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Lyme on the rise The black legged tick http://www.lifehouseproductions.com/tick_anim.html
The Increase of Lyme in Minnesota • A local family physician inquires about Lyme disease noting an increase of patients experiencing: • ring shaped rashes • headaches • fever chills • Rigid diagnosis was not made as confirmation requires time that a patient may not have.
High Risk Areas for Tick-borne Diseases in Minnesota • The physician expressed concern that the map by Minnesota Department of Natural Resources may be inaccurate. • People in the Duluth area could be better informed before planning outdoor activities.
Outline • Ticks • Life cycle of ticks, life cycle of disease • Lyme Disease • symptoms • Collecting Ticks • GIS • BorreliaBurgdorferi • The bacteria responsible for Lyme • Vaccines • Discussion
Deer Tick Habitat • High concentration in northeast region of U.S. • Wooded areas, forests, over-grown grassy areas and trails • Prefer moist and humid environments • Sit on tips of grass and quest for a host Black legged tick, Ixodesscapularis, questing on a stick.
Deer Tick Life Cycle 3 stages of life, 1 feeding each stage • Year 1 – Spring, Summer • Eggs hatch into larvae • Feed once and molt into nymphs • Nymphs become dormant • Year 2, May – July • Nymphs feed • At this time, the nymph may transmit disease (shown in grey) • Year 2, Oct - Nov • Adults feed primarily in Fall. • Eat, spit eggs and die Graphic courtesy of Green Pest Control MN American Lyme Disease Foundation
Infested Ticks They’re small • Nymphal ticks are the worst for infection • Hard to detect • Their bites cause much milder pain than adult ticks’ • Ticks carry Borrelia burgdorferi(Bb) in their gut • The bacteria responsible for Lyme Disease
Infectious Ticks • A tick embeds its proboscis into the skin • Releases saliva that anesthetizes the area and thins the blood • Outward-flowing saliva alternates with inward-moving blood • Infection enters to body system with the saliva video and image generated by LifeHouse Productions
Transfer of B. burgdorferi to Ticks • Bb occurs in nature and is picked up by rodents and other small mammals. • Deer ticks take blood meal from these small mammals -during the larval stage of life- and contract bacterium.
Transfer of B. burgdorferi to Humans • Bb attaches to the gut • Outer surface protein A (OspA) • Bb stays in the gut until the next meal • Blood meal • Osp A, Osp C • Bb goes to salivary glands where it can enter the host
Lyme Disease Symptomology
Contracting Lyme Disease • The bite of an infested nymph or adult tick can transmit Lyme after it attaches to the host for 36 – 48 hrs • generation time of bacteria B. burgdorferi: ~ 12 hrs • It takes several hours before a large enough infectious dose of Bb can infiltrate the new host. Nature Reviews / Microbiology
Symptomology of Lyme Disease • Lyme is a multisystem inflammatory disease • affects the skin in the early stage • then spreads to the joints, nervous system and may eventually affect organ systems. • Symptoms are divided into 3 stages • each stage more advanced than the previous.
Stage 1 Symptoms Early localized infection • Skin Rash Around Tick Bite • 40 -75% present with rash • Mild Illness • Flu-like Symptoms • Fevers • Chills • Swollen Lymph Nodes • Headache • Stiff Neck • Muscle Fatigue • These symptoms may appear up to a month after infection.
Stage 2 Symptoms • Within weeks of stage one symptoms, the bacterium may spread to other parts of the body through the bloodstream Early Disseminated Infection • Multiple rashes • Cardiac • Neurologic • Muscular
Long Term Lyme STAGE 3
Late-Stage Symptoms • This is the most serious stage of the disease, when treatment was either not successful or never started • May occur months to years after initial infection. • Symptoms at this stage are primarily rheumatologic and neurologic, and mostly untreatable.
Stage 3 • Also known as: • Post-Lyme Disease Syndrome • Chronic Lyme Disease • Diagnosis • Difficult to diagnose • If symptoms persist for 6 months after treatment
Stage 3 • A systemic debilitating condition • Persistent • Months to Years • Damage to joints, nerves, brain
Symptoms • Rheumatoid Arthritis • Atrioventricular conduction abnormalities • (AV heart block) ~ irregular heartbeat • Encephalopathy ~ disease on the brain • Decreased memory • Sleep Disturbances • Mood changes • Ataxia ~ nervous system • Depression • Anxiety
Disease Process • Bacteria penetrates blood vessels • Bacteria exits vessels in various organs and tissues • Body may fight off infection • Host immune system may attack healthy tissue • Probable cause of long term complications • There are clues to the mechanisms of Post-Lyme Disease but it is not fully understood
Diagnosis • Clinical Evidence • Enzyme Linked ImmunosorbentAssay (ELISA) • Western Blotting • Indirect Immunofluorescence • Detect antibodies • Lacks sensitivity and specificity • PCR Diagnosis of Early Lymes. Journal of Clinical Microbiology. http://jcm.asm.org/cgi/reprint/30/12/3082
Treatment • Short Term Treatment • Antibiotics can shorten EM and prevent arthritis • Penicillin • Amoxicillin • Tetracycline • Can still have symptoms of Chronic Lyme • Chronic Lyme • Risks are high and benefits are low to antibiotics • Immunosuppressive drugs The Clinical Spectrum and Treatment of Lyme Disease. The Yale Journal of Biology and Medicine http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2590003/?tool=pmcentrez
How we did it… Collecting Ticks
Our Tick Collection Methods • Materials: • Light-colored bed sheet • Hand held GPS devices • Sealable plastic containers • Methods: • We stopped at the banks of pre-selected locations listed on a GPS. • We separated into groups of two, held sheets open, and swept the ground. • After 100 yards we examined the sheet in hopes of finding black-legged ticks.
Our Results • We collected over two days, a total of eight stops. • We found 6 ticks. • All of the ticks found were in their nymph stage and were not much larger than the point of a pencil. • Our sampling was done during the mid summer season rather than the late spring or fall • this may be why so few deer ticks were collected. • Some observations were made about the general environment in which the ticks were found.
How we would like to do it better… Collecting Ticks
Tick Collection Methods • What criteria, procedures, and equipment should be used when collecting ticks in the wild?
Where are ticks generally located in the Midwest? • Near or in deciduous forests • Dry to mesic (moderate moisture) forests • Alfisol-type soils of sandy or loam-sand textures overlying sedimentary rock • Along ecotones-boundaries between varying ecosystems
Constructing Dragging Equipment • 70 x 90cm piece of light-colored corduroy • 1cm diameter wooden dowel along leading edge • Steel rod sewn into trailing edge for added weight • Rope or wood handle to allow front edge of sheet to contact vegetation VS.
Collection Techniques from Schulze/Jordan: • The same individual should perform the dragging • Consistency -speed, height • Collect hourly from dawn ‘til dusk • 100m long transects (sections) • collect every 10m to prevent ticks from falling off • Randomize dragging order, direction of travel, location within each transect (left, right, center) to minimize repeated dragging of same areas • Minimize dew collection by drying sheets in between collections
Statistics • For each sampling event use a ‘Weather Station’: • Place Weather Station in center of area, 1m above vegetation height • Ambient Temperature • Ambient Humidity • Litter temperature and humidity (digital thermometer) • At least 2.5cm below leaf litter surface but not into soil
Works Cited for Collection Techniques: • Shulze, Terry, Jordan, Robert. “Meteorologically Mediated Diurnal Questing of Ixodesscapularis and AmblyommaAmericanum Nymphs.” Journal of Medical Entomology. 2003. • Lindstrom, Anders, Jaenson, Thomas. “Distribution of the Common Tick, Ixodesricinus, in different vegetation types in Southern Sweden.” Journal of Medical Entomology. 2003.
GIS Modeling: the Interrelationshipof Ticks, Mice, and their Environment • Use an appropriate collection device • Sample small specific areas • Test ticks for Borrelia burgdorferi • Look for evidence of a pattern in the incidence of infected ticks • If specific reservoirs of bacteria are found, a map could be made based on likelihood of the existence of the bacteria.
What is Borrelia burgdorferi
Characteristics • Named after American scientist Willy Burgdorfer who in 1982 isolated and determined the bacterium. • Lyme Disease is the most common tick-borne disease in the US. • Borrelia burgdorferi are • spiral shaped microorganism (spirochetes) • Gram-negative • Motile
Borrelia burgdorferi complete genome • Chromosomal Gene Summary • 853 genes • 793 protein coding genes • 502 genes assigned a role • 51 genes not assigned a role • 102 hypothetical genes • DNA Molecule Summary • 18 DNA molecules • 28.5%G+C chromosomal bases • 63.1% linear DNA bases
Characteristics • Chemo-organotropic • derive energy by metabolizing organic molecules. • They cannot synthesize their own amino acids, fatty acids, enzyme cofactors, and nucleotides. • Microaerophilic • Too much or lack of oxygen can be harmful to them. • Catalase negative • they are unable to break down hydrogen peroxide. • Optimal growth temperature is 34° to 37°C.
Surface proteins on Borrelia burgdorferi • OspA • expressed while Bb is in the tick’s midgut • OspC • expressed during tick’s blood meal • allows Bb to relocate to salivary glands (36-48 hr)
OspC binds to Salp15 in the tick salivary gland Salp15 Facilitates transmission of Bb from tick to host Allows Bb to evade host immune system Has immunosuppressive activity in the host
Immunosuppressive activity of Salp15 within host Salp15 binds to CD4+ of T-cells inhibiting: the normal production and secretion of interleukin-2 TCR-triggered calcium signals activation of transcription factors
Current Vaccines • Originally approved by the FDA in 1998 to help prevent the disease, the vaccine was pulled from the market by the manufacturer in 2002 due to poor sales and concern that the vaccine could trigger arthritis problems though the FDA never found conclusive evidence that the vaccine was dangerous. (WebMD) • Currently, there is no human vaccine on the market. • One did exist called LYMErixbut is no longer available.
Possibilities for a Future Vaccine • If there is some way to produce a vaccine with Salp15, this could allow the host’s body to recognize and fight off the bacteria faster and more efficiently. • If there are other ways to degrade the protein in the host’s body the bacteria would become vulnerable to an immune response. • Salp 15 is the protein that enables the bacteria to enter the host initially undetected.
Problem Based Learning Mike, CHRISTINA,
Discussion • Prevention • Life cycle interruption • Habitat • Surface protein • Human immunity • Salp 15 • glycoprotein