Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
54 Cards in this Set
- Front
- Back
|
Borrelia spp.
General Information Fig 20.8 |
-gram (-) spirochete
-major pathogens: 1.) B. burgdorferi (Lyme dis, minor antigenic shifts) 2.) B. recurrentis (relapsing fever, major antigenic shifts) -antigenically related to Treponema pallidum (syphilis) |
|
|
B. burgdorferi (Lyme disease)
Pathogenesis and clinical manifestations |
-occurs in stages (like syphilis)
-minor antigenic shift 1. Early infection: Stage 1 2. Early infection: Stage 2 3. Late infection: Stage 3 |
|
|
B. burgdorferi (Lyme disease)
Early infection: Stage 1 fig 20.7 |
-erythema migrans ("bulls eye" only in a minority of larger lesions)
~10% bulls eye ~30% central erythema ~50% humogenous -perhaps fever, minor constitutional symptoms or regional lymphadenopathy |
|
|
B. burgdorferi (Lyme disease)
Early infection: Stage 2 |
-disseminated infection
-sever fatigue, secondary annular lesions and joint and muscle pain -less common symptoms include rash, meningitis, CN palsy including Bell's, conjunctivitis, mild hepatitis, and resp distress |
|
|
B. burgdorferi (Lyme disease)
Late infection: Stage 3 |
-persistent infection
-longer episodes of arthritis and crhonic arthritis -skin lesions that appear bluish-red and swollen, and perhaps chronic encephalomyelitis or keratitis |
|
|
****CDC Clinical case definition of Lyme Disease
|
-erythema migrans (> or = 5 cm in diameter) and at least one late manifestation (musculoskeletal, nervous system, or cardiovascular involvement) and lab confirmation of infection
|
|
|
B. recurrentis (relapsing fever)
Pathogenesis and clinical manifestations |
aka tick fever and recurrent fever
-major antigenic shifts -generalized infection with an abrupt onset -symptoms include chills, fever, severe headache, muscular and joint pains, and enlargment and tenderness of spleen and liver epidemis borreliosis and endemic borreliosis -->both relapses due to cyclic antigenic variations |
|
|
Epidermis borreliosis
|
-louse-bourne
-usually a single relapse -it is the most severe form of relapsing fever |
|
|
Endemic borreliosis
|
-tick borne
-usually several relapses -less severe than louse-borne |
|
|
B. burgdorferi (Lyme disease)
Epidemiology |
-the CDC estimates that Lyme disease is currently the most common insect vector-borne infection, 27,444 cases in U.S. in 2007
-major foci of infections are the Northeast, upper Midwest, and Pacific West |
|
|
B. burgdorferi (Lyme disease)
Epidemiology Fig 20.9 and 20.10 |
-life cycle involves ticks (Ixodes scapularis) and mice (during larval and nymph stages of the ticks)
-preferred hosts for adult ticks are white tailed deer -more than 90% believed to be transmitted by nymph stage ticks -the ticks parasitize a number of mammals and birds, but illness is not know to develop in these hosts -lyme may occur in some domestic animals (dogs, horses, cows) |
|
|
Epidemic borreliosis
Epidemiology |
-transmitted by a human louse
-picks up the bacterium when feedin on a bactermic pt -transmission to a susceptible individual occurs when the louse is injured by a host -cases in the U.S. are imported |
|
|
Endemic borreliosis
Epidemiology |
geographic location depends on the distribution of tick vectors and animal reservoirs
-infection occurs during the tick feeding process -endemic in the western and southwestern U.S. |
|
|
Lyme Disease
Diagnosis |
-microscopic examination of blood or tissues is not recommended
-CDC lab crit for diagnosis is at least one of the following: -isolation of B. burgdorferi -demonstration of diagnostic levels of IgM or IgG (ELISA) Abs to spirochetes, sig increase in Ab titer btwn acute and convalescent serum samples ***PCR (starred in class) -western blot is used to confirm positive ELISA |
|
|
Lyme disease
Diagnosis *special notes* |
***PCR (starred in class)
-IgM Abs appear 2-4 wks after onset of erythema migrans and peak after 6-8 wks of illness IgGs appear later and peaks after 4-6 months of illness |
|
|
Relapsing fever
Diagnosis |
-clinical signs are not diagnostic
-demonstration of bacteria in blood -there are no accurate serologic tests (***due to antigenic shifts) |
|
|
Lyme disease and relapsing fever
Treatment |
-Antibiotics
|
|
|
Prevention and control of Lyme disease
|
-avoid the vector
-in endemic areas use appropriate clothing (light colored) long sleeved -tick repellents -examination of the skin after walking in suspected tick environments ***vaccine withdrawn from market in 2002 bc of reported side effects, but there is one for dogs |
|
|
Nonhemorrhagic fever diseases (Bacterial agents)
-See Chapt 20.8 |
1. Brucella spp
2. Coxiella burnetii 3. Baronella spp 4. Ehrlichia spp and Anaplasma spp 5. Rickettsia spp 6. Anthrax |
|
|
Brucella spp.
General information |
1. Brucellosis aka undulant fever, Bang's disease (cattle) or Malta fever
2. wide range of hosts (B. abortus -->cattle and B. suis --> pigs) 3. potential bio agent for bioterorism 4. morphology -->small, gram (-) coccobacilli |
|
|
Brucella spp.
Pathogenesis and clinical manifestations |
-bactera can survive and multiply in PMNs and macros, local lymphadeno may precede bacteremia, lesions consist of small granulomas
-incub peroid is days-months (avg 3 wks) -onset is abrupt or insidious with fatigue the most common complaint -others diurnal fever (undulant), anorexia, muscle aches, headaches, and backaches |
|
|
Brucella spp.
Pathogenesis and clinical manifestations |
**relapses are a hallmark, chronic brucellosis usually weakness, fatigue, vague pains, and pression can last 1-20 yrs
|
|
|
Brucella spp.
Epidemiology |
zoonotic disease; it is related to animal infections; major reservoirs of human brucellosis in the US are infected cattle and hogs
ingestion, contact, and inhalation are the major means of transmission; in the U.S. consumption of unpastuerized milk and dairy products is the major source of infections |
|
|
Brucella spp.
Epidemiology and incidence |
worldwide ~.5 mill cases/yr, low in U.S. (137 in 2007), CA and TX highest
-effective vaccination programs for domestic animals has greatly reduced most human cases in developed countries -occupational hazard (vets, dairy farmers, and lab personnel) |
|
|
Brucella spp.
Diagnosis |
-classified among "fevers of unknown origin" bc of nonspecific symptoms
-isolation from blood, bone mar, or liver; its intracellular position may be repsonsible for neg blood culture -serologic tests can indicate active disease (w/ rising titer) |
|
|
Brucella spp.
Control |
1. if brucellosis is suspected, notify the lab, high risk for lab personnel
2. and effective vaccine for animals is available, elimination of the animal reservoir prevents human disease |
|
|
Coxiella burnetii
General information |
-obligate intracellular bacterium; the etiologic agent of Q fever; pot bio agent for bioterrorism
-small gram (-) pleomorph |
|
|
Coxiella burnetii
Clinical manifestations |
-incubation period can be months/yrs and the presentation is often insidious w/ a range of symptoms
-subclinical to flu-like, to atypical pneumonia with prolonged fever and perhaps hepatitis -subacute endocarditis is the most common presentation, **often occurs on prosthetic or previously damaged heart valve |
|
|
Coxiella burnetii
Epidemiology |
-in US outbreaks are associated with livestock or their products or lab infect
-transmission is thought to be arthropod-vertebrate-arthropod cycle -major reserviors are cattle, sheep, goats |
|
|
Coxiella burnetii
Epidemiology and Incidence |
-principle mode of human infection is inhalation of dust particles and aerosols contaminated with organisms from birth tissue or excreta of infected animals
-in US 171 cases were reported in 07 (TX an Cali) -individuals with highest risk are farm workers, meat cutters, vets, lab techs, consumers of raw milk ****Endospore like forms |
|
|
Coxiella burnetii
Diagnosis |
-serology-->
IFA; PCR (blood, heart valve); tissue culture |
|
|
Bartonella spp
General Information |
- gram (-) bacilli
-members of the genus occur in a variety of animal reservoirs -insect vectors have been implicated in some diseases |
|
|
B. Bacciliformis
|
-cause Oroya fever
-endemic to Peru, Ecuador, and Colombia -due to a sandfly vector |
|
|
B. quintana*
|
-cause of trench fever, subacute endocarditis, and bacillary angiomatosis
|
|
|
B. henselae*
|
-also the cause of bacillary angiomatosis
-cause of subacute endocarditis -cat scratch disease (CSD): |
|
|
Bacillary angiomatosis
|
avascular proliferative disease seen primarily in immunocomp pts
-eg AIDS pts -transmitted by a body louse (homeless people) Differences: 1. B. henselae: primarily involving the skin and lymph nodes 2. B. quintana:subcutaneous tissues and bone |
|
|
Cat scratch disease (CSD):
fig 20.14 |
exposure to cats, scratches bites, and contact with cat fleas
-usually occurs in children -signs: fever, lymphadenopathy and ostolytic lesions -treat with antibiotics |
|
|
Ehrlichia spp and Anaplasma spp
General information |
E. chaffensis--> agent for human moncytic ehrlichiosis (HME)
Anaplasma phagocytophilum--> is the agent for human granulocytic anaplasmosis (HGA) -both are gram (-) -obligate intracellular bacteria |
|
|
Ehrlichia spp and Anaplasma spp
Clinical manifestations |
-E. chaffensis is the agent for HME, the disease resembles RMSF
-about 12 days after tick bite, high fever, headache, mailaise, and myalgia develop -leukopenia and thrombocytopenia also occur -rsh develops in 30-40% of pts (more commonly in children than adults, death usually occurs in old and immunocomprimised) |
|
|
Ehrlichia spp and Anaplasma spp
Epidemiology |
-E. chaffensis geo distribution: mid-Atlantic, southeastern, and south central areas of U.S.
-major insect vector is the Lone Star tick (Ambyomma americanum) -white tailed deer and dogs are major reservoirs for bacterium -2007 ~ 1650 US cases of ehrlichiosis/anaplasmosis were reported |
|
|
Ehrlichia spp and Anaplasma spp
Diagnosis |
-culture is not performed
-microscopy is attempted, but not highly sensitive -IFA -DNA amplification/probe test |
|
|
Ehrlichia spp and Anaplasma spp
Treatment and control |
-suspected cases treated with antibiotic prior to lab confirmation
-control is identical to other insect vector borne diseases |
|
|
Rickettsia spp
General information |
1. morphology: very small, gram (-) coccobacilli
2. Physiology: obligate intracellular parasites 3. notable species: -R. rickettsii --> RMSF -R. akari--> rickettsialpox -R. prowazekii --> epidemic typhus -R. typhi ---> murine typhus *all assoc. with arthropod vectors |
|
|
Rickettsia spp
Pathogenesis |
-able to induce phagocytosis, enter endo cells, escape from a phagosome and replicate within the cytoplasm or nucleus of host cells
-replicate until the host cell bursts, releases org which infect other cells -clin widespread vasculitis leads to the classic triad of rickettsial diseases: fever, headache, rash |
|
|
Rickettsia rickettsii
Patho and clinical manifestations |
-the etiologic agent of RMSF
-incub period 3-12 days, onset is sudden sever headache, fever, malaise and myalgia -2-4 days after, rash on palms and soles, later it becomes generalized and may be hemorrhagic -other symptoms include GI complaints, conjunctivitis and stiff neck |
|
|
Rickettsia rickettsii
Patho and clinical manifestations--> Complications Fig 20.16 |
-include resp failure, encephalitis, and renal failure
-infection results in widespread enothelial damage, with occlusion of small vessels, microhem, electrolyte changes and perhaps necrosis, shock and death |
|
|
Rickettsia rickettsii
Epidemiology: Transmission |
-wood tick (Dermacentor anderoni) is common vector in the Rocky Mt states
-dog tick (D. variabilis) and A. americanum are common in southeastern/central states -ticks act as both reservoirs and vectors, acq bact from infected animal host or by transovarial infect |
|
|
Rickettsia rickettsii
Epidemiology: RMSF Fig 20.15 |
-most sever and common rickettsiosis that occurs in the US (2221 in 2007)
-distrib throughout the continental US -highest incidence in NC, OK, TN, VA, GA, LA, and AK -mostly in children and younger adults during warmer months |
|
|
Rickettsia rickettsii
Diagnosis |
-isolation is not recommended
-microscopy using DFA of skin lesion biopsy allows confirmation within hrs -confirmation by detecting Abs by the end of 2nd week with MIF -Weil-Felix test for cross reacting Abs to Proteus (no longer rec) -PCR |
|
|
Rickettsia rickettsii
Treatment and Control |
-Antibiotic treatment should begin immediately based upon clinical signs and history of recent tick attachemnt
-no commercial vaccine is available -avoidance (like Lyme dis) recomm |
|
|
Anthrax
|
-see notes on bacterial diseases affecting the skin p. 11
-etiologic agent is Bacillus anthracis -gram (+) endospore forming rod |
|
|
Anthrax
Signs and symptoms |
-skin (cutaneous anthrax)
-Lungs (pulm anthrax) -GI tract (ingest of contaminated foods) -CN system (anthrax meningitis) |
|
|
Anthrax
Pathogenesis and Virulence Factors |
eg. lethal factor
|
|
|
Anthrax
Transmission and epidemiology |
-animal reservoir
-endospore former -bioterrorism |
