Evidence of Incomplete Feeding Behaviors among South Carolina Tick Populations

TL;DR

South Carolina ticks are feeding on multiple hosts, including humans, which increases the risk of spreading diseases.

Contribution

This study provides the first evidence of incomplete feeding behavior in South Carolina tick populations, linking it to potential disease transmission risks.

Findings

Approximately one-third of collected ticks had fed on humans.

Incomplete feeding patterns varied by species, location, and time of collection.

The behavior aligns with rising tick-borne disease trends in the southeastern USA.

Abstract

In the southeastern United States of America, shifts in the environment such as climate change and host availability are pushing tick populations to spread into new areas. It is hypothesized that, as they migrate, tick populations have developed a behavior known as incomplete feeding. With this, ticks feed on more than one host at each life stage, increasing the chance of pathogen transmission. In South Carolina, we found evidence of ticks displaying this behavior. We collected engorged female ticks from stray dogs at animal shelters across the state in 2022. Testing showed that about a third of these ticks had fed on humans. The patterns varied depending on the tick species, where they were found, and the time of collection. This pilot study reflects the growing trend of tick-borne diseases in the southeastern USA. It is crucial to dig deeper into how factors like the season, location, and species are linked to incomplete feeding behavior in South Carolina’s tick populations.

Dynamic environmental conditions, such as climate change and host availability, have greatly influenced the expansion of medically relevant tick vectors into new regions throughout the southeastern United States of America. As tick populations migrate into new areas, it has been suggested they can exhibit a phenomenon known as incomplete feeding. With this phenomenon, tick vectors feed on more than one host at each life stage, thus increasing the likelihood of pathogen transmission. Although this behavior is not well understood, it presents an important threat to human health. Here we present evidence of incomplete feeding behaviors in multiple tick species in South Carolina. Engorged, blood-fed female ticks were collected from feral dogs at animal shelters across South Carolina in 2022. All ticks were tested for human blood meals using rapid stain identification blood tests. Approximately one third (33.78%) of all ticks tested positive for a human blood meal, with various patterns seen across species, geographic location, and collection month. The results of this pilot study follow the current national trend of increasing rates of tick-borne disease incidence in the southeastern United States of America and warrant further investigation into the relationship between seasonality, geographic distribution, species, and incomplete feeding among tick populations in South Carolina.

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