Although the common cold is usually a major source of annoyance for most people, new research has found that the most prevalent respiratory infection can be far worse than a stuffy nose for one sector of the population — bone marrow transplant patients, according to a report recently published in the journal Haematologica.
This group of vulnerable patients, whose immune defenses have taken a dramatic double hit from both their original disease and the treatments required to repopulate their immune system with donor cells, are especially susceptible to a wide range of infections that usually don’t cause major problems in healthy people. But rhinovirus, the most common respiratory virus, has traditionally been overlooked in this population, noted infectious disease specialist Michael Boeckh, MD, PhD, of Fred Hutchinson Cancer Research Center in Seattle, WA.
“This is such a prevalent virus … about 25% of stem cell transplant patients get infected [with rhinovirus] during the first year,” said Dr. Boeckh, who heads Fred Hutchinson’s Infectious Disease Sciences Program. “The virus was always considered kind of a common cold, a mild virus. People shrugged their shoulders, what should we do about it, it comes and goes.”
In this new study, led by infectious disease researcher Dr. Sachiko Seo, formerly of Fred Hutchinson and now a physician at the National Cancer Research Center East in Chiba, Japan, and Dr. Boeckh, has discovered that like more “serious” viruses, rhinovirus can cause pneumonia — and when it does, it can be deadly to those recovering from transplantation.
The results not only point to the importance of strong infection prevention measures for transplant patients and better care for those with rhinovirus-related pneumonia, but they lend a rationale for drug companies and researchers to prioritize developing effective antiviral drugs for this most common of common cold-causing viruses, Dr. Boeckh explained.
“Just to treat people like you and me who are irritated by the sniffles, that’s not good enough for the market,” he said. “For a company or anybody to step forward and say, ‘I’m going to make this a priority,’ you have to show that there’s a real disease.”
Although their study was not the first to show that transplant patients get rhinovirus, it was the first to definitively link the virus with pneumonia in these patients. That new discovery is thanks to modern virus detection methods — rhinovirus was difficult to pinpoint using older technologies, Dr. Boeckh said. Over the past decade, with the advent of better viral detection, he and other clinicians started to find evidence of rhinovirus in the lungs in transplant patients with pneumonia. However, they didn’t know whether the virus was causing the complication or if it was just along for the ride.
In this study, the researchers took a retrospective look at 697 patients who had received transplants at Seattle Cancer Care Alliance, Fred Hutchinson’s clinical care partner, between 1993 and 2015 and who had also tested positive for rhinovirus. They compared the 128 patients with rhinovirus in the lower respiratory tract with those infected with viruses already known to cause pneumonia, and sometimes death, in transplant patients, namely, influenza, parainfluenza virus (PIV), and respiratory syncytial virus (RSV).
In contrast to what researchers previously believed, their study showed that rhinovirus is linked to pneumonia and death even without any other co-existing infections, strongly suggesting that the so-called mild virus can be dangerous all on its own.
Dr. Boeckh and his colleagues found that rhinovirus infection led to pneumonia less often than the other viruses. About 15% of patients who had an upper respiratory tract infection, the type of infection we typically think of as a “common cold,” went on to develop pneumonia, or an infection of the lower respiratory tract. Progression from cold-like symptoms to pneumonia for patients infected with RSV, for example, happened about twice as often.
But once patients developed pneumonia, rhinovirus turned out to be just as deadly as the other viruses, the researchers found. About 40% of patients in their study who developed pneumonia from any viral infection died.
Even though rhinovirus is less likely, on a case-by-case basis, to lead to pneumonia, it’s actually the most common cause of pneumonia caused by respiratory viruses in transplant patients, Dr. Boeckh explained. That’s because the virus is so common and because it’s present year-round, unlike the other, more seasonal viruses. Overall, these results emphasize the need for better prevention and treatment for the virus, Dr. Boeckh said.
“This is an important pathogen,” he emphasized. “It can’t be disregarded as a common cold virus.” In fact, the scientists believe the pathogen is so important they’ve started an entire research program around it. Dr. Alpana Waghmare, one of the study authors who is a pediatric infectious disease specialist at Seattle Children’s and a Fred Hutch affiliate researcher, is launching a research project to better understand how and why rhinovirus is so dangerous to transplant patients.
As part of that goal, she’s concentrating on understanding which patients are most likely to develop pneumonia from the virus. In another study that Dr. Waghmare presented at the recent annual meeting of the American Society for Blood and Marrow Transplantation in Orlando, Florida, researchers discovered a few risk factors that can drive the development of lower respiratory tract infections, including high levels of steroid use (commonly given to transplant patients for other complications such as graft-vs.-host disease) and a low white blood cell count.
Her team’s next step will be to understand whether certain patients are at higher risk for getting infected with rhinovirus in the first place. They will also ask if there are other risk factors for pneumonia and other poor outcomes from the infection.
Even though there’s no effective drug for rhinovirus on the market yet, understanding who is at highest risk of complications from the virus is still important, Dr. Waghmare noted. Researchers needs to provide evidence of how rhinovirus is harmful to spur such a drug’s development as well as to understand which patients would benefit most once such a treatment is available so clinicians can know who should be monitored or treated more aggressively, she said.
“So many of our patients get rhinovirus, but most of the infections are mild and we want to know who would likely benefit from any potential therapies,” Dr. Waghmare explained. “You need to know how to stratify people to get the most bang for your buck in terms of whom you treat.”
In the meantime, in the absence of an effective drug, there are a few steps transplant patients and their caregivers can take, Dr. Waghmare pointed out.
- Patients who are within the first year of receiving a transplant should always check with their doctor as soon as they develop any cold-like symptoms. “Don’t wait things out,” she said.
- As a general infection control practice, any family members and friends with cold or flu symptoms should limit contact with post-transplant patients as much as possible. Dr. Waghmare acknowledges that this can be difficult in practice though, as for instance when the patient’s caregiver comes down with a cold.
- For cancer care facilities, it’s important to keep employees with any cold symptoms out of the clinic, Dr. Boeckh said. He points out that the SCCA has a very aggressive infection control program and they all make infection prevention in this vulnerable population a top priority.
- For more information on dealing with common infections after cancer, read these tips from infection control expert Dr. Steven Pergam.