Enteric viruses Flashcards
What’s an enterovirus?
Virus that enters via GI tract
Can act locally or replicate then disseminate
What is the genome/structure of enteroviruses like?
How do they enter the body?
All are +ssRNA, part of picornaviridae
Have protein coats (caspids) with icosahedral symmetry
Bind cell surface receptors CD155 & enter the cell via endocytosis
Acid stable, replicate in cells of GI tract/lymph nodes, can enter blood stream
Different enteroviral types have tropism for different anatomic sites which determines the clinical outcome
What type of infections does poliomyelitis cause?
90% are clinically inapparent
Abortive poliomyelitis: nearly the rest are just fever, headache, sore throat
Nonparalytic poliomyelitis: same as above + stiff neck/ photophobia due to meningeal irritation
Spinal paralytic poliomyelitis: weakness, asymetric lower limb paralysis, can involve respiratory muscles
Bulbar paralytic poliomyelitis: CN paralysis, can involve respiratory centers
How do you diagnose polio?
Isolate from oropharynx & culture
Serology
What are the 2 vaccines for polio?
IPV: inactivated version, 95% of recipients get immunity, unclear how long immunity lasts (primary vaccination in US)
OPV: oral, high levels of protection/life long immunity but small risk of vaccine-associated paralytic polio
Both cover all 3 serotypes
What are common manifestations of other enteroviruses?
Most don’t cause GI symptoms
Fever
Rash
Aseptic meningitis i.e. coxsackievirus B - PCR of spinal fluid
Myocarditis/pericarditis: also coxsackie B - due to invasion of cardiomyocytes & inflammatory response
Acute hemorrhagic conjunctivits: coxsackievirus A24 or enterovirus 70
Hand/foot/mouth disease and herpangia (mouth infection): coxsackievirus A16 or enterovirus 71
Enteroviral infections of newborn
What is rotavirus? What disease does it cause? Diagnosis/ treatment? Prevention?
Fecal-oral spread, causes fever and vomiting, then nonbloody diarrhea
Rarely cause extraintestinal complications
Large, non-enveloped dsRNA, segmented genomes, produce enterotoxin NSP4
Diagnose based on clinical presentation & time of year (winter) + ELISA assay in stool
Treat with oral/IV rehydration & electrolyte repletion
Prevent by washing your hands + vaccine (Rotatrix= attenuated, Rotateq= bovine)
What is norovirus?
+ssRNA virus, causes GI illnesses, non-enveloped
Whales = host
Causes sudden vomiting in kids & diarrhea in adults, on cruise ships
Causes blunting of villi, unclear mechanism of diarrhea
Year round, peaks in cold weather
Immunity might not last that light & be strain specific
Diagnose from stool specimins within 48-72 h of onset of symptoms or RT-PCR on samples 5 days after onset
