Do larval ticks carry disease?

Hard ticks (from the Ixodidae family) account for the majority of tick bites on humans, and are named for the hard scutum or shield on their backs. They may bite people and pets during all three of their active life stages: the larval stage when they first hatch from an egg (and with only six legs!), the nymph stage after feeding as a larvae and molting, and the adult stage when they have fed as a nymph and molted into an adult.

The nymph and adult stages are responsible for most pathogen transmission to humans, both because we encounter more nymphs and adults than larvae in general, and because nymphs and adults that have already fed on at least one other animal are more likely to be infected with a pathogen—or several.

How do ticks get infected with pathogens?

Most ticks hatch from the egg without carrying any pathogens. Infection rates across any broad areas are 1% or less. Instead, most infected ticks pick up those pathogens from an infected host during their larva- or nymph-stage blood meals; in many cases these immature ticks feed on rodents such as the white-footed mouse (Peromyscus leucopus), which is the primary reservoir for common tick-borne pathogens like the bacterium that causes Lyme disease (Borrelia burgdorferi). Small rodents like the white-footed mouse exchange pathogens back and forth with ticks, which helps those pathogens survive over time in a given region. Humans are considered “dead end” hosts for most tick-borne pathogens, which means that we can acquire the pathogen from the bite of an infected tick and become sick, but it’s extremely unlikely that a “clean” tick would acquire a pathogen by feeding on us, even if we were experiencing acute illness.

What pathogens do larval ticks carry?

The good news is that most tick larvae are not going to carry germs like those that cause Lyme disease, Anaplasmosis, or Babesiosis. These pathogens do not pass easily from an infected adult female tick to the eggs it develops; this movement from tick “mother” to egg is called transovarial transmission or vertical transmission.

However, continued research has shown that at least two pathogens can be transmitted transovarially in the “deer” tick or black-legged tick (Ixodes scapularis). These pathogens include the Borrelia miyamotoi bacteria and Powassan virus.

Vertical/transovarial transmission of Borrelia miyamotoi, a relative of Lyme bacteria that causes Hard tick relapsing fever, has been known to pass to eggs and larvae since at least the early 2000s, and researchers continue to explore how the bacterium is transmitted and maintained in nature. We occasionally find Ixodes larvae infected with Borrelia miyamotoi in ticks submitted by individuals to our TickReport testing service.

Powassan virus in Ixodes larvae is a more recent discovery. While surveillance work in nature and transmission experiments under laboratory conditions has been an ongoing project for decades, a March 2024 article from surveillance of ticks and deer in New York state provided was important in bridging that gap between theory and practice. That project found Powassan virus RNA in both larvae that were questing for a host to bite and in larvae that were hatched in the lab from infected adult female ticks.

Can I get sick from the bite of a larval tick?

The risk of exposure from larval ticks remains low, but there does seem to be some risk of exposure to Borrelia miyamotoi bacteria or Powassan virus. Other pathogens may be added to that list as time goes on. Due to their small size, tick larvae are very difficult to spot and remove until they have fed for several days and have grown in size from feeding; repellents on skin and clothing are crucial to reducing ticks bites from larvae.

To test a tick for pathogens, visit TickReport.com. Our service has been trusted by individuals and agencies since 2006, and every tick tested feeds into our searchable nationwide database of ticks and tick infections.