12. Infectious Diseases Flashcards
Define: Fever (1)
a practical definition is >38oC/100.4oF oral or rectal
Define: Fever without a source/focus (1)
acute febrile illness (typically <10d duration) with no cause of fever even after careful history and physical
Define: Fever of unknown origin (1)
daily or intermittent fevers for at least 2 consecutive wk of uncertain cause after careful history and physical, and initial laboratory assessment
Describe etiology: Fever (4)
- infectious: anatomic approach (CNS, ears, upper and lower respiratory tract, GI, GU, skin, soft tissue, bones and joints, etc.)
- inflammatory: mainly autoimmune (Kawasaki disease, JIA, IBD, SLE, etc.)
- malignancy: childhood cancers (leukemia, lymphoma, neuroblastoma, etc.)
- miscellaneous: dehydration, drugs and toxins,post-immunization,familial dysautonomia,factitious disorder, etc.
Describe diagnosis of fever (3)
- history: duration, height and pattern of fever, associated symptoms, exposures, constitutional symptoms, recent antipyretic use, ethnic or genetic background, daycare, sick contacts, travel, tick bites, age of child
- physical exam: toxic vs. non-toxic, vitals, growth, complete exams of the skin, HEENT (head, eyes, ears, nose, and throat) , chest, abdomen, lymph nodes, genitalia
- investigations: guided by history, physical exam, and clinical suspicion
Describe: Rochester Criteria (6)
Developed to Identify Infants ≤60 d of Age with Fever at Low Risk of Serious Bacterial Infection
- Clinically: Well
- WBC Count: 5-15 x 109/L
- Bands: <1.5 x 109/L
- Urinalysis: <10 WBC/HPF
- Stool (if diarrhea): <5 WBC/HPF
- Past Health
- Born >37 wk
- Home with/before mom
- No hospitalizations
- No prior antibiotic use
- No prior treatment for unexplained hyperbilirubinemia
- No chronic disease
Describe: Evaluation of Neonates and Infants with Fever (2)
- several protocols exist that attempt to identify neonates and young infants at low risk of serious bacterial infection (e.g. Rochester Criteria)
- such protocols are not as sensitive in the 1-28 d age group; therefore, febrile neonates should be considered high risk regardless of clinical features and laboratory findings
Describe management of fever (5)
- admit to hospital if appropriate
- treat the source if known
- replace fluid losses (e.g.from vomiting, diarrhea, etc.); maintenance fluid needs are higher in febrile child
- reassure parents that most fevers are benign and self-limited
- antipyretics (acetaminophen and/or ibuprofen) may be given if child is uncomfortable
Name criterias for acute otitis media (3)
All of:
- presence of middle ear effusion
- presence of middle ear inflammation
- acute onset of symptoms of middle ear effusion and inflammation
Describe epidemiology: Acute Otitis Media (3)
- 60-70% of children have at least 1 episode of AOM before 3yr of age
- 18mo-6yr most common age group
- 22% of children in this age range will develop AOM in the first wk of a viral URI
- one third of children have had ≥ 3 episodes by age 3; peak incidence January to April
Describe etiology: Acute Otitis Media (3)
- bacterial S.pneumoniae (decreasing since the introduction of PCV7 and PCV13), H.influenza, M. catarrhalis, GAS
- less common - anaerobes (newborns) , Gram-negative enterics (infants)
- viral–more likely to spontaneously resolve
Name risk factors: Acute Otitis Media (4)
- Eustachian tube related:
- dysfunction/obstruction (URTI, allergic rhinitis, chronic rhinosinusitis, adenoid hypertrophy, barotrauma)
- inadequate tensor palatine function (cleft palate)
- genetic syndromes (DS, Crouzon, Apert)
- cilia disruption (Kartagenger’s syndrome, CF)
- genetic predisposition (family history, ethnicity – First Nations and Inuit, low levels of secretory IgA or persistent biofilm in middle ear)
- behavioural and environmental exposures (not breastfed or shorter duration of breastfeeding, prolonged bottle feeding, bottle feeding laying down, pacifier use, second-hand smoke exposure, crowded living conditions/daycare, sick contacts)
- immunosuppression/deficiency (chemotherapy, steroids, DM, hypogammaglobulinemia, CF)
Describe pathogenesis: Acute Otitis Media (1)
- obstruction of Eustachian tube→ air absorbed in middle ear → negative pressure (an irritant to middle ear mucosa) → edema of mucosa with exudate/effusion → infection of exudate from nasopharyngeal secretions
Describe clinical features: Acute Otitis Media (6)
- acute onset of symptoms
- triad of otalgia, fever (especially in younger children), and conductive hearing loss –not all symptoms such as fever or hearing loss may be present
- rarely tinnitus, vertigo, and/or facial nerve paralysis
- otorrhea if tympanic membrane perforated
- infants/toddlers: ear-tugging (this alone is not a good indicator of pathology), hearing loss,balance disturbances (rare), irritable, poor sleeping, vomiting and diarrhea, anorexia
- otoscopy of TM: hyperemia, bulging, pus may be seen behind TM, loss of land marks (e.g.handle and long process of malleus not visible), discolouration (hemmorhagic, grey, red, yellow)
Describe diagnosis: Acute Otitis Media (1)
Requires middle ear effusion and signs of inflammation (most important is a bulging TM)
Describe management: Acute Otitis Media (4)
- symptomatic therapy: antipyretics/analgesics (e.g.acetaminophen or ibuprophen)
- watchful waiting if criteria met
- antibiotic therapy if <6mo or moderate-severe illness
- signs of a perforated TM should always be treated with antimicrobial therapy (most commonly topical Ciprodex) and examined for complications
Describe antibiotic therapy if <6mo or moderate-severe: Acute Otitis Media (2)
- 1st line: high dose amoxicillin 75-90mg/kg/d dosed BID (if penicillin allergic: macrolides,TMP-SMX)
- 2nd line: amoxicillin-clavulanic acid, cephalosporins: cefuroxime axetil, ceftriaxone, cefaclor, cefixime
- used when AOM unresponsive and clinical signs/symptoms persist beyond 48 h of antibiotic
- treatment, or for treatment of otitis-conjunctivitis syndrome
Describe prevention: Acute Otitis Media (2)
- parent education about risk factors, pneumococcal and influenza vaccines, surgery (e.g. tympanostomy tubes)
- choice of surgical therapy for recurrent AOM depends on whether local factors (Eustachian tube dysfunction) are responsible (use ventilation tubes), or regional disease factors (tonsillitis, adenoid hypertrophy, sinusitis) are responsible
Name EXTRACRANIAL complications: Acute Otitis Media (8)
- hearing loss and speech delay (secondary to persistent middle ear effusion)
- TM perforation
- extension of suppurative process to adjacent structures (mastoiditis, petrositis, labyrinthitis)
- cholesteatoma
- facial nerve palsy
- middle ear atelectasis
- ossicular necrosis
- vestibular dysfunction
Name INTRACRANIAL complications: Acute Otitis Media (5)
- meningitis
- epidural and brain abscess
- subdural empyema
- lateral and cavernous sinus thrombosis
- carotid artery thrombosis
Define: Otitis Media with Effusion (1)
presence of fluid in the middle ear without signs or symptoms of ear infection
Define epidemiology: Otitis Media with Effusion (4)
- most common cause of pediatric hearing loss
- not exclusively a pediatric disease
- follows AOM frequently in children
- middle ear effusions have been shown to persist following an episode of AOM for 1mo in 40% of children, 2 mo in 20%, and >3 mo in 10%
Define risk factors: Otitis Media with Effusion (1)
Same as AOM
Describe clinical features: Otitis Media with Effusion (4)
- conductive hearing loss ± tinnitus
- fullness – blocked ear
- ± pain
- low grade fever
Describe results of otoscopy of TM in Otitis Media with Effusion (6)
- discolouration – amber or dull grey ■
- eniscus fluid level behind TM
- air bubbles
- retraction pockets/TM atelectasis
- flat tympanogram
- most reliable finding with pneumatic otoscopy is immobility
Describe treatment: Otitis Media with Effusion (5)
- expectant: 90% resolve by 3mo
- document hearing loss with audiogram(
- no statistical proof that antihistamines, decongestants, antibiotics clear disease faster
- surgery: myringotomy ± ventilation tubes ± adenoidectomy (if enlarged or on insertion of second set of tubes after first set falls out)
- ventilation tubes to equalize pressure and drainear
Name complications: Otitis Media with Effusion (5)
- hearing loss, speech delay, learningproblemsinyoungchildren
- chronic mastoiditis
- ossicular erosion
- cholesteatomae specially when retraction pockets involve pars flaccida
- retraction of tympanic membrane, atelectasis, ossicular fixation
Describe history: Gastroenteritis (3)
- non-specific: diarrhea, vomiting, fever, anorexia, headache, myalgias, abdominal cramps
- bacterial and parasitic agents more common in older children (2-4yr)
- recent infectious contacts: symptoms usually begin 24-48h after exposure
Describe physical exam: Gastroenteritis (2)
- febrile
- dehydrated: must assess extent
Describe investigations: Gastroenteritis (2)
- not usually necessary in young children
- stool analysis: leukocytes/erythrocytes suggests bacterial or parasitic etiology; pH<6 and presence of reducing substances suggests viral etiology
Name complications: Gastroenteritis (3)
- viral gastro enteritisus ually self-limiting (lasts 3-7d in most cases)
- adverse effects related to hypovolemia, shock, tissue acidosis, and rapid onset and over-correction of electrolyte imbalances
- death in severe dehydration (rare in developed countries)
Describe etiology: Gastroenteritis (3)
- Viral Infection
- Most common cause of gastroenteritis
- Commonly: rotaviruses (most common), enteric adenovirus, norovirus (typically older children)
- Bacterial Infection
- Salmonella, Campylobacter, Shigella, pathogenic E. coli, Yersinia, C. difficile
Describe clinical features: Gastroenteritis
- Viral (3)
- Bacterial (3)
- Viral:
- Associated with URTIs
- Resolves in 3-7 d
- Slight fever, malaise, vomiting, vague abdominal pain
- Bacterial
- Severe abdominal pain
- High fever
- Bloody diarrhea
Name risk factors: Gastroenteritis (2)
- Daycare, young age, sick contacts, immunocompromised
- Bacterial infection: travel, poorly cooked meat, poorly refrigerated foods, antibiotics
Describe management: Gastroenteritis (6)
- Prevention and treatment of dehydration most important
- Early refeeding advisable, with age-appropriate diet upon completion of rehydration
- Ondansetron for suspected gastroenteritis with mild to moderate dehydration or failed ORT and significant vomiting
- Antibiotic or antiparasitic therapy when indicated, antidiarrheal medications not indicated
- Notify Public Health authorities if appropriate
- Promote regular hand-washing and return to school 24 h after last diarrheal episode to prevent transmission Rotavirus vaccine
Describe epidemiology: Toddler’s Diarrhea (2)
- most common cause of chronic diarrhea during infancy
- onset between 6-36 mo of age, ceases spontaneously between 2-4yr
Describe clinical features: Toddler’s Diarrhea (5)
- diagnosis of exclusion in thriving child
- 4-6 bowel movements per day
- diet history (e.g.excess juice intake overwhelms small bowel resulting in disaccharide malabsorption)
- stool may contain undigested food particles
- excoriated diaper rash
Describe management: Toddler’s Diarrhea (2)
- reassurance that it is self-limiting
- 4Fs (adequate Fibre, normal Fluid intake, 35-40% Fat , discourage excess Fruit juice)
Describe: Erythema Infectiosum
- Pathogen(s)
- Incubation Period
- Communicability
- Mode of Transmission
(i.e. Fifth Disease/ Slapped Cheek)
- Pathogen(s): Parvovirus B19
- Incubation Period: 4-14 d
- Communicability: Low risk of transmission once symptomatic
- Mode of Transmission:
Describe rash: Erythema Infectiosum
(i.e. Fifth Disease/ Slapped Cheek) (3)
- Appearance:
- uniform
- erythematous
- maculopapular ‘lacy’ rash
- Timing: 10-17 d after symptoms (immune response)
- Distribution: bilateral cheeks (‘slapped cheeks’) with circumoral sparing; may affect trunk and extremities
Describe associated features: Erythema Infectiosum
(i.e. Fifth Disease/ Slapped Cheek)
- Initial 7-10 d of flu-like illness and fever
- Rash may be warm, non-tender, and pruritic
- Less common presentations include ‘gloves and socks syndrome’ or STAR complex (sore throat, arthritis, rash)
Describe management: Erythema Infectiosum
(i.e. Fifth Disease/ Slapped Cheek) (1)
Supportive
Describe outcomes and complications: Erythema Infectiosum
(i.e. Fifth Disease/ Slapped Cheek)
Rash fades over days to week, but may reappear months later with sunlight, exercise Aplastic crisis
Describe: Gianotti-Crosti Syndrome (i.e. Papular Acrodermatitis)
- Pathogen(s)
- Incubation Period
- Communicability
- Mode of Transmission
- Pathogen(s): EBV and Hep B (majority)
- Incubation Period: Variable
- Communicability: None
- Mode of Transmission: -
Describe rash: Gianotti-Crosti Syndrome (i.e. Papular Acrodermatitis)
- Appearance: asymptomatic symmetric papules
- Distribution: face, cheeks, extensor surfaces of the extremities, spares trunk
Describe associated features: Gianotti-Crosti Syndrome (i.e. Papular Acrodermatitis) (2)
- Viral prodrome
- May have lymphadenopathy and/ or hepatosplenomegaly
Describe management: Gianotti-Crosti Syndrome (i.e. Papular Acrodermatitis) (2)
- Supportive
- Pain control
Describe outcomes and complications: Gianotti-Crosti Syndrome (i.e. Papular Acrodermatitis) (1)
Resolves in 3-12 wk
Describe: Hand, Foot, and Mouth Disease
- Pathogen(s)
- Incubation Period
- Communicability
- Mode of Transmission
- Pathogen(s): Coxsackie group A
- Incubation Period: 3-5 d
- Communicability: Likely 1-7 d after symptoms but may be up to months
- Mode of Transmission: Direct and indirect contact with infected bodily fluids, fecal-oral
Describe rash: Hand, Foot, and Mouth Disease (2)
- Appearance: vesicles and pustules on an erythematous base
- Distribution: acral, but may exentend up the extremity
Describe associated features: Hand, Foot, and Mouth Disease (1)
Enanthem: vesicles in the POSTERIOR oral cavity (pharynx, tongue)
Describe management: Hand, Foot, and Mouth Disease
Supportive
Describe outcomes and complications: Hand, Foot, and Mouth Disease (1)
Mainly dehydration
Describe: Herpes Simplex
- Pathogen(s)
- Incubation Period
- Communicability
- Mode of Transmission
- Pathogen(s): HSV 1, 2
- Incubation Period: 1-26 d
- Communicability: -
- Mode of Transmission: Direct contact, often through saliva for HSV-1 and sexual contact for HSV-2
Describe rash: Herpes Simplex (1)
Grouped vesicles on an erythematous base
Describe associated features: Herpes Simplex (2)
- Enanthem: vesicles/erosions in the ANTERIOR oral cavity (buccal mucosa, tongue)
- May present with herpetic whitlow (autoinoculation)
Describe management: Herpes Simplex (2)
- Mainly supportive
- Consider oral or topical antivirals
Describe outcomes and complications: Herpes Simplex (4)
- Local: secondary skin infections, keratitis, gingivostomatitis
- CNS: encephalitis
- Disseminated hepatitis, DIC
- Eczema herpeticum
Describe: Measles
- Pathogen(s)
- Incubation Period
- Communicability
- Mode of Transmission
- Pathogen(s): Morbillivirus
- Incubation Period: 8-13 d
- Communicability: 4 d before and after rash
- Mode of Transmission:
Describe:
- Pathogen(s)
- Incubation Period
- Communicability
- Mode of Transmission
- Pathogen(s):
- Incubation Period:
- Communicability:
- Mode of Transmission:
Describe rash: Measles (3)
- Appearance: erythematous maculopapular
- Timing: 3 d after start of symptoms
- Distribution: starts at hairline and spreads downwards with sparing of palms and soles
Describe associated features: Measles (4)
- Prodome of cough, coryza, conjunctivitis (3 Cs)
- Enanthem: Koplik’s spots 1-2 d before rash
- Desquamation
- Positive serology for measles IgM
Describe management: Measles (4)
- Infected: supportive
- Unimmunized contacts: measles vaccine within 72 h of exposure or IgG within 6 d of exposure
- Respiratory isolation, report to Public Health
- Prevention: MMR vaccine