under the microscope
under the microscope
By Rodney E . Rohde , PhD , MS , SM ( ASCP ) CM , SVCM , MBCM , FACSc
Should We be Worried About Human Parainfluenza Viruses ?
Once upon a time , in a 2009 World Health Organization Summary , I read a statement that has always stuck with me as a public health and medical laboratory infectious disease specialist . It stated , “ the only thing certain about influenza viruses is that nothing is certain .”
I am an American Society for Clinical Pathology ( ASCP ) board-certified specialist in virology , specialist in microbiology , and molecular Biology . I started my career in 1992 with the Texas Department of State Health Services in the Bureau of Laboratories and Zoonosis Control Division and transitioned to medical laboratory and academic environment since 2002 . I ’ ve worked in this hybrid profession between public health and medical laboratories for over 30 years , experiencing everything from being involved in the eradication of canine rabies from Texas , to watching West Nile Virus enter New York and burn across the United States , to the 2001 anthrax scare , avian influenza , Ebola , COVID-19 , and other diabolical microbial foes .
I respect all microbes and their potential to erupt at any given time . But the respiratory agents that continue to leap from zoonotic origins to human pathways are the ones that always create a storm . Respiratory viruses are often a perfect storm . Influenza and coronaviruses are part of most everyone ’ s vocabulary these days . What about a group of viruses known as the Human Parainfluenza Viruses ( HPIVs )? Remember , with zoonotic and respiratory agents , nothing is certain .
What are Human Parainfluenza Viruses ?
The Centers for Disease Control and Prevention share that Human parainfluenza viruses ( HPIVs ) belong to the Paramyxoviridae family . They are enveloped RNA viruses which have four types ( 1 through 4 ) and two subtypes ( 4a and 4b ). The clinical and epidemiologic features for each HPIV type are variable . In the United States , HPIV-1 infections usually peak every other year with infections from HPIV-2 substituting when HPIV-1 is low . HPIV-3 usually has peaks annually , particularly when HPIV-1 and HPIV-2 are low . Infections with HPIV-4 are less well-defined but appear to occur yearly . Like many respiratory viruses , HPIVs commonly infect infants and young children and immunocompromised individuals but anyone can acquire the infection .
Signs , Symptoms , and Illnesses
HPIVs have an incubation period ( the time from getting infected with HPIV to onset of symptoms ) usually from two to six days . There are four major types of HPIVs .
● HPIV-1 and HPIV-2 are most often associated with croup , with HPIV-1 most often identified as the cause in children . Both can also cause upper and lower respiratory illness , and cold-like symptoms .
● HPIV-3 is more often associated with bronchiolitis , bronchitis , and pneumonia .
● HPIV-4 is recognized less often but may cause mild to severe respiratory tract illnesses .
Most HPIVs cause symptoms much like the common cold . One can experience a range of issues , including fever , running nose , cough , sneezing , and a sore throat . Occasionally , there may be symptoms of ear pain , irritability , and decreased appetite . Children can show more serious symptoms from HPIVs including :
● croup ( infection of the vocal cords ( larynx ), windpipe ( trachea ) and sometimes into the bronchial tubes ( bronchi )
● bronchitis ( infection of the main air passages that connect the windpipe to the lungs )
● bronchiolitis ( infection in the smallest air passages in the lungs )
● pneumonia ( an infection of the lungs )
● barking cough
● hoarseness
● stridor ( noisy or high-pitched sound with breathing )
● wheezing .
Adults tend to not have as many serious complications with upper respiratory infections and bronchitis as the most common illnesses . Signs and symptoms mirror those less serious ones seen in children . Older adults may be more likely to have pneumonia .
Transmission , Prevention , and Treatment
HPIVs , like many other respiratory agents , are typically spread by direct contact with infectious droplets or by airborne spread when an infected person breathes , coughs , or sneezes . Viral particles within respiratory droplets can remain infectious for several hours in the air and on surfaces . Most people are contagious in the early stages of illness and HPIVs occur year-round .
To date , there is no vaccine to prevent HPIV infection and researchers continue to work to develop vaccines . Unfortunately , there is no specific antiviral treatment for HPIV illness . Most HPIV illnesses are mild and typically require only treatment of symptoms .
In hospital settings , healthcare providers should follow contact precautions , such as handwashing and wearing protective gowns and gloves . For more information , see CDC ’ s 2007 Guideline for Isolation Precautions : Preventing Transmission of Infectious Agents in Healthcare Settings .
The Future
Overall , lower respiratory tract infections ( LRI ) cause approximately 25 percent to 30 percent of total deaths in preschool children in the developing world . HPIVs are believed to be associated with 10 percent of all LRI cases , thus remaining a significant cause of mortality . While it ’ s always difficult to predict “ Disease X ” regarding the next major microbial agent to cause a pandemic or global emergency , we must all keep our radars finely tuned with a One Health strategy to mitigate that perfect storm on the horizon .
Rodney E . Rohde , PhD , MS , SM ( ASCP ) CM , SVCM , MBCM , FACSc , is the Regents ’ Professor , Texas State University System ; University Distinguished Chair & Professor , Clinical Laboratory Science ( CLS ); TEDx Speaker & Global Fellow – Global Citizenship Alliance ; Texas State Honorary Professor of International Studies ; Associate Director , Translational Health Research Initiative ; Past President , Texas Association for CLS .
8 december 2023 • www . healthcarehygienemagazine . com