ABUNDANCE AND DISTRIBUTION OF MEDICALLY IMPORTANT HARD TICKS AND ASSOCIATED IXODES-BORNE PATHOGENS IN RHODE ISLAND
Abstract
Rhode Island has one of the highest per capita rates of human tick-borne disease incidence in the United States. Novel pathogens previously unknown to occur in the Northeastern US, known as emerging tick-borne pathogens (TBP), have expanded beyond their previously established geographic ranges and become a new threat to public health. These include Borrelia burgdorferi and B. mayonii, the etiological agent of Lyme disease, B. miyamotoi (tick-borne relapsing fever), Anaplasma phagocytophilum (Anaplasmosis), Babesia microti (Babesiosis), Ehrlichia muris eauclairensis (Ehrlichiosis), and Powassan virus. Additionally, hard tick vectors (Acari: Ixodidae) such as Ixodes scapularis, Amblyomma americanum, Dermacentor variabilis, and the invasive Haemaphysalis longicornis have expanded beyond their previously recognized ranges. Despite this, no attempt has been made to quantify their abundance and distribution in Rhode Island. Additionally, no active surveillance system has quantified the infection rate of emerging TBP’s in Rhode Island. Using flag sampling we collected four species of tick vectors to understand their inter-seasonal abundance and distribution. For I. scapularis, we tested for 12 pathogen species to understand their prevalence and distribution in local nymphal I. scapularis populations. Finally, we analyzed if co-infection between certain pathogens was more likely to occur than singular pathogen rates would suggest. In 2022, we collected 1760 nymphal and 180 adult I. scapularis, 131 nymphal and 16 adult A. americanum, and zero nymphal and 372 adult D. variabilis. In 2023, we found 4803 nymphal and 403 adult I. scapularis, 403 nymphal and 40 adultA. americanum, two nymphal and 187 adult D. variabilis, and seven H. longicornis nymphs. scapularis nymphs in 2022, we found infection rates of 16.98% for B. burgdorferi, .89% for B. miyamotoi, 6.70% for A. phagocytophilum, 6.83% for Ba. microti, and .25% for Powassan virus. Additionally, we found a significant relationship in co-infection between B. burgdorferi and Ba. microti but no other significant association between co-infections of other pathogens.