Seasonality of acarological risk of exposure to Borrelia miyamotoi from questing life stages of Ixodes scapularis collected from Wisconsin and Massachusetts, USA

Ticks and Tick-borne Diseases
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Abstract

Measures of acarological risk of exposure to Ixodes scapularis-borne disease agents typically focus on nymphs; however, the relapsing fever group spirochete, Borrelia miyamotoi can be transmitted transovarially, and I. scapularis larvae are capable of transmitting B. miyamotoi to their hosts. To quantify the larval contribution to acarological risk, relative to nymphs and adults, we collected questing I. scapularis for 3 yr at Fort McCoy, Wisconsin (WI, n = 23,367 ticks), and Cape Cod, Massachusetts (MA, n = 4,190) in the United States. Borrelia miyamotoi infection prevalence was estimated for I. scapularis larvae, nymphs, females, and males, respectively, as 0.88, 2.05, 0.63, and 1.22% from the WI site and 0.33, 2.32, 2.83, and 2.11% from the MA site. Densities of B. miyamotoi-infected ticks (DIT, per 1,000 m2) were estimated for larvae, nymphs, females, and males, respectively, as 0.36, 0.14, 0.01, and 0.03 from the WI site and 0.05, 0.06, 0.03, and 0.02 from the MA site. Thus, although larval infection prevalence with B. miyamotoi was significantly lower than that of nymphs and similar to that of adults, because of their higher abundance, the larval contribution to the overall DIT was similar to that of nymphs and trended towards a greater contribution than adults. Assuming homogenous contact rates with humans, these results suggest that eco-epidemiological investigations of B. miyamotoi disease in North America should include larvae.A fuller appreciation of the epidemiological implications of these results, therefore, requires an examination of the heterogeneity in contact rates with humans among life stages.

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Publication type Article
Publication Subtype Journal Article
Title Seasonality of acarological risk of exposure to Borrelia miyamotoi from questing life stages of Ixodes scapularis collected from Wisconsin and Massachusetts, USA
Series title Ticks and Tick-borne Diseases
DOI 10.1016/j.ttbdis.2020.101556
Volume 12
Issue 1
Year Published 2021
Language English
Publisher Elsevier
Contributing office(s) Patuxent Wildlife Research Center
Description 101556, 7 p.
Country United States
State Massachusetts, Wisconsin
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