What a difference a vaccine makes

A 3-month-old infant boy was admitted to the hospital in early July because of a 3-day history of vomiting followed by 2 more days of explosive, watery diarrhea. By the time the infant was hospitalized the diarrhea had flecks of blood and tested positive by guaiac. Blood, urine, stool, and cerebrospinal fluid cultures were performed because of concern about bacterial infection, and he was treated with ampicillin and ceftriaxone IV for 48 hours until cultures were determined to be negative. Before the onset of diarrhea, an upper GI study was done because of concern about pyloric stenosis.

It was not until the 6th day of illness, after multiple additional tests had been performed, that rotavirus was even considered. Ultimately, the test results came back negative, but that does not diminish the fact that rotavirus should have been included in the initial differential diagnosis. By the time the infant was tested, his clinical condition had greatly improved, and he was discharged.

Despite the fact that rotavirus has typically been seen in the winter and spring in the United States, and only rarely in the summer months, it is difficult to imagine that rotavirus would not have been an early consideration in this child in past years. Everything about the clinical course was typical. Even the flecks of blood in the infant's stool, which, though not common in rotavirus diarrhea, is certainly not inconsistent with that diagnosis.

Formal recommendations for routine rotavirus vaccination were made by the Centers for Disease Control and Prevention and the American Academy of Pediatrics in the summer of 2006. Surveillance conducted at sentinel laboratories throughout the United States has shown that since then there has been a marked reduction in the frequency of rotavirus infection. When the 2007/2008 and 2008/2009 years are compared to the years from 2000 to 2006, the number of tests for rotavirus had not declined—the total at the 29 laboratories was between 14,000 and 15,000 per year—but the percentage of those tests that were positive had fallen from 25% down to 9% to 10% (Morbidity and Mortality Weekly Report, 2009;58:1146-1149). This decline was noted despite data from sentinel immunization sites indicating that only about 58% of infants had received a dose of rotavirus vaccine by 3 months of age and only about 31% had received more than 1 dose by 2 years of age. These sentinel sites document a delay in the onset of rotavirus season by as much as 11 weeks since the introduction of the vaccine.

How quickly we forget! After only 3.5 years of routine use of rotavirus vaccine, infection because of this virus has marched farther and farther down our list of possible diagnoses for an infant with vomiting followed by diarrhea. Just as we've seen with conditions such as epiglottitis and measles, rotavirus and other diseases that are effectively prevented by vaccines could, over time, be unrecognized by pediatricians familiar with those infections only through tales from more experienced faculty members and by reading about them in textbooks. Although those of us with that first-hand knowledge may decry the lack of familiarity our less experienced colleagues will have with these "classic" presentations, I don't think the children or their parents will complain.

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