Parasitic Hookworms Could Help Protect Against Severe COVID-19, Reveals New Study
A recent study conducted by the US National Institute of Allergy and Infectious Diseases (NIAID) has revealed that prior infection by a parasitic hookworm could potentially protect against severe COVID-19. The study offers an explanation as to why certain populations in Africa and Asia seem to have fared better during the height of the pandemic.
Dr. Kerry Hilligan from NIAID explains that observations from the early days of the pandemic showed that regions where hookworm infections are endemic had fewer cases of severe COVID-19 infections compared to other parts of the world. Dr. Hilligan suggests that the endemic hookworm infection might interfere with the establishment of more severe viral infections caused by SARS-CoV-2.
Previous research has shown that helminth infections, including hookworms, can shape the immune response to other pathogens. In mouse studies, prior infection with helminths has been found to help withstand challenges from respiratory viruses like influenza. Dr. Hilligan and her collaborators wanted to investigate whether this effect could also apply to SARS-CoV-2.
To test their hypothesis, the researchers developed a mouse model of SARS-CoV-2. They infected some mice with a helminth worm called N. brasiliensis, which mimics human hookworm infection. The results were promising, with 60% of the mice with prior worm infection surviving when exposed to lethal doses of SARS-CoV-2, compared to only 20% of mice without worm infection.
Further experiments showed that the lung-migrating aspect of N. brasiliensis played a critical role in enhancing resistance to severe COVID-19. The researchers found that adaptive immune responses, specifically an increase in a type of immune cell called CD8 T cells, were responsible for controlling the virus. Depletion of CD8 T cells led to a significant increase in SARS-CoV-2 burden in worm-experienced mice.
The study results demonstrate that N. brasiliensis infection in the lung primes macrophages, a type of immune cell, to quickly recruit CD8 T cells and control subsequent SARS-CoV-2 infections. What’s intriguing is that this effect seems to be long-lasting, even after the hookworm infection has cleared from the body.
While these findings are promising, it’s important to conduct further immunologic studies using clinical samples to fully understand whether they align with observations from epidemiological studies. Dr. Oyebola Oyesola, who plans to continue her research at NIAID, aims to explore how parasitic worm infections can remodel innate immune responses and influence responses to viral infections.
Dr. Hilligan and her team are eager to unravel the signals that bring CD8 T cells to the lung and understand the mechanisms by which the worm creates specialized macrophages. The ultimate goal is to replicate this effect without the need for the worm as an intermediary.
This study sheds light on the potential benefits of parasitic hookworm infections in protecting against severe COVID-19. However, more research is needed to fully comprehend the complexities of these interactions and their broader implications for mitigating the impact of the virus.
In conclusion, this study offers valuable insights into the role of helminth infections in shaping immune responses and potentially protecting against severe COVID-19. As scientists continue to delve into the intricate workings of the immune system, further discoveries may pave the way for innovative strategies to combat the ongoing pandemic.
