scholarly journals Reported County-Level Distribution of the American Dog Tick (Acari: Ixodidae) in the Contiguous United States

2019 ◽  
Vol 57 (1) ◽  
pp. 131-155 ◽  
Author(s):  
Aine Lehane ◽  
Christina Parise ◽  
Colleen Evans ◽  
Lorenza Beati ◽  
William L Nicholson ◽  
...  
Keyword(s):  
United States ◽  
Spotted Fever ◽  
Geographical Area ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Accurate Information ◽  
Suitable Habitat ◽  
County Level ◽  
American Dog Tick ◽  
Dog Tick

Abstract In the United States, tick-borne diseases are increasing in incidence and cases are reported over an expanding geographical area. Avoiding tick bites is a key strategy in tick-borne disease prevention, and this requires current and accurate information on where humans are at risk for exposure to ticks. Based on a review of published literature and records in the U.S. National Tick Collection and National Ecological Observatory Network databases, we compiled an updated county-level map showing the reported distribution of the American dog tick, Dermacentor variabilis (Say). We show that this vector of the bacterial agents causing Rocky Mountain spotted fever and tularemia is widely distributed, with records derived from 45 states across the contiguous United States. However, within these states, county-level records of established tick populations are limited. Relative to the range of suitable habitat for this tick, our data imply that D. variabilis is currently underreported in the peer-reviewed literature, highlighting a need for improved surveillance and documentation of existing tick records.

scholarly journals Dermacentor variabilis is the Predominant Dermacentor spp. (Acari: Ixodidae) Feeding on Dogs and Cats Throughout the United States

2021 ◽  
Author(s):  
Kathryn T Duncan ◽  
Meriam N Saleh ◽  
Kellee D Sundstrom ◽  
Susan E Little
Keyword(s):  
United States ◽  
Spotted Fever ◽  
Rocky Mountain ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Western United States ◽  
Its2 Region ◽  
Rrna Gene ◽  
Rocky Mountain Spotted Fever ◽  
Dermacentor Albipictus

Abstract Throughout North America, Dermacentor spp. ticks are often found feeding on animals and humans, and are known to transmit pathogens, including the Rocky Mountain spotted fever agent. To better define the identity and distribution of Dermacentor spp. removed from dogs and cats in the United States, ticks submitted from 1,457 dogs (n = 2,924 ticks) and 137 cats (n = 209 ticks) from veterinary practices in 44/50 states from February 2018-January 2020 were identified morphologically (n = 3,133); the identity of ticks from regions where Dermacentor andersoni (Stiles) have been reported, and a subset of ticks from other regions, were confirmed molecularly through amplification and sequencing of the ITS2 region and a 16S rRNA gene fragment. Of the ticks submitted, 99.3% (3,112/3,133) were Dermacentor variabilis (Say), 0.4% (12/3,133) were D. andersoni, and 0.3% (9/3,133) were Dermacentor albipictus (Packard). While translocation of pets prior to tick removal cannot be discounted, the majority (106/122; 87%) of Dermacentor spp. ticks removed from dogs and cats in six Rocky Mountain states (Montana, Idaho, Wyoming, Nevada, Utah, and Colorado) were D. variabilis, suggesting this species may be more widespread in the western United States than is currently recognized, or that D. andersoni, if still common in the region, preferentially feeds on hosts other than dogs and cats. Together, these data support the interpretation that D. variabilis is the predominant Dermacentor species found on pets throughout the United States, a finding that may reflect recent shifts in tick distribution.

scholarly journals Exploring the niche of Rickettsia montanensis (Rickettsiales: Rickettsiaceae) infection of the American dog tick (Acari: Ixodidae), using multiple species distribution model approaches.

2020 ◽  
Author(s):  
Catherine Lippi ◽  
Holly D Gaff ◽  
Alexis L White ◽  
Heidi K St John ◽  
Allen L Richards ◽  
...  
Keyword(s):  
Species Distribution ◽  
Species Distribution Model ◽  
Health Planning ◽  
Spotted Fever ◽  
Dermacentor Variabilis ◽  
Distribution Model ◽  
Spotted Fever Group ◽  
Modeling Framework ◽  
American Dog Tick ◽  
Dog Tick

The American dog tick, Dermacentor variabilis (Say), is a vector for several human disease causing pathogens such as tularemia, Rocky Mountain spotted fever, and the understudied spotted fever group rickettsiae (SFGR) infection caused by Rickettsia montanensis. It is important for public health planning and intervention to understand the distribution of this tick and pathogen encounter risk. Risk is often described in terms of vector distribution, but greatest risk may be concentrated where more vectors are positive for a given pathogen. When assessing species distributions, the choice of modeling framework and spatial layers used to make predictions are important. We first updated the modeled distribution of D. variabilis and R. montanensis using MaxEnt, refining bioclimatic data inputs, and including soils variables. We then compared geospatial predictions from five species distribution modeling (SDM) frameworks. In contrast to previous work, we additionally assessed whether the R. montanensis positive D. variabilis distribution is nested within a larger overall D. variabilis distribution, representing a fitness cost hypothesis. We found that 1) adding soils layers improved the accuracy of the MaxEnt model; 2) the predicted "infected niche" was smaller than the overall predicted niche across all models; and 3) each model predicted different sizes of suitable niche, at different levels of probability. Importantly, the models were not directly comparable in output style, which could create confusion in interpretation when developing planning tools. The random forest (RF) model had the best measured validity and fit, suggesting it may be most appropriate to these data.

Emergence of Ixodes scapularis (Acari: Ixodidae) in a Small Mammal Population in a Coastal Oak-Pine Forest, Maine, USA

2021 ◽  
Author(s):  
Susan P Elias ◽  
Jack W Witham ◽  
Elizabeth F Schneider ◽  
Peter W Rand ◽  
Malcolm L Hunter ◽  
...  
Keyword(s):  
United States ◽  
Small Mammal ◽  
Ixodes Scapularis ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Mouse Population ◽  
Small Mammal Population ◽  
Prevalence Proportion ◽  
Dog Tick ◽  
White Footed Mouse

Abstract In the United States, surveillance has been key to tracking spatiotemporal emergence of blacklegged ticks [Ixodes scapularis Say (Ixodida:Ixodidae)] and their pathogens such as Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner (Spirochaetales: Spirochaetaceae), the agent of Lyme disease. On the Holt Research Forest in midcoastal Maine, collection of feeding ticks from live-trapped small mammal hosts allowed us to track the emergence and establishment of I. scapularis, 1989–2019. From 1989–1995, we collected only I. angustus Neumann (Ixodida: Ixodidae)(vole tick), Dermacentor variabilis Say (Ixodida: Ixodidae) (American dog tick), and I. marxi Banks (Ixodida: Ixodidae) (squirrel tick) from seven species of small mammals. The most abundant tick host was the white-footed mouse [Peromyscus leucopus Rafinesque (Rodentia:Cricetidae)] followed by the red-backed vole (Myodes gapperi Vigors (Rodentia: Cricetidae)). Emergence of I. scapularis was signaled via the appearance of subadult I. scapularis in 1996. Emergence of B. burgdorferi was signaled through its appearance in I. scapularis feeding on mice in 2005. There was a substantial increase in I. scapularis prevalence (proportion of hosts parasitized) and burdens (ticks/host) on white-footed mice and red-backed voles in 2007. The ~11-yr time-to-establishment for I. scapularis was consistent with that seen in other studies. White-footed mice comprised 65.9% of all captures and hosted 94.1% of the total I. scapularis burden. The white-footed mouse population fluctuated interannually, but did not trend up as did I. scapularis prevalence and burdens. There were concurrent declines in I. angustus and D. variabilis. We discuss these results in the broader context of regional I. scapularis range expansion.

scholarly journals Exploring the Niche of Rickettsia montanensis (Rickettsiales: Rickettsiaceae) Infection of the American Dog Tick (Acari: Ixodidae), Using Multiple Species Distribution Model Approaches

2020 ◽  
Author(s):  
Catherine A Lippi ◽  
Holly D Gaff ◽  
Alexis L White ◽  
Heidi K St. John ◽  
Allen L Richards ◽  
...  
Keyword(s):  
Species Distribution ◽  
Species Distribution Model ◽  
Health Planning ◽  
Spotted Fever ◽  
Dermacentor Variabilis ◽  
Distribution Model ◽  
Spotted Fever Group ◽  
Modeling Framework ◽  
American Dog Tick ◽  
Dog Tick

Abstract The American dog tick, Dermacentor variabilis (Say) (Acari: Ixodidae), is a vector for several human disease-causing pathogens such as tularemia, Rocky Mountain spotted fever, and the understudied spotted fever group rickettsiae (SFGR) infection caused by Rickettsia montanensis. It is important for public health planning and intervention to understand the distribution of this tick and pathogen encounter risk. Risk is often described in terms of vector distribution, but greatest risk may be concentrated where more vectors are positive for a given pathogen. When assessing species distributions, the choice of modeling framework and spatial layers used to make predictions are important. We first updated the modeled distribution of D. variabilis and R. montanensis using maximum entropy (MaxEnt), refining bioclimatic data inputs, and including soil variables. We then compared geospatial predictions from five species distribution modeling frameworks. In contrast to previous work, we additionally assessed whether the R. montanensis positive D. variabilis distribution is nested within a larger overall D. variabilis distribution, representing a fitness cost hypothesis. We found that 1) adding soil layers improved the accuracy of the MaxEnt model; 2) the predicted ‘infected niche’ was smaller than the overall predicted niche across all models; and 3) each model predicted different sizes of suitable niche, at different levels of probability. Importantly, the models were not directly comparable in output style, which could create confusion in interpretation when developing planning tools. The random forest (RF) model had the best measured validity and fit, suggesting it may be most appropriate to these data.

Occurrence of the American Dog Tick, Dermacentor variabilis (Say) in Western Nova Scotia

1961 ◽  
Vol 93 (10) ◽  
pp. 891-893 ◽  
Author(s):  
R. R. Hall ◽  
J. A. McKiel
Keyword(s):  
United States ◽  
Nova Scotia ◽  
Dermacentor Variabilis ◽  
Coastal Plains ◽  
Eastern United States ◽  
Male And Female ◽  
American Dog Tick ◽  
Far North ◽  
Dog Tick

The American dog tick, Dermacentor variabilis (Say) is abundant in many localities throughout the coastal plains of eastern United States (Bequaert, 1946) and according to Lewis (1960) occurs in sparse numbers as far north as the Bangor area in Maine. In Canada, it is found from Saskatchewan to Nova Scotia (Gregson, 1956) but seemingly only in small numbers and in widely separated areas east of Manitoba. The published information on its occurrence in Nova Scotia is limited to a single record by Twinn (1944) who mentioned that male and female American dog ticks in “considerable numbers” were taken at the upper waters of the Sissiboo River in Digby County. Since its presence in western Nova Scotia in infestation numbers does not appear to be generally known outside that province, it is felt that a note on our observations on D. variabilis might be of interest.

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