Multisystem Infections Flashcards
Lyme Dz
Etiology: Borrelia
Vector: Ixodes tick
Pathogenesis: immunopathogenic
Stage 1: erythema chronicum migrans (ECM)
Stage 2: arthritis, cardio and neuro sx’s
Stage 3: chronic arthritis or progressive CNS dz
RMSF
Etiology: Rickettsia rickettsii
Vector: tick (Dermacentor spp.)
Pathogenesis: damage to endothelium + thrombocytopenia
ROS: macular/petechial rash (centripetal), hyponatremia, hypoalbuminemia
Anaplasmosis (HGA)
Etiology: A. phagocytophilium (G-ve) Vector: Ixodes tick Pathogenesis: pancytopenia, hepatic injury ROS: constitutive sx's (RARELY a rash) Diagnosis: morulae in RBC
Ehrlichiosis
Etiology: Ehrlichia chafeensis (G-ve, non-motile rod)
Vector: Lone Star tick
Pathogenesis: targets macrophage, stays in endosome to avoid killing
ROS: constitutive sx’s, conjunctivitis, GI and CNS sx’s, (rarely rash - in children; not covering palms/soles like in RMSF)
Diagnosis: morulae in PB, serology, IFA
Visceral Leishmaniasis (aka Kala-azar)
Etiology: Leishmania donovani (flagellated protozoa)
Vector: sand fly
Pathogenesis: promastigote engulfed by macrophages of RES then converted to amastagote inside macrophage
ROS: fever, wt loss, anemia, hepatosplenomegaly,
Diagnosis: amastagotes in macrophages
African Sleeping Sickness
Etiology: Trypanosoma brucei gambiense (flagellated protozoan)
Vector: tsetse fly (painful)
Stage 1: trypomastigotes multilpy in blood/lymph/CNS, produce sx’s of recurrent fever/HA/joint pn/lymphadenopathy
Stage 2: cross BBB and cause behavior change, confusion, disturbed sleep pattern can lead to lethargy and eventually death
Diagnosis: small kinetoplasts in blood or CSF
Chagas Disease
Etiology: Trypanosoma cruzi (flagellated protozoa)
Vector: Riduviid bug (“kissing bug” - defecates in bite)
Pathogenesis: trypomastigotes engulfed by macrophages, fibroblasts and myocytes then turn into amastigotes that will replicate and lyse the cells
ROS: parasitic myocarditis, toxic megacolon causing constipation, pseudoachalasia
Diagnosis: large C-shaped kinetoplasts in blood or CSF
Tularemia (aka Rabbit Fever)
Etiology: Francisella tularensis (G-ve short rods, requires Fe2+ and cysteine to grow)
Epidemiology: SW to Central US (zoonosis)
Infectious dose: < 100 (low)
Transmission: inhalation or injection
Pathogenesis: infects macrophages then replicates/survives in cytoplasm
Diagnosis: direct fluorescent Ab, serology
Prevention: vaccine for lab workers
Ulcero-glandular Tularemia
Transmission: injection
ROS: painful regional lymphadenopathy and ulcerated skin lesion
Glandular Tularemia
Tender lymphadenopathy w/o evidence of local cutaneous lesion
Occuloglandular Tularemia
ROS: unilateral purulent conjuunctivitis, corneal ulceration, lymphadenopathy
Oropharyngeal Tularemia
Transmission: consumption of infected meat/water
ROS: exudative pharyngitis, abd pn, lymphadenopathy, GI bleed, N/V
Typhoidal Tularemia
Transmission: ingestion
ROS: bacteremia w/ secondary pneumonitis (NO lymphadenopathy or ulcers) mimics typhoid fever
Pneumonic Tularemia
Transmission: inhalation (highest mortality)
ROS: resembles plague pneumonia
Yellow Fever
Etiology: YFV (Flavivirus)
Vector: Aedes mosquito
Pathogenesis: replicates in macrophages and dendritic cells in LN then gets to liver and infects Kupffer cells, councilman bodies in hepatocyte cytoplasm
ROS: abrupt onset of fever, severe cases can have hematemesis, jaundice, hepatosplenomegaly
Prevention: vaccine for travelers to endemic areas
Dengue virus
Etiology: Flavivirus
Vector: Aedes mosquito
Pathogenesis: infects RES cells (kupffer cells of liver), ADE makes 2nd infection worse than first
ROS: maculopapular rash, retro-orbital HA, muscle/joint pain often called “break-bone fever”
Dengue Hemorrhagic Fever
Caused by leaking plasma, fluid accumulation
ROS: resp disttress, severe bleeding/organ damage
Warning signs: severe abd pn, persistent vomiting, tachypnea, bleeding gums, fatigue, hematemesis
Chikungunya
Family: Togaviridae
Vector: Aedes mosquito
Pathogenesis: replicates in fibroblasts, disseminates to target tissues (muscle, joint, skin, RES), inflammatory infiltrate so joints inflamed in response to infection
ROS: joint pain, fever (joint pain persists for months)
Q Fever
Etiology: Coxiella burnetti Risk: vet/farmer Reservoir: cattle/sheep/goats Transmission: aerosols Pathogenesis: obligate intracellular ROS: pneumonia (HA/fever), hepatitis Diagnosis: serology
Brucellosis
Etiology: Brucella spp.
Transmission: unpasteurized dairy (or direct occupational exposure to pig/cow)
ROS: undulating fever, anorexia, osteomyelitis can later develop
Hydatid Dz
Etiology: Echinococcus granulosus
Transmission: sheep-to-dog
Epidemiology: sheep-rearing countries (low SES)
ROS: anaphylactic shock if cyst ruptures
Imaging (CT): egg-shell calcifications
Echinococcus multilocularis
Transmission: rodent-to-fox
ROS: mass effect in liver d/t cysts
Leptospirosis
Etiology: Leptospira interrogans
Epidemiology: Hawaii
Risk: vet/farmer/butcher
Pathogenesis: multiply rapidly and damage endothelium
ROS: sudden febrile illness, flu-like sx’s
Diagnosis: MAT (microscopic Ab agglutination test)
Weil Dz
Etiology: Leptospira interrogans
ROS: vasculitis, jaundice, renal failure, hemorrhagic rash, retro-orbital HA, B/L calf tenderness, CNS involvement
Candida auris
Transmission: HA
Pathogenesis: survival on external surfaces, resistant to antifungals
Diagnosis: blastoconidia, -ve germ tube test, slender pseudohyphae
Coxsackie A
Clinical presentations: HFMD, Herpangina
Transmission: fecal-oral
Pathogenesis: binds to ICAM-1 and CD55
ROS: fever, maculopapular rash, constitutional sx’s
EBV (HHV-4)
Transmission: kissing (swapping saliva)
Pathogenesis: infects oral/tonsillar B cells, promotes growth of B cells, CD8+ T-cells respond to the EBV ag on infected B cells
Complication: Burkitt’s Lymphoma, nasopharyngeal ca, GBS and splenic rupture
Dx: presence of heterophile Ab (Monospot test +ve)
CMV (HHV-5)
Transmission: all secretions literally everything
ROS: pneumonia in immunocompromised
AIDS: retinitis, colitis, esophagitis
Diagnosis: Heterophile -ve mononucleosis, ELISA, owl eye inclusions, cotton wool retina
Congenital CMV
ROS: visions loss, MR, microcephaly, jaundice, hepatosplenomegaly
