A naplasmosis is an emergent tickborne disease caused by the obligate intracellular bacterium Anaplasma phagocytophilum (1). Initially termed human granulocytic ehrlichiosis, human infection with A. phagocytophilum was fi rst described in 1994 in patients from Minnesota and Wisconsin, USA (1,2). Now referred to as human granulocytic anaplasmosis or simply anaplasmosis, this infection is characterized by a nonspecifi c infl uenza-like illness marked by fever, fatigue, muscle aches, and headache (3). Although severe complications and death occur in rare instances, most patients recover fully after treatment with appropriate antimicrobial drugs (4).Human infection with A. phagocytophilum has now been documented in patients in North America, Europe, and Asia, and a notable incidence has occurred in the United States (5). Anaplasmosis became a nationally notifi able disease in the United States during 1999, and nationwide case counts have since increased >16-fold, from 348 cases during 2000 to 5,762 cases during 2017 (6). Most of these infections occur in the northeastern and upper midwestern states, where well-established populations of Ixodes scapularis (blacklegged or deer ticks) transmit A. phagocytophilum in addition to the infectious agents of Lyme disease, babesiosis, and Powassan virus disease (7-9).New York State (NYS), which is situated within the northeastern United States, to which tickborne diseases are endemic, has reported the second highest number of anaplasmosis cases of any state, closely behind Minnesota (10-12). Surveillance of anaplasmosis cases by the NYS Department of Health (NYSDOH) indicates that since the fi rst NYS case was reported in 1994, the burden of anaplasmosis has increased substantially, accounting for a larger proportion of NYS tickborne disease cases every year (≈4% during 2010 vs. ≈11% during 2018) (13). Since 2015, anaplasmosis has consistently surpassed babesiosis as the second most common tickborne disease in NYS, after Lyme disease (13). In addition to surveillance of tickborne disease cases, the NYSDOH also conducts routine vector surveillance to monitor the dynamics of tick populations and the prevalence of tickborne pathogens, including A. phagocytophilum, to estimate

Human granulocytic anaplasmosis (HGA) and human babesiosis are tick-borne diseases spread by the blacklegged tick (Ixodes scapularis Say, Acari: Ixodidae) and are the result of infection with Anaplasma phagocytophilum and Babesia microti, respectively. In New York State (NYS), incidence rates of these diseases increased concordantly until around 2013, when rates of HGA began to increase more rapidly than human babesiosis, and the spatial extent of the diseases diverged. Surveillance data of tick-borne pathogens (2007 to 2018) and reported human cases of HGA (n = 4,297) and human babesiosis (n = 2,986) (2013–2018) from the New York State Department of Health (NYSDOH) showed a positive association between the presence/temporal emergence of each pathogen and rates of disease in surrounding areas. Incidence rates of HGA were higher than human babesiosis among White and non-Hispanic/non-Latino individuals, as well as all age and sex groups. Human babesiosis exhibited higher rates among non-White individuals. Climate, weather, and landscape data were used to build a spatially weighted zero-inflated negative binomial (ZINB) model to examine and compare associations between the environment and rates of HGA and human babesiosis. HGA and human babesiosis ZINB models indicated similar associations with forest cover, forest land cover change, and winter minimum temperature; and differing associations with elevation, urban land cover change, and winter precipitation. These results indicate that tick-borne disease ecology varies between pathogens spread by I. scapularis.

Surveillance for the emerging infectious disease Eastern equine encephalitis, and its causative virus in mosquitoes, continued within New York State from 2013 to 2019. There were increases in geographic area and number of consecutive years, with cases in four mammalian species, and virus in 11 mosquito species. The first cases in a goat and in an emu were reported. The first detection of virus in Aedes cinereus was reported. Virus in phylogenetic group NY4 was isolated from a horse and from mosquitoes 6 kilometers and 13 days apart in 2013. Phylogenetic groups NY4 and NY5 were found 15 days apart in two towns 280 kilometers distant in 2013. Within four adjacent counties there was a pattern of overlap, where four had NY5, two adjacent counties had NY6, two adjacent counties had NY7, and one county had NY5, NY6, and NY7, reducible to a Euler diagram. Virus in phylogenetic group NY5, found within an 11-kilometer wide area in New York State, was related to FL4 found in Florida 1,398 kilometers distant. This was consistent with a phylogenetic group originating in Florida, then being moved to a specific location in New York State, by migratory birds in consecutive years 2013 and 2014.

Anaplasmosis, caused by the tickborne bacterium Anaplasma phagocytophilum , is an emerging public health threat in the United States. In the northeastern United States, the blacklegged tick ( Ixodes scapularis ) transmits the human pathogenic genetic variant of A. phagocytophilum (Ap-ha) and a nonpathogenic variant (Ap-V1). New York has recently experienced a rapid and geographically focused increase in cases of anaplasmosis. We analyzed A. phagocytophilum– infected I. scapularis ticks collected across New York during 2008–2020 to differentiate between variants and calculate an entomological risk index (ERI) for each. Ap-ha ERI varied between regions and increased in all regions during the final years of the study. Space-time scan analyses detected expanding clusters of Ap-ha located within documented anaplasmosis hotspots. Ap-ha ERI was more positively correlated with anaplasmosis incidence than non-genotyped A. phagocytophilum ERI. Our findings help elucidate the relationship between the spatial ecology of A. phagocytophilum variants and anaplasmosis.

1. The causative bacterium of Lyme disease, Borrelia burgdorferi, expanded from an undetected human pathogen into the etiologic agent of the most common vector-borne disease in the United States over the last several decades. Systematic field collections of the tick vector reveal increases in the geographic range and prevalence of B. burgdorferi-infected ticks that coincided with increases in human Lyme disease incidence across New York State.2. We investigate the impact of environmental features on the population dynamics of B. burgdorferi. Analytical models developed using field collections of nearly 19,000 nymphal Ixodes scapularis and spatially and temporally explicit environmental features accurately explained the variation in the nymphal infection prevalence of B. burgdorferi across space and time.3. Importantly, the model identified environmental features reflecting landscape ecology, vertebrate hosts, climatic metrics, climate anomalies and surveillance efforts that can be used to predict the biogeographical patterns of B. burgdorferiinfected ticks into future years and in previously unsampled areas.4. Forecasting the distribution and prevalence of a pathogen at fine geographic scales offers a powerful strategy to mitigate a serious public health threat. Synthesis and applications.A decade of environmental and tick data was collected to create a model that accurately predicts the infection prevalence of Borrelia burgdorferi over space and time. This predictive model can be extrapolated to create a high-resolution risk map of the Lyme disease pathogen for future years Journal of Applied Ecology TRAN et al.