Half of the chicken pox cases turned out not to be chicken pox

An itchy rash and fever are well-known manifestations of chickenpox, or simply varicella. However, a recent study in the United States showed that when medical professionals make this diagnosis based on symptoms, it is often not confirmed by laboratory tests.

Chickenpox is a common viral infection of the herpesvirus family (Herpesviridae). Its causative agent, the Varicella zoster virus (Varicella zoster), is transmitted by airborne droplets and is considered a record-breaker in terms of virulence, i.e. the ability to infect the human body. Contact with it in 90 percent of cases leads to disease in those who have not previously encountered this infection or not immunized against it.

The outward manifestations of chickenpox can easily be confused with symptoms of other diseases such as measles, enteroviruses and skin infections. The diagnosis of chickenpox can be confirmed by testing for its causative agent. The weekly epidemiological digest published by the U.S. Centers for Disease Control and Prevention (CDC) shows the usefulness of such a test. The fresh document highlights the incidence of chickenpox in Minnesota, where local health authorities have been expanding laboratory confirmation of the infection since 2016.

From 2016 through 2023, 208 patients diagnosed with chickenpox at a health care facility following a face-to-face clinical examination had PCR tests to detect the pathogen. Only 93 people, i.e. only 45 percent, tested positive for Varicella zoster virus. Other pathogens detected included enterovirus and herpes simplex virus type 1.

In five of the 208 patients examined, vaccination status could not be established; 100 had been vaccinated against chickenpox and 103 had not. Among those vaccinated, chickenpox was confirmed in only 22 people, while in the unvaccinated group there were 68 such people, which indicates the effectiveness of vaccination.

In addition, the study looked at 420 people with suspected chickenpox, but without an official diagnosis from medics. The average age of these patients was five years old, and nearly a quarter of them collected samples for analysis at home.

A total of 157 people, or 37 percent of the sample, tested positive for varicella-zoster virus. Another 47 had enterovirus, and 20 patients were found to have herpes simplex type 1. Two people had undetermined test data, and the remaining 194 people tested were negative for the three types of pathogen mentioned and for herpes simplex virus type 2 (genital).

We would like to add that although the majority of those who contract chickenpox are children, it can be contracted at any age, and in adults the disease is more likely to run with complications, including neurological ones. In addition, if you get chickenpox in childhood in a mild form, there is a risk of getting it again in older age. Infectious disease doctors consider vaccination to be the safest way to acquire immunity from chickenpox.

According to the U.S. Centers for Disease Control and Prevention, in the United States, where varicella vaccine is included in the national vaccination calendar, immunization has reduced morbidity by more than 97 percent since 1995.

In Russia, this problem is quite relevant, given that the economic damage from chickenpox is estimated at tens of billions of rubles a year. Based on American data, it is possible that a significant part of this waste is the result of incorrect diagnosis.