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

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.

The potential risk of exposure to Borrelia garinii, Anaplasma phagocytophilum and Babesia microti in the Wolinski National Park (north-western Poland).

Ixodes ricinus (Acari: Ixodida) is the main vector in Europe of Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum and Babesia microti. Wolinski National Park (WNP) is situated by the Baltic Sea and is frequently visited by tourists. The aim of the study was to determine the potential risk of exposure to tick borne infection with B. burgdorferi s.l., A. phagocytophilum and B. microti on the areas of WNP. In total, 394 I. ricinus were tested. The pathogens in ticks were detected by PCR, nested PCR, RFLP and sequencing. Altogether, pathogens were detected in 12.69% of the studied ticks. B. burgdorferi s.l., was shown in 0.25% of the studied I. ricinus, while A. phagocytophilum and B. microti were detected in 1.01% and 10.65% of studied ticks, respectively. Co-infection by A. phagocytophilum and B. microti was shown in only one I. ricinus nymph. Analysis of B. burgdorferi s.l., genospecies showed that 0.25% of the studied ticks were infected with Borrelia garinii. The obtained results show the potentially high human risk of exposure to tick-borne infection with B. microti, and the low potential risk of infection with B. garinii and A. phagocytophilum on the studied areas of WNP.

Babesia microti from humans and ticks hold a genomic signature of strong population structure in the United States.

BACKGROUND: Babesia microti is an emerging tick-borne apicomplexan parasite with increasing geographic range and incidence in the United States. The rapid expansion of B. microti into its current distribution in the northeastern USA has been due to the range expansion of the tick vector, Ixodes scapularis, upon which the causative agent is dependent for transmission to humans. RESULTS: To reconstruct the history of B. microti in the continental USA and clarify the evolutionary origin of human strains, we used multiplexed hybrid capture of 25 B. microti isolates obtained from I. scapularis and human blood. Despite low genomic variation compared with other Apicomplexa, B. microti was strongly structured into three highly differentiated genetic clusters in the northeastern USA. Bayesian analyses of the apicoplast genomes suggest that the origin of the current diversity of B. microti in northeastern USA dates back 46 thousand years with a signature of recent population expansion in the last 1000 years. Human-derived samples belonged to two rarely intermixing clusters, raising the possibility of highly divergent infectious phenotypes in humans. CONCLUSIONS: Our results validate the multiplexed hybrid capture strategy for characterizing genome-wide diversity and relatedness of B. microti from ticks and humans. We find strong population structure in B. microti samples from the Northeast indicating potential barriers to gene flow.