The prevalence of diarrhea and with vomiting in patients with acute gastroenteritis can help distinguish between different pathogens during an outbreak.


diarrhea-to-vomiting ratio = D/V ratio =

= (percentage of patients with diarrhea) / (percentage of patients with vomiting)



• Some patients will have both diarrhea and vomiting.


Interpretation (Dalton et al, page 12):

• A ratio >= 2.5 suggests an ETEC (enterotoxigenic E. coli) outbreak. This reflects that diarrhea is more common than vomiting. The range (1.3 to 45.5) had a median of 7.1

• A ratio < 2.5 suggests a viral gastroenteritis. The range (0.6 to 5.5) had a median of 1.4.

• Patients with ETEC and a ratio < 2.5 had a median duration of illness > 60 hours (Dalton et al, page 14).


Using the data ranges:



< 1.3


1.3 to 2.49

probably viral

2.5 to 5.5

probably ETEC

> 5.5




• A cutoff >= 2.5 has a sensitivity of 82% and specificity of 92%.



• The interpretation may be misleading if the number of affected patients is low or if the total number of people with diarrhea and/or vomiting is low.


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