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1.
J Med Entomol ; 61(2): 504-507, 2024 Mar 13.
Article in English | MEDLINE | ID: mdl-38195205

ABSTRACT

The invasive tick, Haemaphysalis longicornis Neumann, is now present across most of the mid-Atlantic States in the eastern United States. This tick ends its seasonal activity in late October to early November, with larvae being the last life-stage observed questing. Previous research has revealed that the activity of H. longicornis is influenced by photoperiod: short daylight lengths trigger diapause in nymphs, marking it as the primary overwintering stage. However, whether engorged larvae can enter diapause or are affected by short daylight is unclear. In this study, we tested in the laboratory whether the photoperiod Affects the development of H. longicornis engorged larvae and engorged nymphs under constant temperature and humidity. The results showed that engorged larvae molted significantly faster (3 days faster) when the photoperiod was 9 h of light as opposed to 14 h. In contrast, changes in the photoperiod did not affect the molting of engorged nymphs. Our results demonstrate that engorged larvae respond to short daylight length, by molting faster. These results suggest that engorged larvae are unlikely to overwinter under field conditions and support the expectation that nymphs are the primary overwintering stage for H. longicornis in the United States.


Subject(s)
Ixodidae , Ticks , Animals , Haemaphysalis longicornis , Photoperiod , Temperature , Larva , Nymph
2.
Infect Immun ; 92(1): e0024423, 2024 Jan 16.
Article in English | MEDLINE | ID: mdl-38099660

ABSTRACT

Interactions among pathogen genotypes that vary in host specificity may affect overall transmission dynamics in multi-host systems. Borrelia burgdorferi, a bacterium that causes Lyme disease, is typically transmitted among wildlife by Ixodes ticks. Despite the existence of many alleles of B. burgdorferi's sensu stricto outer surface protein C (ospC) gene, most human infections are caused by a small number of ospC alleles ["human infectious alleles" (HIAs)], suggesting variation in host specificity associated with ospC. To characterize the wildlife host association of B. burgdorferi's ospC alleles, we used metagenomics to sequence ospC alleles from 68 infected individuals belonging to eight mammalian species trapped at three sites in suburban New Brunswick, New Jersey (USA). We found that multiple allele ("mixed") infections were common. HIAs were most common in mice (Peromyscus spp.) and only one HIA was detected at a site where mice were rarely captured. ospC allele U was exclusively found in chipmunks (Tamias striatus), and although a significant number of different alleles were observed in chipmunks, including HIAs, allele U never co-occurred with other alleles in mixed infections. Our results suggest that allele U may be excluding other alleles, thereby reducing the capacity of chipmunks to act as reservoirs for HIAs.


Subject(s)
Borrelia burgdorferi , Borrelia , Coinfection , Ixodes , Lyme Disease , Animals , Humans , Borrelia burgdorferi/genetics , Borrelia/genetics , Alleles , Lyme Disease/microbiology , Ixodes/genetics , Ixodes/microbiology , Antigens, Bacterial/genetics , Bacterial Outer Membrane Proteins/genetics , Sciuridae/genetics , Host Specificity
3.
Parasitology ; 150(11): 1063-1069, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37791496

ABSTRACT

Piroplasms, which include the agents of cattle fever and human and dog babesiosis, are a diverse group of blood parasites of significant veterinary and medical importance. The invasive Asian longhorned tick, Haemaphysalis longicornis, is a known vector of piroplasms in its native range in East Asia and invasive range in Australasia. In the USA, H. longicornis has been associated with Theileria orientalis Ikeda outbreaks that caused cattle mortality. To survey invasive populations of H. longicornis for a broad range of piroplasms, 667 questing H. longicornis collected in 2021 from 3 sites in New Jersey, USA, were tested with generalist piroplasm primers targeting the 18S small subunit rRNA (395­515 bp, depending on species) and the cytochrome b oxidase loci (1009 bp). Sequences matching Theileria cervi type F (1 adult, 5 nymphs), an unidentified Theileria species (in 1 nymph), an undescribed Babesia sensu stricto ('true' Babesia, 2 adults, 2 nymphs), a Babesia sp. Coco (also a 'true Babesia', 1 adult, 1 nymph), as well as Babesia microti S837 (1 adult, 4 nymphs) were recovered. Babesia microti S837 is closely related to the human pathogen B. microti US-type. Additionally, a 132 bp sequence matching the cytochrome b locus of deer, Odocoileus virginanus, was obtained from 2 partially engorged H. longicornis. The diverse assemblage of piroplasms now associated with H. longicornis in the USA spans 3 clades in the piroplasm phylogeny and raises concerns of transmission amplification of veterinary pathogens as well as spillover of pathogens from wildlife to humans.


Subject(s)
Apicomplexa , Babesia , Deer , Ixodidae , Parasites , Piroplasmida , Theileria , Ticks , Animals , United States/epidemiology , Humans , Dogs , Cattle , Piroplasmida/genetics , Ixodidae/genetics , Ticks/parasitology , Parasites/genetics , Cytochromes b , Apicomplexa/genetics , Babesia/genetics , Theileria/genetics , RNA, Ribosomal, 18S/genetics , Nymph/parasitology
4.
Int J Parasitol ; 53(14): 809-819, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37467875

ABSTRACT

The northeastern United States (US) is a hotspot for tick-borne diseases. Adding to an already complex vector landscape, in 2017 large populations of the invasive Haemaphysalis longicornis, the Asian longhorned tick, were detected in New Jersey (NJ) and later found to be widespread from Connecticut to Georgia. In its native range in northeastern Asia, H. longicornis is considered an important vector of deadly pathogens to humans, companion animals, and livestock. To identify the primary hosts of H. longicornis, we surveyed synanthropic small and medium-sized mammals in three different sites in suburban New Brunswick, NJ. Specifically, we collected approximately 9,000 tick specimens belonging to nine species from 11 different species of mammals sampled between May and September 2021. We found that H. longicornis feeds more frequently on rodents than previously thought, and that this invasive tick is likely exposed to important enzootic and zoonotic pathogens. Overall, we obtained detailed information about the seasonal dynamics and feeding patterns of six tick species common in the northeastern US, Haemaphysalis longicornis, Amblyomma americanum, Dermacentor variabilis, Ixodes scapularis, Ixodes texanus and Ixodes cookei. We found that unlike I. scapularis that feeds on mammals of all sizes, H. longicornis feeds on hosts following the general pattern of A. americanum, favoring larger species such as skunks, groundhogs, and raccoons. However, our survey revealed that unlike A. americanum, H. longicornis reaches high densities on Virginia opossum. Overall, the newly invasive H. longicornis was the most numerous tick species, both on multiple host species and in the environment, raising significant questions regarding its role in the epidemiology of tick-borne pathogens, especially those affecting livestock, companion animals and wildlife. In conclusion, our findings provide valuable insights into the tick species composition on mammalian hosts in NJ and the ongoing national expansion of H. longicornis.


Subject(s)
Didelphis , Ixodes , Ixodidae , Tick Infestations , Animals , Humans , Tick Infestations/epidemiology , Tick Infestations/veterinary , Mammals , New England
6.
Insects ; 14(3)2023 Mar 05.
Article in English | MEDLINE | ID: mdl-36975943

ABSTRACT

People often use parks and other forested areas for outdoor activities such as hiking and walking their dogs. Areas of primary use are paths or grassy meadows on the edges of the forests that constitute transitional areas between different plant communities (aka ecotones). In this study, we monitored the seasonal dynamics of questing ticks in forest/meadow and forest/path ecotones in five areas in Middlesex County, New Jersey (NJ). We found anthropophilic species such as Ixodes scapularis, Amblyomma americanum, and Dermacentor variabilis coexisting with Haemaphysalis longicornis, an invasive tick species first detected in NJ in 2017. Surveillance was conducted weekly from March to November 2020, and collected ticks were identified. The most abundant tick species was H. longicornis (83%), followed by A. americanum (9%), I. scapularis (7%), and D. variabilis (<1%). The seasonal dynamics of A. americanum and I. scapularis in the ecotone were similar to previous surveys in forest habitats. The presence of anthropophilic ticks, particularly I. scapularis, suggests the need for specific control approaches to target these habitats. In addition, the extraordinarily high numbers of H. longicornis collected in ecotones (1.70 ticks/m2) and frequent reports of this species on dogs highlight the importance of monitoring its expansion due to its potential as a vector of animal and human diseases.

7.
Ticks Tick Borne Dis ; 14(3): 102157, 2023 05.
Article in English | MEDLINE | ID: mdl-36917863

ABSTRACT

The soft ticks (Argasidae) are known vectors of human and animal pathogens around the globe and are relatively understudied. Our aim was to assess the presence of Rickettsia and Borrelia bacteria in Alectorobius kelleyi (Argasidae) parasitizing synanthropic bats in the highly urbanized northeastern United States. By collaborating with parasitologists, bat scientists and wildlife rehabilitators we were successful in obtaining A. kelleyi from five states. Since Argasid larvae will attach to their hosts for many days, most A. kelleyi examined (92%) were larvae collected from sick or injured big brown bats, Eptesicus fuscus, undergoing care at rehabilitation centers. In addition, we obtained adult A. kelleyi captured in residential living areas and trapped in attics. An in-depth analysis of a A. kelleyi found to be infected with a spotted fever group Rickettsia (SFGR) revealed a dual infection with a R. belli-like taxon (ancestral group) as well as an SFGR closely related to R. peacockii, likely the same previously found in A. kelleyi from Iowa and Kansas. We found that 36% of the A. kelleyi tested carried the SFGR. Furthermore, we detected a relapsing fever spirochete, likely Candidatus Borrelia johnsonii, in 25% of the A. kelleyi from Pennsylvania. While it is unclear if these bacteria constitute a health risk to either bats or humans, our study indicates that human exposure to ectoparasites infesting peridomestic wildlife should be considered in the epidemiology of tick-borne diseases.


Subject(s)
Argasidae , Borrelia , Chiroptera , Ornithodoros , Relapsing Fever , Rickettsia , Adult , Animals , Humans , Argasidae/microbiology , Chiroptera/parasitology , Relapsing Fever/epidemiology , Relapsing Fever/veterinary , Ornithodoros/microbiology , Animals, Wild
8.
Ticks Tick Borne Dis ; 14(2): 102126, 2023 03.
Article in English | MEDLINE | ID: mdl-36682197

ABSTRACT

The Asian longhorned tick (Haemaphysalis longicornis) is a vector of multiple arboviral and bacterial pathogens in its native East Asia and expanded distribution in Australasia. This species has both bisexual and parthenogenetic populations that can reach high population densities under favorable conditions. Established populations of parthenogenetic H. longicornis were detected in the eastern United States in 2017 and the possible range of this species at the continental level (North America) based on climatic conditions has been modeled. However, little is known about factors influencing the distribution of H. longicornis at geographic scales relevant to local surveillance and control. To examine the importance of local physiogeographic conditions such as geology, soil characteristics, and land cover on the distribution of H. longicornis we employed ecological niche modeling using three machine learning algorithms - Maxent, Random Forest (RF), and Generalized Boosting Method (GBM) to estimate probability of finding H. longicornis in a particular location in New Jersey (USA), based on environmental predictors. The presence of H. longicornis in New Jersey was positively associated with Piedmont physiogeographic province and two soil types - Alfisols and Inceptisols. Soil hydraulic conductivity was the most important predictor explaining H. longicornis habitat suitability, with more permeable sandy soils with higher hydraulic conductivity being less suitable than clay or loam soils. The models were projected over the state of New Jersey creating a probabilistic map of H. longicornis habitat suitability at a high spatial resolution of 90×90 meters. The model's sensitivity was 87% for locations sampled in 2017-2019 adding to the growing evidence of the importance of soil characteristics to the survival of ticks. For the 2020-2022 dataset the model fit was 57%, suggestive of spillover to less optimal habitats or, alternatively, heterogeneity in soil characteristics at the edges of broad physiographic zones. Further modeling should incorporate abundance and life-stage information as well as detailed characterization of the soil at collection sites. Once critical parameters that drive the survival and abundance of H. longicornis are identified they can be used to guide surveillance and control strategies for this invasive species.


Subject(s)
Ixodidae , Ticks , Animals , New Jersey , Ecosystem , Soil
9.
Ticks Tick Borne Dis ; 14(2): 102106, 2023 03.
Article in English | MEDLINE | ID: mdl-36516481

ABSTRACT

Forest thinning is a management tool used in the New Jersey Pinelands and elsewhere to improve forest health and resilience, mitigate wildfire risk, and manage for wildlife. Forest thinning leads to warmer drier microclimates, which have been shown in both field and laboratory studies to reduce tick survival and reproduction. To directly assess the effects of forest thinning on the abundance and diversity of ticks and on the prevalence of tick-borne human pathogens, we sampled ticks weekly from March to November 2021 at three replicated pairs of thinned and unthinned forest sites composed primarily of pitch-pine, shortleaf pine, and various oak species. We characterized microclimate in the understory and forest floor at each sampling plot by deploying multiple data loggers to monitor temperature and relative humidity throughout the study period. As expected, we found that thinned plots were significantly drier and warmer than unthinned plots. We also found that average questing tick abundance was 92% lower in thinned as compared with unthinned plots. Of the three main tick species collected in unthinned plots (Amblyomma americanum, Ixodes scapularis, and Dermacentor albipictus) only A. americanum and a single I. scapularis were collected in thinned plots. Prevalence of Ehrlichia species in A. americanum did not differ between treatments, and the sole I. scapularis collected in a thinned plot was infected with Borrelia burgdorferi sensu lato. However, the significant and much lower tick abundance in thinned plots indicates a lower risk of human-tick encounters. Our results add to the growing evidence that landscape and forest management can reduce local tick abundance, thereby reducing tick-borne disease risk.


Subject(s)
Borrelia burgdorferi , Ixodes , Animals , Humans , New Jersey/epidemiology , Forests , Animals, Wild
10.
Malar J ; 21(1): 249, 2022 Aug 29.
Article in English | MEDLINE | ID: mdl-36038897

ABSTRACT

BACKGROUND: Plasmodium parasites that cause bird malaria occur in all continents except Antarctica and are primarily transmitted by mosquitoes in the genus Culex. Culex quinquefasciatus, the mosquito vector of avian malaria in Hawai'i, became established in the islands in the 1820s. While the deadly effects of malaria on endemic bird species have been documented for many decades, vector-parasite interactions in avian malaria systems are relatively understudied. METHODS: To evaluate the gene expression response of mosquitoes exposed to a Plasmodium infection intensity known to occur naturally in Hawai'i, offspring of wild-collected Hawaiian Cx. quinquefasciatus were fed on a domestic canary infected with a fresh isolate of Plasmodium relictum GRW4 from a wild-caught Hawaiian honeycreeper. Control mosquitoes were fed on an uninfected canary. Transcriptomes of five infected and three uninfected individual mosquitoes were sequenced at each of three stages of the parasite life cycle: 24 h post feeding (hpf) during ookinete invasion; 5 days post feeding (dpf) when oocysts are developing; 10 dpf when sporozoites are released and invade the salivary glands. RESULTS: Differential gene expression analyses showed that during ookinete invasion (24 hpf), genes related to oxidoreductase activity and galactose catabolism had lower expression levels in infected mosquitoes compared to controls. Oocyst development (5 dpf) was associated with reduced expression of a gene with a predicted innate immune function. At 10 dpf, infected mosquitoes had reduced expression levels of a serine protease inhibitor, and further studies should assess its role as a Plasmodium agonist in C. quinquefasciatus. Overall, the differential gene expression response of Hawaiian Culex exposed to a Plasmodium infection intensity known to occur naturally in Hawai'i was low, but more pronounced during ookinete invasion. CONCLUSIONS: This is the first analysis of the transcriptional responses of vectors to malaria parasites in non-mammalian systems. Interestingly, few similarities were found between the response of Culex infected with a bird Plasmodium and those reported in Anopheles infected with human Plasmodium. The relatively small transcriptional changes observed in mosquito genes related to immune response and nutrient metabolism support conclusions of low fitness costs often documented in experimental challenges of Culex with avian Plasmodium.


Subject(s)
Culex , Culicidae , Malaria, Avian , Malaria , Parasites , Passeriformes , Plasmodium , Animals , Canaries , Culex/genetics , Culex/parasitology , Hawaii , Humans , Malaria, Avian/parasitology , Oocysts , Passeriformes/parasitology
11.
PLoS Negl Trop Dis ; 16(8): e0010689, 2022 08.
Article in English | MEDLINE | ID: mdl-35939523

ABSTRACT

Understanding patterns of diversification, genetic exchange, and pesticide resistance in arthropod disease vectors is necessary for effective population management. With the availability of next-generation sequencing technologies, one of the best approaches for surveying such patterns involves the simultaneous genotyping of many samples for a large number of genetic markers. To this end, the targeting of gene sequences of known function can be a cost-effective strategy. One insect group of substantial health concern are the mosquito taxa that make up the Culex pipiens complex. Members of this complex transmit damaging arboviruses and filariae worms to humans, as well as other pathogens such as avian malaria parasites that are detrimental to birds. Here we describe the development of a targeted, gene-based assay for surveying genetic diversity and population structure in this mosquito complex. To test the utility of this assay, we sequenced samples from several members of the complex, as well as from distinct populations of the relatively under-studied Culex quinquefasciatus. The data generated was then used to examine taxonomic divergence and population clustering between and within these mosquitoes. We also used this data to investigate genetic variants present in our samples that had previously been shown to correlate with insecticide-resistance. Broadly, our gene capture approach successfully enriched the genomic regions of interest, and proved effective for facilitating examinations of taxonomic divergence and geographic clustering within the Cx. pipiens complex. It also allowed us to successfully survey genetic variation associated with insecticide resistance in Culex mosquitoes. This enrichment protocol will be useful for future studies that aim to understand the genetic mechanisms underlying the evolution of these ubiquitous and increasingly damaging disease vectors.


Subject(s)
Culex , Culicidae , Animals , Genetic Variation , Humans , Insecticide Resistance/genetics , Mosquito Vectors/genetics
12.
J Med Entomol ; 59(4): 1434-1442, 2022 07 13.
Article in English | MEDLINE | ID: mdl-35639921

ABSTRACT

We report the multi-year collection of the Gulf Coast tick, Amblyomma maculatum Koch (Acaridae: Ixodida: Ixodidae) in Staten Island, New York City (NYC) as well as their detection in Brooklyn, NYC, and in Atlantic and Cumberland counties in southern New Jersey, USA. The first and most common detections were of adults, however in Freshkills Park on Staten Island larvae were also collected in a following year. The presence of larvae indicates that adults are successfully finding hosts in Staten Island. While it is still unknown how A. americanum reached Staten Island, immatures of this species often parasitize migratory birds, which are now often seen in Freshkills Park. We describe the landscape features of the area in Staten Island where populations were highest and larvae were detected, which could have facilitated the establishment of A. maculatum. Notably, we also report the presence of human pathogens Rickettsia parkeri in 5/10 (50%) of adults tested and R. felis in 1/24 (4.17%) of larvae tested. In addition to established populations in Staten Island we found evidence of A. maculatum in NJ and other NYC boroughs, suggesting current or future establishment is possible. The failure thus far to detect established populations in these areas may be due to inherent difficulties in detecting low density, spatially heterogeneous incipient populations, which could require targeted surveillance efforts for this species. We discuss the consequences to public health of the establishment of A. maculatum and detection of two additional rickettsial pathogens in the densely populated northeastern United States.


Subject(s)
Ixodidae , Rickettsia , Spotted Fever Group Rickettsiosis , Ticks , Amblyomma , Animals , Humans , Ixodidae/microbiology , Larva/microbiology , New England
13.
PLoS Negl Trop Dis ; 16(3): e0010310, 2022 Mar.
Article in English | MEDLINE | ID: mdl-35316268

ABSTRACT

[This corrects the article DOI: 10.1371/journal.pntd.0006845.].

14.
J Med Entomol ; 59(2): 784-787, 2022 03 16.
Article in English | MEDLINE | ID: mdl-35041004

ABSTRACT

The soft tick Carios kelleyi (Cooley and Kohls, 1941) is an ectoparasite of bats that can harbor bacteria known to cause disease in humans, such as Rickettsia spp., Bartonella spp., and relapsing fever Borrelia spp. Human-tick encounters may occur when bats occupy attics or similar dwellings with access points to human-inhabited areas. During May 2021, a partially engorged adult female C. kelleyi was collected from a Vermont home with an attic that was being used as a roost by big brown bats, Eptesicus fuscus (Chiroptera: Vespertilionidae). The source of the blood in the tick was the domestic dog, Canis lupus familiaris. Subsequently, eight C. kelleyi larvae were collected from a rescued E. fuscus adult. This is the first report of a soft tick species from Vermont and it is unknown how long C. kelleyi has been present in this state. Reports of C. kelleyi are on the rise across the northeastern United States but the implications for the health of humans, domestic animals, and bats in northern New England remain unclear. Bat management plans should consider the importance of bat exclusion in preventing tick encounters with members of the household and should include a tick monitoring component if bats are evicted.


Subject(s)
Acari , Argasidae , Chiroptera , Ticks , Animals , Chiroptera/parasitology , Dogs , Female , United States , Vermont
15.
J Med Entomol ; 59(1): 376-379, 2022 01 12.
Article in English | MEDLINE | ID: mdl-34761255

ABSTRACT

Ixodes scapularis Say is a three-host tick that has been recorded feeding on over 150 different species of terrestrial vertebrates (mammals, birds, and reptiles). This tick is found throughout the northeastern, coastal southeastern, and upper midwestern United States and is considered the most significant vector of tick-borne pathogens to humans in North America. Despite its ubiquity and broad host range, I. scapularis previously has not been reported feeding on bats (Chiroptera). However, during 2019 and 2020, larvae and nymphs of I. scapularis were recovered from big brown bats, Eptesicus fuscus (Palisot de Beauvois), at four locations in rural New York State, USA. All Ixodes infested bats were injured and found on the ground; therefore, parasitism by I. scapularis was likely opportunistic. Nonetheless, the large number of pathogens known to be associated with bats and the frequency with which I. scapularis bites people suggest that this host-tick relationship is of at least potential epidemiological significance.


Subject(s)
Chiroptera/parasitology , Ixodes , Tick Infestations , Animals , Disease Reservoirs , Disease Vectors , Host Specificity , Humans , Ixodidae , New York , North America
16.
J Med Entomol ; 58(2): 939-942, 2021 03 12.
Article in English | MEDLINE | ID: mdl-32901802

ABSTRACT

The soft tick Carios kelleyi (Cooley and Kohls), a parasite of bats known to occur in at least 29 of the 48 conterminous U.S. states, is here reported from New Jersey for the first time, based on larvae collected from big brown bats, Eptesicus fuscus. Although thought to be widespread in North America, the ecology of C. kelleyi is not well understood, despite reports of this species feeding on humans and its consequent potential as a disease vector. The association of C. kelleyi with bat species that regularly roost in human-made structures, such as attics and barns, and recent isolations from this tick of pathogens capable of infecting humans, companion animals, and livestock underscore the need for further studies of these bat ectoparasites.


Subject(s)
Argasidae/classification , Chiroptera/parasitology , Animals , Arachnid Vectors , Disease Vectors , Ectoparasitic Infestations/epidemiology , Humans , Public Health , Tick Infestations/epidemiology , United States/epidemiology
17.
Sci Rep ; 10(1): 15611, 2020 09 24.
Article in English | MEDLINE | ID: mdl-32973327

ABSTRACT

An infestation of cat fleas in a research center led to the detection of two genotypes of Ctenocephalides felis biting humans in New Jersey, USA. The rarer flea genotype had an 83% incidence of Rickettsia asembonensis, a recently described bacterium closely related to R. felis, a known human pathogen. A metagenomics analysis developed in under a week recovered the entire R. asembonensis genome at high coverage and matched it to identical or almost identical (> 99% similarity) strains reported worldwide. Our study exposes the potential of cat fleas as vectors of human pathogens in crowded northeastern U.S, cities and suburbs where free-ranging cats are abundant. Furthermore, it demonstrates the power of metagenomics to glean large amounts of comparative data regarding both emerging vectors and their pathogens.


Subject(s)
Flea Infestations/transmission , Insect Vectors/parasitology , Metagenome , Metagenomics , Rickettsia Infections/epidemiology , Rickettsia felis/genetics , Skin Diseases/epidemiology , Animals , Cats , Flea Infestations/epidemiology , Flea Infestations/parasitology , Genotype , Humans , New England/epidemiology , Rickettsia Infections/diagnosis , Rickettsia Infections/parasitology , Rickettsia felis/isolation & purification , Rickettsia felis/pathogenicity , Skin Diseases/diagnosis , Skin Diseases/parasitology , Urban Population
18.
Zoonoses Public Health ; 67(6): 637-650, 2020 09.
Article in English | MEDLINE | ID: mdl-32638553

ABSTRACT

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.


Subject(s)
Animal Distribution , Ixodidae/physiology , Animals , DNA, Mitochondrial/genetics , Electron Transport Complex IV/genetics , Gene Expression Regulation, Enzymologic , United States
19.
Am J Trop Med Hyg ; 103(3): 1009-1016, 2020 09.
Article in English | MEDLINE | ID: mdl-32588804

ABSTRACT

For the last decade, the New Jersey (NJ) Department of Health has reported between 42 and 144 new cases each year of "spotted fever group rickettsiosis" (SFGR), a statistic that reflects uncertainty regarding which rickettsial agents (Proteobacteria: Rickettsiaceae: Rickettsia) are infecting NJ residents. To identify the Rickettsia circulating in NJ ticks, we used a combination of conventional and real time PCR approaches to screen 560 Dermacentor variabilis Say and 245 Amblyomma americanum L. obtained from a 1-day state-wide surveillance in May 2018 and an additional 394 D. variabilis collected across NJ in 2013-2018. We found zero D. variabilis infected with Rickettsia rickettsii, the agent of Rocky Mountain spotted fever and, on average, 1.3% infected with presumed nonpathogenic Rickettsia montanensis. We also found zero A. americanum infected with R. rickettsii, and 20% infected with Rickettsia amblyommatis, a prevalence somewhat lower than in more southern states. Overall, we conclude that it is unlikely that R. rickettsii vectored by D. variabilis is a primary cause of SFGR cases in NJ and discuss our findings in the context of known facts and current limitations. We conclude that understanding the causes of SFGR east of the Mississippi will require collaboration among medical doctors, public health authorities, and medical entomologists to follow up presumptive human cases of SFGR with detailed histories of exposure, species-specific molecular assays, and active surveillance of putative vectors and the pathogens they may carry.


Subject(s)
Arachnid Vectors/microbiology , Dermacentor/microbiology , Ixodes/microbiology , Rocky Mountain Spotted Fever/epidemiology , Spotted Fever Group Rickettsiosis/epidemiology , Animals , Bacterial Typing Techniques , DNA, Bacterial/genetics , Humans , Larva/microbiology , New Jersey/epidemiology , Nymph/microbiology , Real-Time Polymerase Chain Reaction , Rickettsia/classification , Rickettsia/genetics , Rickettsia/isolation & purification , Rickettsia rickettsii/classification , Rickettsia rickettsii/genetics , Rickettsia rickettsii/isolation & purification , Rocky Mountain Spotted Fever/transmission , Spotted Fever Group Rickettsiosis/transmission
20.
PLoS Negl Trop Dis ; 14(6): e0007870, 2020 06.
Article in English | MEDLINE | ID: mdl-32569323

ABSTRACT

Emerging mosquito-borne viruses like Zika, dengue, and chikungunya pose a major threat to public health, especially in low-income regions of Central and South America, southeast Asia, and the Caribbean. Outbreaks of these diseases are likely to have long-term social and economic consequences due to Zika-induced congenital microcephaly and other complications. Larval control of the container-inhabiting mosquitoes that transmit these infections is an important tool for mitigating outbreaks. However, metapopulation theory suggests that spatiotemporally uneven larvicide treatment can impede control effectiveness, as recolonization compensates for mortality within patches. Coordinating the timing of treatment among patches could therefore substantially improve epidemic control, but we must also consider economic constraints, since coordination may have costs that divert resources from treatment. To inform practical disease management strategies, we ask how coordination among neighbors in the timing of mosquito control efforts influences the size of a mosquito-borne infectious disease outbreak under the realistic assumption that coordination has costs. Using an SIR (Susceptible-Infectious-Recovered)/metapopulation model of mosquito and disease dynamics, we examine whether sharing surveillance information and coordinating larvicide treatment among neighboring patches reduces human infections when incorporating coordination costs. We examine how different types of coordination costs and different surveillance methods jointly influence the effectiveness of larval control. We find that the effect of coordination depends on both costs and the type of surveillance used to inform treatment. With epidemiological surveillance, coordination improves disease outcomes, even when costly. With demographic surveillance, coordination either improves or hampers disease control, depending on the type of costs and surveillance sensitivity. Our results suggest coordination among neighbors can improve management of mosquito-borne epidemics under many, but not all, assumptions about costs. Therefore, estimating coordination costs is an important step for most effectively applying metapopulation theory to strategies for managing outbreaks of mosquito-borne viral infections.


Subject(s)
Costs and Cost Analysis , Disease Transmission, Infectious/prevention & control , Mosquito Control/methods , Mosquito Control/organization & administration , Vector Borne Diseases/prevention & control , Zika Virus Infection/prevention & control , Humans , Models, Theoretical , Mosquito Control/economics , Vector Borne Diseases/transmission , Zika Virus Infection/transmission
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