosci Lett, 2018.
  24. Bryant AS, Ruiz F, Gang SS, Castelletto ML, Lopez JB, Hallem EA. A Critical Role for Thermosensation in Host Seeking by Skin-Penetrating Nematodes. Curr Biol, 2018.
  25. Banerjee N, Hallem E. Sexual Dimorphisms: How Sex-Shared Neurons Generate Sex-Specific Behaviors. Curr Biol, 2018.
  26. Ruiz F, Castelletto ML, Gang SS, Hallem EA. Experience-dependent olfactory behaviors of the parasitic nematode Heligmosomoides polygyrus. PLoS Pathog, 2017.
  27. Gang SS, Castelletto ML, Bryant AS, Yang E, Mancuso N, Lopez JB, Pellegrini M, Hallem EA. Targeted mutagenesis in a human-parasitic nematode. PLoS Pathog, 2017.
  28. Guillermin ML, Carrillo MA, Hallem EA. A Single Set of Interneurons Drives Opposite Behaviors in C. elegans. Curr Biol, 2017.
  29. Park HB, Sampathkumar P, Perez CE, Lee JH, Tran J, Bonanno JB, Hallem EA, Almo SC, Crawford JM. Stilbene epoxidation and detoxification in a Photorhabdus luminescens-nematode symbiosis. J Biol Chem, 2017.
  30. Cevallos JA, Okubo RP, Perlman SJ, Hallem EA. Olfactory Preferences of the Parasitic Nematode Howardula aoronymphium and its Insect Host Drosophila falleni. J Chem Ecol, 2017.
  31. Rengarajan S, Hallem EA. Olfactory circuits and behaviors of nematodes. Curr Opin Neurobiol, 2016.
  32. Gang SS, Hallem EA. Mechanisms of host seeking by parasitic nematodes. Mol Biochem Parasitol, 2016.
  33. Lee JH, Dillman AR, Hallem EA. Temperature-dependent changes in the host-seeking behaviors of parasitic nematodes. BMC Biol, 2016.
  34. Peña JM, Carrillo MA, Hallem EA. Variation in the susceptibility of Drosophila to different entomopathogenic nematodes. Infect Immun, 2015.
  35. Castelletto ML, Gang SS, Okubo RP, Tselikova AA, Nolan TJ, Platzer EG, Lok JB, Hallem EA. Diverse host-seeking behaviors of skin-penetrating nematodes. PLoS Pathog, 2014.
  36. Carrillo MA, Guillermin ML, Rengarajan S, Okubo RP, Hallem EA. O2-sensing neurons control CO2 response in C. elegans. J Neurosci, 2013.
  37. Chaisson KE, Hallem EA. Chemosensory behaviors of parasites. Trends Parasitol, 2012.
  38. Dillman AR, Guillermin ML, Lee JH, Kim B, Sternberg PW, Hallem EA. Olfaction shapes host-parasite interactions in parasitic nematodes. Proc Natl Acad Sci USA, 2012.
  39. Guillermin ML, Castelletto ML, Hallem EA. Differentiation of carbon dioxide-sensing neurons in Caenorhabditis elegans requires the ETS-5 transcription factor. Genetics, 2011.