Thanks to a vaccination program that began in 1995, chickenpox is now relatively rare. He has reduced cases of miserable and itchy conditions by more than 97%. But while kids have all but forgotten about oatmeal baths and oven mitts, doctors have apparently gotten their diagnostic skills a little shaky.
According to a study published Thursday, Minnesota public health researchers found that 55 percent of people diagnosed with chickenpox based on symptoms actually tested negative for the varicella-zoster virus, the virus that causes chickenpox. The study noted that all people were diagnosed directly by health care workers at health facilities. However, laboratory tests revealed that some patients were not actually infected with chickenpox, but with enterovirus, which causes a rash, or herpes simplex virus type 1, which causes cold sores.
The study, published in the U.S. Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report, supports expanded laboratory testing of suspected chickenpox cases in state programs and says symptom-based diagnosis is “unreliable.” It emphasizes that
For one thing, doctors are seeing far fewer cases of chickenpox these days, thanks to vaccine protection. Chickenpox cases in the United States used to reach 4 million annually, with 10,500 to 13,500 hospitalizations, and 100 to 150 deaths, but now there are fewer than 150,000 cases and 1,400 hospitalizations each year. The number of deaths is less than 30. CDC report. Vaccination is more than 90% effective in preventing disease. In the rare cases in which vaccinated people get chickenpox, the rash is inconspicuous and difficult to see. But even in unvaccinated children, chickenpox can be difficult to detect. It is easily confused with measles, insect bites, enteroviruses, skin infections such as scabies and impetigo, herpesvirus, and hand, foot, and mouth disease.
Since 2016, the Minnesota Department of Health has worked to expand clinical testing, including educating health care providers and the public about the importance of testing to confirm suspected chickenpox.
Between 2016 and 2023, 208 people diagnosed with chickenpox directly at a health facility submitted specimens to the state health department for testing. Only 93 of 208 (45%) tested positive for the virus. Of these, the vaccination status of 203 people is known: 100 were vaccinated and 103 were not vaccinated. Only 22 (22%) of vaccinated people tested were found to have chickenpox, compared to 68 (66%) of unvaccinated people. disease, which reflects the effectiveness of vaccination.
In the larger group of 420 people, which included people who self-diagnosed, the accuracy rate was unsurprisingly lower. Of the 420 people suspected of having chickenpox, only 157 (37%) tested positive for the varicella-zoster virus. Of the remaining 263 people, 47 were positive for enterovirus, 20 were positive for herpes simplex virus type 1, 0 were positive for herpes simplex virus type 2 (genital herpes), 2 had unknown test results, and 194 had been tested. All four viruses tested negative. .
The authors emphasize that the findings are important because people with suspected chickenpox are encouraged to miss school and work longer hours at home than people with other viral infections. More testing can ensure appropriate clinical management.
