What causes chronic disease? At a time when studying the root causes of diseases like cancer is presumably a priority, with an emphasis on factors like diet and environmental toxins, there is another piece of the puzzle that requires attention: infectious disease.
Indeed, from Long COVID to multiple sclerosis, the list of conditions with known or emerging ties to infectious diseases is growing. By interrogating the ins and outs of infection-and using those insights to develop new preventive tools and technologies-we can simultaneously expand our knowledge of chronic disease and protect people's health in the long run.
Infection as One of Many Root Causes of Chronic Disease
Humans are afflicted by an alphabet soup of health conditions. One fact that holds true across the spectrum is that disease is complicated. Science has shown us time and again that there is no single root cause of disease-there are roots. There's a root for genetics, one for the microbiome, another for age. There are roots for diet and environmental factors, like pollution or toxins (e.g., pesticides). And there is a root for infection.
While infection has historically been viewed through a "get infected, get better, move on" lens, we know that this isn't entirely accurate. Getting better isn't a given, and infection can spur long-term health disruptions and conditions, sometimes years after an infection occurred.
Epstein-Barr virus (EBV), for instance, is tied to multiple sclerosis and cancer; other viruses, including human papillomavirus (HPV) and hepatitis B and C, also cause cancer. Heart disease, depression and diabetes are some of many outcomes associated with Long COVID-a long-term implication of SARS-CoV-2 infection characterized by a laundry list of conditions in both children and adults. Conditions like inflammatory bowel disease, psoriasis and even obesity may also have infectious underpinnings. And while viruses are key culprits, other types of microbes, like bacteria, are triggers of infection-fueled health issues (e.g., chronic Lyme disease), as well. Some mechanisms underlying infectious-chronic disease connections are known (for example, how EBV disrupts DNA to spur cancer development), while many, such as those modulating Long COVID, are active areas of investigation.
There is no "1 size fits all" when it comes to the development and progression of disease; there may be similarities and trends within a population, but everyone is a little bit different. It is, thus, prudent to explore all factors with roles to play-and infectious disease increasingly appears to be one of them. Maintaining focus on the infection factor is particularly important in an era defined by the spread of pathogens with known chronic health implications (SARS-CoV-2), as well as unknown or emerging pathogens whose impacts are less clear.
Preventing Infections Helps Prevent Some Chronic Diseases
If infection is a possible steppingstone toward chronic disease, it stands to reason that efforts toward understanding and preventing the former can, and do, apply to the latter. Take HPV-the cause of genital warts and one of the most prolific sexually transmitted viruses in the world-as an example.
Through extensive research, scientists found that HPV is integral in the development of certain cancers (e.g., cervical cancer). They went on to discover the viral proteins that cause host cells to continuously reproduce and become cancerous, as well as the surface proteins that modulate viral cellular binding and internalization.
Additional investigation showed that those surface proteins self-assemble into virus-like particles (VLPs)-essentially, viruses without any genetic material inside. What did scientists do with that information? They made a stellar vaccine. HPV vaccines, comprised of VLPs from different HPV types, train the immune system to recognize viral particles and destroy them. They are more than 90% effective at preventing cancer-a particularly devastating chronic disease-triggered by the virus.
This is just 1 case, and the path from molecular insights to useful tools, like vaccines, differs in the context of other infections. The point is that harnessing and advancing knowledge of the infectious process leads to tactics that simultaneously minimize the risk of both acute and chronic health problems. It is also absolutely worth exploring how modifications in, for instance, diet or environmental pollution support long-term health. The idea is that investigating chronic disease requires a "yes, and" approach, with the understanding that insights into infection are not extraneous, but necessary.
More Than Vaccines
Such insights lead to advancements that go beyond vaccines, too. This is not to say vaccines aren't crucial-they are. But it's worth noting that the more scientists study infectious disease, the more they can develop novel, external methods to manage them as well.
For instance, studies on the molecular make-up of SARS-CoV-2 informed the development of a device that detects the virus in the air within 5 minutes and with 77-83% accuracy; a biosensor with a similar detection time was recently developed for avian influenza A (H5N1). Such devices offer real-time methods for monitoring the presence of viruses to inform disease control measures. Knowing how environmental variables, like carbon dioxide (CO2) levels, which rise in places like crowded rooms, impact viral survival can further influence how buildings are designed and ventilated to lower the risk of infection. Researchers are also inventing tools like a portable device that sterilizes virus-containing aerosols generated by patients during clinical respiratory care, with potential use in non-clinical environments, as well as innovative surface coatings that kill microbes in minutes and for extended periods of time.
Collectively, these examples demonstrate multi-faceted approaches for mitigating problematic microbes. By, again, looking ahead, those methods have the potential to not only influence short-term health, but also long-term health. Think about it in the context of Long COVID: coupling improved air filtration with technologies that detect and kill SARS-CoV-2 could help lower the chances of (repeat) infection and, in turn, its associated chronic outcomes.
Healthy Science, Healthy People
Of course, how one thinks about and approaches studying chronic diseases is meaningless if one can't study them at all. Funding and staffing cuts at and by U.S. federal research agencies undermine efforts to investigate all roots of disease, which negatively affects the development of countermeasures, like new medications. As such, while it is critical to examine chronic disease without disregarding known risk factors (i.e., infection), it is even more crucial, in this moment, to protect the health and integrity of the scientific enterprise to ensure those examinations can happen at all. Our long-term health depends on it.
Contact your representatives to share the impact recent executive orders and funding caps have on your work and scientific research in their district and state.
