TABLE 2
FIGURE 1
Map of Missouri Counties Surveyed for Ticks, 2019 and 2021
Tick Species and Number of Specimens Collected in Missouri, Summer 2019
Species
# of Specimens Collected
Amblyomma americanum Amblyomma maculatum Dermacentor variabilis
2,049
25
129
Ixodes scapularis
1
from dogs and horses. Additionally, ticks from turkeys and deer were brought in by hunters (Table 3). The results of laboratory confirmation of tick identification using molecular tech- niques did not detect any specimens of H . longicornis in 2019. In 2021, however, the presence of H . longicornis was established in Greene County by molecular detection of nymphal specimens. The primary purpose of our study was to demonstrate the importance of tick surveil- lance and determine the prevalence of tick species of importance in Missouri. To estab- lish our objective, we focused on 34 conser- vation areas in 22 counties in summer 2019. The tick flagging technique was reinforced by the use of sticky bait traps to collect a full range of ticks. Overall, only four species of ticks were identified ( A . americanum , A . mac- ulatum , D . variabilis , and I . scapularis ), with one or more species of Ixodes spp. Due to challenges in 2019 with obtaining ticks from specific hosts (e.g., rabbits, birds, cattle, deer) that could harbor H . longicornis , we further expanded our survey in 2021 to include an additional 31 counties (Figure 1) and a variety of hosts. As a result of the expanded surveillance involving a variety of hosts, specimens of H . longicornis were iden- tified in Greene County. The main limitation of our study is that specimens from Miami County (Kansas) and Madison County (Illinois) were included in our study. Because animals migrate season- ally, it seems plausible that specimens that were identified as H . longicornis might have been collected from a host that migrated from Kansas or Illinois.
Note. Red dots indicate counties that were surveyed. Map created with https://d-maps.com.
Identification of Ticks Ticks were transported to a laboratory facil- ity at Missouri State University for micro- scopic visual identification. Specimens of H . longicornis were sent to a CDC laboratory in Atlanta, Georgia, for species confirmation using molecular techniques. Results and Discussion In 2019, we employed flagging and sticky bait traps to collect ticks. Overall, 2,204 ticks were collected during the collection time frame. We also identified and retrieved 1,504 larvae from the legs of workers using masking tape. Visually, the collected larvae appeared to be A . americanum . Only four species of ticks of medical impor- tance were identified throughout the summer 2019 collection period (Table 2): A . america- num (2,049), A . maculatum (25), D . variabilis (129), and I . scpaularis (1). St. Charles and Macon counties had larger tick populations,
but most of the ticks were collected in Ozark County. St. Charles and Macon counties are relatively rural with lots of farmland and wild- life conservation areas, which provide a good habitat for ticks. Ozark County is, however, completely rural, has milder winters, and typi- cally has hot, sunny, and humid conditions during the summer months. These conditions have been reported to be tick-prone, so it could be plausible that ticks might have migrated to Ozark County during the winter months and stayed till the summer months when surveil- lance was conducted. In 2021, only the tick dragging tech- nique was used to collect ticks and a total of 799 ticks were collected using this technique. Further, 4,223 ticks were col- lected from veterinary oces throughout Missouri. During collection, the dragging method was more eective in collecting A . americanum ticks than I . scapularis ticks. The largest number of ticks was retrieved
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July/August 2024 • Journal of Environmental Health
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