June 2002

A 2-year-old girl was admitted to the hospital for evaluation and treatment of a febrile illness with a rash and a seizure. The onset of fever was with the seizure prior to admission. The seizure was generalized and lasted about five minutes, requiring no medical intervention. She is on no medications.

Her past medical history and family history are unremarkable, but she does attend day care. Her immunizations are up to date. In fact, she had just received her varicella vaccine (Varivax, Merck) about one week earlier.

The emergency department staff performed a complete blood count, urinalysis, electrolytes, blood and urine cultures and a CT scan of the head. The cultures are pending and the rest are normal, including the scan.

Examination revealed a normal appearing 2-year-old female with a fever of 101° F and a rash consisting of a few maculopapular lesions, some of which appeared to have a tiny vesicular dome (figures 1-3). The remainder of her examination was normal.

What’s Your Diagnosis?

1. Sepsis/meningitis
2. Enteroviral exanthem
3. Varicella vaccine rash
4. Disseminated herpes simplex

Answer

This was a varicella vaccine rash, which occurs in 3% to 5% of recipients between one and three weeks later, usually within two weeks. It typically consists of only a few lesions that may be maculopapular and/or vesicular. Concerns have been raised about its ability to transmit varicella to susceptible contacts. This has been a rare event, and seen only in those with vesicles. According to Dr. Larry K. Pickering, the senior advisor to the director of the National Immunization Program at the CDC, more than 26 million doses of vaccine have been distributed, but only three cases of vaccine-associated varicella (secondary transmission) have been documented (22nd Annual National Pediatric Infectious Diseases Seminar in New Orleans). Each case resulted in mild disease without complication. Again, transmission only occurred in these cases on exposure to a vaccinated patient with a vesicular rash (figure 4). Other rashes (maculopapular) after vaccination have not been associated with secondary transmission.

While this live-virus vaccine produces a good, measurable antibody response (over 95% of those vaccinated), its efficacy in children is somewhat less. About 10% to 15% of vaccinated children will remain susceptible to varicella upon household exposure. However, these children only express mild disease. Neither mortality nor serious morbidity has been reported in these children. Therefore, it is almost 100% effective at preventing severe disease. There is over 20 years experience with this vaccine in Japan, with evidence that the duration of immunity is at least that long. However, once wild varicella is further reduced in communities, and therefore, the chances of exposure goes down, the booster or anamnestic effect in vaccinated individuals will also go down. This may impact on duration of immunity data that we have.

Postimmunization zoster is another concern. However, while data are still being collected on this issue, current data are reassuring that there is at least no increased incidence of zoster due to varicella vaccine. In fact, it is most likely that there is a significantly less chance of developing zoster after varicella vaccine when compared with varicella disease. We will just have to wait to get the final word on this issue.

Varicella resources

Lastly, the issue of vaccine shortages has been on the front pages of newspapers and magazines like this (March 2002) for the last several months. For a variety of reasons, varicella vaccine is included among those in short supply. I would recommend you review the CDC Web site for the latest recommendations. Just go to www.CDC.gov and search under “vaccine shortage.” In February, the CDC recommended postponing the varicella vaccine until the child turns 18 months, with a callback system for those caught in this postponement period. It is expected that the shortage will be resolved soon.

For the best single source on varicella disease and vaccine, I would recommend the 2000 Red Book. And if you want to spend a little more, but get a lot more, I recommend the Visual Red Book. Dr. Ed Ledbetter headed up the effort to put this together on a compact disc with hundreds of photographs to go with the various infectious diseases discussed in the Red Book. It is well worth the investment for those who take care of children. Since its 2000 publication, the Visual Red Book has been updated once, and work is being done to put out a 2003 edition. I do not believe you can find an atlas of infectious diseases of comparable value for the money. Also, if you do a lot of teaching, the photos in the Visual Red Book can be copied and pasted to your Power Point presentations. Obviously, you have to get permission to use them in any publication format, but, according to the conversations I have had with the AAP, the pictures apparently can be used to teach students, residents and others as much as you like. For any questions, I would refer you to the copyright section at the end of the Visual Red Book, or call the AAP directly. Kudos to Dr. Ledbetter and the Committee on Infectious Diseases (Red Book Committee) for an excellent educational resource. I am anxiously looking forward to the next edition. I would also recommend reading Dr. Philip Brunell’s editorial on varicella vaccine in the March 2002 issue of this newspaper. Dr. Brunell is truly one of the world’s leading experts in this area of infectious diseases.

The other answers

Sepsis/meningitis was a choice, but never a serious consideration. She simply was not that sick. The rash of bacterial sepsis, like meningococcemia, is shown in figures 5 and 6. Her seizure was considered to be a simple febrile seizure. We normally do not admit those patients to the hospital, but sometimes they sneak in during the night.

Since we are now well into the summer, enteroviral infections are occurring with increasing frequency, and in keeping with the special focus of this issue, I felt it should be included in the differential. An enteroviral exanthem is common, and may look exactly like this patient (figure 7). The clue to the diagnosis was in the history of recent varicella vaccine. Except for that fact, however, I don’t think anyone would be able to tell the difference in these two patients. Furthermore, the fact that there is a temporal association with the patient having recently received a varicella vaccine does not prove that the febrile illness and rash was due to the vaccine.

So, one could argue that the real answer could be either #2 or #3, even in “nonseasonal” times of the year. We recovered an echovirus from the spinal fluid of a child with aseptic meningitis last January. We also had an outbreak of influenza A in a nearby summer camp last summer. These and other infectious diseases may have seasonal peaks, but never go away altogether.

Disseminated herpes simplex infection is always a concern in a febrile child with a rash and seizures. However, such a patient would have a vesicular rash on a much sicker child, and would be very uncommon.

Correction: In the April 2002 issue of IDC, I answered a number of letters regarding the STAR complex. In my reply I incorrectly referred to the STAR complex as a nomogram. Obviously, it is an acronym, which is a word formed from the first letters of a series of words (Sore throat, Temperature elevation, Arthritis, Rash). A nomogram is a set of scales for variables in a problem or condition, which are placed so that a straight line drawn between two known points will give the answer to an unknown at the intersection of the line and a third scale. An example that we commonly use is the surface area nomogram. I’m surprised that I did not get any mail on this error. Either no one is reading those letters, or you have all become so used to my stupid mistakes that you don’t have enough time to keep correcting me. – James Brien, DO

For Your Information:

• James H. Brien, DO, Pediatric Infectious Disease, Scott and White's Children's Health Center and Texas A&M University, College of Medicine, Temple, Texas. E-mail: jhbriend@aol.com