Lyme & Powassan Virus in Blacklegged Ticks

Charles E. Hart, et al., published a study in the journal Viruses that was designed to determine the risk of human exposure to I. scapularis ticks that were coinfected in a lab with Powassan virus (POWV) and B. burgdorferi, the bacteria that causes Lyme disease.

Adult male and female I. scapularis ticks were inoculated with either both of the pathogens, POWV only, or B. burgdorferi only, and one group remained uninfected. Following 21 days, the ticks were dissected, and RNA was isolated from their midguts and salivary glands. It was found that in the infected midguts, the amount of POWV in the coinfected ticks was higher than those with only POWV. Additionally, the salivary glands of the ticks with infected midguts had heightened POWV dissemination compared to those with only POWV.

These results show that POWV and B. burgdorferi can coincide in I. scapularis ticks with no adverse interaction and with a decrease in the replication of both pathogens. The presence of B. burgdorferi in the tick midgut enhances the replication and dissemination of POWV within the tick. The researchers speculate that, in nature, the level of co-infection can be projected to be at least the result of the rates of B. burgdorferi and POWV within a tick population. Therefore, most ticks infected with POWV can also be expected to be infected with B. burgdorferi based on its distribution in the area. 

The researchers advise that people who are living in or traveling through these areas are at risk for exposure to both pathogens from a single tick bite. They warn that most cases of POWV transmitted by I. scapularis ticks can be expected to also involve Lyme, with the risk of this element being undiagnosed.

For More Information

Read the study in Viruses.

Read more about Powassan virus.