A Comparative Spatial and Climate Analysis of Human Granulocytic Anaplasmosis and Human Babesiosis in New York State (2013–2018)

Abstract

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.

Risk of tick-borne pathogen spillover into urban yards in New York City

“…In the northeastern USA, Lyme disease, caused predominantly by the bacterium Borrelia burgdorferi sensu stricto [3] accounts for the majority of disease burden [4], and its expansion has been associated with the geographic spread of the primary vector, Ixodes scapularis [5][6][7][8][9][10]. Ixodes scapularis is also a vector of multiple other pathogens of concern, including Babesia microti [11], Anaplasma phagocytophilum [12], Borrelia miyamotoi [13] and Powassan virus [14], which are also spreading throughout the USA [15,16]. More recently, the lone star tick (Amblyomma americanum), which until recently has been considered a nuisance species and is most abundant in southern USA, has been spreading northward [17].…”

Climate change and parasitic risk to the blood supply

“…45 There is a consensus that moderately increasing environmental temperatures and non-arid conditions positively affect ticks that transmit Babesia species. 6,7 Ticks can over-winter at low temperatures with insulating effects of snow or leaf litter. 45 Transitioning of environments from arid dunes to deciduous forests has been shown to be associated with an increase in overwinter survival of blood-fed female Ixodes ticks.…”

“…; all are vector‐borne (i.e., mosquitoes, ticks, triatomine [reduviid bugs], and sand flies respectively) 2–5 . These parasites continue to emerge due to human migration into new geographical locations where they encounter relevant vectors and reservoir hosts and ongoing changes in various environmental factors 6,7 . Particularly important among environmental factors is the potential for climate change to impact the epidemiology and associated risk of parasites to blood transfusion safety 8 …”

Associations ofAnaplasma phagocytophilumBacteria Variants inIxodes scapularisTicks and Humans, New York, USA

“…ing 2010-2018; the median was 454 (range 220-1,112) cases/year. Anaplasmosis incidence increased statewide nearly 4-fold over a period of a decade, from 2.0 cases/100,000 persons in 2010 to 7.6 cases/100,000 persons during 2018; that increase was not spatially homogenous (12,13). Specifically, the largest increase in anaplasmosis incidence occurred in the Capital District region of New York, where incidence increased from 3.0/100,000 persons in 2008 to 5.3/100,000 persons in 2018 (13).…”