As shown in the NETS poster, Ixodes scapularis and Amblyomma americanum are the two most prevalent species of ticks found on horses year-round. The NETS team has compared and contrasted the characteristics of these two ticks as they relate to horses. Below are the results of this comparison.
Geographic Distribution
Over the course of the survey, both Ixodes scapularis and Amblyomma americanum began to show a geographical pattern. I. scapularis tends to be localized in the northeast, while A. americanum submissions have primarily come from the southeast, as shown by the heat maps below. Our data is consistent with the expected distributions of these tick species, with some geographical expansion demonstrated. The NETS team speculates that this expansion is multi-factorial, due to the increased transport of horses across state lines, a growing White Tail Deer population nationwide, and climate change. These dynamic distributions are important because introduction of a new tick species to an area also introduces novel pathogens. Click here for a heat map of all tick submissions.
Ixodes scapularis submissions by state
Amblyomma americanum submissions by state
Seasonal Distribution
Each of these tick species strongly correlate to a specific time of year. The graph below breaks down I. scapularis, A. americanum, and all tick submissions by season. I. scapularis submissions peaked in the fall months, which is consistent with their known seasonal activity. A similar consistency is seen in A. americanum submissions, which peaked during known seasonal activity in the spring months. It is also worth noting that submissions were received in every season and every month. Most people associate finding ticks and tick bites with the spring and summer months, but our survey results show that ticks are a year-round problem.
Total Ticks Collected includes all species
Distribution On-host
When ticks are collected, we ask those submitting to provide some additional information, including where the tick(s) were found on the horse. Back at the lab, we correlate the designated tick location with 1 of 13 pre-determined zones of the horse body. This diagram shows the layout of these zones and how frequently these tick species were found in each zone. I. scapularis tended to be collected from the ventral neck and axillary regions, while A. americnum was most often found in the inguinal region. An additional diagram, found here, shows that at least one tick has been found in every zone of the body throughout the survey, emphasizing the importance of checking the entire horse for ticks.
Ixodes scapularis and Amblyomma americanum represent the two most prevalent tick species that threaten horses year-round. In particular, I. scapularis transmits the bacteria that cause Lyme Disease and Anaplasmosis, both of which affect horses. For more information on all the tick species submitted to the National Equine Tick Survey, click here.