Tracy Fischer, PhD Associate Professor of Microbiology and Immunology Tulane National Primate Research Center

COVID-19: Neurological Complications May Be First and Only Complication Interview with:

Tracy Fischer, PhD Associate Professor of Microbiology and Immunology Tulane National Primate Research Center

Dr. Fischer

Tracy Fischer, PhD
Associate Professor of Microbiology and Immunology
Tulane National Primate Research Center  What is the background for this study?

Response: We investigated multiple regions of the brain from SARS-CoV-2 infected Rhesus macaques and African green monkeys for the presence of inflammation and other pathology that may result from COVID-19. Most animals were infected for approximately one month before our investigation, however, two of the African green monkeys developed acute respiratory distress syndrome (ARDS) prior to the study endpoint.  What are the main findings?

Response: Significant inflammation was seen in the brain of all animals, even among those that did not develop severe respiratory disease. We also see an increase in the number of microhemorrhages, which are small bleeds in the brain, and neuronal cell death. These findings are in agreement with the majority of case reports of human patients, as well as autopsy studies on brain of patients who died from COVID-19. What should readers take away from your report?

Response: Neurological manifestations can be a complication of SARS-CoV-2 infection. In fact, they may be the initial or only symptom of infection for some individuals. Additionally, infected patients may experience continuing neurological issues, such as difficulties with concentration and/or memory, or being able to find or understand words. This is not necessarily associated with a severe infection and may occur even in mild or asymptomatic patients. Our findings suggest injury to the brain, as well as continued inflammation may underlie the neurological symptoms of long COVID. What recommendations do you have for future research as a result of this work? 

Response:  Our study was on non-human primates of advanced age. It is important to investigate how the brain is impacted in the context of SARS-CoV-2 infection in younger animals, as neurological manifestations are experienced by individuals across the lifespan. This may also provide insight into the underlying mechanisms of injury to the brain with infection. Additional study of patients with long-term neurological manifestations is also needed to advance our current understanding of the prevalence, types and severities of symptoms, and time to resolution for patients who recover. I would also like to see more advanced neuroimaging of patients experiencing symptoms. Is there anything else you would like to add?

Response: I would like to add that our findings were not influenced by findings among human subjects. We began this study at the start of the pandemic and at that time little to no recovery of brain tissues was done at autopsy due to the additional risks for virus exposure that arise from recovering the brain. This was a very unique situation for us, as we usually have patient information, and it was scientifically interesting to have our findings confirmed as more data from human autopsies, as well as case reports of living patients emerged.  

Any disclosures? I have no disclosures.


Ibolya Rutkai, Meredith G. Mayer, Linh M. Hellmers, Bo Ning, Zhen Huang, Christopher J. Monjure, Carol Coyne, Rachel Silvestri, Nadia Golden, Krystle Hensley, Kristin Chandler, Gabrielle Lehmicke, Gregory J. Bix, Nicholas J. Maness, Kasi Russell-Lodrigue, Tony Y. Hu, Chad J. Roy, Robert V. Blair, Rudolf Bohm, Lara A. Doyle-Meyers, Jay Rappaport, Tracy Fischer. Neuropathology and virus in brain of SARS-CoV-2 infected non-human primates. Nature Communications, 2022; 13 (1) DOI: 10.1038/s41467-022-29440-z

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Last Updated on April 7, 2022 by Marie Benz MD FAAD