A case of tick-borne Powassan virus in a child

Given the increasing number of tick-borne viruses such as Powassan virus in Canada, clinicians should consider these infections in patients with encephalitis, as a case study in Journal of the Canadian Medical Association.

Although Powassan virus is rare, it is a serious disease. In people with encephalitis, the mortality rate is 10-15%. After infection, it can have lasting health consequences. The virus can be transmitted within 15 minutes of a tick bite, and symptoms can appear one to five weeks later.

In this case study, a 9-year-old child with current vaccinations was hospitalized following an emergency department visit for fever, neck stiffness, and headache that occurred one week after a camping trip in Northern Ontario.

Doctors conducted extensive tests for a number of diseases, including Epstein-Barr virus, Lyme disease, bacterial meningitis and others. They also sent serological samples to the Public Health Ontario laboratory for testing, but the results were not available for several weeks. The final diagnosis, confirmed after the child was discharged, was Powassan virus.

Cases of Powassan virus encephalitis and other tick-borne diseases have increased over the past 20 years, and the authors stress that it is important to take these into account. Recent travel to an endemic region, outdoor activities such as hiking and camping, and possible contact with animals or ticks are important for diagnosis.

“Due to the nonspecific clinical features, laboratory investigations, neuroimaging findings in encephalitis, as well as the impact of climate change on the rate of tick-borne infection, comprehensive serologic testing for arboviruses should be considered in patients with encephalitis, particularly during the summer and fall,” writes Dr. Zachary Blatman, chief pediatrician at CHEO in Ottawa, Ontario, along with other authors.