Picornavirus infections
Picornavirus infections are caused by a group of single-stranded RNA viruses within the Picornaviridae family, which includes notable genera such as Enterovirus, Hepatovirus (hepatitis A), and Parechovirus. These viruses are globally prevalent, with transmission primarily occurring through the fecal-oral route, respiratory route, and, in some cases, sexually or during childbirth. While many infections are asymptomatic, common symptoms can include fever, respiratory illness, lethargy, and rash, with severe cases leading to complications like hepatitis, pancreatitis, myocarditis, and neurological issues.
Individuals who are immunocompromised or young are at a higher risk of severe outcomes. Diagnosis typically involves testing various bodily fluids, and while most infections resolve without treatment, symptomatic care may be necessary in more severe cases. Prevention strategies focus on vaccination for specific viruses, along with good hygiene practices to minimize spread. As understanding of these infections evolves, awareness of risk factors and preventive measures remains crucial for public health.
Picornavirus infections
- ANATOMY OR SYSTEM AFFECTED: All
Definition
Picornaviruses are single-stranded RNA (ribonucleic acid) viruses that belong to the Picornaviridae family. This family has twelve genera, although some of these are unique either to plants or to animals. Common examples of the genera affecting humans include Enterovirus (coxsackie virus, echovirus, poliovirus, rhinovirus), Hepatovirus (hepatitis A virus), and Parechovirus (respiratory tract virus). Picornaviruses are common and have worldwide prevalence with the exception of poliovirus, which has been virtually eliminated in most countries.
Causes
Picornaviruses are most commonly transmitted by the fecal-oral route or by the respiratory route. They also may be sexually acquired, as with hepatitis A, or during pregnancy through the placenta or labor and delivery. Also, many enteroviruses are often spread in hospitals because of improper handwashing or through contaminated equipment.
Risk Factors
Immunocompromised persons are at greatest risk. Enterovirus infections may occur at any age, but the younger the person, the higher the risk. Hepatitis A infections increase with age, sexual contact with the virus, or illicit drug use. Additional risk factors include occupational exposure, such as in a daycare or hospital setting, and poor living conditions. Seasonal variations also may be observed and differ among virus type.
Symptoms
Symptoms depend on the type of picornavirus diagnosed. Many infections are asymptomatic. Common findings include a flulike fever, upper respiratory tract infection, lethargy, irritability, poor feeding, and rash. More severe findings are inflammation of the liver (hepatitis), pancreas (pancreatitis), heart (myocarditis), and brain (encephalitis or meningitis), which place a person at an increased risk for long-term complications such as liver dysfunction or neurological deficits. The greatest risk for morbidity and mortality exists with hepatitis and poliomyelitis.
Screening and Diagnosis
Testing is performed by sampling through serum, throat, or rectal swab; stool sample; or cerebrospinal fluid. The diagnosis is confirmed by isolating the virus in cell culture. Reverse transcriptase polymerase chain reaction (RT-PCR) is also available with the benefit of a shorter turnaround time. Prenatal diagnostic tests such as amniocentesis may be available for specific types of enteroviruses.
Treatment and Therapy
The majority of affected persons have mild symptoms that do not require treatment, as many infections independently resolve within one week. Antiviral therapy is not available for most infections. Thus, medical care is provided based on specific symptoms. Possible avenues of treatment include medication for cold and flu symptoms, hospitalization, immunoglobulins, diet modification, or liver transplantation in the case of hepatitis.
Prevention and Outcomes
No method exists to prevent all picornavirus infections. However, recommendations for some include routine vaccination for poliovirus and hepatitis. Universal hygiene practices such as handwashing, avoiding contact with contaminated items, and safer sexual practices may reduce the spread of picornaviruses.
Bibliography
Holmes, Robert L., and Larry I. Lutwick. “Picornavirus: Overview.” Available at http://emedicine.medscape.com/article/225483-overview.
Nouwen, Lonnekev. "Modulation of Nucleotide Metabolism by Picornaviruses." PLOS Pathogens, 8 Mar. 2024, https://doi.org/10.1371/journal.ppat.1012036. Accessed 4 Feb. 2025.
Rotbart, Harley, and Frederick Hayden. “Picornavirus Infections: A Primer for the Practitioner.” Archives of Family Medicine 9 (2000): 913-920.
Tebruegge, M., and N. Curtis. “Enterovirus Infections in Neonates.” Seminars in Fetal and Neonatal Medicine 14 (2009): 222-227.