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Most tickborne disease studies in the United States are conducted in low-intensity residential development and forested areas, leaving much unknown about urban infection risks. To understand Lyme disease risk in New York, New York, USA, we conducted tick surveys in 24 parks throughout all 5 boroughs and assessed how park connectivity and landscape composition contribute to Ixodes scapularis tick nymphal densities and Borrelia burgdorferi infection. We used circuit theory models to determine how parks differentially maintain landscape connectivity for white-tailed deer, the reproductive host for I. scapularis ticks. We found forested parks with vegetated buffers and increased connectivity had higher nymph densities, and the degree of park connectivity strongly determined B. burgdorferi nymphal infection prevalence. Our study challenges the perspective that tickborne disease risk is restricted to suburban and natural settings and emphasizes the need to understand how green space design affects vector and host communities in areas of emerging urban tickborne disease.

Established populations of Asian longhorned ticks (ALT), Haemaphysalis longicornis, were first identified in the United States (US) in 2017 by sequencing the mitochondrial cytochrome c oxidase subunit I (cox1) ‘barcoding’ locus followed by morphological confirmation. Subsequent investigations detected ALT infestations in 12, mostly eastern, US states. To gain information on the origin and spread of US ALT, we (1) sequenced cox1 from ALT populations across 9 US states and (2) obtained cox1 sequences from potential source populations [China, Japan and Republic of Korea (ROK) as well as Australia, New Zealand and the Kingdom of Tonga (KOT)] both by sequencing and by downloading publicly available sequences in NCBI GenBank. Additionally, we conducted epidemiological investigations of properties near its initial detection locale in Hunterdon County, NJ, as well as a broader risk analysis for importation of ectoparasites into the area. In eastern Asian populations (China/Japan/ROK), we detected 35 cox1 haplotypes that neatly clustered into two clades with known bisexual versus parthenogenetic phenotypes. In Australia/New Zealand/KOT, we detected 10 cox1 haplotypes all falling within the parthenogenetic cluster. In the United States, we detected three differentially distributed cox1 haplotypes from the parthenogenetic cluster, supporting phenotypic evidence that US ALT are parthenogenetic. While none of the source populations examined had all three US cox1 haplotypes, a phylogeographic network analysis supports a northeast Asian source for the US populations. Within the United States, epidemiological investigations indicate ALT can be moved long distances by human transport of animals, such as horses and dogs, with smaller scale movements on wildlife. These results have relevant implications for efforts aimed at minimizing the spread of ALT in the United States and preventing additional exotic tick introductions.

A 3-year study was undertaken to examine the parity status, survival, and prevalence of West Nile virus (WNV) in overwintering populations of Culex pipiens pipiens collected from a hibernaculum located in a WNV endemic region in New York City. Nearly 6,000 females were collected from December through April. Parity rates were highest among females collected in December and January, ranging from 12.3% to 21.9%, depending on the year. In each year of the study, the proportion of parous females declined significantly during the course of the winter; the percentage of parous females found in April ranged from 0.9% to 10%. Results provide unequivocal evidence that parous Cx. p. pipiens females from this region of the northeastern US enter hibernacula in the fall in comparatively high proportions not previously recognized for this species, and while these females experience significant mortality during the winter, some survived to April to emerge in the spring. The absence of any detectible blood remnants in overwintering females reaffirms that blood feeding does not occur among diapausing females during the winter. The possibility that a portion of the diapausing population may be autogenous as a result of hybridization with sympatric belowground populations of Cx. p. pipiens "form molestus" is discussed. A single isolation of WNV was obtained in Vero cell culture from a pool of 50 females collected on January 11, 2007, representing an infection prevalence of 0.07% in the overwintering population in 2007 (n = 1,370 mosquitoes, 33 pools). No isolations of WNV were made from mosquitoes collected in 2008 (n = 1,870 mosquitoes, 190 pools) or 2009 (n = 1,767 mosquitoes, 184 pools). Findings provide further evidence for local overwintering of WNV in diapausing Cx. p. pipiens, albeit at very low rates, consistent with the paucity of WNV-positive mosquitoes detected in June and early July despite the emergence of females from hibernacula in early May in this region.

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