A 3-year-old boy is brought in to the GP by his mother for severe watery diarrhea the past two
days. He appears pale and his orbits are sunken. His history is significant for not having received
childhood vaccinations. Which of the following best describes the most likely viral etiology?
- A) RNA; enveloped; single-stranded; non-segmented
- B) RNA; enveloped; single-stranded; segmented
- C) RNA; enveloped; double-stranded; non-segmented
- D) RNA; enveloped; double-stranded; segmented
- E) RNA; non-enveloped; single-stranded; non-segmented
- F) RNA; non-enveloped; single-stranded; segmented
- G) RNA; non-enveloped; double-stranded; non-segmented
- H) RNA; non-enveloped; double-stranded; segmented
0 voters
EXP:
This child has rotavirus, which is the world’s leading cause of severe, dehydrating diarrhea in
children under age 5.1, 2Older children and adults can also experience infection but not to the same
degree of prevalence as in young children.3, 4, 5
Symptoms usually start two days after fecal-oral exposure. Vomiting and watery diarrhea tend to
last 3-8 days.6
Rotavirus vaccine is administered orally at age 2, 4, and 6 months (3 doses total).7
On the USMLE, if you get a vignette of a young child with watery diarrhea and they don’t
mention anything about vaccination history, rotavirus is the answer.
If the USMLE question specifically mentions that the child was vaccinated or that the parents
and/or siblings also simultaneously have diarrhea, then rotavirus is less likely. Norwalk virus
(Norovirus) is the second-leading cause of diarrhea in children after rotavirus8
, and it is also
common in older children and adults.9
The USMLE wants you to know that rotavirus is a double-stranded segmented virus (11
segments).10
Bottom line: Rotavirus is the most common cause of diarrhea in children under age 5; it
is less common in older children and adults. Norwalk virus (Norovirus) is the second-leading cause
of diarrhea in young children; it is common in older children and adults.