Where have all the grouse ticks gone? Apparent decline in collections of Haemaphysalis chordeilis Packard.

Haemaphysalis chordeilis Packard, also known as the grouse or bird tick, is a three-host tick native to North America. Literature from the early 20th century reported a widespread distribution of this tick across the US and Canada. As its name implies, ground-dwelling birds such as grouse and quail were frequent hosts, and occasionally large infestations were reported in domestic flocks making it a pest of economic importance. However, after the mid-1900's records of this species appear scarce, and a number of more recent studies of ticks on birds (including ostensibly favored host species) did not detect it. To confirm this perception with data, we conducted a literature search for collection records of this species and compared the records across two eras (pre-1965 and post-1965), finding very few records of H. chordeilis in recent years, despite increased attention brought to this genus by the detection of exotic Haemaphysalis longicornis Neumann populations in the eastern US. We also compiled a list of studies after 1965 that examined appropriate hosts for ectoparasites but failed to find H. chordeilis. We interpret the apparent decline of ticks in the context of documented population declines in several major host species over the same time frame and discuss whether ectoparasite populations should be subject to the same conservation consideration as their hosts.

The Gulf Coast Tick, Amblyomma maculatum (Ixodida: Ixodidae), and Spotted Fever Group Rickettsia in the Highly Urbanized Northeastern United States.

We report the multi-year collection of the Gulf Coast tick, Amblyomma maculatum Koch (Acaridae: Ixodida: Ixodidae) in Staten Island, New York City (NYC) as well as their detection in Brooklyn, NYC, and in Atlantic and Cumberland counties in southern New Jersey, USA. The first and most common detections were of adults, however in Freshkills Park on Staten Island larvae were also collected in a following year. The presence of larvae indicates that adults are successfully finding hosts in Staten Island. While it is still unknown how A. americanum reached Staten Island, immatures of this species often parasitize migratory birds, which are now often seen in Freshkills Park. We describe the landscape features of the area in Staten Island where populations were highest and larvae were detected, which could have facilitated the establishment of A. maculatum. Notably, we also report the presence of human pathogens Rickettsia parkeri in 5/10 (50%) of adults tested and R. felis in 1/24 (4.17%) of larvae tested. In addition to established populations in Staten Island we found evidence of A. maculatum in NJ and other NYC boroughs, suggesting current or future establishment is possible. The failure thus far to detect established populations in these areas may be due to inherent difficulties in detecting low density, spatially heterogeneous incipient populations, which could require targeted surveillance efforts for this species. We discuss the consequences to public health of the establishment of A. maculatum and detection of two additional rickettsial pathogens in the densely populated northeastern United States.

Surveillance for Amblyomma maculatum (Acari: Ixodidae) and Rickettsia parkeri (Rickettsiales: Rickettsiaceae) in the State of Delaware, and Their Public Health Implications.

Amblyomma maculatum Koch is the primary vector of Rickettsia parkeri, the etiologic agent of tidewater spotted fever, and can also carry and transmit a variety of other pathogens. This tick historically has been a costly nuisance to livestock owners in the southeastern United States. Over the past 6 yr, A. maculatum has been collected in numbers sufficient to demonstrate their establishment in Kent County, Delaware, and the presence of R. parkeri has been documented. Our goals were to determine the geographic distribution of A. maculatum and R. parkeri in Delaware, and to equate this to relative risk to the public of encountering R. parkeri-infected ticks. We surveyed for ticks in four locations throughout the state from May to August 2019, and found established A. maculatum populations in all three counties. Laboratory analysis of collected specimens by quantitative polymerase chain reaction detected R. parkeri in A. maculatum populations across the state. These results indicate that A. maculatum could present a health risk to inhabitants of the state, and they also historically have posed a risk to the livestock industry, making them an important consideration in the development and implementation of continued tick surveillance efforts and future policies regarding tick management.

Effects of Deltamethrin Treatment on Small Mammal and Ectoparasite Population Dynamics and Plague Prevalence in a North American Mixed-Grass Prairie System.

Sylvatic plague affects many species in North American prairie ecosystems. Deltamethrin is commonly used to manage fleas in potential outbreak areas. Understanding the role of small mammals and their ectoparasites in sylvatic plague maintenance is pertinent to understanding the ecology of plague and its persistence in nature. This study examined the effects of plague management using deltamethrin on communities of small mammals, their flea faunas, and Yersinia pestis prevalence. We trapped small mammals from 2014 to 2016 on the Lower Brule Indian Reservation (LOBR), South Dakota, and analyzed the effects of deltamethrin treatment on small mammal populations, flea loads, and Y. pestis prevalence. We collected higher flea loads from small mammals on sites not treated with deltamethrin (1.10 fleas per animal) than from deltamethrin-treated sites (1.03 fleas per animal). We observed significant negative trends in mean flea load per animal between pre- and post-treatment collections. We detected no significant effects of deltamethrin treatment on animal captures pre- and post-treatment, but observed significant differences in animal captures by experimental unit. We detected no serological evidence for the presence of Y. pestis antibodies in small mammals and 1.2% Y. pestis prevalence across all sampled fleas. Although there is little overlap in the species of fleas infesting small mammals and prairie dogs, the occurrence of flea spillover has been documented. In our study, treatment with deltamethrin reduced flea loads on small mammals by up to 49%. Our data suggest that although the efficacy of deltamethrin on the LOBR-a mixed-grass system-may not be as high as that found in a comparable study in a short-grass system, deltamethrin is still a useful tool in the management of plague.

Surveillance for Ixodes scapularis (Acari Ixodidae) and Borrelia burgdorferi in Eastern South Dakota State Parks and Nature Areas.

Ixodes scapularis (Acari: Ixodidae) is the principal vector of Borrelia burgdorferi (the etiologic agent of Lyme disease) in the eastern and midwestern United States. Recent efforts have documented the first established population of I. scapularis in South Dakota, representing a western expansion of the known species distribution. Our goal was to describe the current distribution of I. scapularis in eastern South Dakota and to survey for the presence of B. burgdorferi in questing I. scapularis. We surveyed for the presence of adult and nymphal I. scapularis in seven counties within South Dakota, including 13 locales from 2016 to 2017. We then tested all I. scapularis, including those collected in 2015 from a previous study, for the presence of B. burgdorferi sensu stricto, via quantitative and conventional polymerase chain reaction. Here, we document the presence of I. scapularis in four new counties in South Dakota, and report the first instance of B. burgdorferi in a questing tick in South Dakota. Coupled with data from the Centers for Disease Control and Prevention and Companion Animal Parasite Council our data show that the risk of contracting Lyme disease in South Dakota is low, but existent and should be an important consideration with regard to public health, pets, and wildlife.

Flea and Small Mammal Species Composition in Mixed-Grass Prairies: Implications for the Maintenance of Yersinia pestis.

Maintenance of sylvatic plague in prairie dogs (Cynomis spp.) was once thought unlikely due to high mortality rates; yet more recent findings indicate that low-level enzootic plague may be maintained in susceptible prairie dog populations. Another hypothesis for the maintenance of sylvatic plague involves small mammals, other than prairie dogs, as an alternative reservoir in the sylvatic plague system. These hypotheses, however, are not mutually exclusive, as both prairie dogs and small mammals could together be driving sylvatic cycles of plague. The concept of a bridging vector has been used to explain the transmission of pathogens from one host species to another. In the case of sylvatic plague, this would require overlap in fleas between small mammals and prairie dogs, and potentially other species such as carnivores. Our goal was to evaluate the level of flea sharing between black-tailed prairie dogs (Cynomis ludovicianus) and other small mammals in a mixed-grass prairie in South Dakota. We investigated the species richness of small mammals and small-mammal fleas in a mixed-grass prairie system and compared findings with previous studies from a short-grass ecosystem in Colorado. Over the summer field seasons 2014-2016 we live-trapped small mammals, collected fleas, and showed differences between both the flea and small mammal composition of the two systems. We also recorded higher densities of deer mice and lower densities of northern grasshopper mice in mixed versus shortgrass prairies. We confirmed, as is the case in shortgrass prairies, a lack of substantial flea species overlap on small mammal hosts and fleas from prairie dogs and their burrows. Moreover this study demonstrates that although small mammals may not play a large part in interepizootic plague cycling in shortgrass prairie ecosystems, their role in mixed-grass prairies requires further evaluation.

First Evidence of an Established Population of Ixodes scapularis (Acari: Ixodidae) in South Dakota.

Ixodes scapularis Say (Acari: Ixodidae) is the most important vector of human disease in the United States. Recent efforts by public health officials to determine its presence on a county-by-county basis have been undertaken to assist in Lyme disease risk assessment. Recent modeling efforts show that South Dakota can potentially support populations of I. scapularis based on favorable climatic conditions and presence of suitable hosts to support tick populations within the state. We provide the first documentation of an established population of I. scapularis in Clay County, SD, providing only the third record of the presence of this tick species within the state.

Persistence of two Trichomonas gallinae isolates in chlorinated and distilled water with or without organic material.

Trichomonas gallinae is a protozoan parasite commonly found in columbids, passerines, and raptors. In passerines and columbids, trichomonosis causes significant morbidity and mortality associated with contaminated bird feeders and waters. However, there has been little work on the persistence of T. gallinae in water to determine if artificial waters are a likely source of infection for naive birds. To examine drinking water as a source of T. gallinae transmission, we inoculated 1 x 10(6) trichomonads into containers with 500 ml of either distilled or chlorinated water. In addition, we inoculated the same number of trichomonads in distilled or chlorinated water contaminated with 15 g organic matter. Aliquots of 0.5 ml were collected from each container at 0, 0.5, 1, 5, 10, or 20 min; inoculated into a Trichomonas culture packet; and incubated at 37 C for 6 days. Survival was best in the presence of organic matter, with either distilled or chlorinated water. Uncontaminated chlorinated water did not allow survival at any sampling period.