Entomology Commons^™

Genetic Divergence Of Chikungunya Virus Plaque Variants From The Comoros Island (2005), Caroline Wasonga, Shingo Inoue, Cecilia Rumberia, George Michuki, James Kimotho, Juliette R. Ongus, Rosemary Sang, Lillian Musila

All Peer-Reviewed Publications

Chikungunya virus (CHIKV) from a human sample collected during the 2005 Chikungunya outbreak in the Comoros Island, showed distinct and reproducible large (L2) and small (S7) plaques which were characterized in this study. The parent strain and plaque variants were analysed by in vitro growth kinetics in different cell lines and their genetic similarity assessed by whole genome sequencing, comparative sequence alignment and phylogenetic analysis. In vitro growth kinetic assays showed similar growth patterns of both plaque variants in Vero cells but higher viral titres of S7 compared to L2 in C6/36 cells. Amino acids (AA) alignments of the CHIKV …

Linalool Oxide: Generalist Plant Based Lure For Mosquito Disease Vectors, Vincent O. Nyasembe, David P. Tchouassi, Charles M. Mbogo, Catherine L. Sole, Christian Pirk, Baldwyn Torto

All Peer-Reviewed Publications

Background: Lack of effective vaccines and therapeutics for important arboviral diseases such as Rift Valley fever (RVF) and dengue, necessitates continuous monitoring of vector populations for infections in them. Plant-based lures as surveillance tools has the potential of targeting mosquitoes of both sexes and females of varied physiological states; yet such lures are lacking for vectors of these diseases. Here, we present evidence of the effectiveness of linalool oxide (LO), a single plant-based lure previously developed for malaria vectors in trapping RVF vectors, Aedes mcintoshi and Aedes ochraceus, and dengue vector, Aedes aegypti. Methods: For RVF vectors, we used CDC …

An Introduction To Insects Of Regulatory Concern, Robert Phillips

Department of Entomology: Distance Master of Science Projects

No abstract provided.

Bacterially-Based Immune Challenges And Trauma Elicit Terminal Investment In Male Aedes Aegypti, Molly K. Schumacher

Theses and Dissertations

Investment in life history traits such as immune function and reproduction is constrained by finite available resources. A cost-of-immunity trade-off may occur in response to infection when resources are diverted away from reproductive effort and into an immune response. Alternatively, an infected individual may enhance reproductive effort to maximize terminal reproductive success in response to the survival threat inherent to infection (terminal investment). We measured male Aedes aegypti reproductive behavior following inoculations with: living bacteria; killed bacteria as an immune elicitor; and a sham control. Mating competitiveness relative to naïve males was also determined through a binary mate choice experiment …

In Vitro And In Vivo Evaluation Of Infestation Deterrents Against Lice, Kyong-Sup Yoon, Jennifer K. Ketzis, Samuel W. Andrewes, Christopher S. Wu, Kris Honraet, Dorien Staljanssens, Bart Rossel, J Marshall Clark

SIUE Faculty Research, Scholarship, and Creative Activity

The human head louse is a cosmopolitan ectoparasite and frequently infests many people, particularly school-age children. Due to widespread pyrethroid resistance and the lack of efficient resistance management, there has been a considerable interest in the protection of uninfested people and prevention of reinfestation by disrupting lice transfer. In this study, two nonclinical model systems (in vitro and in vivo) were used to determine the efficacy of the infestation deterrents, Elimax lotion and Elimax shampoo, against human head lice or poultry chewing lice, respectively. With in vitro assessments, female head lice exhibited significantly higher avoidance responses to hair tufts treated …

Distribution And Diversity Of The Vectors Of Rift Valley Fever Along The Livestock Movement Routes In The Northeastern And Coastal Regions Of Kenya, Samwel O. Arum, Christopher W. Weldon, Benedict Orindi, Tobias Landmann, David P. Tchouassi, Hippolyte D. Affognon, Rosemary Sang

All Peer-Reviewed Publications

Background: Knowledge of vector ecology is important in understanding the transmission dynamics of vector borne disease. In this study, we determined the distribution and diversity of mosquitoes along the major nomadic livestock movement routes (LMR) in the traditional pastoral ecozone of northeastern Kenya. We focused on the vectors of Rift Valley fever virus (RVFv) with the aim of understanding their ecology and how they can potentially influence the circulation of RVFv. Methods: Mosquito surveys were conducted during the short and long rainy seasons from November 2012 to August 2014 using CO2-baited CDC light traps at seven sites selected for their …

Mosquito-Borne Diseases In Mississippi, Ryan J. Rodriguez

Department of Entomology: Distance Master of Science Projects

Life Cycle:
Egg Must be exposed to water to hatch
Larvae Live in aquatic habitats
Pupa Stay near the surface of water to breath
Adults: Only females feed on blood; Males feed on nectar

Public Health •Besides being a nuisance, they cause numerous health hazards to humans (and other animals) •In some cases, they may cause severe allergic reactions •Diseases they transmit: •Eastern Equine Encephalitis •Japanese Encephalitis •La Crosse Encephalitis •St. Louis Encephalitis •West Nile Virus •Western Equine Encephalitis •Dengue Fever •Malaria •Rift Valley Fever •Yellow Fever

Mosquito-Borne Diseases in Mississippi and its Vectors •Chikungunya Virus •Aedes species •Eastern Equine …

The Effects Of Landscape On Malaria Vectors Of The Neotropics, William David Lainhart

Legacy Theses & Dissertations (2009 - 2024)

Worldwide malaria control efforts have had varying degrees of success, leaving many countries either eliminating malaria or controlling malaria. In order to maintain forward momentum toward malaria elimination, malaria-eliminating and –controlling countries require different information regarding risk factors, spatial distributions of cases and vectors, vector biology metrics, and vector population genetics. The goal of this dissertation work was to provide information that addresses the knowledge gaps preventing the creation of effective vector and malaria control programs in one malaria-eliminating country (Panama) and two malaria-controlling countries (Peru and Brazil). Case data from Panama were analyzed to assess differences in risk factors …

Sewer Overflows And The Vector Mosquito Proximity To Human West Nile Virus Infections, Andrea Simone Bowers

Walden Dissertations and Doctoral Studies

DeKalb and Fulton Counties, which share the metropolitan Atlanta area, have seen an increase in West Nile infected vector mosquitoes; the increase is associated with close proximity to combined sewer overflow facilities. Despite completion of the remediation system in 2008, the mosquito population testing positive for West Nile virus has increased each year from 2010 through 2012. Guided by the Geographical Information System framework and using spatial analysis and regression analyses, this study described and quantified the relationship between sewer system overflows and amplification of vector mosquitoes; an additional goal was to investigate their proximity to human cases of West …

Evolution Of Hematophagous Habit In Triatominae (Heteroptera: Reduviidae), Fernando Otálora-Luna, Antonio J. Pérez-Sánchez, Claudia Sandoval, Elis Aldana

Harold W. Manter Laboratory of Parasitology: Library Materials

All members of Triatominae subfamily (Heteroptera: Reduviidae), potential vectors of Trypanosoma cruzi, etiologic agent of the Chagas disease, feed on blood. Through evolution, these bugs have fixed special morphological, physiological, and behavioral aptations (adaptations and exaptations) adequate to feed on blood. Phylogeny suggests that triatomines evolved from predator reduvids which in turn descended from phytophagous hemipterans. Some pleisiomorphic traits developed by the reduvid ancestors of the triatomines facilitated and modeled hematophagy in these insects. Among them, mouthparts, saliva composition, enzymes, and digestive symbionts are the most noticeable. However, the decisive step that allowed the shift from predation to hematophagy …

Population Genetics Of Two Key Mosquito Vectors Of Rift Valley Fever Virus Reveals New Insights Into The Changing Disease Outbreak Patterns In Kenya, David P. Tchouassi, Armanda D.S. Bastos, Catherine L. Sole, Mawlouth Diallo, Joel Lutomiah, James Mutisya, Francis Mulwa, Christian Borgemeister, Rosemary Sang, Baldwyn Torto

All Peer-Reviewed Publications

Rift Valley fever (RVF) outbreaks in Kenya have increased in frequency and range to include northeastern Kenya where viruses are increasingly being isolated from known (Aedes mcintoshi) and newly-associated (Ae. ochraceus) vectors. The factors contributing to these changing outbreak patterns are unclear and the population genetic structure of key vectors and/or specific virus-vector associations, in particular, are under-studied. By conducting mitochondrial and nuclear DNA analyses on >220 Kenyan specimens of Ae. mcintoshi and Ae. ochraceus, we uncovered high levels of vector complexity which may partly explain the disease outbreak pattern. Results indicate that Ae. mcintoshi consists of a species complex …

Stability, Bifurcation And Chaos Analysis Of Vector-Borne Disease Model With Application To Rift Valley Fever, Sansao A. Pedro, Shirley Abelman, Frank T. Ndjomatchoua, Rosemary Sang, Henri E.Z. Tonnang

All Peer-Reviewed Publications

This paper investigates a RVF epidemic model by qualitative analysis and numerical simulations. Qualitative analysis have been used to explore the stability dynamics of the equilibrium points while visualization techniques such as bifurcation diagrams, Poincaré maps, maxima return maps and largest Lyapunov exponents are numerically computed to confirm further complexity of these dynamics induced by the seasonal forcing on the mosquitoes oviposition rates. The obtained results show that ordinary differential equation models with external forcing can have rich dynamic behaviour, ranging from bifurcation to strange attractors which may explain the observed fluctuations found in RVF empiric outbreak data, as well …

Sma-Causing Missense Mutations In Survival Motor Neuron (Smn) Display A Wide Range Of Phenotypes When Modeled In Drosophila, Kavita Praveen, Ying Wen, Kelsey M. Gray, John J. Noto, Akash R. Patlolla, Gregory D. Van Duyne, A. Gregory Matera

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Mutations in the human survival motor neuron 1 (SMN) gene are the primary cause of spinal muscular atrophy (SMA), a devastating neuromuscular disorder. SMN protein has a well-characterized role in the biogenesis of small nuclear ribonucleoproteins (snRNPs), core components of the spliceosome. Additional tissue-specific and global functions have been ascribed to SMN; however, their relevance to SMA pathology is poorly understood and controversial. Using Drosophila as a model system, we created an allelic series of twelve Smn missense mutations, originally identified in human SMA patients. We show that animals expressing these SMA-causing mutations display a broad range of …

Human African Trypanosomiasis Research Gets A Boost: Unraveling The Tsetse Genome, Serap Aksoy, Geoffrey Attardo, Matt Berriman, Alan Christoffels, Mike Lehane, Dan Masiga, Yeya Toure

All Peer-Reviewed Publications

Human African trypanosomiasis (HAT), also known as sleeping sickness, is a neglected disease that impacts 70 million people distributed over 1.55 million km2 in sub-Saharan Africa [1]. Trypanosoma brucei gambiense accounts for almost 90% of the infections in central and western Africa, the remaining infections being from T. b. rhodesiense in eastern Africa [1]. Furthermore, the animal diseases caused by related parasites inflict major economic losses to countries already strained [2]. The parasites are transmitted to the mammalian hosts through the bite of an infected tsetse fly.

The Biology And Taxonomy Of Head And Body Lice: Implications For Louse-Borne Disease Prevention, Denise L. Bonilla, Lance A. Durden, Marina E. Eremeeva, Gregory A. Dasch

Harold W. Manter Laboratory of Parasitology: Library Materials

Sucking lice (Phthiraptera: Anoplura) are obligate blood-feeding ectoparasites of placental mammals including humans. Worldwide, more than 550 species have been described and many are specific to a particular host species of mammal. Three taxa uniquely parasitize humans: the head louse, body louse, and crab (pubic) louse. The body louse, in particular, has epidemiological importance because it is a vector of the causative agents of three important human diseases: epidemic typhus, trench fever, and louse-borne relapsing fever. Since the advent of antibiotics and more effective body louse control measures in the 1940s, these diseases have markedly diminished in incidence. However, due …

Comparative Diagnostic And Analytical Performance Of Pcr And Lamp-Based Trypanosome Detection Methods Estimated Using Pooled Whole Tsetse Flies And Midguts, Imna I. Malele, Johnson O. Ouma, John C.K. Enyaru, Enock Matovu, Vincent Alibu, Joanna E. Auma, Samuel G. Onyoyo, Rosemary Bateta, Robert E. Changasi, Phoebe W. Mukiria, Kariuki Ndung'u, Purity K. Gitonga, Lilian M. Mwaniki, Hamisi S. Nyingilili, Eugene A. Lyaruu, Lupakisyo A. Kapange, Peter Kuria Kamau, Daniel K. Masiga

All Peer-Reviewed Publications

Detection of trypanosomes that cause disease in human beings and livestock within their tsetse fly hosts is an essential component of vector and disease control programmes. Several molecular-based diagnostic tests have been developed for this purpose. Many of these tests, while sensitive, require analysis of trypanosome DNA extracted from single flies, or from pooled tsetse fly heads and amplified trypanosome DNA. In this study, we evaluated the relative analytical and diagnostic sensitivities of two PCR-based tests (ITS and TBR) and a Trypanozoon specific LAMP assay using pooled whole tsetse flies and midguts spiked with serially diluted procyclics of a laboratory …

Gene Expression-Based Biomarkers For Anopheles Gambiae Age Grading, Mei Hui Wang, Osvaldo Marinotti, Daibin Zhong, Anthony A. James, Edward Walker, Tom Guda, Eliningaya J. Kweka, John Githure, Guiyun Yan

All Peer-Reviewed Publications

Information on population age structure of mosquitoes under natural conditions is fundamental to the understanding of vectorial capacity and crucial for assessing the impact of vector control measures on malaria transmission. Transcriptional profiling has been proposed as a method for predicting mosquito age for Aedes and Anopheles mosquitoes, however, whether this new method is adequate for natural conditions is unknown. This study tests the applicability of transcriptional profiling for age-grading of Anopheles gambiae, the most important malaria vector in Africa. The transcript abundance of two An. gambiae genes, AGAP009551 and AGAP011615, was measured during aging under laboratory and field conditions …

Influence Of Horn Flies And Breed Type On Milk Production, Calf Production Traits, Pasture Behavior, And Temperament Measurements In Beef Cattle, Angela Rene Mays

Graduate Theses and Dissertations

An experiment conducted in El Reno, Oklahoma during the fly season (May - September/October) evaluated the effects of horn flies on milk production, calf performance, and pasture behavior and temperament measurements of beef cow calf pairs. Cows (n = 53) sired by Bonsmara (BONS; n = 7), Brangus (BRAN; n = 13), Charolais (CHAR; n = 8), Gelbvieh (GELV; n = 5), Hereford (HERF; n = 12), and Romosinuano (ROMO; n = 8) from Brangus dams and their Angus sired calves (n = 51) were used in the study. Horn fly counts (HFC) and milk yield and quality estimates were …

Parasitological Prevalence Of Bovine Trypanosomosis In Kubo Division Of Kwale County Of Coastal: Baseline Survey, N. Mbahin, H. Affognon, J. Andoke, M. Tiberius, D. Mbuvi, J. Otieno, P. Muasa, R. K. Saini

All Peer-Reviewed Publications

Prior to field trials of large scale tsetse repellent technology validation in July 2011, a cross-sectional survey of bovine trypanosomosis and its vectors was carried out to know the disease level in Kwale County of Coastal Kenya. A total of 584 adult cattle were examined at ten different Locations. The trypanosome prevalence in cattle with regard to age, sex, location and apparent tsetse density was investigated. The overall trypanosome prevalence in cattle in Kubo Division of Kwale County was 33.9%. Two types of infections were recorded in various parts of the Division in the following proportions: T. congolense 61.1%, T. …

Repellent, Irritant And Toxic Effects Of 20 Plant Extracts On Adults Of The Malaria Vector Anopheles Gambiae Mosquito, Emilie Deletre, Thibaud Martin, Pascal Campagne, Denis Bourguet, Andy Cadin, Chantal Menut, Romain Bonafos, Fabrice Chandre

All Peer-Reviewed Publications

Pyrethroid insecticides induce an excito-repellent effect that reduces contact between humans and mosquitoes. Insecticide use is expected to lower the risk of pathogen transmission, particularly when impregnated on long-lasting treated bednets. When applied at low doses, pyrethroids have a toxic effect, however the development of pyrethroid resistance in several mosquito species may jeopardize these beneficial effects. The need to find additional compounds, either to kill disease-carrying mosquitoes or to prevent mosquito contact with humans, therefore arises. In laboratory conditions, the effects (i.e., repellent, irritant and toxic) of 20 plant extracts, mainly essential oils, were assessed on adults of Anopheles gambiae, …

Ixodid Ticks Associated With Feral Swine In Texas, David M. Sanders, Anthony L. Schuster, P. Wesley Mccardle, Otto F. Strey, Terry L. Blankenship, Pete D. Teel

United States Army: Publications

Ixodid ticks were collected from feral swine in eight Texas ecoregions from 2008-2011. Sixty-two percent of 806 feral swine were infested with one or more of the following species: Amblyomma americanum, A. cajennense, A. maculatum, Dermacentor albipictus, D. halli, D. variabilis, and Ixodes scapularis. Juvenile and adult feral swine of both sexes were found to serve as host to ixodid ticks. Longitudinal surveys of feral swine at four geographic locations show persistent year-round tick infestations of all gender-age classes for tick species common to their respective geographic locations and …

Common Host-Derived Chemicals Increase Catches Of Disease-Transmitting Mosquitoes And Can Improve Early Warning Systems For Rift Valley Fever Virus, David P. Tchouassi, Rosemary Sang, Catherine L. Sole, Armanda D.S. Bastos, Peter E.A. Teal, Christian Borgemeister, Baldwyn Torto

All Peer-Reviewed Publications

Rift Valley fever (RVF), a mosquito-borne zoonosis, is a major public health and veterinary problem in sub-Saharan Africa. Surveillance to monitor mosquito populations during the inter-epidemic period (IEP) and viral activity in these vectors is critical to informing public health decisions for early warning and control of the disease. Using a combination of field bioassays, electrophysiological and chemical analyses we demonstrated that skin-derived aldehydes (heptanal, octanal, nonanal, decanal) common to RVF virus (RVFV) hosts including sheep, cow, donkey, goat and human serve as potent attractants for RVFV mosquito vectors. Furthermore, a blend formulated from the four aldehydes and combined with …

Sheep Skin Odor Improves Trap Captures Of Mosquito Vectors Of Rift Valley Fever, David P. Tchouassi, Rosemary Sang, Catherine L. Sole, Armanda D.S. Bastos, Klaus Mithoefer, Baldwyn Torto

All Peer-Reviewed Publications

In recent years, the East African region has seen an increase in arboviral diseases transmitted by blood-feeding arthropods. Effective surveillance to monitor and reduce incidence of these infections requires the use of appropriate vector sampling tools. Here, trapped skin volatiles on fur from sheep, a known preferred host of mosquito vectors of Rift Valley fever virus (RVFV), were used with a standard CDC light trap to improve catches of mosquito vectors. We tested the standard CDC light trap alone (L), and baited with (a) CO2 (LC), (b) animal volatiles (LF), and (c) CO2 plus animal volatiles (LCF) in two highly …

Viral Metagenomics Demonstrates That Domestic Pigs Are A Potential Reservoir For Ndumu Virus, Charles Masembe, George Michuki, Maria Onyango, Cecilia Rumberia, Martin Norling, Richard P. Bishop, Appolinaire Djikeng, Stephen J. Kemp, Alan Orth, Robert A. Skilton, Karl Ståhl, Anne Fischer

All Peer-Reviewed Publications

Background: The rising demand for pork has resulted in a massive expansion of pig production in Uganda. This has resulted in increased contact between humans and pigs. Pigs can act as reservoirs for emerging infectious diseases. Therefore identification of potential zoonotic pathogens is important for public health surveillance. In this study, during a routine general surveillance for African swine fever, domestic pigs from Uganda were screened for the presence of RNA and DNA viruses using a high-throughput pyrosequencing method. Findings. Serum samples from 16 domestic pigs were collected from five regions in Uganda and pooled accordingly. Genomic DNA and RNA …

Mediation Of A Plant-Spider Association By Specific Volatile Compounds, Ximena J. Nelson, Andrew J. Pratt, Xavier Cheseto, Baldwyn Torto, Robert R. Jackson

All Peer-Reviewed Publications

Evarcha culicivora, an East African jumping spider (Salticidae), is the only spider for which there is evidence of innate olfactory affinity for particular plant species. Evarcha culicivora also actively chooses as preferred prey the females of Anopheles mosquitoes, and both sexes of Anopheles are known to visit plants for nectar meals. Here, we identified compounds present in the headspace of one of these species in Kenya, Lantana camara, and then used 11 of these compounds in olfactometer experiments. Our findings show that three terpenes [(E)-β-caryophyllene, α-humulene and 1,8 cineole] can be discriminated by, and are salient to, E. culicivora. The …

Surveillance Of Mosquitoes For Arthropod-Borne Viruses In El Paso, Tx., Stephanie Coronado, Douglas Watts

COURI Symposium Abstracts, Summer 2012

West Nile encephalitis is the only arthropod-borne virus that causes annual cases of human illness in El Paso, Texas. Cases more commonly affect the young and elderly and the illness may range from a mild febrile disease to fatal encephalitis. The primary vector(s) of West Nile virus are Culex species mosquitoes, including Culex tarsalis and Culex quinquefaciatus. Further, surveillance is needed to determine the relative importance of these and possibly other mosquito species. More recently, cases of dengue fever and fatal hemorrhagic fever have been occurring in communities along the USA-Mexico border. Dengue has been endemic in Mexico since the …

A Century And A Half Of Research On The Stable Fly, Stomoxys Calcitrans (L.) (Diptera: Muscidae), 1862-2011: An Annotated Bibliography, K. M. Kneeland, Steven R. Skoda, Jerome A. Hogsette, A. Y. Li, Jaime Molina-Ochoa, Kimberly Hutchinson Lohmeyer, John E. Foster

Department of Entomology: Faculty Publications

The stable fly, Stomoxys calcitrans, is a cosmopolitan pest of livestock, wild animals, pets, and humans. It is a primary pest of cattle in the United States, estimated to cause more than $1 billion in economic losses annually. It also causes dissension at the rural-urban interface and is a problem in recreation areas such as Florida beaches and the Great Lakes. Due to its pestiferous nature and painful bite, methods to control stable flies have been investigated for over a century. A large amount of research has been reported on stable fly biology, ecology, genetics, physiology, and vector competence. …

Trapping Of Rift Valley Fever (Rvf) Vectors Using Light Emitting Diode (Led) Cdc Traps In Two Arboviral Disease Hot Spots In Kenya, David P. Tchouassi, Rosemary Sang, Catherine L. Sole, Armanda D.S. Bastos, Lee W. Cohnstaedt, Baldwyn Torto

All Peer-Reviewed Publications

Background: Mosquitoes response to artificial lights including color has been exploited in trap designs for improved sampling of mosquito vectors. Earlier studies suggest that mosquitoes are attracted to specific wavelengths of light and thus the need to refine techniques to increase mosquito captures following the development of super-bright light-emitting diodes (LEDs) which emit narrow wavelengths of light or very specific colors. Therefore, we investigated if LEDs can be effective substitutes for incandescent lamps used in CDC light traps for mosquito surveillance, and if so, determine the best color for attraction of important Rift Valley Fever (RFV) vectors. Methods. The efficiency …

Effects Of Methoprene On The Survivorship Of Adult Aedes Mosquitoes: A Strategy Or Inactivating Released Mosquitoes, Peter J. Brabant Iii

Theses and Dissertations--Entomology

Methoprene is a Juvenile Hormone (JH) analogue commonly used for the control of mosquito larvae. When applied to a mosquito breeding site, methoprene enters the haemolymph, where it mimics the function of JH and interferes with normal metamorphosis, resulting in larval mortality. Methoprene is commonly used for the control of larvae and has not been used as an adulticide, due to an absence of acute effects. This study evaluated possible chronic effects caused by the exposure of adult Aedes mosquitoes to methoprene. Methoprene was applied, in both technical grade and the commercially available Altosid®, topically to adults through droplet application …

Human Risk Of Infection With Borrelia Burgdorferi, The Lyme Disease Agent, In Eastern United States, Maria A. Diuk-Wasser, Anne Gatewood Hoen, Paul Cislo, Robert Brinkerhoff, Sarah A. Hamer, Michelle Rowland, Roberto Cortinas, Gwenaël Vourc’H, Forrest S. Melton, Graham J. Hickling, Jean I. Tsao, Jonas Bunikis, Alan G. Barbour, Uriel Kitron, Joseph Piesman, Durland Fish

Department of Entomology: Faculty Publications

The geographic pattern of human risk for infection with Borrelia burgdorferi sensu stricto, the tick-borne pathogen that causes Lyme disease, was mapped for the eastern United States. The map is based on standardized field sampling in 304 sites of the density of Ixodes scapularis host-seeking nymphs infected with B. burgdorferi, which is closely associated with human infection risk. Risk factors for the presence and density of infected nymphs were used to model a continuous 8 km × 8 km resolution predictive surface of human risk, including confidence intervals for each pixel. Discontinuous Lyme disease risk foci were identified in …