First hemispheric report of invasive tick species Haemaphysalis punctata, first state report of Haemaphysalis longicornis, and range expansion of native tick species in Rhode Island, USA

Background Invasive arthropod vectors and the range expansions of native vectors can lead to public and veterinary health concerns, as these vectors may introduce novel pathogens or spread endemic pathogens to new locations. Recent tick invasions and range expansion in the USA has been attributed to climate and land use change, an increase in global travel, and importations of exotic animals. Methods A 10-year surveillance study was conducted on Block Island, Rhode Island, from 2010 to 2020 including sampling ticks from small mammal and avian hosts. Results We report the discovery and establishment of the red sheep tick (Haemaphysalis punctata) for the first time in the western hemisphere and in the US. This invasive species was first collected in 2010 on Block Island, was collected continuously throughout the study, and was collected from an avian host. We document the first report of the invasive Asian longhorned tick (Haemaphysalis longicornis) in the state of Rhode Island, first observed at our sites in 2018. Finally, we present data on the range expansion and establishment of two native tick species, the lone star tick and the rabbit tick, on Block Island. Conclusion This study emphasized the importance of long-term surveillance to detect changes in tick host communities, including invasive and expanding native vectors of potential significance to humans and wildlife. Graphical abstract

First Hemispheric Report of Invasive Tick Species Haemaphysalis Punctata Canestrini Et Fanzago, 1878, First State Report of Haemaphysalis Longicornis Neumann, and Range Expansion of Native Tick Species in Rhode Island, USA

Invasive arthropod vectors and the range expansions of native vectors can lead to public and veterinary health concerns, as these vectors may introduce novel pathogens or spread endemic pathogens to new locations. Recent tick invasions and range expansion in the United States has been attributed to climate and land use change, an increase in global travel, and importations of exotic animals. A 10 year surveillance study was conducted on Block Island, Rhode Island from 2010–2020 including sampling ticks from small mammal and avian hosts. We report the discovery and establishment of the red sheep tick for the first time in the western hemisphere and in the United States. This invasive species was first collected in 2010 on Block Island, was collected continuously throughout the study, and was collected from an avian host. We document the first report of the invasive Asian longhorned tick in the state of Rhode Island, first observed at our sites in 2018. Finally, we present data on the range expansion and establishment of two native tick species, the lone star tick and the rabbit tick on Block Island. This study emphasized the importance of long-term surveillance to detect changes in tick host communities, including invasive and expanding native vectors of potential significance to humans and wildlife.

Ixodes scapularis (Acari: Ixodidae) Nymphal Survival and Host-Finding Success in the Eastern United States

The blacklegged tick (Ixodes scapularis Say) is the primary vector of Borrelia burgdorferi sensu stricto (Spirochaetales: Spirochaetaceae), the Lyme disease agent in North America. The basic reproduction number (R0) for B. burgdorferi in I. scapularis in the Northeast is highly sensitive to the probability that engorged larvae survive the winter, molt into nymphs, and find a host. These processes are dependent on local environmental variables, including climate, host population size and movement, and tick behavior. A simple model is presented for estimating host-finding success from the ratio of tick abundance in two subsequent years, accounting for overwinter survival and possible differences in host associations between nymphs and larvae. This model was parameterized using data from two sites in mainland Connecticut and two on Block Island, RI. Host abundance and tick burdens were estimated via mark–recapture trapping of the primary host, Peromyscus leucopus Rafinesque. Overwintering survival was estimated using engorged larvae placed in field enclosures at each site. Only nymphs were recovered alive, and no significant differences in model parameters were observed between Connecticut and Block Island. Host-finding success was predicted to be high across a wide range of host association patterns at three of four sites. Assuming equivalent host association between larvae and nymphs, R0 was also estimated to be greater than one at three of four sites, suggesting these conditions allow for the persistence of B. burgdorferi. The model output was highly sensitive to differences between nymphal and larval host associations.

762. Climate Change and the Seroprevalence of Borrelia burgdorferi over 25 Years in Rhode Island

Background The Ixodes scapularis tick (deer tick or black-legged tick) is the primary vector of Borrelia burgdorferi, the causative agent of Lyme disease. Climatic conditions, specifically temperature, relative humidity, and rainfall, have been shown to affect I. scapularis tick densities. We hypothesized that temperature and moisture correlate with the frequency of human Lyme disease. Methods We have carried out a biannual B. burgdorferi serosurvey on Block island, Rhode Island over the past 25 years using a standard B. burgdorferi two-tier ELISA and Western blot assay. Residents of the Island were invited to participate and we only used first visit results. We analyzed B. burgdorferi seroprevalence and weather pattern trends (temperature, rainfall, relative humidity) among a cohort of 2,439 Block Island residents over the past 25 years. Results During the months in which ticks are active, we found that both temperature and relative humidity increased on Block Island over the past 25 years (p=0.04 and p=0.03, respectively). We also found that the seroprevalence of B. burgdorferi on the Island increased over the course of the study (p< 0.01), and that increased temperature and moisture in a given season is associated with increased B. burgdorferi seroprevalence in the following season. For example, we found that every inch increase in total rainfall in a given season was associated with a 2% (95% CI 1.01-1.03) increase in the odds of B. burgdorferi seropositivity during the following season. Similarly, we found that every degree Fahrenheit increase in temperature in the spring was associated with a 2% (95% CI 1.02-1.03) increase in the odds of seropositivity in the fall. Conclusion We conclude that increasing temperature and moisture are associated with increased frequency of B. burgdorferi infection in humans. Disclosures All Authors: No reported disclosures