Comprehensive: RNA Viruses-Fungi Flashcards
1
Q
Pneumocystis jiroveci Pneumonia
A
- Inhaled, common in AIDS patients (probably latent endogenous infection), often fatal.
- Trophozoites (yeast-like) reproduce in alveolar type 1 cells and form cysts and rupture - alveoli fill with frothy eosinophillic material; diffuse lung inflitrate.
- Best seen with methenamine silver stains
2
Q
Candida (albicans)
A
- Usually superficial (deep infections uncommon and life threatening)
- Endogenous flora, most common precipitating factor = antibiotic use. Yeast converts to invasive hyphae or pseudohyphae form.
- Limited to mucocutaneous sites:
- Thrush = oral cavity, fuzzy white coat on tongue (maceration predisposes)
- Vulvovaginitis = thick white discharge, itchy (antibiotics, preg., diabetes, steroids)
- Sepsis and disseminated candidiasis = usually deadly (catheter, IV, dialysis)
- Endocarditis = large vegetations (IV drug use)
- Other surfaces include esophagitis, paronychia (nailbeds), diaper rash and intertrigo (opposed skin surfaces)
3
Q
Aspergillosis
A
-spores (conidia) inhaled
-Allergic bronchopulmonary aspergillosis: restricted to
asthmatics, spores can germinate in airways and cause long-term antigen exposure → exacerbation and infiltrates
-Aspergilloma (fungus ball): Occur in old TB cavities. Cavity wall is collagenous connective tissue with lymphs and plasma cells. Usually left untreated if asymptomatic.
-Inasive Aspergillosis: Occurs when neutrophil count is low (steroids, leukemia). Produces lung and pleural infarcts, but often spreads to blood and causes disseminated infec tion and thrombosis. Usually fatal, antifungals may help.
4
Q
Mucormycosis (Zygomycosis)
A
- Environmental fungi, cause severe necrotizing, invasive infections that begin in sinuses and lungs (spores are inhaled)
- Rhinocerebral: creates a black crust with friable/hemorrhagic underlying tissue - spreads to vessels and brain. Tx = surgery, amphotericin B, may be fatal
- Pulmonary: Usually fatal, looks like aspergillosis (sepsis and infarction)
- Subcutaneous zygomycosis: In the tropics, hard inflamm. mass (infects subcutaneous fat) on shoulder, trunk, buttock, thigh
5
Q
Cryptococcosis (C. neoformans) - encapsulated
A
- Inhaled- natural reservoir is pigeon droppings
- Impaired cell-mediated immunity common (AIDS, hodkins disease, leukemia)
- CNS = site of primary infection–meningitis. Also causes progressive pulmonary disease
- Fatal without treatment
- Proteoglycan capsule is critical for virulence, - stains poorly with H&E - stains with mucicarmine
- India Ink stain of CNS infection
6
Q
Histoplasmosis
A
- Histoplasma capsulatum.
- Primarily effects lung, typically SELF_LIMITED in HEALTHY.
- Intracellular, macrophages = > granulomatous, may resemble TB. => caseous necrosis + calcifications.
- Can dissemminate bone, spleen, liver, adrenal glands, mucocutaneous membranes–AIDS, hepatosplenomegaly (granulomatous deposits) immunocompromised–fatal,
7
Q
Coccidioidomycosis “Valley fever” “Desert Fever”
A
- “Valley fever” “Desert Fever”
- Coccidioides immitis or Coccidioides posadasii
- Endemic in certain parts of Arizona, California, Nevada, New Mexico, Texas, Utah.
- Flu-like, maculopapular rash,
- Begins with pulmonary infection (granuloma-caseous)–nodules form in lung with hemoptysis, then disseminates, can cause meningitis in immunocompromised.
- usually after pulomary infection, appearance of eryhthema nodosum (IgG deposits-allergic reaction in fat underneath skin)
8
Q
Blastomycosis (Blastomyces dermatitidis)
A
- Very similar to coccidiomycosis, granulomatous, but also suppurative pulmonary dissease–cavitary pneumonia and meningitis with cerebral abscesses.
- Endemic to Midwest, Mississippi river and Ohio river basins, and around the Great Lakes.
- Skin (>50%) and bones (>10%) are most common sites of extrapulmonary involvement.
- skin lesions from disseminated infection resembling squamous cell carcinoma.
- Usually self-limited (1/3 of patients)
9
Q
Paracoccidioidomycosis (South American/Brazilian Blastomycosis)
A
- similar to coccidiodomycosis + blastomycosis
- chronic granulomatous infection (with purulent exudates) starting with lung involvement–dissemination in immunocompromised to skin, oropharynx, adrenals, and macrophages of lymphatic system.
- central + south america
- usually acute, self-limited and mild disease
10
Q
Sporotrichosis
A
- Rose Gardner’s disease
- accidental inoculation through breaks in skin from thorns piercing skin.
- chronic granulomatous skin infection with suppurative center-necrosis and ulceration–lead to secondary cellulitis
- can disseminate through lymphatic vessels-spread to joints and bone.
11
Q
Chromomycosis
A
- tropics and subtropics
- barefooted agricultural workers
- inoculation through skin–lesion(papule) and become verrucous (wart like with ulceration)
12
Q
Dermatophyte Infections (Microsporum, Epidermophyton and Trichophyton)
A
- obtain nutrients from keratin–common and benign
- Athlete’s foot or tinea pedis
- Ringworm of the body or tinea corpora
- Facial ringworm or tinea faciei
- Blackdot ringworm or tinea capitis
- Scalp ringworm or tinea capitis
- Ringworm of the hands or tinea manuum
- Ringworm of the nail, Onychomycosis, or tinea unguium
13
Q
Mycetoma
A
- chronic granulomatic + suppurative cutaneous disease-through breaks in the skin
- tropical workers–affect feet: MADURA FOOT
- disfiguring skin infection–abscesses that combine–large abscesses with ulceration–purulent discharge-white or black.
14
Q
Tuberculosis (Mycobacterium tuberculosis hominis, M. bovis)
A
- Spreads by aerosols from person to person, enters into the lungs
- Forms GHON COMPLEX lesions in lungs (area of infection + lymph nodes) - contains caseous granuloma (necrotizing center) / hilar lymphadenopathy,
- Most cases of primary TB are asymptomatic. In progressive cases (kids, immunocompromised, homeless) non specific symptoms (fever, night sweats, weight loss, fatigue).
- Secondary TB (reactivation or reinfection) - T-cells are already familiar with antigen and cause necrosis and cavities in lungs. Same as primary symptoms + hemoptysis. Disease may disseminate (miliary) and become fatal.
- Todays treatment - long term antibiotics.
15
Q
Leprosy (Mycobacterium leprae)
A
-Spreads person to person through intimate contact - respiratory tract or open wounds
-Proliferates in areas of lower body temperature (hands and face)
-Infection occurs in 5% of exposed people and is either tuberculoid or lepromatous
Tuberculoid = Moderate: few lesions, dermal granulomas with sensory loss (not caseous). Reflects appropriate TH1 activation
Lepromatous = Severe: foamy macrophages act as incubators and form globi. Form diffuse, tumor like lesions of skin, eyes, testes, nerves, lymph nodes and spleen–claw shaped hands, saddle nose. Results from deficient TH1 activation.
16
Q
Mycobacterium avium-intracellulare Complex (MAI)
A
- Spreads by aerosols from infected water (or infected food, soil)
- Immunocompromised older people (⅓ of AIDS patients!). COPD predisposes.
- Begins in lungs - causes TB like pulmonary cavities and caseating granulomas (but slow progressing)-years to decades. Macrophages engulf (but dont kill) bugs, then spread throughout body
- Antibiotics may control but not cure.
17
Q
Atypical Mycobacteria
A
- Not common, may be inhaled, ingested, or inoculated
- M. kansasii - granulomatous disease similar to MAI in older people
- M. scrofulaceum - granulomatous, cervical lymphadenitis in young children
- M. marinum - granulomatous or pyogenic, localized skin lesions - from water (pools)
- M. chelonae or fortuitum - painless abscesses from trauma that ulcerate and then heal
18
Q
Atypical pneumonia (Mycoplasmal pneumoniae) = Walking pneumonia
A
- Light or non-productive cough.
- Non-lobar, very small localizations. “Patchy consolidation” often in lower lung.
- Caused by unexpected organisms (Not: Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis)
- Caused by atypical bacteria, viruses, fungi,
- smallest free-living prokaryotes
19
Q
Rocky Mountain Spotted Fever
A
- Tick-borne, caused by Rickettsia rickettsii , Gram (-) coccobaccilus.
- obligate intracellular pathogen
- Serious, life-threatening illness.
- Early presentation is non-specific, febrile.
- 2-5 days after fever
- Maculopapular or petechial rash spreading from limbs toward trunk.: from infection of vascular smooth muscle and endothelium of large and small vessels
- microthrombi–infarction + dic from hemorrhaging of blood vessels–fatalities
- other symptoms: pulmonary edema,
20
Q
Epidemic (Louse-Borne) Typhus
A
- Caused by Rickettsia prowazekii,
- Transmitted by lice, often during disasters, war, or in prisons; human pool.
- Obligate intracellular pathogen–endothelial cells
- Early stage = Febrile
- Later = A rash begins on the chest (infects capillary endothelial cells) about five days after the fever appears, and spreads to extremities (from trunk).
- vasculitis from invasion of enothelial cells–severe
- typhus nodules on liver and spleen.
21
Q
Endemic (Murine) Typhus
A
- Caused by Rickettsia Typhi
- Transmitted by flea; rodent pool.
- Similar phenotype to epidemic louse-bourne typhus, but less dangerous.
-Flea feces can be inhaled–pulmonary infection
22
Q
Scrub Typhus
A
- Orientia tsutsugamushi, a Gram-negative α-proteobacterium of Rickettsia family.
- Transmitted by Chigger (mites) bite, leaving a black eschar that helps with diagnosis.
- Endemic to parts of Russia, Korea and Japan.
- Generalized lymphadenopathy
- Can be fatal without treatment.
- Similar effects to those above.–obligate intracellular pathogen–infects endothelial cells–hemorrhaging and intravascular coagulation
- myocarditis, meningioencephalitis other complications
23
Q
Q Fever
A
- Coxiella burnetii
- From animals–inhalation of aerosolized dropletts
- phagocytosed and proliferation inside macrophages.
- focal bronchopneumonia–atypical pneumonia (from immune response to granulomas
- Typically a self-limited systemic infection, particularly lungs and liver.
- Granulomatous hepatomegaly.
24
Q
Chlamydiae trachomatis Infections
A
- most common STD
- Intracellular, cant make ATP -Elementary body attached to cell and becomes endocytosed
- Reticulate body becomes active inside cell, pirates the cell machinery.
- Genital and Neonatal Infections
- Serovars D through K -Asymptomatic in approx 60% women.
- Inflammation of GU tracts, exudate, PID
- Generally non lethal, can cause permanent damage to reproductive system.
- Lymphogranuloma Venereum
- Serovars 1 through 3
- Buboes or abscesses in the groin (inguinal) region where draining lymph nodes are located, progress to necrotizing lymphadenitis.
- Often seen with HIV.
- Trachoma
- Serovars A,B,C
- Leading cause of blindness in underdeveloped.
- Neonatal exposure from mom.
- Effects eyes: characteristic roughening of the inner surface of the eyelids. -Painful, Can lead to visual impairmnent.
25
Psittacosis (Ornithosis) (Chlamydiae psittaci)
- Spread from Birds in tropics--zoonotic.
- inhalation--atypical pneumonia: no lobar infiltrates
- obligate intracellular pathogen--alveolar cells + macrophages
- Self-limited interstitial pneumonia--alveolar cell lining necrosis and invasion of macrophages
- disseminates--necrosis in liver and spleen and mononuclear infiltrates (macrophages) in heart, kidney and brain. Rose colored spots appear: Horder's spots
- splenomegaly
- death from complications from hepatitis, endocarditis, myocarditis, encephalitis (
26
Chlamydia pneumoniae
- obligate intracellular pathogen
- invade epithelial and alveolar cells of lung--necrosis
- atypical pneumonia--bronchopneumonia--no lobar consolidation
- Acute, self-limiting.
- P2P droplet spread.
- fever, sore throat, cough
27
Syphilis (Treponema pallidum)
- Gram(-), highly motile. -granulomatous--taken up by macrophages
- Pyogenic STD with 3 characteristic stages
- Primary: Chancre (firm, painless) with luetic vasculitis, occasionally multiple lesions in immunecompromised.
- Secondary: (involves systemic spread) Maculopapular rash on palms and soles of the feet, follicular and numular syphilids-cutaneous + mucous membran lesions, condylomata lata (white plaques on perineum region), obliterative endarteritis.
- Latent stage: Asymptomatic
- Tertiary (3-15 yrs after infection): Gumma: soft, tumor-like balls of inflammation which may vary considerably in size--necrotic center with inflammed reddened surrounding--leads to cardiac and cerebral complications if present in heart, or brain. NeuroSyphilis - meningitis, seizure, dementia + tabes doralis (peripheral nerve demyelination) Cardiovascular syphilis- aortitis =\> aneurism.
- Congenital syphilis can cause snuffles, saddle nose, saber shins, and Hutchinson teeth in newborn
28
Yaws (Treponema pallidum pertenue)
- Found in tropics, skin-to-skin transmission
- Pyogenic: neutrophilic Raspberrry-like papilloma lesion.
- Diffuse skin lesions, ones on the sole of feet can cause “Crab Yaw” walking
- hyperkeratosis-darkening of skin with infection
- After a latent period, re-emerges as face and upper airway lesions
29
Bejel (endemic syphilis) (Treponema pallidum endemicum).
- gummas in skin, airways, bone
- transmission is mouth-to-mouth, breast-to-mouth, or utensil-to-mouth
- usually begins in childhood as a small mucous patch, often on the interior of the mouth, followed by the appearance of raised, eroding, Pyogenic lesions on the limbs and trunk. Periostitis (inflammation) of the leg bones is commonly seen, and gummas of the nose and soft palate develop in later stages.
- Mediterrenian/West Africa
30
Pinta (Treponema carateum)
- spirochete, invade macrophages
- Skin-to-skin transmission
- Mexico, Central America
- Colored spots, scaly/flakey, disease limited to the skin; may leave behind areas of hyperpigmentation
31
Lyme disease (Borrelia burgdorferi)
- Zoonotic spirochete, Transmitted by ticks, reservoir = mice, deer.
- Stage 1: erythema chronicum migrans (characteristic annular red lesions), fever, malaise
- Stage 2: muscle, heart, and nerve problems, including meningitis and facial nerve palsy
- Stage 3: more joint, skin, and nerve problems - mimics rheumatoid arthritis
- Late manifestations (years later): acrodermatits chronica atrophicans, patchy atrophy and sclerosis of skin
- Diagnosis usually established using antibody titers
32
Leptospirosis
- Transmission: Water w/ animal urine contacts breaks in the skin.
- Usually mild and self-limited, sever forms cause hepatic and renal failure
- Leptospiremic phase: bacteremic: 1-2 weeks of nonspecific fever, shaking chills, headache, myalgia that resolve on their own (Gets in CSF, but not very virulent--does not cause severe disease by itself)
- Immune phase / Weil disease: 3 days after the leptospiremic phase, symptoms return with vasculitis, hemorrhage, meningitis (CNS pleocytosis), liver and kidney failure, shock and death.
- Mortality of Weil disease is 5-30%
33
Relapsing Fever (Borrelia recurrentis)
- Epidemic fever disease from lice, caused by Borrelia recurrentis: high untreated mortality
- Endemic version is from ticks, many species
- General symptoms: fever, lethargy, arthralgia, headache, myalgia, petechiae -More specific symptoms: splenomegaly with miliary microabscesses, hemorhages, hepatomegaly because the spirochetes live in liver sinusoids → inflammation
- Sickness comes and goes abruptly in 1-2 week long waves, each time the duration is shorter and symptoms are milder.
- Spirochetes also change their antigenic coats in between each febrile period
- can be fatal
34
Tropical Phagedenic Ulcer (Bacillus fusiformis and Treponema vincentii)
- a.k.a Tropical Foot, fusospirochetal infection
- Follows trauma (lesions) in the tropics, malnutrition is a factor.
- Painful leg legion with necrosis, sloughing of skin, and gray putrid exudate -May be complicated by tibial osteomyelitis and squamous cell carcinoma
- Deep wounds that persist for years, often need reconstructive surgery to fix
35
Noma / gangrenous stomatits / cancrum oris
- A disfiguring, smelly facial necrosis that destroys both soft tissue and bones of mouth and face
- Often targets malnourished kids in and immune compromised in the tropics
- Common bacteria: T. vincentii, B. fusiformis (fusospirochetal), Bacteroides, Corynebacterium
- Underlying bone may be revealed.
- Usually need antibiotics and reconstructive surgery
36
Actinomyces (Actinomycosis)
- filamentous, anaerobic, Gram(+) commensual saprophytes present in oropharynx, GI tract, vagina--requires trauma to cause disease (anaerobic environment)
- Cervicofacial: jaw injury or after dental surgery--leads to purulent abscesses in jaw. "lumpy jaw" -form sulfur granules made of Splendore-Hoeppli material (tangled masses of branching filaments in polysaccharide protein matrix)
- Sinus tracts that penetrate lobe to lobe in pulmonary infections
- progressive, slow growing (anaerobic), disease that is well controlled by antibiotics
- Fatal if untreated
37
Nocardia (Nocardiosis)
- respiration or cutaneous inoculation
- gram(+) aerobic filamentous
- May affect lungs, brain, skin or systemic dissemination in immunocompromised
- Disease of immunocompromised.
- Pyogenic: Pulmonary abcesses-pyogenic pneumonia w/ central necrosis.
- Fatal if untreated, long term antibiotics.
38
Brucellosis (Brucella)
- Facultative intracellular parasites causing chronic disease, which usually persists for life.
- four types: goats/sheep, cattle, swine, dogs
- enter through lungs, through skin, oropharynx
- produces UNDULANT FEVER (waxes and wanes)
- multiply in macrophages (lymph nodes, spleen, liver): multi-organ non-necrotizing granulomas
- common complications: spondylitis, arthralgia, meningitis, endocarditis--treat with tetracycline -usually self-limited. mortality
39
Yersinia pestis
- Gram-negative rod-shaped coccobacillus. It is a facultative anaerobe
- survive/proliferate inside macrophages (granulomatous + necrotizing)
- Produces plasminogen activator: hemorrhaging
- Bubonic plague: spread by fleas on rats-septic shock and bulbous enlargements of lymph nodes
- Septicemic plague: direct blood contamination (death quick-48 hours)
- Pneumonic plague: inhalation of airborne particles, necrotizing pneumonia-hemoptysis-endotoxic shock in 1-2 days after infection period which follows 2-5 day incubation -tetracyclin with streptomycin
40
Tularemia (Francisella tularensis)
- reservoir in rabbits and rodents infection from contact; vector is ticks, deerflies, and mosquitoes.
- metastatic infection--survives within macrophages (granulomatous reaction)
- Acute febrile disease, lymphatic distribution.
- Distribute to major organs via lymph =\> enlarge, hard nodes =\> granulomas (necrotizing, described as ‘palisading’)
- Ulceroglandular: pustular lesions (necrosis) with lymphadenopathy and acute febrile illness--significant mortality if untreated
- Occuloglandular = Spread from eye to parotid gland
41
Anthrax (Bacillus anthracis)
- Gram-positive, endospore-forming, rod-shaped bacterium
- spore form in dead animals/soil and reservoir in goats/sheep/cattle/dogs/pigs/horses
- spread through inhalation, breaks in skin, ingestion with germination in body
- Malignant pustule: Cutaneous form (most common) papule/ulcer--lymphadenitis can lead to septicemia. (without dissemination--self-limited no complications)
- Pulmonary: "woolsorter's disease" respiratory failure and shock within 24-48 hours.
- Septicemic: DIC, exotoxin depresses respiratory center--antibiotics ineffective against exotoxin
- Gastrointestinal: rare, eating contaminated meat: stomach + bowel ulceration--death caused by fulminant diarrhea and massive ascites
42
Listeriosis (Listeria monocytogenes)
- reservoir: many species of mammals and birds--rare spread from animal to human
- spread: unpasteurized milk and dairy products
- evades intracellular + extracellular host responses: acidic phagosome activate listeriolysin O exotoxin--escape into cytoplasm and usurps cytoskeleton to form portrusions to dock with other cells (spread without staying in extracellular environmentz)
- Pregancy listeriosis: lead to abortion or premature delivery
- Septicemic listeriorsis: severe febrile illness in immunocompromised--shock and DIC: death without treatment (heavy duty antibiotic course needed)
- Self-limited in healthy host
43
Cat-Scratch Disease (Bartonella henselae)
- proteobacteria
- spread from cat scratches inoculated skin or contact with eye.
- papule at site of infection
- invades macrophages--granulomatous--lymphadenopathy
- swollen lymph nodes persist for months
- Parinaud oculoglandular (granulomatous conjunctivitis with swollen facial lymph nodes) syndrome secondary to conjunctival infection
44
Glanders
- Rare, granulomatous disease.
- Zoonotic; associated with horses.
- Burkholderia mallei aka pseudomonas mallei
- Transmission via cuts in the skin, via musoca, or inspiration.
- invade macrophages-acute granulomatous infection
- Nodular lesions in the lungs and ulceration of the mucous membranes in the upper respiratory tract
- Acute bacteremia =\> Almost always fatal. Generally a 50% mortality rate and very small minimum infectious dose.
45
Bartonellosis (Bartonella bacilliformis)
- aka Carrion's disease
- gram(-) pleomorphic bacteria
- vector: sandflies of Peru, Ecuador, Colombia
- proliferates in endothelial cells then invades erythrocytes--hemolysis
- Oroya fever: acute hemolytic anemia--untreated leads to 40% mortality rate
- verruga peruana: dermal eruptive phase--eruptive lesions-purulent and blood and ulcers that limit joint movement (osteoarticular pain)
46
Clostridium Perfringens
- obligate anaerobe, spore forming, gram(+)
- bacterial benign, diarrheal food poisoning
- rare: necrotizing enteritis (enterotoxins-ulcerating ß-toxin)--necrosis: fatal
- GAS GANGRENE: myotoxin--alpha toxin (alpha lecithinase--phospholipase) that destroys cell membranes leading to severe hemolysis and muscle necrosis--SEVERE
47
Tetanus (Clostridium Tetani)
- obligate anaerobe, gram(+), spore forming
- causes ascending paralysis
- produces potent neurotoxin tetanospasmin (blocks release of inhibitory neuropeptides) that causes lock jaw, and respiratory spasm--death
- invades through contamination of open wounds
48
Botulism (Clostridium Botulinum)
- neurotoxin present in improperly canned food (blocks acetylcholine release): Don't feed newborns honey
- descending paralysis, blurred vision
- untreated: lethal
- antitoxin- 25% mortality
49
Clostridium difficile
- obligate anaerobe, spore forming, gram(+)
- acute necrotizing infection of small bowel and colon responsible for antibiotic-associated diarrheas (clindamycin most responsible)
- Produces cytotoxins A + B
- opportunistic--resides in colon flora
- pseudomembranous colitis
50
Klebsiella (pneumoniae) + Enterobacter
- short, encapsulated, facultative anaerobic, gram(-) rods
- necrotizing lobar pneumonia with cavitations
- 10% of nosocomial infections: P2P spread
- patients with COPD, endotracheal tubes, catheters, and immunosuppressed.
- complication from influenza or other viral infections
- characteristic THICK MUCOID SPUTIM
- can lead to fulminating, deadly septicemia--requires aggressive antibiotic treatment
51
Legionella pneumophilia
- small, aerobic bacillus, gram(-)
- respiratory spread: aerosols of infected sources, NOT CONTAGIOUS
- pneumoina: Legionaire's Disease (life-threatening) and Pontiac fever (milder, self-limiting)
- proliferate inside resident macrophages (granulomatous)--macrophages show eccentric nuclei pushed aside by vacuoles containing L. pneumophila
- alveolar necrosis, fever, nonproductive cough followed by hypoxia leading to death.
- Silver grain stain, Urine antigen test for diagnosis
52
Pseudomonas aeruginosa
- Gram-negative, aerobic, coccobacillus bacterium
- highly antibiotic-resistant
- nosocomial bronchopneumonia, wound infections, UTI, and sepsis
- proteoglycan coat protects against ciliary action, complement, and phagocytes
- elastase, alkaline protease, cytotoxin (exotoxin A)-- ADP-ribosylate/inhibit EF-2 (like diptheria toxin) facilitate tissue invasion
- ECTHYMA GANGRENOSUM: disseminated septicemia infections causes these skin lesions
- AGRESSIVE: rapid sepsis progression (exotoxin + endotoxin production)--hemorrhagic necrosis + thrombosis
53
Meliodosis (Burkholderia pseudomallei)
- a pulmonary infection that can cause cavitary pneumonia with high fever
- splenomegaly, hepatomegaly, septicemia, septic arthritis and shock--SEVERE
- flourishes in wet environments (Vietnam) and enters skin through lesions, burns, or wounds as well as aerosolized droplets
- incubation time months to years
- liver, spleen abscesses in 25% of infected
54
Escherichia coli
- antigenically diverse, aerobic (facultatively anaerobic), gram(-) rod, most commensal and opportunistic
- synthesize vitamin K2, virulence after plasmid transfer
- 90% of all urinary tract infections -bladder mucosa infection--dysuria, pyuria (leukocytes in urine)
- Immunocompromised: Pneumonai, sepsis
- neonatal meningitis: colonizes vaginal canal
- Four strains:
- ENTEROTOXIGENIC: traveler's diarrhea from contaminated water and food, self-limited (Africa, Latin America)--produce 3 enterotoxins--secretory dysfunction of small bowel (one similar to cholera-adenylyl cyclase, other acts on guanylyl cyclase)
- ENTEROPATHOGENIC: diarrheal illness in tropical regions among infants and children, spread from contaminated food and water, deforms microvilli of intestinal epithelial cells, fever + malaise
- ENTEROHEMORRHAGIC: bloody diarrhea, fever, cramping abdominal pain, hemolytic-uremic syndrome (anemia, acute kidney failure, thrombocytopenia), contaminated meat/milk, enterotoxin similar to Shigatoxin
- ENTEROINVASIVE: food-borne DYSENTERY, indistinguishable from shigella (similar toxin to shiga toxin)-self-limited, invades and destroys mucosal cells of ileum and colon. abdominal pain, fever, tenesmus (feeling of incomplete defecation), bloody diarrhea. week long illness
55
Salmonella Enterocolitis
- gram(-) rod, facultatively anaerobic
- SELF-LIMITED -spread by fecal-oral route, contaminated foodstuff
- proliferate and invade enterocytes in ileum and colon-acute inflamation and some superficial ulceration
- diarrhea (self-limited), nausea, vomiting, abdominal cramping, fever--food poisoning: takes 12-48 hours to manifest (no exotoxin production like S. aureus)
- antibiotics rarely improve clinical course
- major cause of childhood mortality in 3rd world countries (lack of oral rehydration therapy)
56
Salmonella typhi
- P2P spread (chronic carriers commonly old women with gallstones or biliary scarring), and contaminated water/food--dairy and shellfish, oral-fecal route rarer
- granulomatous infection: proliferation inside infected macrophages
- Typhoid fever (SEVERE): degeneration of intestinal epithelium brush border (Peyer patch hypertrophy as well)--capillary thrombosis with ulcerated bowel tissue leading to infectious peritonitis; Systemic dissemination: focal granulomas in liver, spleen (typhoid nodules-macrophages with ingested bacteria,erythrocytes, dead lymphocytes)
- 10-14 day incubation period
- Signs: Bacteremia/invasion: daily increase in temperature (IL-1 + TNF), malaise, arthralgias, abdominal pain--Fastigium: fever/malaise increase--septicemia from release of endotoxin from dead bacteria and hepatomegaly and splenomegaly. Fever abates over weeks to months -10-20% mortality in untreated patients (complications including pneumonia)
- Typhoid antitoxin curative if given within 3 days of fever onset.
57
Shigellosis (Shigella dysenteriae)
- aerobic, gram(-) rods
- SELF-LIMITED necrotizing infection -spread oral-fecal route (fecally contaminated food/water or surfaces)--areas of poor sanitation
- self-limiting disease (3-8 days) with watery diarrhea
- 300,000 annual cases in US diarrhea/dysenteric stools, abdominal pain, tenesmus, fecal urgency
- Produces Shiga exotoxin: inhibits protein synthesis and inhibits fluid absorption in colon)--affects distal colon and sometimes distal ileum--dysentery
- infected mucosa is edematous, inflamed, eroded with presence of pseudomembrane composed of neutrophils, fibrin, and necrotic epithelium (healing complete in 10-14 days)
58
Cholera (Vibrio cholerae)
- aerobic, curved, gram(-) rod
- spread from ingesting contaminated food/water; shellfish are natural reservoir--sporadic outbreaks
- epidemics in areas where human feces pollute water supply -cholera exotoxin: binds GM1 ganglioside in enterocyte cell membrane to enter cell and activated adenylyl cylase- increase cAMP and increase Na+/H20 secretion into intestinal lumen. -severe watery diarrhea with flecked mucus (rice water stools)--leads to fluid and electrolyte loss that leads to shock
- 50% mortality rate in untreated patients (lacking electrolyte and oral rehydration therapy +antibiotis)
- vaccine available (50% effectiveness)
59
Campylobacter jejuni
- microaerophilic, curved, gram(-) rod (similar to vibrios) self-limited
- spread through contaminated food/water + fecal-oral route
- most common cause of bacterial diarrhea in developed world--2 million annual cases in US -affects farm animals--huge economic losses
- causes superficial enterocolitis--terminal ileum and colon with focal necrosis of interstitial epithelium and acute inflammation -severe cases: ulcers and patchy inflammatory exudates (necrotic cells, fibrin, neutrophils)
- cytolethal distending toxin (DNA damaging-necrosis)
- watery stools, gross blood containing stools
- associated with Guillain-Barre syndrome (autoimmune peripheral neuropathy)
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Yersinia enterocolitica + pseudotuberculosis
- gram(-) coccobacillus, facultative anaerobes
- fecal-oral route and contaminated water + milk.
- painful diarrhea
- enerocolitica: contaminated meat; proliferates in ileum and invades mucosa--necrosis and ulceration of Peyer patches--fever, diarrhea (bloody), and abdominal pain (can be confused with appendicitis); rare septicemia
- 50% mortality rate in those persons
- pseudotuberculosis (Far East scarlet-like fever): contact with infected animals, penetrates ileal mucosa, localizes in ileal-cecal lymph nodes and causes abscesses and granulomas in lymph nodes, spleen, and liver--fever, diarrhea, and abdominal pain (appenicitis mimic)
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Gonnorrhea (Neisseria Gonorrhoeae)
- P2P: sexually transmitted + perinatal transmission
- aerobic, bean-shaped, gram(-) diplococcus
- pili with IgA protease: attach to transitional epithelium of columnar/transitional epithelium of urogenital tract
- acute inflammtory response-abscecess
- Men: purulent urethral discharge, dysuria, orchitis, epididymitis (may cause infertility)
- Women: 50% asymptomatic, endocervicitis, vaginal discharge/bleeding, urethritis with dysuria, chronic salpingitis, pelvic inflammatory disease (infertility if tubes swell/blocked with pus), endometritis, Fitz-Hugh-Curtis Syndrome (healing fibrous attachement liver--parietal peritoneum)
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Chancroid (Haemophilus ducreyi)
- gram(-) bacillus, histology looks like school of fish
- P2P: sexually
- Chancroid: leading cause of genital ulcers in 3rd world countries (facilitate spread of HIV)
- opportunistic: enters through breaks in skin
- painful, unilateral, suppurative, inguinal lymphadenitis (bubo)
- erythromycin: effective treatment
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Granuloma Inguinale (Calymmatobacterium granulomatis)
- small, encapsulated, nonmotile, gram(-) bacillus
- Granuloma inguinale: chronic, superficial ulceration of genitalia and inguinal and perianal regions
- lesion is granulation tissue--macrophages, plasma cells, neutrophils and lymphhocytes
- Donovan bodies: interspersed macrophages containing bacteria
- genital elephantiasis: obstruction of lymphatics--thickening of skin and edema (NO BUENO)
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Corynebacterium diphtheriae
- aerobic, gram(+) rod, pleomorphic
- P2P spread: respiratory droplets + oral secretions
- diphteria exotoxin--prevent protein synthesis--necrosis
- thick, gray, leathery membranous lesions from upper respiratory epithelium-tonsils (necrotic debris, fibrin, neutrophils,
- fever, sore throat, malaise -treated with antitoxin and antibiotics
- most in western world immunized
- peripheral nerve demyelination w/ neural involvement
- heart affected: fat droplets in myocytes and focal necrosis
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Bordetella Pertussis
- Gram(-) coccobacillus
- highly contagious, P2P: respiratory aerosols
- tracheobronchitis with necrosis of ciliated respiratory epithelium (acute inflamed response)
- Whooping cough: paroxysmal stage
- catarrhal stage: upp resp illness w/ low fever, runny nose, conjunctivitis, cough
- vaccine: unimmunized--50 million cases w/ 1 million deaths per year.
- secondary bacterial pneumonia--causes death
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Haemophilus influenzae
- aerobic, pleomorphic, gram(-) coccobacillus, nonencapsulated, capsulated(Type B): most virulent
- P2P spread: respiratory droplets and secretions
- Normal flora of oropharynx -pyogenic infection, MENINGITIS (#1 cause in
- broncopneumonia, epiglottitis (obstruct airway), septic arthritis (bacteremic), facial cellulitis (bacteremic)
- vaccine: nearly eliminated infantile meningitis
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Neisseria meningitides (Meningococcus)
- paired, bean-shaped, gram(-) cocci
- commensual nasopharynx (5-15% population)
- epidemic in crowded areas (military barracks)
- P2P spread: respiratory droplets
- confined to CNS or disseminated
- fulminant fever, stiff neck, headache
- meningococcal sepsis: fever, shock, mucocutaneous hemmorhages, diffuse vascular endothelium damage, petechiae, purpura
- Rare: vasculitis, thrombosis--Waterhous-Friderichsen Syndrome (adrenal hemorrhagic necrosis)
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Streptococcus Pyogenes (Group A)
-normal bacterial flora of skin and oropharynx
-pharyngitis (strep throat), cellulitis, myositis, pneumonia, puerperal sepsis.
-exotoxins plus cytotoxins.
-Rheumatic fever and glomerulonephritis--complications -
Scarlet Fever (red rash-erythrogenic toxin)
-erysipelas (erythematous swelling of skin)
-Impetigo (intraepidermal infection): spread direct contact in children
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Staphylococcus Aureus (coagulase positive)
- natural flora on skin--innoculation following injury
- leading cause of infective endocarditis -furuncles, carbuncles, scalded skin syndrome (desquamantion), osteomyelitis, bacterial arthritis
- Septicemia, TSS, food posioning,
- MRSA-antibiotic resistance plus virulence factors (toxins + proteolytic enzymes) encoded on plasmids.
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Coagulase negative Staphylococcus Epidermitis
- Gram(+) bacteria
- normal bacterial flora (skin, mucosal surfaces)
- not as serious as S. aureus infections
- low grade fever
- spread from contaminated medical and prosthetic devices. -nosocomial variants multidrug resistant. (use non-beta lactam antibiotics)
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Streptococcus Pneumoniae (pneumococcus)
- Gram(+) cocci
- pneumonia, sinusitis, otitis media, meningitis
- normal flora in oropharynx (opportunist)
- infection follows cold or influenza
- insults such as smoking and alcohol
- capsule blocks opsonization by complement C3b (inhibits macrophages, antibody needed to kill) -Self limiting, Not severe
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Group B Streptococci
- Gram(+) cocci
- Neonatal Pneumonia, meningitis, and sepsis
- 30% infected infants die (1000's infected yearly)
- Normal vaginal flora in 10-30% women
- spread to infant through birth canal
- Risk factor is low level of maternal IgG antibodies
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Kuru
- prototypical prion disease
- neurodegenerative
- transmitted via ingestion (cannibalism of flesh)
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Gerstmann-Straussler-Scheinker Syndrome
- rare transmissable spongiform encepalopathy
- dementia common feature
- some rare sporadic cases, usually familial
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Fatal familial insomnia
- inheirited, rare disorder
- progressive degree of insomnia to sleeplesness
- autonomic instability, motor system degeneration, spongiform changes (like CJD)
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Creutzfeldt-Jakob Disease
- sporadic, familial, iatrogenic (from pituitary of cadaveric victims)
- neurodegenerative -myoclonus, behavioral changes, dementia
- New Variant (vCJD): associated with mad cow
- genetic susceptibility (met-met at codon 129 of gene PRNP -fatal (no cure)
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Varicella-Zoster
- chicken pox, skin vesicular eruptions
- latent in dorsal ganglion--shingles in older patients (herpes zoster)
- pain in single dermatome in shingles--localized painful vesicular eruption.
- neutrophil filled vesicles.
- fever, malaise, rash
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Smallpox (Variola virus)
- Epidemiology: ancient disease. named after latin "varius" meaning "pimple/spot". Common in Europe. Arrived in the new world by explorers and decimated native populations. Edward Jenner (1796) performed first vaccination by innoculating child with lymph from hand of milkmaid infected with cowpox. WHO began eradication campaign in 1967 leading to eradication in 1978 (Somalia last endemic cases). CDC and Russia still have virus stockpiled.
- Etiology: Spread between infected and susceptible hosts via droplets or aerosol of infected saliva. Virus highly stable and remains infective for long periods outside human host. Variola major (Asia and parts of Africa--prototypical) and Variola minor (Africa, South America, and Europe--minor systemic toxicity and lesions).
- Pathology: Skin vesicles of variola show reticular degeneration and areas of ballooning degeneration. Guarnieri bodies (eosinophilic, intracytoplasmic inclusion bodies) are seen, but not specific to smallpox (most poxviral infections). Vesicles also occur in palate, pharynx, trachea, and esophagus. Severe cases produce gastric and intestinal involvement, hepatitis, and interstitial nephritis.
- Clinical Features: Incubatin period: 12 days (7-17 days). Spreads to regional lymph nodes to produce viremia. Abrupt malaise, fever, vomiting, and headache manifest. Characteristic rash (face and forearms) follows in 2-3 days. After eruptions on lower extremities, rash spreads central during next week to trunk. Lesions: macules--\>papules--\>pustular vesicles--\>scabs--\>scars. Fatality rate is 30% in unvaccinated.
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Monkeypox
- similar to smallpox, milder.
- fever, headache, lymphadenopathy, malaise, myalgia, back ache.
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Human Parvovirus B19
- Epidemiology: spreads person to person by respiratory route. Infection common and occurs in outbreaks, mostly among children.
- Pathology: gains entry to erythroid precursor cells via P erythrocyte antigen and produces certain cytopathic effects: enlarged nuclei with peripheral chromatin displacement and eosinophilic material nuclear inclusion bodies.
- Clinical Features: Mild exanthematous illness (rash) known as erythema infectiosum, accompanied by interruption of erythropoiesis (mostly asymptomatic). Potentially fatal anemia caused in hosts with chronic hemolytic anemia--transient aplastic crisis. Fetal infection leads to severe anemia, hydrops fetalis, and death in utero (10% of maternal infections).
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Human Papillomavirus
- person to person contact (STD) -genital warts + cervical cancer (common manifestations)
- depressed cell-mediated immunity with spread of HPV lesions
- koilocytosis: large squamous cells with shrunken nuclei in large cytoplasmic vacuoles.
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Herpes Simplex Virus 1 and 2
- HSV1: oral secretions
- HSV2: genital secretions
- painful ulcerating lesions on skin or mucous membranes
- Herpes encephalitis and hepatitis (rare HSV1)
- neonatal Herpes--serious complication of maternal genital herpes (high mortality)
- acyclovir effective
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Epstein-Barr Virus
- infectious mononucleosis: fever, malaise, pharyngitis, splenomegaly
- lymphadenopathy--spleen and lymph nodes (cervical)
- atypical lymphocytes
- heterophilic antibody--distinguishing lab test
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Cytomegalovirus
- infects lymphocytes and monocytes--Infectious Mononucleosis
- symptomatic in immune suppressed patients (as is EBV)
- encephalitis, pneumonitis, GI hemmorhage
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Adenovirus
- Pathology: necrotizing bronchitis and bronchiolitis, with sloughed epithelial cells and inflammatory infiiltrate (lymphocytic) fill damaged bronchioles. Interstitial pneumonia is characterized by areas of consolidation with extensive necrosis, hemorrhage, and mononuclear inflammatory infiltrate. Intracellular inclusions, smudge cells and Cowdry type A inclusions involve bronchiolar epithelial cells and alveolar lining cells.
- Clinical Features: necrotizing bronchitis and bronchiolitis. Adenovirus type 40 + 41 infect colonic and small intestinal epithelial cells--cause diarrhea in both immunocompetent and compromised victims. AIDS patients susceptible to Adenovirus type 35--urinary tract infections.
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Rubella (German Measels)
Epidemiology: Spreads by respiratory route. World wide locus. Not highly contagious (only 10-15% unvaccinated women remain susceptible into reproductive years). live attenuated viral vaccine prevents rubella.
Pathology: Infects repiratory epithelium and spreads to bloodstream and lymphatics. Rash results from immunologic response to virus and resolves in 3 days. Fetal infection occurs through placenta during viremic phase of maternal illness. Fetus remains persistently infected. Heart, brain, eyes most frequently affected in fetus.
Clinical Features: Febrile illness, rhinorrhea, conjunctivitis, postauricular lymphadenopathy. 30% infections asymptomatic. Fetus: pulmonary valvular stenosis, pulmonary artery hypoplasia, ventricular septal defects, and patent ductus arteriosus. Cataracts, glaucoma, and retinal defects. Microcephally and mental retardation
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Rubeola (Measels)
- Spread via respiratory tract and secretions (person-person) -Necrosis of respiratory epithelium, with predominate lymphocytic infiltrate.
- Warthin-Finkeldey giant cells (up to 100 nuclei).
- fever, rhinorrhea, cough, and conjunctivitis. -Progresses to characteristic mucosal and skin lesions (Koplik spots) develope -Subacute sclerosing panencephalitis (SSPE) -more deadly in immunocompromised
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Severe Acute Respiratory Syndrome (SARS)
- SARS-associated coronavirus (SARS-CoV) from bats.
- aerosol respiratory spread -alveolar damage (multinucleate cells without viral inclusions) -fever, headache, cough, dyspnea + some liver involvement (rare)
- higher fatality in elderly
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Respiratory syncytial Virus (Paramyxoviridae)
- Epidemiology: Belongs to same family as influenza. Spreads rapidly from child to child in aerosols and secretions--daycare centers, hospitals and other areas with confined children.
- Pathology: Viral surface proteins interact with receptors on host respiratory epithelium-viral binding and fusion. Causes necrosis and sloughing off of bronchial, bronchiolar, and alveolar epithelium. Multinucleated syncytial cells seen.
- Clinical Features: Young children with RSV bronchiolitis or pneumonitis have wheezing, cough, and respiratory distress. Illness self-limited (1-2 weeks duration). older adults produces much more mild illness. 20-40% mortality among hospitalized children with congenital heart disease.
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Influenza Type A, B, C
- Epidemeology: 10-40 million annual cases for 35,000 deaths. Highly contagious and epidemics spread world wide. Hemagluttinin (H) and Neuraminidase (N) designate serotype.
- Pathology: Necrosis and desquamination of ciliated respiratory tract epithelium--lymphocytic infiltrate. infection of lungs leads to necrosis and sloughing of alveolar lining cells.
- Clinical Features: Rapid onset of fever, chills, myalgia, headaches, weakness and nonproductive cough. Upper respiratory infection Deaths from both influenza and its complications. Vaccine 75% effective in preventing influenza.
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Rotavirus
- Epidemiology: spreads by oral-fecal route. Most common amongst children. siblings, parents, playmates, food, water, and surfaces face contamination. 6 months to 2 years is peak age of infection. (all infected by age 4). 100 deaths in young children in US. 1 million deaths worldwide.
- Pathology: confined to duodenum and jejunem, where there is shortening of intestinal villi and mild infiltrate of neutrophils and lymphocytes
- Clinical Features: Vomiting (2-3 days duration), fever, abdominal pain, and profuse watery diarrhea (5-8 days duration). Without fluid replacement, diarrhea can produce fatal dehydration in young children.
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Parainfluenza Virus
-Epidemiology: Common in children under 3 years. Spread from person to person through respiratory aerosols and secretions. Highly contagious. Isolated from 10% of young children with acute respiratory tract illness.
-CROUP Pathology: Infect and kill ciliated respiratory epithelial cells and cause inflammatory response. Extends to lower respiratory tract in young children causing bronchiolitis and pneumonitis.
Clinical Features: Local edema of laryngotracheitis compresses upper airway to obstruct breathing and cause croup (laryngotracheobronchitis causing inspiratory stridor and barking cough). Causes fever, hoarseness, and cough. Symptoms mild in adults.
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Yellow Fever
- mosquito vector (South America + Africa) flavivirus -coagulative necrosis of hepatocytes
- Presence of apoptotic (Councilman) bodies in liver biopsies.
- abrupt onset of fever, chills, headache, myalgias, nausea, and vomiting.
- 3-5 days, hepatic failure with jaundice, clotting factor deficiencies, and diffuse hemorrhages.
- "Black vomit" is classic feature of severe cases.
- High mortality rate
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Mumps
- Epidemiology: Present worldwide--disease of childhood. Highly contagious--infects 90% of exposed with 60-70% showing symptoms. Live attenuated viral vaccine prevents mumps.
- Pathology: Viral infection of respiratory epithelium--necrosis. Disseminates through blood and lymphatic systems to salivary and parotid glands, CNS, pancreas, and testes. 50% cases involve CNS. Epididymoorchitis (unilateral; no sterility) present in 30% males (swollen to three times normal size)--causing local infarctions. Swollen glands and ducts lined by necrotic epithelium and interstitium infiltrated by lymphocytes.
- Clinical Features: Fever and malaise followed by painful swelling of salivary glands, one or both of parotids. Symptomatic meningeal involvement manifests as headache, stiff neck, and vomiting. Prior to vaccination, mumps was leading cause of viral meningitis. Patients exhibit elevated serum amylase levels though sever pacreatitis is rare.
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Ebola Virus (Filoviridae)
- Epidemiology: First emerged in Africa, Zaire and Sudan in 1976. Outbreaks caused by Ebola Zaire and Sudan strains primarily. Outbreaks occured in Gabon, Republic of Congo, and Uganda. Fatality rate 53 to 89%. January 2008--Ebola Bundibugyo strain emerged in Uganda. Fruit bats are reservoir for virus. Virus can be spread by bodily secretions, blood, and used needles.
- Pathology: widespread destructive tissue lesions--most damage of all viral hemorrhagic fever agents. Replicates in endothelial cells, mononuclear phagocytes, and hepatocytes. Necrosis is most severe in liver, kidneys, gonads, spleen, and lymph nodes. Hepatocellular necrosis + Kupffer cell hyperplasia, Councilman bodies, and microsteatosis seen in liver biopsies. Lungs hemorrhagic and petechial hemorrhages seen in skin, mucous membranes, and internal organs. Injury to microvasculature--increase vascular permeability leads to shock.
- Clinical Features: incubation time is 2 to 21 days. Initial symptoms headache, weakness, and fever, followed by diarrhea, nausea, and vomiting. Severe disease characterized by overt hemorrhage including bleeding from injection sites, petechia, GI bleeding, and gingival hemorrhage.
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West Nile Virus (Flaviviridae)
- CSF with leukocytosis,CSF is clear with mild pleocytosis and elevated protein in CNS infection.
- meningoencephalitis (Medulla).
- Fever, Rash, lymphadenopathy, and polyarthropathy.
- not very infectious, but severe disease has moderate mortality
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