Infectious Diseases

Question 0

Visceral Leshmaniasis

Answer 0

Th1 response to parasite infection (from sand flies);
increased risk if immunocompromised.
Sx: fever, weight loss, hepatosplenomegaly, pancytopenia/increased gamma globulin.
** often FATAL!

Question 1

Leshmaniasis

Answer 1

Parasite infection spread by sand fly.
* onset may be months-years after initial infection
Varied presentations (cutaneous, visceral, or mucosal)
Dx: PCR, CBC + blood smear, clinical Hx, +/- Antibodies

Question 2

Cutaneous Leshmaniasis

Answer 2

Th1 & Th2 reaction to parasite infection
(from sand flies, esp. in Middle East, N. Africa, or Central Asia)
ranges from mild (localized) to severe, but not fatal.
- Diffuse: starts localized, does not ulcerate, may last lifetime
- Recidivans: on face, relapsing, leaves scar @ center of lesion
*May progress to Mucosal

Question 3

Pathology of cutaneous Leshmaniasis

Answer 3

= Th1 and Th2 reaction:

1. acute/chronic inflammation
   
   • -> PMNs, plasma cells & focal necrosis
2. granulomatous response

Question 4

Lymphatic Filariasis clinical picture

Answer 4

painful lymphedema of extremities/breasts/scrotum;
spread by mosquito bites (many bc does not replicate in human),
esp. in: C/S America, Africa, C. Asia, Oceana
Dx: see microfilaria in blood & stain
Tx: doxycycline/albendazole for 5 years!

Question 5

Lymphatic Filariasis Pathology

Answer 5

Organisms: Wucheria bancrofti, Brugia malayi
Process: adaptive T cell rxn
–> may cause severe disfguration/disability (esp w/ limbs)

Question 6

Tropical Pulmonary Eosinophilia

Answer 6

Organisms: Wucheria brancrofti, Brugia malayi
Sx: nocturnal asthma, cough, fever & weight loss
Path: triggers activation of Antibodies & IgE
=> progressive interstitial fibrosis (complication if not treated)
Tx: diethylcarbamazine (14 days), surgery if hydroceles

Question 7

Ocular Trachoma

Answer 7

Organism: chlamydia trachomatis
Transmission: hand -> eye & flies
Sx: Chron. follicular conjunctivitis, papillary hypertrophy, vision loss
(scarred cornea & eyelids, eyelashes turn in => ulceration)
Dx: Hx + Ag detection
Tx: systemic antibiotics, * may resolve 1st inf. spontaneously, but likely to recur.

Question 8

Ocular trachoma epidemiology

Answer 8

Common in areas w/ poor hygeine & massive fly problem.
Public health Preventative Rx: (“SAFE”)
S - surgery for deformed eyelid
A - Azithromycin (even mass population Tx)
F - Face washing
E - Environmental improvement (control flies)

Question 9

Chlamydia life cycle

Answer 9

biphasic

1. elementary body - extracellularly transmissable
2. Reticulate body - persists in body @ low level activity

Question 10

Vibrio parahaemolyticus

Answer 10

Organism: bacteria in shellfish from warm H2O
Sx: explosive diarrhea, fever, cramps
Dx: stool culture
Tx: Rest & fluids, +/- tetracycline or quinolone to shorten course

Question 11

Viral Encephalitis

Answer 11

Cause: Flavivirus, spread by mosquitos/pigs/aquatic birds (Asian)
* incubation time = 5-15 days*
Sx: mild aseptic meningitis & fever OR severe delirium, abnormal mvmt, hyperreflexia
* high risk in travelers w/o natural Abs; prevent w/ inactive vaccine
Dx: white matter edema on MRI, abnormal brainstem & spinal cord
Tx: supportive (anti-virals don’t help)

Question 12

Dengue fever

Answer 12

Cause: flavivirus spread by mosquitos,
* incubation time = 4-7 days
Sx: fever, headache, muscle ache
no Tx

Question 13

Viral Encephalitis

Answer 13

Cause: West Nile Virus (flavivirus) or Herpes Simplex (HSV-1)
* WNV spread by mosquitos in river valleys, esp. affect older pts.
Sx: most = asymptomatic, 1/50 = ataxia, optic neuritis, seizures/flaccid paralysis, maculopapular rash
Tx: supportive care

Question 14

brain abscess

Answer 14

Organisms: streptococci (#1), E. Coli w/ K1 Ag, Nocardia, Staph aureus, haemophilus, g- rods
Sx: headache, fever, focal neuro deficit
Dx: CT or MRI (no LP bc risk herniation)
Tx: antibiotics, glucocorticoids if large; surgery if large, accessible, & hard to Tx

Question 15

Acute Aseptic Meningitis

Answer 15

Causes: enterovirus (#1), HSV-2, arbovirus, HIV, measles, mumps (!)
* esp in summer/fall, in temperate climates
Sx: fever, non-focal neuro deficits, lethargy
Dx: LP w/ PCR
(no need PCR if Hx of mumps => post-infectious meningitits)

Question 16

Bacterial Meningitis

Answer 16

Causes: H. influenza (#1), Neisseria m, meningococcus, strep pneumo
Sx: decreased consciousness, fever, diffuse CNS Sxs, high ICP
Dx: LP Tx: antibiotics, +/- glucocorticoids (for ICP)
Prevention: vaccines for meningococcus G, A, C, Y, W; & pneumococcal polysaccharide (get if high risk)

Question 17

Nadir of infant immunity

Answer 17

6-18 months old

maternal Abs present from birth to ~9 months

Question 18

Subdural Empyema

Answer 18

= localized collection of pus inside dura, from strep or staph inf.
*esp in males age 20-30
Sx: RAPID progression of focal neuro deficits
Dx: CT or MRI (LP = dangerous)
Tx: antibiotics + surgery

Question 19

Epidural Abscess

Answer 19

infection OUTside dura, from staph or strep.
Sx: Hx of head infection + subacute/indolent neuro deficits
Tx: surgery + antibiotics

Question 20

Creutzfeldt-Jakob Disease

Answer 20

transmissible Prion disease (PrPsc glycoprotein) -> self-propagates
Cause: familial/sporadic or from “infected” meat.
Sx: progressively “crazy,” pruritis, ataxia, slowed mvmt, memory loss, anxiety
Dx: EEG & MRI (histochem. is gold standard)

Question 21

bacterial cellulitis

Answer 21

Organisms: Staph aureus, encapsulated strep
Sx: unilateral acute inflammation of dermis
Dx: blood cultures & WBC count;
Tx: B-lactams, admit if risk bacteremia

Question 22

Risk factors for bacterial cellulitis

Answer 22

• vascular/lymphatic insufficiency (obesity, CHF, etc.)
• concurrent infection
• Hx of leg surgery

Question 23

Risk factors for Necrotizing Fasciitis

Answer 23

• portal of entry (surgery, IV drug use)
• foreign matter/pathogens introduced under skin
• diabetes, alcoholism - vessel damage
• chemical injury - vasoconstriction

Question 24

Necrotizing Fasciitis

Answer 24

= subdermal bacterial infection w/ necrosis & tissue damage.
Causes: Strep, staph aureus, clostridium (usually > 1)
Sx: painful/numb discolored skin w/ blisters/sores
Dx: Roentgenograph (xray)
Tx: IV antibiotics + surgery (always!)

Question 25

Lymphocutaneous Syndrome

Answer 25

Cause: nocardia, sporothrix schencki (in soil)
Sx: erythematous, tender skin lesions/ulcers + honey-colored eschar; + Hx of spoil exposure w/ broken skin
Dx: branching g+ rods on blood stain
Tx: trimeth-sulfa (Bactrim) for 2-4 months!

Question 26

Trichinosis

Answer 26

Cycle: larvae in pork/bear –> Food poisoning Sxs –> enter vasculature, go to mm & eyes
Sx: periorbital edema, fever, muscle weakness, eosinophilia
Dx: elevated creatinine kinase, blood culture
Tx: supportive. notify health department

Question 27

Psoas abscess

Answer 27

Causes: GI flora from rupture (diverticulitis) (#1) or bacteremia
Sx: acute flank pain & fever, w/ Psoas sign
Dx: blood and muscle stain & culture, abdominal xray/CT
Tx: IV antibiotics + surgical drainage

Question 28

Osteomyelitis

Answer 28

bone infection w/ candida (spinal myelitis)
Sx: acute or subacute onset pain in bony area (ie: back) < 1 mo.
Dx: aspiration & culture (+ CBC)
Tx: fluconazole for 2 wks BEYOND last + blood culture

Question 29

Septic Arthritis

Answer 29

Sudden inflammation of 1-2 joints w/ bone degradation (irreversible)
Cause: staph aureus
Dx: synovial fluid analysis (high WBCs & PMNs), xray
Tx: nafcillin/oxacillin or cefaxzolin for 4 wks

Question 30

Gonococcal Arthritis

Answer 30

Acute joint pain w/ recent Hx of unprotected sex
+ scattered papules/pustules on body
Cause: N. gonorrhea