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30 Cards in this Set
- Front
- Back
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Tick-Borne Infections in the US
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Lyme disease
Rocky Mountain spotted fever Ehrlichiosis Tularemia Babesiosis Tick-borne relapsing fever Colorado tick fever Tick-borne encephalitis (common in Europe) Tick paralysis |
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Classification of Ticks
Class Arachnida includes (3) Nymphs and adults have _ legs, larva have _ Hard (_______) vs. soft (______) ticks; the _______ is more responsible for disease |
Class Arachnida includes scorpions, spiders, ticks, mites
Nymphs and adults have 8 legs, larva have 6 Hard (ixodes) vs. soft (irgasid) ticks; the ixodes is more responsible for disease |
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Ixodes Scapularis
adult female Responsible for which disease? |
Responsible for lyme disease
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Ticks Are Effective Vectors
Feed on _____? Host Range? |
Feed on blood
Wide host range Persistent attachment – wide dispersal Longevity Few natural enemies Resistant to environmental stresses High reproductive potential Transovarial transmission of some agents |
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What kind of rash seen in lyme disease?
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Erythema migrans
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Characteristics of Borrelia
_________ shape with a helical configuration surrounding multiple axial filaments (7-11 in Borrelia), enclosed within an ______ _______ ______ (20-30 microns) and very ______ (0.2 - 0.3 microns) Multiple ________ (some are linear) Multiple lipoproteins, including ______ _ - _ Can be grown in ______ _________ |
Cylindrical shape with a helical configuration surrounding multiple axial filaments (7-11 in Borrelia), enclosed within an outer sheath
Long (20-30 microns) and very thin (0.2 - 0.3 microns) Multiple plasmids (some are linear) Multiple lipoproteins, including OspA-F (outer surface proteins) Can be grown in liquid media (not usually done in clinical labs though) |
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Ecology of B. Burgdorferi
Natural reservoir:? Accidental hosts:? Vector:? Transovarial transmission? |
Natural reservoir: Peromyscus leucopus (white-footed mouse)
Accidental hosts: dogs, deer, humans Vector: Ixodes scapularis No transovarial transmission Bugs come and feed on mouse and then it feeds on dogs/deer/humans --> cycles |
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Life Cycle of Ixodes Scapularis Tick
Egg --> Larvae (in 1 month) --> Feeds once during summer, 2 days, (Mouse is preferred host) --> As an adult, feeds once in the fall, (3-4 days, mouse is preferred host) --> next winter, feeds once more, deer is now preferred host, --> following spring, lays eggs again |
Egg --> Larvae (in 1 month) --> Feeds once during summer, 2 days, (Mouse is preferred host) --> As an adult, feeds once in the fall, (3-4 days, mouse is preferred host) --> next winter, feeds once more, deer is now preferred host, --> following spring, lays eggs again
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Early Manifestations of Lyme Disease
Erythema migrans - Occurs _-__ days after bite - _____ lesion (single/multiple), average size 15 cm - Systemic symptoms? - Secondary lesions? Other Manifestations (3) |
Erythema migrans
- Occurs 8-14 days after bite - Single lesion, average size 15 cm - Systemic symptoms may be present - Secondary lesions may occur Other Manifestations - Carditis - Aseptic meningitis - Bell’s palsy (during summer - lyme's disease becomes most common cause of meningitis) |
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Late Manifestations of Lyme Disease
_________ - _______ involved in 90% - Usually resolve, _-_ weeks - May recur ____ disease - difficulty concentrating, confusion, mild cognitive symptoms |
Arthitis
- Knees involved in 90% - Usually resolve, 1-2 weeks - May recur CNS disease - difficulty concentrating, confusion, mild cognitive symptoms |
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Pathogenesis of B. burgdorferi Infection (Lyme Disease)
Multiplication of B. burgdorferi in tick midgut, expressing OspA Blood meal stimulates Borrelia to travel to _______ ________, from where it is introduced into mammalian host. ____ is downregulated, _____ is upregulated Local multiplication in ________ host Dissemination through bloodstream to: (3) Mechanism of tissue damage? |
Multiplication of B. burgdorferi in tick midgut, expressing OspA
Blood meal stimulates Borrelia to travel to salivary gland, from where it is introduced into mammalian host. OspA is downregulated, OspC is upregulated Local multiplication in mammalian host Dissemination through bloodstream to skin, heart, central nervous system Mechanism of tissue damage poorly understood |
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Diagnosis of Lyme Disease
Recognition of characteristic findings Serology - ______ - ______ ____ ________ - esp. skin lesions _____ - esp. joint fluid |
Recognition of characteristic findings
Serology - ELISA - Western blot Culture - esp. skin lesions PCR - esp. joint fluid |
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Treatment of Lyme Disease
________ or __________ are curative in early stages Some complications require intravenous __________ Vaccine? |
Doxycycline or amoxicillin are curative in early stages
Some complications require intravenous ceftriaxone Vaccine introduced in 1999, discontinued in 2002 (due to joint complications) |
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Southern Tick Associated Rash Illness (STARI)
ECM - ? Serology - usually negative Complications - Rare Vector - Lone star Tick Etiologic Agent - Borrelia lonestari? |
ECM (rash) - Yes
Serology - usually negative Complications - Rare Vector - Lone star Tick Etiologic Agent - Borrelia lonestari? |
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_________ looks exactly like lyme disease in early stage
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Southern Tick Associated Rash Illness (STARI)
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Petechiae = bleeding into skin = ITP, leukemia, WORRY about __________
Very characteristic of ___________ Infection in _______ cells |
platelet count
Very characterisitic of rocky mountain spotted fever Infection in endothelial cells |
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Characteristics of Rickettsia
Gram? Size? Stain results? Intra/extracellular? RNA/DNA? Replication? Cannot be grown on? |
Small gram-negative coccobacilli
Poorly stained by Gram stain. Can be visualized using Gimenez stain Contain RNA and DNA Replicate free in cytoplasm by binary fission Replicate within cytoplasm of infected cells Obligate intracellular parasite Cannot be grown on cell-free media |
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Ecology of Rickettsia
Close association with _________ Some species have a _________ host R. rickettsiae is maintained within the tick population by ______ and _________ transmission. _________ and ______ can also be infected ________ are accidental hosts, infected by the bite of an infected arthropod |
Close association with arthropods
Some species have a non-human vertebrate host R. rickettsiae is maintained within the tick population by transstadial and transovarial transmission. Small mammals and dogs can also be infected Humans are accidental hosts, infected by the bite of an infected arthropod |
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Epidemiology of Rocky Mountain Spotted Fever
Age group? month of onset? |
more in children
may-august (summer) |
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Symptoms and Findings in Rocky Mountain Spotted Fever
Incubation period __-__ days Early symptoms: (3) Rash begins few days after onset - Petechial - Peripheral distribution also think about what when you see petechial rash? |
Incubation period 2-14 days
Early symptoms: fever, headache, myalgias Rash begins few days after onset - Petechial - Peripheral distribution also think about meningococcal when you see petechial rash |
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Laboratory Diagnosis of Rocky Mountain Spotted Fever
_______ first, then worry about making diagnosis Seroconversion or rise in titer Rickettsial-specific antibody tests Weil-Felix test _______ - impractical, hazardous Visualization of organisms in biopsy ______- developmental |
Treat first, then worry about making diagnosis
Seroconversion or rise in titer Rickettsial-specific antibody tests Weil-Felix test Culture - impractical, hazardous Visualization of organisms in biopsy PCR - developmental |
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Treatment of Rocky Mountian Spotted Fever
Treatment of Choice? |
Doxycycline (Treatment of Choice)
Chloramphenicol |
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Characteristics of Ehrlichia
Gram? Live and replicate within __________ Intra/extracellular? |
Gram-negative, coccoid morphology
Obligate intracellular parasite Live and replicate within phagosomes Cannot be grown on cell-free media Complex intracellular life cycle |
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Ecology of Ehrlichia
Vector? Reservoir? |
Vector: Ixodes ticks
E. chaffeensis - A. americanum A. phagocytophila - I. scapularis Transstadial but not transovarian transmission Reservoir: E. chaffeensis - White-tailed deer A. phagocytophila - White-footed mouse |
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Epidemiology of Ehrlichiosis
Seasons? Cases follow distribution of infected vector More common in _______ and _______ adults Patients have history of? or were in a _______ area |
Spring-summer
Cases follow distribution of infected vector More common in middle-aged and elderly adults Patients have history of tick bite or were in a tick-infected area |
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Clinical Manifestations of Ehrlichiosis
Symptoms? Physical Findings? Lab? |
Symptoms
- Fever - Headache - Myalgias Physical findings - Maculo-papular rash in approximately 1/3 Lab - Decreases in all cell lines, esp. white blood cells and platelets |
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Severe Ehrlichiosis
Manifestations? (5) |
Meningitis
Pneumonitis Severe hepatitis Hemphagocytic syndrome Disseminated intravascular coagulation |
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Treatment of Ehrlichiosis
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Doxycycline
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Prevention of Tick-Borne Infections
Avoid ________ areas Wear _________ clothing Use _____-containing insecticides Spray _________ on clothes Remove attached ticks promptly (Do not squeeze) |
Avoid tick-infested areas
Wear protective clothing Use DEET-containing insecticides Spray permethrin on clothes Remove attached ticks promptly (Do not squeeze) |
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Diagnosis of Ehrlichiosis
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PCR
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