Infectious diseases

the predilection for viruses to infect certain cells and not others

major determinant= presence of viral receptors

pattern of tissue reaction in infection that is the reaction to acute tissue damage

increased vascular permeability and leukocytic infiltration, predominantly neutrophils (attracted by pyogenic bacteria)

response to viruses, intracellular bacteria, or intracellular parasites

cell mediated immune response

specific inflammation response in which activated macrophages (epithelioid cells) accumulate and may fuse together to form giant cells

caused by infectious agents that resist eradication

reactions usually produced by viruses

lesions are characterized by cell necrosis or cellular proliferation, usually with sparse inflammatory cells

blistering, warts, etc

response to organisms that secrete powerful toxins

tissue damage is the dominant feature; resemble infarcts with disruption or loss of basophilic nuclear staining and preservation of cellular outlines

leading cause of vaccine preventable death worldwide

Blotchy reddish brown rash on face, trunk, and proximal extremities produced by dilated skin vessels, edema, and a moderate, non specific, mononuclear perivascular infiltrate

ulcerated mucosal lesions in oral cavity near stensen ducts

marked follicular proliferation in the lymphoid organs

Warthin Finkelday cells

multinucleate giant cells which have eosinophilic nuclear and cytoplasmic inclusion bodies

affected parotid glands that are large, have a doughy consistency, are moist and glistening

reddish brown parotid glands on cross section; neutrophils and necrotic debris may fill ductal lumen and cause focal damage

lesions may cause parenchymal and fat necrosis in the pancreas

mumps infection that causes testicular swelling via edema, mononuclear cell infiltration, and focal hemorrhage

may cause sterility due to scarring adn atrophy of the testis after resolution of the viral infection

mumps infection causing perivenous demyelination and perivascular cuffing

virus transmitted by fecal-oral route

infects tissues in oropharynx first; swallowed, multiplies in intestinal mucosa

ability to invade CNS; viremia and fever

Africa, Middle East, Europe, SE Asia, Australia

transmitted by mosquitos to birds to mammals

usually asymptomatic

20% of individuals it gives rise to mild, short-lived febrile illness asociated with headache and myalgia

maculopapular rash

rare complications include hepatitis, myocarditis, and pancreatitis

infections that grow predominantly by budding or filamentous extension called hyphae

most frequent cause of fungal infections

oral thrush, vaginitis, diaper rash

warm moist surfaces

diabetics/burn patients

Th1 responses

infections that appear as blastoconidia, pseudohyphae, and true hyphae (less common)

most commonly takes form of superficial infection

superficial infection on the mucosal surfaces of the oral cavity

gray-white, dirty looking pseudomembrane composed of matted organisms adn inflammatory debris

mucosal hyperemia and inflammation

newborns, debilitated patients, children receiving oral steroids, following course of broad spectrum antibiotics

HIV positive

dysphagia, retrosternal pain

endoscopy-> white plaques adn pseudomembranes

AIDS patients adn those wiht hematolymphoid malignancies

common form of vaginal infection in women

diabetics, pregnancy, oral contraceptives

intense itching; thick, curd-like discharge

infection of the nail proper

infection of the nail folds

infection of the hair follicle

infection of moist, intertriginous skin such as armpits or webs of the fingers and toes

infection of teh penile skin

chronic refractory disease afflicting the mucous membranes, skin, hair, nails

associated with underlying T-cell defect

blood borne dissemination of organisms to various tissues or organs

renal abscesses, myocardial abscesses and endocarditis, brain involvement, endophthalmitis, hepatic ascesses, pneumonia

suppurative response, occasionally produce granulomas

most common fungal endocarditis

prosthetic heart valves, IV drug abusers

encapsulated yeast present in soil and bird droppings that infects patient when inhaled

polysaccharide capsule= major virulence factor; no phagocytosis by alveolar macrophages

serine proteinases cleave fibronectin and other basement membrane proteins

yeast without pseudohyphal or hyphal forms; thick gelatinous capsule

India ink preps create a negative image, visualizing the thick capsule as a clear halo within a dark background; do no stain yeast

lung is primary site of localization; may form a solitary pulmonary granuloma

may evoke virutally no inflammatory reaction in immunosuppressed patients; soap bubble lesions w/in gray matter

chronic granulomatous reaction composed of macrophages, lymphocytes, and foreign body type giant cells in nonimmunocompromised pt

ubiquitous mold that causes allergies in otherwise healthy people and serious sinusitis, pneumonia, and fungmeia in immunocompromised

growth of fungus in pulmonary cavities with minimal or no invasion of the tissues

proliferating masses of fungal hyphae called fungus balls-> brownish masses lying free within the cavities

recurrent hemoptysis

opportunistic infection confined to immunosuppressed and dibilitated hosts

lungs, heart valves, brain, kidneys

necrotizing pneumonia with sharply delineated borders (target lesions)

fruiting bodies

tendency to invade blood vessels; areas of hemorrhage and infarction usually superimposed on necrotizing inflammatory tissue reactions

opportunistic infection caused by "bread mold fungi"

immunosuppressed pt

airborne asexual spores; can also infect via percutaneous exposure or ingestions

nonseptate, irregularly wide fungal hyphae with frequent right angle branching

nasal sinuses, lungs, GI

inhaled/ingested

lung involvement may be primary or secondary to rhinocerebral disease

fungus spread from nasal sinuses to orbit adn brain

Africa, Asia, Latin America protozoa transmited by anopheles mosquito

within RBC parasites grow in membrane bound digesive vacuole, hydrolyzing hemoglobin through secreted enzyme

congestion and enlargement of the speen, increased phagocytic activity of spenic macrophages; spleen becomes increasing fibrotic and brittle, parenchyma is gray or black

liver becomes progressively enlarged and pigmented

kidneys often elarged and congested with dusting pigment in glomeruli and hemoglobin casts in tubules

P. falciparum infection in which brain vessels are plugged with parasitized red cells, each containing dots of hemozoin pigment

degeneration of neurons, focal ischemic softening, scant inflammatory infiltrates in the meninges with severe hypoxia

infection resembling P. falciparum ring stages but lacking hemozoin pigment; more pleomorphic

form characteristic tetrads (Maltese cross)

white footed mouse=reservoir

Middle East, S. Asia, Africa, Latin America

exacerbated by AIDS

evade host immunity by altering macrophage gene expression and impairing development of Th1 response

hepatosplenomegaly, lymphadenopathy, pancytopenia, fever, weight loss

phagocytic cells enlrged, many plasma cells present, normal architecture of spleen obscured

hyperpigmentation of skin in extremities

mesangioproliferative glomerulonephritis

relatively mild, localized disease consisting of single ulcer on exposed skin

begins as itching papule surrounded by induration, changes into shallow adn slowly expanding ulcer with irregular borders

New World only

moist, ulcerating or nonulcerating lesion in larynx and at mucocutaneous junction of the nasal septum, anus, or vulva

eventually lesions remit and scar; reactivation may occur after long intervals

rare form of dermal infection

Ethiopia, E. Africa, Central and S. America

single skin nodule, which continues spreading until entire body covered by nodular lesions

foamy macrophages

respond poorly to treatment

Large, red, rubbery chncre forms at the site of teh insect bite

large numbers of parasites surrounded by dense, largely mononuclear, inflammatory infiltrate

enlarged spleen, lymph nodes

parasite concentrates in capillary loops such as choroid plexus and glomeruli

eventually demyelinating panencephalitis occurs; flame cells/mott cells

plasma cells containing glycoprotein globules

S. America/Brazil

transient, erythmatous nodule (chagoma

often mural thrombi; inflammatory infiltration heaviest at Right bundle branch of cardiac conduction system

scattered foci of myocardial cell necrosis and fibrosis_> aneurysmal dilation and thinning

dilation of esophagus or colon

S.E. US, S. America, SE Asia, Sub-Saharan Africa

worms, mainly larvae, present in duodenal crypts but not in underlying tissue

eosinophil rich infiltrate

invasion of larvae int colonic submucosa, lymphatics, blood vessels; associated mononuclear infiltrate

beef tape worm

Fish tape worm

tapeworms whose hosts are dogs and sheep

Tapeworms associated with foxes

cysticerci most commonly in brain, muscles, skin, heart

inflammation, focal scarring, and calcifications following cyst degeneration

inflammatory reaction composed mostly of mononuclear leukocytes and eosinophils

cyst= enclosing opalescent fluid is nucleated germinative layer adn outer opaque nonnucleated layer; many layers gelatin

fever, myalgias, marked eosinophilia, periorbital edema

destruction can be widespread but is rarely lethal; patchy interstitial myocarditis characherized by many eosinophils and scattered giant cells

trapped larvae in lungs cause focal edema and hemorrhage

focal gliosis in ad about small caps in brain

eosinophil rich mononuclear cell infiltrate

undercooked pig meat

White pinhead-sized granulomas are scttered throughout the gut and liver

liver darkened by regurgitated heme derived pigments from schistosome gut; irn negative and accumulate in Kupffer cells and splenic macrophages

inflammatory patches or pseudopolyps may form in colon

surface of liver is bumpy

pipe-stem fibrosis

presinusoidal portal hypertension adn severe congestive splenomegaly, esophageal varices, ascites

bladder inflammatory patches due to massive egg deposition adn granulomas appear early-> hematuria

sandy appearance may line wall of bladder adn cause a dense concentric rim

inflammation and fibrosis of theureteral walls, obstruction, hydronephrosis, chronic pyelonephritis

squamous cell carcinoma of bladder

Latin America, sub-Saharan Africa, SE Asia

persistent lymphedema of scrotum, penis, vulva, leg, or arm

hydrocele and lymph node enlargement

elephantiasis; epidermis is thickened adn hyperkeratotic

polypoid infoldings of vessels with persisting eosinophilic and lymphocytic infiltrates

Th2 responses adn cytokine production; Meyers-Kouvenaar bodies

Africa, S. America, Yemen

punctate keratitis caused by inflammation around degenerating microfilaria

chronic, itchy dermatitis with focal darkening or loss of pigment adn scaling-> leopard, lizard, elephant skin

areas of hyperpigmentation with pigment incontinence, dermal atrophy, and fibrosis

vision loss

inability to recover infectious particles from cells that harbor a virus

virus that exhibits latency; spread to sensory neurons that innervate primary sites of replication

resolves in a few weeks in immunocompetent hosts

evade antiviral CTL by inhibiting MHC class I recognition pathway; elude humoral immune defenses by producing receptors for Fc and inhibitors of complement

major infectious cause of corneal blindness and fatal sporadic encephalitis

Lesions marked by formation of large, pink to purple intranuclear inclusions that contain intact and disrupted virions

inclusion-bearing multinucleated syncytia

fever blisters or cold sores that favor facial skin around mucosal orifices

virus usually encountered in children caused by HSV-1

vesicular eruption extending from tongue to retropharynx

causing cervical lymphadenopathy

swollen erythematous HSV lesions of fingers or palm

genital lesions caused by HSV-1 or 2; usually caused by HSV2

rapidly converted to superficial ulcerations rimmed by inflammatory infiltrate

virus that can be passed mom to infant via the birth canal

may be mild, more often fulminating with generalized lymphadenopathy, splenomegaly, and necrotic foci throughout the lungs, liver, adrenals, and CNS

Virus-induced cytolysis of teh superficial epithelium that is sensitive to antiviral drugs

corneal lesions presenting as infiltrates of mononuclear cells around keratinocytes adn endothelial cells leading to neovascularization, scarring, opacification or the cornea and eventual blindness

generalized vesiculating involvement of the skin in herpes virus

confluent, pustular, or hemorrhagic blisters, often with bacterial superinfection adn viral dissemination to internal viscera

characteristic enlargement of infected cells can be appreciated histologically

intranuclear basophilic inclusions

clear halo

parenchymal epithelial cells are affected; neurons in the brain, alveolar macrophages/epithlial/endothelial cells, tubular epithelial/glomerular endothelial cells in the kidneys

focal necrosis with minimal inflammation in virtually any organ

CMV in immunocompetent person

CMV in immunocompromised

rash that occurs approximately 2 weeks after a respiratory infection and travels from torso to the head adn extremities

dewdrop on a rose petal lesion

intranuclear inclusions in epithelial cells like those of HSV-1

lesions rupture after a few days, crust over, and heal by regeneration

VZV that remained latent in the dorsal root ganglia after previous chicken pox infection are reactivated and infect sensory nerves that carry virus to one or more dermatomes

intense itching, burning, or sharp pain due to simultaneous radiculoneuritis

peripheral blood shows absolute lymphocytosis

Large atypical lymphocytes

lymph nodes are typically discrete adn enlarged throughout the body, principally i nthe posterior cervical, axillary, and troin

spleen enlarged; soft adn fleshy with hyperemic cut surface; expansion of white pulp and red pulp

liver function almost always transiently impaired

CNS may congestion edema, perivascular mononuclear infiltrates in the leptomeninges

grape like clusters

pyogenic inflammation distinctive for its destructiveness

skin infections centered aound hair follicles

faruncles and carbuncles

focal suppurative inflammation of the skin and subcutaneous tissue

either solitary or multiple or recurrent

skin lesion associated with deeper suppuration that spreads laterally beneath the deep subcutaneous fascia and then burrows superficially to erupt in multiple adjacent sinuses

usually on the upper back and posterior neck

exfoliative A and B toxins

exfoliative dermatitis that most frequently occurs in children with staphylococcal infections of the nasopharynx or skin

sunburn like rash that spreads over the entire body an forms fragile bullae

diffuse interstitial neutrophilic infiltrates with minimal destruction f host tissue

less of a tendency to cause abscess

middle aged persons in warm climates

rapidly spreading erythematous cutaneous swelling that may begin on the face; may form butterfly distribution on face

leukocytic infiltration intense around vessels adn the skin adnexa

major antecedent of poststreptococcal glomerulonephritis

edema, epiglottic swelling, puctate abscesses of the tonsillar crypts sometimes accompanied by cervical lymphadenopathy

may be encroachement on airways

tonsillitis caused by S. pyogenes

age 3 to 15

punctate erythematous rash abundant over trunk and inner aspects of arms and legs; face also involved but small area around mouth usually unaffected

inflammatory involvement of skin followed by hyperkeratosis of the skin; scaling

Inhaled organism; release of exotoxin causes necrosis of the epithelium accompanied by dense fibrinosuppurative exudate

tough dirty gray to black superficial membrane

marked vascular congestion, interstitial edema, fibrin exudation

hyperplasia of spleen and lymph nodes; fatty change and focal necrosis of parenchymal cells of liver, kidneys, adrenals

exudative pattern of inflmmation with numerous neutrophils

G+ mostly intracellular bacilli in the CSF

Focal abscesses alternate with grayish or yellow nodules representing necrotic amorphous basophilic tissue debris

infants born with this have a papular red rash over extremities; abscesses on placenta

necrosis and exudative inflammation with infiltration of neutrophils adn macrophages

boxcar shaped G+ extracellular bactria in chains

enlarged hilar and peribronchial lymph nodes

perihilar interstitial pneumonia with infiltration of macrophages and neutrophils and pulmonary vasculitis

predominantly in alveolar capillaries adn venules; to a lesser degree within the alveolar space

G+ organisms arranged in branchin filaments

filaments have beaded appearance

acid fast stains

suppurative response with central liquifaction and surrounding granulation and fibrosis; granulomas do not form