Unveiling the Most Crucial Virus You May Not Be Aware Of
CNN Reports: Throughout the recent winter season, respiratory viruses such as RSV, influenza, and Covid-19 took a heavy toll. However, just as these infections were subsiding, a lesser-known virus with similar symptoms, including lower lung infection, persistent cough, runny nose, sore throat, and fever, began gaining momentum.
Human metapneumovirus (HMPV) cases surged during the spring, as revealed by the US Centers for Disease Control and Prevention’s surveillance systems for respiratory viruses. This led to a significant influx of young children and vulnerable seniors into hospital intensive care units, as they are the most susceptible to these infections. In mid-March, HMPV reached its peak with nearly 11% of tested specimens yielding positive results. This figure represents a 36% increase compared to the average test positivity of 7% during pre-pandemic seasonal peaks.
Interestingly, many individuals who contracted HMPV likely remained unaware of their infection, as it is typically not tested for outside of hospitals or emergency rooms. Unlike Covid-19 and the flu, there is no available vaccine or antiviral medication specifically targeting HMPV. Consequently, healthcare professionals primarily focus on managing the symptoms of severely ill patients.
Human Metapneumovirus: An Underestimated Respiratory Threat
Studies Reveal the Significant Impact of HMPV: Research indicates that Human Metapneumovirus (HMPV) poses a considerable burden in the United States, rivaling the flu and a closely related virus, RSV, in terms of its impact. A comprehensive study analyzing patient samples collected over 25 years found that HMPV ranked as the second most prevalent cause of respiratory infections in children, trailing only RSV. Another study conducted in New York during four consecutive winters demonstrated that HMPV was as prevalent among hospitalized seniors as both RSV and the flu. Notably, similar to these infections, HMPV can lead to severe cases of pneumonia, even resulting in intensive care and fatalities in older adults.
The Experience of Diane Leigh Davison:
Diane Leigh Davison, a 59-year-old entertainment lawyer from Baltimore, contracted human metapneumovirus during a family celebration in early April. Within two weeks, her cough became so intense that she struggled to speak on the phone. Despite her concerns, she tested negative for Covid-19 after undergoing six rapid tests. As an immunocompromised individual, Davison had been cautious throughout the pandemic. Worried about the possibility of pneumonia, she obtained a clear X-ray from a radiology clinic near her home. However, her doctor persisted and referred her to an emergency room for further testing, ultimately diagnosing her with HMPV through blood tests.
Unveiling the Origins of HMPV: Human metapneumovirus was discovered by Dutch virus hunters in 2001 when they analyzed 28 samples from children in the Netherlands with unexplained respiratory infections. Although some of these children had experienced severe illness requiring mechanical ventilation, they tested negative for known pathogens. By culturing the samples in various types of cells derived from monkeys, chickens, and dogs, and observing the cultures under an electron microscope, the researchers detected a structure resembling the paramyxoviridae family a group of viruses known to cause respiratory diseases such as measles, mumps, and respiratory syncytial virus (RSV). Further examination of the virus’s genetic makeup revealed its close relationship with avian metapneumovirus, which primarily infects birds. Consequently, the novel virus was named human metapneumovirus. Scientists hypothesize that it likely crossed over from birds to humans at some point and subsequently evolved within the human population. Astonishingly, when blood samples from 72 patients dating back to 1958 were tested, all exhibited evidence of prior exposure to this enigmatic virus, indicating its undetected circulation among humans for at least the previous five decades.
Medical Community and Patients Uninformed About an Ongoing Mystery
Respiratory infections pose a grave threat to children worldwide, causing the highest number of child deaths and hospitalizations in the United States. However, a significant portion of these infections remains shrouded in mystery, according to Dr. John Williams, a pediatrician at the University of Pittsburgh dedicated to researching vaccines and treatments for Human Metapneumovirus (HMPV).
Dr. Williams explains that extensive epidemiological studies conducted in the 1950s and 1960s aimed to uncover the causes of respiratory infections. Surprisingly, only about half of the cases could be attributed to a known virus, leaving researchers to question the origin of the other half. While HMPV does not account for all unidentified viruses, it contributes substantially, with a prevalence comparable to that of RSV or influenza.
Unfortunately, HMPV remains relatively unknown. Dr. Williams describes it as “the most important virus you’ve never heard of.” He emphasizes that HMPV, along with RSV and influenza, represents the three major viruses responsible for severe illness, hospitalizations, and even fatalities in both children and adults. Nursing homes are particularly susceptible to these viruses, causing severe illness and mortality among older individuals.
As testing for HMPV is predominantly conducted within hospitals, the true burden of the disease remains uncertain. Blood tests indicate that most children have been exposed to HMPV by the age of 5. A study published in Lancet Global Health in 2020 estimated that in 2018 alone, there were over 14 million HMPV infections, leading to more than 600,000 hospitalizations and over 16,000 deaths among children under the age of 5. Moreover, HMPV infections do not confer robust or long-lasting immune protection, resulting in recurrent infections throughout individuals’ lives.
Efforts are underway to develop vaccines against HMPV, with companies like Moderna, known for their Covid-19 vaccine, recently completing an early study on an mRNA vaccine targeting HMPV and parainfluenza, as reported on the clinicaltrials.gov website.
The US Centers for Disease Control and Prevention (CDC) advises doctors to consider HMPV testing during the winter and spring, when the virus tends to peak. However, doctors often refrain from testing due to limited awareness of the virus. Additionally, a positive test result may not significantly alter patient care, as the treatment approach would remain largely unchanged. Nevertheless, testing for HMPV helps exclude other treatable causes like Covid-19 or the flu.
Diane Leigh Davison, who experienced a severe bout of bronchitis due to HMPV, acknowledges having dealt with respiratory infections in the past. However, her encounter with HMPV was exceptionally challenging, leaving her ill for a month. Although she has recovered, she expresses relief at having overcome the ordeal, remarking that it was the most severe respiratory illness she has ever experienced.