Infectious Diseases

Question 1

HIV infxn

Answer 1

• women infected younger than men, 76% men (exposed via MSM, IVDU, heterosexual contact, MSM + IVDU)
• transmission: blood-blood
• RF: sex w/ infected person, IV exposure to infected blood by transfusion or needle sharing, perinatal exposure
• sxs: asx (mean 10y); primary HIV infxn → fever, night sweats, wt loss, skin lesions, pharyngitis, swollen lymph nodes → lasts days-weeks)
• signs: hair leukoplakia, dissem kaposi sarcoma, cutaneous bacillary angiomatosis, gen LAD
• dx: HIV ELISA, western blot (confirmatory), HIV rapid Ab test, CBC (anem, neutropen, thrombocytopen), absolute CD4 (monitor q3-6mos), CD4 %, viral load, CXR, blood cx if fever, crytococcal Ag, sinus CT or XR
• tx: start tx regardless of CD4 and perform resistance testing prior to ART initiation; primary goal is complete suppression of replication; combo tx w/ at least 3 meds

Question 2

AIDS

Answer 2

• coccidioidomycosis, enceph, histoplasmosis, isosporiasis with D >1mo, kaposi, lymphoma of brain, non-hodgkin lymphoma of B cell, MAC, extrapulm TB, salmonella septicemia, HIV wasting syndrome, pulm TB, recurrent PNA, invasive cervical CA
• dx: HIV serology +, CD4 count <200cells or <14%

Question 3

bacterial meningitis

Answer 3

• acute → hrs to days
• chronic → wwks to mos (mycobacteria, fungi, lyme dz, parasites)
• inflamm of meningeal membrs around brain and spine, infxs agents colonise nasopharynx and resp tract
• MCC: strep pneumo, H flu, N meningitidis
• sxs: TRIAD (fever, nuchal rigidity, AMS), HA, N/V, stiff, painful neck, malaise, photophobia
• signs: nuchal rigidity, rash (maculopapular w/ petechia for N meningitidis) or vesicular (varicella/HSV), inc ICP, cranial nerve palsies, +Kernig/Brudzinski sign
• dx: LP (neut predominant, cell cnt >1000, low gluc, high prot), CT scan head, blood cx
• tx: empiric after LP, IV abx immediately if CSF cloudy, steroids if cerebral edema present
• vaccinade adults >65 for S. pneumo
• vaccinate asplenic pts
• vaccinate immunocomp for meningococcus
• Prophylaxis: rifampin or ceftriaxone for close contacts of meningococcal meningitis

Question 4

aseptic (viral) meningitis

Answer 4

• caused by a variety of nonbact pathogens, frequently viruses (entero, coxsackievirus, and HSV)
• MC in summer and fall temps
• sxs: acute onset subacute fever, chills, HA, photophob, pain on eye mvmt, N/V/D, myalgias, rash, pleurodynia, myocarditis, herpangina
• signs: meningismus w/out . local neuro signs, drowsiness or irritability
• dx: pleocytosis, lymphocyte predom, cell cnt <1000, normal gluc, elevated prot
• tx: supportive, analgesics and fever reduction, better prognosis than acute bact meningitis

Question 5

lyme disease

Answer 5

• northeastern (main-maryland), midwest, west coast; incubation = 3-32d
• transmission: ticks, mice, deer; caused by Borrelia burgdorferi
  
  • stage 1: erythema chronicum migrans (hallmark) → large, painless, well-demarcated target shaped lesion on trunk, thigh, groin, axilla
  • stage 2: disseminated, flu like sxs (HA, stiff neck, fever/chills, fatigue, malaise, myalgias); after a few weeks → meningitis, encephalitis, cranial neruitis, peripheral radiculoneruopathy, bell palsy; within wks to mos → AV block, pericarditis, carditis
  • stage 3: late, persistent; arthritis large jnts, chronic CNS dz, mild enceph, transverse myelitis, axonal polyneuropathy, acrodermatitis chronica atrophicans (reddish-purple plaques and nodules on extensor surfaces of legs)
• clinical dx: ELISA in 1st mo, western blot to confirm
• tx: early disease, localized → 10d abx; if beyond skin, PO doxy x21d (amox and ceguroxime are alternatives)

Question 6

mononucleosis (what do you not give)

Answer 6

• caused by epstein-barr virus (rarely CMV), adolescents, college students, or military recruit
• transmisison: saliva, 90% adults infected previously are carriers, lifelong immunity w/ 1 infxn
• sxs: fever, LAD, pharyngitis → fever resolves in 2 wks, sore throat, malaise, myalgias, weakness
• signs: LAD, posterior cervical, tonsillar, enlarged, painful, tender; pharyngeal erythema and/or exudate, splenomegaly, maculopapular rash, hepatomeg, palatal petechiae and periorbital edema
• dx: monospot, WBC count with diff, transaminitis, EBV specific Ab, peripheral smear shows lymphocytic leukocytoisis with large, atypical lymphocytes
• tx: supportive, short course steroids, avoid sports 3-4wks (SPLENIC RUPTURE)
• complicaitons: hep, meningoencephalitis, Guillain Barre, splenic rupture, thrombocytopenia, URTI
• DONT GIVE AMOX or AMP → can cause maculopap rash

Question 7

influenza

Answer 7

• orthomyxovirus
• transmission: resp droplets, winter months
• sxs: rapid onset of fever, chills, malaise, myalgia (legs or lumbosacral area), fever, HA (generalized or frontal), nonproductive cough (may last more than 1 wk), ocular signs/sxs (pain w/ motion of eyes, photophob, bruning of eyes), sore throat, +/-N
• signs: cervical LAD, rhonchi, wheezes, scattered rales
• dx: RT-PCR = most sensitive and specific (can differentiate subtypes and detect avian flu
• tx: supportive care (tylenol or NSAIDs . for HA, myalgias, fever; no cough suppressants, neruaminidase inhib: zanamivir or oseltamivir for flu type A and B → reduces sxs by 1-1.5d if started w/in 2 days of onset