Enteroviruses Flashcards
Describe the characteristics of picornaviruses
recall that these are small, non-enveloped, icosahedral capsid, +ve sense ssRNA viruses
they replicate in cytoplasm, the viral RNA is translated into polyprotein and cleaved into enzymes and structural proteins
How are enteroviruses transmitted?
What time of the year would you expect a pt to present with symptoms of an enterovirus infection?
Transmission: Person-to-person via fecal-oral route; respiratory droplets; fomites
Seasonality: late summer/autumn in temperate climates
Describe the pathogenesis of enterovirus
Enteroviruses are ingested or inhaled >> enter and replicate in oropharynx >> intestines >> regional lymph nodes >> blood stream (cause primary viremia – illness ends here if pt has immunity) >> sustained viremia (virus targets tissues) >> can disseminate to liver, brain, meninges, skin, muscle etc
What conditions can occur when enteroviruses spp enter the organs shown in the schematic below?
Poliovirus targets the ___ cells of the spinal cord, causing a (asymmetric/symmetric) ___ paralysis without sensory loss
Poliovirus targets the anterior horn cells of the spinal cord, causing an asymmetric flaccid paralysis without sensory loss
The presentation of polio includes __, intense myalgia and loss of ___
Describe the 2 phases of the disease
Which groups of muscles are mainly affected by polio?
Presentation: high fever, intense myalgia and loss of deep tendon reflexes
Phases: initial phase = minor illness; later phase = sudden onset of asymmetric paralysis or paresis
Muscle groups affected: proximal and lower limb muscles
How is polio diagnosed? (5 ways)
Clinical presentation
Aseptic meningitis
MRI ventral horn defects
PCR
Cell culture** - best way to Dx polio (can differentiate wild type strain from vaccine strain)
Describe the Salk polio vaccine
K in Salk = killed vaccine (delivered by injection – gives good systemic immunity but gives less local mucosal immunity)
(inactivated killed poliovirus vaccine)
advantages: can be given to the immunocompromised since its killed, combined w other vaccine and efective in tropical areas
**used in US and other developed countries**
Contrast the Salk poliovirus vaccine with the Sabin poliovirus vaccine
Sabin poliovirus vaccine is oral, live attenuated so:
can give good systemic AND local immunity, and life-long immunity
but: because it’s live attenuated, the virus can revert back to a disease-causing form and cause disease in the pt; also can’t be used in the immunocompromised and has low response to type 3 polio
3 types of paralytic poliovirus that can occur from the oral polio vaccine are ___
VAPP (vaccine associated paralytic polio)
VDPV (vaccine-derived poliovirus)
cVDPV (circulating VDPV)
Describe VAPP, VDPV and cVDPV
VAPP – when the attenuated form converts to a mutated, disease causing form and causes paralysis
VDPV – disease occurs in someone that is unvaccinated and they somehow acquired the vaccine, which reverts back to a disease causing form
cVDPV –happening in the community and there’s more than one strain of VDPV circulating in community
Which strains of poliovirus are in the oral polio vaccine vs the inactivated polio vaccine?
Which strain is currently circulating in the global community?
OPV: all three strains (types 1-3)
IPV: types 1 and 3 because noone’s reported a case of type 2 since the 90s
Only polio type 1 is now circulating
The most common manifestation of non-polio enterovirus infection is ___
Most common manifestation is asymptomatic infection
Name 3 types of non-polio enteroviruses
ECHOvirus (Enteric cytopathic human ophan viruses)
Coxsackievirus
Other enteroviruses
Non polio enteroviruses can cause a variety of infections.
Name the skin infections that are seen with these viruses and which virus causes them
Herpangina/stomatitis: painful vesicles on soft palate & post. pharynx;
pt presents with the above and fever, headache, sore throat; caused by Coxsackie A (like A herpangina)
Hand-foot-mouth disease: vesicular stomatitis; vesicles or papules on hands, feet, groin
pt presents with above and fever, headache, sore throat; also caused by Coxsackie virus spp and Enterovirus 71, which is actually ass’d w/ outbreaks in India
Pts can also develop mobiliform rash
**note that these 2 have the same general presentation but what’s different is where the vesicles are on the body
Which condition is illustrated below?
hand foot and mouth disease caused by coxsackie A virus
What condition arises from nonpolio enterovirus infection of the heart muscle?
Myopericarditis (inflammation of cardiac muscle)
What condition is depicted below and which virus causes it?
Acute Hemorrhagic Conjunctivitis
can be caused by Coxsackie A24 and Enterovirus 70 but can also be caused by adenovirus, etc
