is a vector of arboviruses with high rates of morbidity and mortality. The northern limit of
in the northeastern United States runs through New York state (NYS) and Connecticut. We present a ...landscape-level analysis of mosquito abundance measured by daily counts of
from 338 trap sites in 12 counties during May-September 2017. During the study period, the mean number of
caught per day of trapping across all sites was 3.21. We constructed four sets of negative binomial generalized linear models to evaluate how trapping methodology, land cover, as well as temperature and precipitation at multiple time intervals influenced
abundance. Biogents-Sentinel (BGS) traps were 2.78 times as efficient as gravid traps and 1.49 times as efficient as CO
-baited CDC light traps. Greater proportions of low- and medium-intensity development and low proportions of deciduous cover around the trap site were positively associated with increased abundance, as were minimum winter temperature and March precipitation. The cumulative precipitation within a 28-day time window before the date of collection had a nonlinear relationship with abundance, such that greater cumulative precipitation was associated with increased abundance until approximately 70 mm, above which there was a decrease in abundance. We concluded that populations are established in Nassau, Suffolk, and New York City counties in NYS; north of these counties, the species is undergoing population invasion and establishment. We recommend that mosquito surveillance programs monitoring the northward invasion of
place BGS traps at sites chosen with respect to land cover.
Tick-borne pathogens pose a considerable disease burden in Europe and North America, where increasing numbers of human cases and the emergence of new tick-borne pathogens has renewed interest in ...resolving the mechanisms underpinning their geographical distribution and abundance. For Borrelia burgdorferi and tick-borne encephalitis (TBE) virus, transmission of infection from one generation of ticks to another occurs when older nymphal ticks infect younger larval ticks feeding on the same host, either indirectly via systemic infection of the vertebrate host or directly when feeding in close proximity. Here, expressions for the basic reproduction number, R0, and the related tick type-reproduction number, T, are derived that account for the observation that larval and nymphal ticks tend to aggregate on the same minority of hosts, a tick feeding behaviour known as co-aggregation. The pattern of tick blood meals is represented as a directed, acyclic, bipartite contact network, with individual vertebrate hosts having in-degree, kin, and out-degree, kout, that respectively represent cumulative counts of nymphal and larval ticks fed over the lifetime of the host. The in- and out-degree are not independent when co-aggregation occurs such that T∝〈kinkout〉〈kin〉,where 〈.〉 indicates expected value. When systemic infection in the vertebrate host is the dominant transmission route R02=T, whereas when direct transmission between ticks co-feeding on the same host is dominant then R0=T and the effect of co-aggregation on R0 is more pronounced. Simulations of B. burgdorferi and TBE virus transmission on theoretical tick-mouse contact networks revealed that aggregation and co-aggregation have a synergistic effect on R0 and T, that co-aggregation always increases R0 and T, and that aggregation only increases R0 and T when larvae and nymphs also co-aggregate. Co-aggregation has the greatest absolute effect on R0 and T when the mean larval burden of hosts is high, and the largest relative effect on R0 for pathogens sustained by co-feeding transmission, e.g. TBE virus in Europe, compared with those predominantly spread by systemic infection, e.g. B. burgdorferi. For both pathogens, though, co-aggregation increases the mean number of ticks infected per infectious tick, T, and so too the likelihood of pathogen persistence.
Tick-borne pathogens pose a considerable disease burden in Europe and North America, where increasing numbers of human cases and the emergence of new tick-borne pathogens has renewed interest in ...resolving the mechanisms underpinning their geographical distribution and abundance. For Borrelia burgdorferi and tick-borne encephalitis (TBE) virus, transmission of infection from one generation of ticks to another occurs when older nymphal ticks infect younger larval ticks feeding on the same host, either indirectly via systemic infection of the vertebrate host or directly when feeding in close proximity. Here, expressions for the basic reproduction number, R
, and the related tick type-reproduction number, T, are derived that account for the observation that larval and nymphal ticks tend to aggregate on the same minority of hosts, a tick feeding behaviour known as co-aggregation. The pattern of tick blood meals is represented as a directed, acyclic, bipartite contact network, with individual vertebrate hosts having in-degree, k
, and out-degree, k
, that respectively represent cumulative counts of nymphal and larval ticks fed over the lifetime of the host. The in- and out-degree are not independent when co-aggregation occurs such that Formula: see text where 〈.〉 indicates expected value. When systemic infection in the vertebrate host is the dominant transmission route R
=T, whereas when direct transmission between ticks co-feeding on the same host is dominant then R
=T and the effect of co-aggregation on R
is more pronounced. Simulations of B. burgdorferi and TBE virus transmission on theoretical tick-mouse contact networks revealed that aggregation and co-aggregation have a synergistic effect on R
and T, that co-aggregation always increases R
and T, and that aggregation only increases R
and T when larvae and nymphs also co-aggregate. Co-aggregation has the greatest absolute effect on R
and T when the mean larval burden of hosts is high, and the largest relative effect on R
for pathogens sustained by co-feeding transmission, e.g. TBE virus in Europe, compared with those predominantly spread by systemic infection, e.g. B. burgdorferi. For both pathogens, though, co-aggregation increases the mean number of ticks infected per infectious tick, T, and so too the likelihood of pathogen persistence.
An inverse relationship between biodiversity and human health has been termed the ‘dilution effect’ paradigm. In the case of tick-borne infections such as Lyme disease, the key assumption is that ...Borrelia burgdorferi sensu lato abundance is increased by the loss of less competent (dilution) hosts as biodiversity declines. White-tailed deer play a dual role in the pathogen cycle, as key reproductive hosts for adult ticks and incompetent hosts for the pathogen. While the role of deer as hosts of adult ticks is well established, the extent to which deer also feed immature ticks and reduce the proportion infected is unknown because of logistic constraints in measuring this empirically. We estimated the proportion of larvae that fed on deer in an extremely species-poor community on Block Island, RI, where tick nymphal infection prevalence was found to be lower than expected. In 2014, we measured the density, larval tick burdens, and realized reservoir competence of small mammal and bird hosts on Block Island, RI. In 2015, we measured the infection prevalence of host-seeking Ixodes scapularis nymphs resulting from larvae fed on available hosts in 2014. We back-estimated the proportion of larvae expected to have fed on deer in 2014 (the only unknown parameter) to result in the nymphal infection prevalence observed in 2015. Back-estimation predicted that 29% of larval ticks must have fed on deer to yield the observed 30% nymphal infection prevalence. In comparison, the proportion of larvae feeding on mice was 44% and 27% on birds. Our study identified an influential role of deer in reducing nymphal tick infection prevalence and a potential role as dilution hosts if the reduction in nymphal infection prevalence outweighs the role of deer as tick population amplifiers. Because both deer and competent hosts may increase in anthropogenic, fragmented habitats, the links between fragmentation, biodiversity, and Lyme disease risk may be complex and difficult to predict. Furthermore, a nonlinear relationship between deer abundance and Lyme disease risk would reduce the efficacy of deer population reduction efforts to control Lyme disease.
Since 1999, West Nile virus (WNV) disease has affected the northeastern United States. To describe the spatial epidemiology and identify risk factors for disease incidence, we analyzed 8 years ...(1999-2006) of county-based human WNV disease surveillance data. Among the 56.6 million residents in 8 northeastern states sharing primary enzootic vectors, we found 977 cases. We controlled for population density and potential bias from surveillance and spatial proximity. Analyses demonstrated significant spatial spreading from 1999 through 2004 (p<0.01, r2 = 0.16). A significant trend was apparent among increasingly urban counties; county quartiles with the least (<38%) forest cover had 4.4-fold greater odds (95% confidence interval CI 1.4-13.2, p = 0.01) of having above-median disease incidence (>0.75 cases/100,000 residents) than counties with the most (>70%) forest cover. These results quantify urbanization as a risk factor for WNV disease incidence and are consistent with knowledge of vector species in this area.
Shifts in activity patterns during the COVID-19 pandemic might have impacted the benefits of outdoor activities for mental health. By leveraging an existing mobile application, we collected ...self-reported data on daily outdoor activities, emotional well-being, and the influence of COVID-19 on participant’s outdoor activity levels during April–July 2020. Individuals reporting outdoor activities, in greenspaces or in their residence, had higher well-being scores and this effect increased with age. Self-reported impacts of COVID-19 on emotional well-being were associated with lower well-being scores. This work suggests that outdoor activities may have improved mental health during the COVID-19 pandemic.
•No pathogens were recovered from any life stage, questing or host-derived ticks.•Virus enrichment and shotgun bacterial metagenomics approaches were utilized and analyzed.•H. longicornis is ...potentially not a vector of tick-borne pathogens in NYC.
Haemaphysalis longicornis, the Asian longhorned tick, is an invasive tick species that has spread rapidly across the northeastern and southeastern regions of the United States in recent years. This invasive pest species, known to transmit several tick-borne pathogens in its native range, is a potential threat to wildlife, livestock, domestic animals, and humans. Questing larval (n = 25), nymph (n = 10), and adult (n = 123), along with host-derived adult (n = 25) H. longicornis ticks were collected from various locations on Staten Island, NY. The pathobiome of each specimen was examined using two different high throughput sequencing approaches, virus enrichment and shotgun metagenomics. An average of 45,828,061 total reads per sample were recovered from the virus enriched samples and an average of 11,381,144 total reads per sample were obtained using shotgun metagenomics. Aside from endogenous viral sequences, no viruses were identified through either approach. Through shotgun metagenomics, Coxiella-like bacteria, Legionella, Sphingomonas, and other bacterial species were recovered. The Coxiella-like agent was ubiquitous and present at high abundances in all samples, suggesting it may be an endosymbiont. The other bacterial agents are not known to be transmitted by ticks. From these analyses, H. longicornis do not appear to host any endemic human tick-borne pathogens in the New York City region.
West Nile virus (WNV) infection is mainly asymptomatic but can be severe in elderly persons. As part of studies on immunity and aging in Connecticut, USA, we detected WNV seroconversion in 8.5% of ...nonimmunosuppressed and 16.8% of immunosuppressed persons. Age was not a significant seroconversion factor. Our findings suggest that immune factors affect seroconversion.
Because of their capacity for long-range movement, birds may play an important role in the spread and range expansion of zoonotic pathogens and their vectors. The black-legged tick (
Ixodes ...scapularis
) is the principal vector for the Lyme disease bacterium
Borrelia burgdorferi
, and commonly parasitizes a wide variety of vertebrate hosts, including at least 71 species of North American birds. Although the role of birds in
B burgdorferi
transmission dynamics is often discounted, data compiled from published studies indicate that the majority (58.6%%) of bird species that have been evaluated are capable of infecting larval
I scapularis
with
B burgdorferi
. We estimated -– for two bird species -– that the number of individual birds required to produce one infected
I scapularis
larva is as low as three, and we conclude that bird-mediated tick movement is an important factor in the range expansion of both
I scapularis
and
B burgdorferi
.
The risk of transmission of West Nile virus (WNV) to humans is associated with the density of infected vector mosquitoes in a given area. Current technology for estimating vector distribution and ...abundance is primarily based on Centers for Disease Control and Prevention (CDC) light trap collections, which provide only point data. In order to estimate mosquito abundance in areas not sampled by traps, we developed logistic regression models for five mosquito species implicated as the most likely vectors of WNV in Connecticut. Using data from 32 traps in Fairfield County from 2001 to 2003, the models were developed to predict high and low abundance for every 30 x 30 m pixel in the County. They were then tested with an independent dataset from 16 traps in adjacent New Haven County. Environmental predictors of abundance were extracted from remotely sensed data. The best predictive models included non-forested areas for Culex pipiens, surface water and distance to estuaries for Cx. salinarius, surface water and grasslands/agriculture for Aedes vexans and seasonal difference in the normalized difference vegetation index and distance to palustrine habitats for Culiseta melanura. No significant predictors were found for Cx. restuans. The sensitivity of the models ranged from 75% to 87.5% and the specificity from 75% to 93.8%. In New Haven County, the models correctly classified 81.3% of the traps for Cx. pipiens, 75.0% for Cx. salinarius, 62.5% for Ae. vexans, and 75.0% for Cs. melanura. Continuous surface maps of habitat suitability were generated for each species for both counties, which could contribute to future surveillance and intervention activities.
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