Move over nymphal ticks, larval deer ticks now pose a threat
The blacklegged tick has four life stages - egg, larva, nymph and adult. After it hatches, the tick must eat a blood meal (host) at every stage in order to survive. Researchers have long believed that adult female ticks could not transfer pathogens to their eggs. Therefore, larval ticks were considered pathogen-free and harmless. A new study, however, sheds light on disease transmission between life stages and suggests that we take these tiny, microscopic larvae a bit more seriously.
by Daniel J. Cameron, MD, MPH
According to investigators from the Centers for Disease Control and Prevention (CDC), larval ticks can already be infected with Borrelia miyamotoi, after they hatch from the eggs.  This occurs through a process called transovarially transmission in which the adult tick transmits the B. miyamotoi bacteria to its offspring by infecting the eggs in its ovary.
Researchers infected experimental mice with Borrelia miyamotoi, the relapsing fever bacteria. They found that “minimal or partial blood meals by single-feeding transovarially B. miyamotoi-infected larvae also resulted in approximately half of experimental hosts developing infections detectable by examination of blood for presence of B. miyamotoi DNA,” writes Breuner from the CDC’s National Center for Emerging and Zoonotic Infectious Diseases.Larval ticks need to be taken seriously, as new research finds they can transmit the relapsing fever spirochete Borrelia miyamotoi. Click To Tweet
The authors suggest that public health officials consider revising the message for tick bite prevention campaigns to include larval ticks and the season they are most active – July and August. This is a time of year when people spend a lot of time outdoors, the authors state, and may be less vigilant protecting themselves from tick bites, as they mistakenly perceive this to be a safer season.
- Breuner NE, Hojgaard A, Replogle AJ, Boegler KA, Eisen L. Transmission of the relapsing fever spirochete, Borrelia miyamotoi, by single transovarially-infected larval Ixodes scapularis ticks. Ticks Tick Borne Dis. 2018.