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Infectious Disease

Links

• local: adult parvovirus, Diagnostic Dilemmas and D/Dx , Pediatrics, Prophylaxis and Exposures, Rabies, Therapeutics, Thyroiditis
• Evaluating the Febrile Patient with a Rash - August 15, 2000 - American Family Physician
• Lymphadenopathy Differential Diagnosis and Evaluation - October 15, 1998 - American Academy of Family Physicians

Acute HIV

How to Recognize and Treat Acute HIV Syndrome - 8/1999 - American Academy of Family Physicians

• suspect when flu-like illness (fever, fatigue, rash, myalgia, etc) and mucocutaneous ulceration (mouth, esoph, anus, penis) in person with risk factors.
• onset days to weeks after exposure, lasts days to weeks.
• test: HIV (sero-negative), p24 antigen test and/or viral RNA titer
• if suspect get ID consultation (may be routine algorithms at some facilities)

Babesiosis

• same distribution as Lyme, often very mild, but co-infection with Lyme Disease can be very serious
• "American malaria" - intra-erythrocytic parasite, produces variable hemolytic anemia
• treat with anti-malarial agents

Brucellosis

• Cecil's: Brucellosis
• transmission via milk products or occupational exposure
• several disease presentations
  • sheep and goats: may be severe, acute flu-like disease due to B. melitensis. Spain, Greece, Mexico
  • cattle: mild, sporadic disease due to B. abortus
  • dogs: like cattle, but more chronic and relapsing, due to B. canis
  • swine: suppurative lesions, prolonged course due to B. suis.

Cat-scratch disease

• Bartonella henselae (indirect fluorescent antibody test > 1:164) ( http://www.hosppract.com/ Dec 98)

Ehrlichiosis (Human Granulocytic and Monocytic Ehrlichiosis)

Looks like flu without cough, but hepatitis, leukopenia, thrombocytopenia anomaly. A "mild" RMSF without the rash. 10-30% have macular red rash of trunk.

• regional differences -- similar disease, different serology
  • Southern US - HME: ehrlichia morula gather in monocytes
  • Upper Midwest (MN, WI, MI, OR, WA) - HGE: ehrlichia morula gather in lymphocytes
• Ehrlichia chaffensis -- rickettsia-like organism: headache, vomiting, fever, abdominal pain, hepatitis, leukopenia, thrombocytopenia.
• Ehrlichia equi (carried by dog and deer tick): fever, myalgia, headache (flu), leukopenia, thrombocytopenia.

Hepatitis A

• major infectivity 2 weeks before symptoms
• vaccines: HAVRIX and VAQTA. Both are very effective, they can be mixed.
• IgM Ab: recent infection, IgG Ab: past infection

Hepatitis B

• HepB sAg: if present pt is actively infectious, disappears with immunity, may persist in chronic infection.
• HepB sAb: infection or immunization, indicates immunity, clears the infection, hence negative in early stages.
• HepB cAb: IgM in acute phase, IgG later, indicates infection (past or chronic)
• HepB eAg: high infectivity
• HepB eAb: resolving acute infection, quiescent chronic HepB
• HepB cAg: not detectable in serum (inside virion)

Hepatitis C

• 20% cirrhosis, 5% CA liver
• monitor ALT, if elevated check HCV-RNA levels/liver biopsy
• Rx if high viral titer or biopsy suggest cirrhotic progression with interferon alfa-2b and/or ribavarin
• 50% have good response, but half responders relapse (better with dual therapy)

Herpes Labialis

• 125 mg aspirin qD with onset of symptoms (early reports)
• any barrier protection (lip balm) applied with very early symptoms may reduce duration and severity
• routine use lip balm with sunscreen may reduce flares

Immunizations

• Practice Guidelines 2001 Schedule - January 1, 2001 - American Family Physician

HIB

• the greatest thing to happen to pediatrics in the past 20 years. I love those guys.

Lyme

• 3 dose: initial, 1 mo and 12 month
• myalgia and flu-like symptoms
• about 75% effective
• not a "winner" of a vaccine

Pneumovax

• one time revaccination after 5 years for persons > 65 vaccinated before age 65 and persons aged 64 who are immunocompromized
• 2001: added to child schedule (pneumo conjugage)

Influenza

• Rimantadine for Influenza A (H1N1 and H3N2) in persons > 18 y
• Zanamivir for A&B > 7yo
• Oseltamivir A&B > 18 y

Legionnaire's Disease

• diarrhea, dyspnea, cough, confusion, relative bradycardia
• hyponatremia, LFT elevation, hypoxia
• patchy interstital infiltrates

Leptospirosis

• See 5 Minute Clinical Consult. Spirochete
• southern US, fever, meningitis (lymphocytic), hepatitis, nephritis

Listeriosis

• 5 Minute Clinical Consult, Red Book ($)
• see also Listeriosis (food borne)
• gram positive, food born: hot dogs, cheese or veterinarians
• serious in newborn, fetus (ab), immunosuppressed
• flu-like illness with meningitis
• generally only suspect if epidemic or in sick newborn with ill mother
• CBC may have lots of monocytes
• CIE latex agglutination

Lyme Disease

Local Endemic Areas (MSP)

• Pine, Kanabec, Crow Wing
• Western Wisconsin
• NE Anoka county, northern edge Ramsey County, Chisag county, rural Washington County
• Elm Creek Park Reserve

Testing

• EIA/ELISA or IFA serologic screening. Repeat if negative and symptoms persist. IgM appear @2-4 weeks after rash, peak at 6-8 weeks, decline by 4-6 months. IgG detectable at 6-8 weeks, peak 4-6 months, persist years.
• Western blot IgM and IgG confirmation if EIA/IFA positive.

Testing Strategy

• definitive disease (?testing unnecessary): Erythema migrans + exposure history
• intermediate probability: testing necessary. Uncertain exposure history but objective findings, such as atypical shingles, AV block, Bell's palsy, acute monoarticular arthritis

Findings and Presentations

Early

• Erythema migrans: 90%, usually 7-10 days after bite, grows 1-2 cm/day, clearing center after first 1-2 weeks. Often @ 15 c on presentation, popliteal fossa, buttocks, axillae, groin, back. Technically rash must persist for at least 7 days to be a classic Lyme rash. The growing 'circle' can be quite large.
• "influenza" out of season with Lyme exposure moderate probability. Lyme serology ("stat"), blood cultures x 2 (more if consider endocarditis) and Rx for Lyme pending serology and culture reports.

Early Disseminated

• Bell's palsy (esp. bilateral)
• meningitis
• radiculoneuropathy: Shingles w/o rash
• carditis: Mobitz I AV glock, palpitations, syncopy
• acute monoarticular arthritis: sudden joint pain, swelling, massive effusion

Late/Chronic

• low-grade encephalopathy, chronic arthritis

Prophylaxis and Exposures

• Pertussis - adult exposure (kind of whacky, can't imagine this really being done)
  • treat with erythromycin for 2 weeks, off work first 5 days
  • consider acellular pertussis booster
• Meningococcal Meningitis
  • rifampin or cipro for close contacts only (2008)

Rocky Mountain Spotted Fever (RMSF)

• most common Rickettsial disease, much more than Lyme, caused by R Ricketsii
• a "severe flu": myalgia, headache, fever bed fast, photophobia, lasting 5-7 days without pulmonary symptoms - progressive worsening
• petechial rash around wrist and ankle @ day 6 is an obliterative endarteritis (vasculitis); vasculitis causes brain, lung, kidney injury
• hyponatremia and thrombocytopenia
• obtain serology and treat presumptively with doxycycline esp. if endemic area or history of tick bite - expect quick response

Smallpox 2/15/03

(PS - jf personal opinion 2/15/2003: HIV infection cannot propagate in a world where smallpox is endemic. In a world of endemic HIV is a rapidly lethal disease of low contagiousness -- such a disease cannot become epidemic. HIV emerged from African in the 1960s, after smallpox had become rare in Africa. In a sense, the prevention of smallpox enabled AIDS.)

• MN Department of Health - Smallpox Dx and Response and Vaccinia Procedures - 612-676-5414. The MNDH document is the best I've seen.
• www.smallpox.gov

Presentation and Management

• anyone developing fever within 3 weeks of exposure to smallpox should be treated as if infected
• fatality rate in never vaccinated persons is 50% (historical note: death of the amerindian peoples)
• incubation @13 days, rash has 28 day course with varying fever periods
  (This course is for an average HIV negative person)
  • day 0: severe flu like picture
  • day 3: tiny red spots on oral mucosa and fever drops
  • day 5: macules on face first then trunk and then distally
  • day 7: mucous membrane macules -> papules-> vesicles. skin macules -> papules ->  opaque vesicles (shed virus, very contagious)
  • day 9: skin lesions pustular, fever may recur
  • day 10-14: pustules grow, umbilicated, crusting begins (if survive), fever may drop.
  • day 14-20: scabs
  • day 20-28:  scarring, depigmentation
• special characteristics: (a very, very sick "chickenpox")
  • the pustules/vesicles are deep, hard/firm, sharp borders
  • on any part of body lesions are at same state of development, but the facial/trunkal lesions are older than the peripheral lesions
  • patient is toxic
• d/dx: vaccinia (in vaccinated person or secondary exposure -- esp. if immuno-suppressed, young child, or atopic dermatitis), zoster, HSV, molluscum contagiosum (HIV - obvious consult), coxsackievirus, drug-induced rash, erythema multiforme, syphilis, etc. See Diagnostic Dilemmas and D/Dx.
• management of suspected case
  • isolation, etc. Should have protocols established and posted (see refs). Dispose of protective clothes, wash hands with 60% plus alcohol rubs or soap/water.
  • phone 612-676-5414 (MN Dept. Health), consult widely, cidofovir

Vaccination

• current US vaccine is Dryvax, reformulated tissue culture and other strains under development
• vaccination of contacts within 3-4 days of exposure will prevent or modify disease course, neutralizing antibodies appear 10 days after primary vaccination, 7 days after re-vaccination, protection is very high (@100% for five years, may last up to 10 years).
• I personally would NOT wear contact lenses post-vaccination until site is totally healed.
• about 1/10,000 young healthy vaccinees get high fever. 1/3 missed work (fever, headache), swollen nodes can last a month, 70% of children develop fever, various maculopapular or urticarial rashes can occur @ day 10. Historic rates of severe events was 52/million but expect significantly higher today.
• treat severe vaccine s/e with Vaccinia immune globulin
• vaccine effectiveness established 6-8 days post-vaccine -- need to see umbilicated vesicle/pustule. Will scar.
• see documents for full vaccine contraindications
  • atopic dermatitis/eczema is most common contraindication to vaccination, including in household members (unclear if matters if it's well controlled or treated)
  • risk of encephalitis in young children, MDH recommends avoid vaccination if child age < 12 mo in household

Vaccinia Complications

• secondary innoculation: if extensive or ocular implantation use VIG (consult in near eye)
• vaccinia keratitis: 10 days after vaccinia transfer, may cause scarring, consult.
• exzema vaccinatum: spread in persons with atopic eczema or history thereof. May be fatal. VIG, consult, etc.

Post-Vaccine Care

• LOTS of handwashing, 60% plus alcohol hand rub (so develop eczema for washing and hence get complications?)
• semi-permable dressing and gauze over-cover, dressings are a bio-hazard (what about trash disposal at home??)

Streptococci explicated

Beta Hemolytic

(Lyse red blood cells, on blood agar. Subdivided into Lancefield groups based upon polysaccharide antigens)

Group A representative species: Strep Pyogenes

• rheumatic fever, glomerulonephritis
• scarlet fever
• otitis media
• sinusitis
• strep throat
• impetigo
• streptococcosis (age < 3 yo)
• streptococcal pneumonia (rare nowadays for some odd reason)

Group B: representative species: S. agalactiae

• neonatal sepsis
• meningitis
• SBE
• UTI

Group D

1. enterococcus: S. fecalis (resistant to most antibiotics except ampicillin/amoxicillin)
2. • subacute bacterial endocarditis
   • UTI, urosepsis
3. nonenterococcis: S. bovis: (a) subacute bacterial endocarditis

Alpha Hemolytic

Partial lysis of RBC on blood agar plates. Just S. viridans: SBE, caries

Non Hemolytic (gamma)

Anaerobic are pathogens: peptostreptococcus: abscesses, gangrene, necrotizing fasciitis, peritonsillar abscess

S. Pneumoniae, Pneumococcus

Very different from other streptococci. S. pneumoniae does not producte any important toxins, all will lyse RBCs (alpha hemolysis under aerobic conditions, beta hemolysis under anaerobic conditions). Has a special capsule which messes up neutrophils, that’s why its so lethal. There are at least 84 different immunologic capsule subtypes, with two different nomenclatures. Pneumonia and:

• otitis media
• sinusitis
• epiglottits
• meningitis
• pericarditis
• endocarditis

Syphilis

• Jarisch-Herxheimer reaction: acute transient febrile reaction within first few hours of Rx for syphilis. May have myalgia, headache, malaise.
• peaks at 6-8 hours, disappears within 12-24 hours

Tb

• PPD positive if > 15 mm (no risk factors) or > 5 mm induration with risk factors (HIV, household contact, clinical signs)

Zoonoses

• Mange (Sarcoptes scabiei var. canis) causes pruritis and hair loss in dogs. In close contact humans it produces  pruritic papular rash on arms, chest, or abdomen. Looks a bit like 'swimmer's itch' -- cutaneous schistosomiasis. The rash should resolve after the dog is treated, Elimite may accelerate resolution.