MLT GlobeVirology: Enteric & other viruses – page 2
63 Virology MCQs on Enteric & other viruses with answers and explanations.
A child has fever, headache and neck stiffness in late summer; enteroviral meningitis is suspected. Which specimen is best for enterovirus RT-PCR?
Enterovirus RT-PCR on CSF is the diagnostic test of choice for aseptic meningitis; a positive result can shorten antibiotic use and hospital stay.
Enteric adenovirus types 40 and 41 cause diarrhoea in young children. Which specimen is used to detect them?
Adenovirus 40/41 replicate in the gut and are shed in feces; they are detected by stool antigen assays or PCR, not culture.
Which feature does NOT describe rotavirus?
Rotavirus is a non-enveloped, triple-layered reovirus with 11 dsRNA segments; stool antigen EIA is the usual test. Lacking an envelope, it resists many disinfectants.
Several passengers on a cruise ship develop sudden vomiting and diarrhoea within 48 hours. Stool RT-PCR is ordered. Which virus is most likely?
Norovirus (a calicivirus) causes explosive outbreaks in closed settings such as ships and camps; it has a low infectious dose and is diagnosed mainly by RT-PCR. Hepatitis A has a weeks-long incubation.
A 10-month-old has severe watery diarrhea during winter. Which test is commonly used to detect the most likely viral cause?
Rotavirus is a major cause of severe infant gastroenteritis. Large amounts of virus are shed in stool, so antigen detection by immunoassay or molecular testing is used.
Which human papillomavirus types are most strongly associated with cervical cancer?
HPV 16 and 18 cause about 70% of cervical cancers. HPV 6 and 11 are low-risk types that cause genital warts.
In late summer, a 6-year-old has fever, headache and neck stiffness. CSF shows 120 WBC/µL, mostly lymphocytes, and normal glucose. Which test is most likely to identify the cause?
Enteroviruses cause most summer-autumn aseptic meningitis in children, and CSF RT-PCR is rapid and sensitive. India ink is for Cryptococcus.
Many passengers on a cruise ship develop sudden vomiting and watery diarrhoea lasting 1–2 days. Which laboratory test is preferred to confirm the likely viral cause?
Norovirus causes most outbreaks of acute gastroenteritis in adults and cannot be grown in routine cell culture; RT-PCR on stool is the test of choice. Rotavirus mainly affects young children.
The Sabin oral polio vaccine (OPV) contains:
OPV is a live attenuated oral vaccine; the Salk vaccine (IPV) is inactivated and injected.
The classic triad of congenital rubella syndrome is:
Rubella in early pregnancy classically causes cataract, sensorineural deafness and congenital heart disease such as PDA.
Small, pearly, umbilicated skin papules (molluscum contagiosum) are caused by a:
Molluscum contagiosum virus is a poxvirus; the lesions show large eosinophilic inclusion (molluscum) bodies.
Poliovirus is most readily isolated in cell culture from which specimen?
Enteroviruses replicate in the gut and are shed in stool for weeks. CSF isolation of poliovirus is rarely successful.
Enteroviruses and rhinoviruses are both picornaviruses. Which property best explains why only enteroviruses establish infection in the gut?
Enteroviruses survive stomach acid and replicate in the intestine; rhinoviruses are acid-labile and grow best at nasal temperature. Both are small, naked, ssRNA viruses.
Which viral disease presents with vesicles and ulcers on the soft palate rather than a maculopapular skin rash?
Herpangina, usually coxsackie A, causes painful oral vesicles. Measles, rubella and fifth disease all give maculopapular rashes.
Adeno-associated virus (a dependoparvovirus) cannot complete replication alone. Which helper virus classically supplies the missing functions?
AAV is a defective parvovirus requiring co-infection with adenovirus (or herpesvirus) for productive replication, hence the name adeno-associated virus.
Which virus typically stays localised at its site of entry in the skin or mucosa rather than spreading through the body?
HPV infects basal epithelial cells and remains localised, producing warts or dysplasia. HBV, HIV and yellow fever virus spread systemically via the blood.
Which virus-disease pairing is INCORRECT?
Astroviruses mainly cause mild watery diarrhoea in young children, though adults can be affected. The other pairings are correct.
An outbreak of painful red eyes with subconjunctival haemorrhage spreads quickly through a school. Which virus group most often causes acute haemorrhagic conjunctivitis?
Enterovirus D70 and coxsackievirus A24 variant cause epidemic acute haemorrhagic conjunctivitis. Adenovirus causes epidemic keratoconjunctivitis, a different syndrome.
After enteroviral infection, virus may be recovered from throat for about one week. From which specimen is it typically shed for several weeks?
Enteroviruses replicate in the gut and are shed in stool for several weeks, much longer than from the throat, making feces a high-yield specimen.
Which statement correctly describes rotavirus?
Rotavirus has 11 dsRNA segments, spreads readily in hospitals, and is routinely diagnosed by stool antigen tests (EIA, immunochromatography) or PCR, not culture.