Enteroviruses Flashcards
What are the two main categories of enteroviruses?
Polioviruses
Non-polio enteroviruses (coxsackie, echoviruses)
What are characteristics of the enterovirus virions?
Small, icosahedral
non-enveloped, (+) ss RNA
Viral RNA translated into polyprotein that’s cleaved into structural proteins and enzymatic proteins
What is the transmission of enteroviruses?
Primarily Fecal-oral
Respiratory droplets
What is the seasonality of enteroviruses?
Summer/autumn
What is the pathogenesis of enterovirus?
Inhaled and virus replicates in oropharynx
Primary minor viremia disseminates to other tissues (muscle, fat, liver, spleen, bone marrow)
Most people contain infection at this stage, producing minor or no symptoms
Some people continue to secondary major viremia that leads to symptoms, depending on what target organ is infected
What is the cause of most of the enterovirus disease manifestations?
Cell destruction by virus (cytolysis)
What is the cause of enterovirus myocarditis and rash?
Host immune response
If enterovirus targets meninges, what disease can manifest?
Aseptic meningitis
If enterovirus targets brain, what disease can manifest?
Encephalitis
Paralytic disease
If enterovirus targets heart, what disease can manifest?
Myocarditis
Pericarditis
If enterovirus targets muscle, what disease can manifest?
Myositis
Pleurodynia
If enterovirus targets skin/mucosa, what disease can manifest?
Hand-foot-mouth disease
Rash, herpangina
What is the most common target of poliovirus?
Anterior horn of spinal cord
where innervation of skeletal muscle occurs
What is the major presentation of poliovirus?
Asymmetric flaccid paralysis without sensory loss
Preferentially affects proximal muscles of lower limbs
How is poliovirus diagnosed?
Clinical
MRI showing ventral horn defects
Cell culture is gold standard
Which polio vaccine is live and which is killed?
Salk - killed
Oral - live
What is the major disadvantage to oral polio vaccine, the reason it’s not used in US
Can mutate and cause paralysis
What are the non-polio enteroviruses?
Coxsackievirus
Echovirus
Numbered enteroviruses
What is the different between Group A and B of the non-polio enteroviruses?
Group A - grow poorly in cell culture
Group B - grow well in cell culture
What are clinical manifestations of exanthems and enanthems of non-polio enteroviruses?
Herpangina/stomatosis (painful vesicles of soft palate & posterior pharynx)
Hand-food-mouth disease (vesicles or papules on hands, feet, groin)
What are clinical manifestations of CNS infections of non-polio enteroviruses?
Aseptic meningitis
Encephalitis
Poliomyelitis-like syndrome (some flaccid paralysis but less severe than poliovirus)
Other neurologic syndromes: Guillan Barre, acute transverse myelitis
What are clinical manifestations of skeletal muscle infections of non-polio enteroviruses?
Pleurodynia (inflammation of chest wall and abdominal muscles)
Myositis (general muscle pain)
Myocarditis
What are additional clinical manifestations of non-polio enteroviruses?
Acute hemorrhagic conjunctivitis
Severe neonatal infection
Chronic infection in immunodeficiency
How are non-polio enteroviruses diagnosed?
Viral isolation from invasive site
Serologic testing
PCR
