More Than Half of Chickenpox Diagnoses Are Wrong, Study Finds

An anonymous reader shares a report: Thanks to the vaccination program that began in 1995, chickenpox is now relatively rare. Cases of the miserable, itchy condition have fallen more than 97 percent. But, while children have largely put the oatmeal baths and oven mitts behind them, doctors have apparently let their diagnostic skills get a little crusty. According to a study published Thursday, public health researchers in Minnesota found that 55 percent of people diagnosed with chickenpox based on their symptoms were actually negative for the varicella-zoster virus, the virus that causes chickenpox. The study noted that the people were all diagnosed in person by health care providers in medical facilities. But, instead of chickenpox, lab testing showed that some of the patients were actually infected with an enterovirus, which can cause a rash, or the herpes simplex virus 1, which causes cold sores.

The study, published in the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report, supports expanding laboratory testing for suspected chickenpox cases in the state's program and highlights that diagnoses based on symptoms are 'unreliable.' For one thing, doctors simply see far fewer chickenpox cases these days because of the protection from vaccines. While chickenpox cases in the US previously reached 4 million each year, with 10,500 to 13,500 hospitalizations and 100 to 150 deaths, there are now fewer than 150,000 cases,1,400 hospitalizations, and 30 deaths each year, the CDC reports. Vaccination is more than 90 percent effective at preventing the disease. In the rare cases where a vaccinated person contracts chickenpox, the muted rashes are challenging to identify by eye. But even in unvaccinated children, chickenpox can be tricky to pick out; it can easily be confused with measles, insect bites, enterovirus, skin infections such as scabies and impetigo, herpes viruses, and hand, foot, and mouth disease.

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