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Paediatrics > Paediatric Infectious Disease > Flashcards

Paediatric Infectious Disease Flashcards

1
Q

Rubella virology: family, type of virus, enveloped v not, hosts, where does replication occur, genome

A

Togavirus family, rubivurs genus
Small, enveloped +ss RNA (encodes 3 proteins)
Humans are only natural host
Viral replication occurs in the cytoplasm

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2
Q

Incubation period and infectious period of rubella

A

14-18 day incubation period
Are infectious from 1-2 weeks prior to clinically apparent infection, and should be isolated for 7 days after the onset of the rash (Viral shedding reduces with appearance of the rash)

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3
Q

Clinical features of rubella

A 
Acute onset of rash:
 - pinpoint maculopapular
 - PINK (not red like measles)
 - First on face - rapid caudal spread over 24 hours
 - Evident for approx 3 days
Lymphadenopathy (post-auricular, suboccipital, posterior cervical)
\+/- low-grade fever
Mild nonexudative conjunctivitis
Forchheimer spots on soft palate
Arthralgia (more common in teens/adults)
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4
Q

Congenital rubella syndrome

A 
Most likely if maternal rubella infection in first trimester of pregnancy
Hearing loss
Mental retardation
Cardiovascular defects
Ocular defects
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5
Q

Diganosis of rubella

A

Rubella serology (IgM and IgG)
Viral isolation from nasopharyngeal secretions
Viral isolation from cord blood or placenta in neonate
Foetal infection diagnosed by CVS

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6
Q

Rubella vaccination

A

Live attenuated
Recommended at 12 & 18 months
Contraindications: pregnancy, immunocompromised

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7
Q

Management of rubella

A

Paracetamol for supportive relief of symptoms
No specific therapy
Offer termination of pregnancy esp. if prior to 16 weeks GA
Droplet precautions
Isolation for 7 days after onset of rash

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8
Q

Epidemiology of pertussis

A

The least well controlled of all vaccine-preventable disease
Epidemics occur every 3-4 years
Maximum risk of infection and severe morbidity is before infants are old enough to have received at least 2 vaccine doses (4 months)
Parents are the source for more than 50% of cases

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9
Q

Microbiology of pertussis

A

Bordatella pertussis
fastidious Gram-negative, pleomorphic bacillus
spreads by aerosols to 90% of susceptible household contacts
Natural infection does not provide long-term protection and repeat infection can occur

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10
Q

Diagnosis of pertussis

A

Clinical diagnosis
Catarrhal stage:
- mild cough and coryza - NASAL DISCHARGE REMAINS WATERY
- cough gradually increases for 1-2 weeks
Paroxysmal stage:
- Paroxysmal coughing spells increasing in severity with inspiratory whoop. May gag or develop cyanosis
- Post-tussive vomiting
- lasts 2-8 weeks
Convalescent stage: cough subsides over weeks to months (median duration of cough - 100 days)

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11
Q

Lab investigations in pertussis

A

Not necessary for diagnosis
WCC usually high with lymphocytosis
B pertussis culture (more difficult after paroxysmal stage has begun)
PCR or serology also options

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12
Q

Complications of pertussis

A

Apnoea
Pneumonia (most common cause of death)
Weight loss secondary to feeding difficulties and post-tussive vomiting
Seizures and encephalopathy

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13
Q

Management of pertussis

A

Supportive care
Hospitalise if: unable to feed, cyanotic, apnoea, seizures, increased work of breathing, concerned for rapid deterioration
Bronchodilators, steroids and antitussive agents are not beneficial
Antibiotic therapy (macrolides e.g. erythromycin) shortens duration and reduces transmission
Droplet precaution until 5 days of effective therapy or 3 weeks after onset of symptoms if untreated

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14
Q

Prevention of pertussis

A

For protection of children under 3 months:

  • direct protection by immunisation of mother in last trimester
  • indirect protection by vaccinating all household contacts at least 2 weeks before beginning contact if over 10 years since last dose
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15
Q

Transmission of varicella zoster

A

Aerolised droplets from nasopharyngeal secretions
OR
Direct cutaneous contact with vesicle fluid from skin lesions

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16
Q

Virology of varicella zoster

A

dsDNA virus

Enveloped with glycoprotein spikes

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17
Q

Average incubation period of chicken pox

A

14-16 days

18
Q

Clinical features of chicken pox

A

GENERALISED VESICULAR RASH + FEVER
Prodrome: low-grade fever, malaise, pharyngitis, anorexia
Rash develops within 24 hours
Begins on trunk/face then spreads to extremities
Rash typically has lesions in different stages (macule-papule-vesicle-pustule-crusted papule)
New vesicle formation ends by day 4
Most lesions fully crusted by day 6

19
Q

Complications of chicken pox

A

Most common in infants, elderly or immunocompromised
- Skin/soft tissue infections
- Neurological (Encephalitis, Reye syndrome, transient focal deficits, aseptic meningitis, transverse myelitis, vasculitis, hemiplegia)
- Pneumonia
- Hepatitis
Diarrhoea, pharyngitis, otitis media

20
Q

Management of chicken pox

A

Self-limiting in uncomplicated disease of immunocompetent patients
Isolation until all lesions fully crusted over (generally 6 days)
Symptomatic (calamine lotion, cool compresses, antihistamines at night)
Cut nail shorts to avoid secondary infection
Oral aciclovir if significant pre-existing skin disease
IV or oral acyclovir if complicated or immunocompromised patient

21
Q

Epidemiology of measles

peak age, complication rate, contagiousness

A

Peak age at 6m (vaccination occurs at 12m, maternal antibodies become ineffective at 6m)
Overall complication rate 22% (mainly diarrhoea, AOM, pneumonia)
90% infection rate for susceptible household contacts

22
Q

Risk factors for measles

A

Children too young for vaccination
Unvaccinated children or those who have not completed their second dose of the vaccine
Travel or contact with ill people from the developing world

23
Q

When is measles contagious

A

Contagious from 5 days before the onset of the rash to 4 days after
Most contagious during late prodrome phase (fever + respiratory symptoms)

24
Q

Clinical features of measles

A

Prodrome (2-3 days)
- fever, malaise, anorexia, conjunctivitis, coryza, cough
- may develop Koplik’s spots
Exanthem stage:
- maculopapular blanching RED rash begins on face, spreads caudally
- PALMS AND SOLES NOT INVOLVED
- lymphadenopathy
- high fever, peaking 2-3 days after rash appears
- pronounced respiratory symptoms
- cough persists for 1-2 weeks, fever for 3-4 days after rash onset

25
Q

Incubation period of measles

A

6-19 days (median 13)

ie 2 weeks

26
Q

What are Koplik spots

A

Pathognomic for measles
1-3mm white/grayish/bluish elevations with erythematous base on buccal mucosa opposite molar teeth, often begin to slough when rash appears

27
Q

Definition of diphtheria

A

An acute infectious respiratory disease caused by toxigenic strains of Corynebacterium diphtheriae named after the Greek word for leather, referring to the tough pharyngeal membrane that is hallmark of the infection

28
Q

Microbiology of Corynebacterium diphtheria

A

Gram-positive bacillus
Non-sporing
Non-capsulate

Produces exotoxin that acts locally on mucous membranes of respiratory tract and systemically on myocardium, nervous system and adrenal glands

29
Q

Clinical features of diphtheria

A

Gradual onset of symptoms
Sore throat, malaise, cervical lymphadenopaty, low-grade fever
Mild erythema, progressing to spots of gray and white exudate
Myocarditis (SOB, red HS, gallop rhythm)
Renal failure
Neurological toxicity (5%)
- local neuropathies (soft palate, posterior pharynx)
- cranial neuropathies (oculomotor, ciliary, facial, laryngeal)

30
Q

Management of diptheria

A 
Erythromycin
Diphtheria antitoxin if severe
Careful airway management
Serial ECGs
Monitor neuro status
Droplet precautions
Isolation until 2 consecutive cultures taken at least 24 hours apart are negative
31
Q

Virology of mumps

A

Paramyxovirus from Rubulavirus genus
SS RNA genome
Rapidly inactivated by formalin, ether, chloroform and light
transmission via aerosol and direct contact with saliva

32
Q

Clinical features of mumps

A 
Asymptomatic in 30%
Non-specific symptoms: 
- fever
- headache
- malaise
- myalgia
- anorexia
Specific symptoms
- bilateral parotid swelling (60-70% clinical cases)
- meningeal symptoms in 10%
- Orchitis (usually unilateral) in 15% of postpubertal males
May result in spontaenous abortion in first trimester of pregnancy
33
Q

Mumps in pregnancy

A

May result in spontatneous abortion

Maternal infection not associated with increased risk of congenital malformation

34
Q

Management of mumps

A

No specific treatment
Supportive management: paracetamol for pain/fever
Avoid sour foods - increase salivation, increase parotid pain
Liquid diet may help if pain on swallowing

35
Q

Definition of tetanus

A

A nervous system disorder caused by the tetanus toxoid from Clostridium tetani and characterised by muscle spasms

36
Q

Microbiology of tetanus

A

Clostridium tetani:
- obligate anaerobe in soil
- spores gain access to damaged human tissue
- rod-shaped bacterium
- produce tetanus toxin (metalloprotease tetanospasmin)
Toxin reaches spinal cord and brainstem via retrograde axonal transport, irreversibly blocking receptors hence neurotransmission

37
Q

Predisposing factors for tetanus

A

Will not grow in healthy tissues, therefore usually requires 2+ of the following:

  • penetrating injury resulting in inocculation of C. tetani spores
  • Coinfection with other bacteria
  • Devitalised tissue
  • Foreign body
  • Localised ischaemia
38
Q

Name of tetanus toxin

A

Metalloprotease tetanospasmin

39
Q

Clinical features of tetanus

A

Incubation period 7-10 days (shorter in neonates)
Generalised tetanus:
- trismus (lockjaw)
- Autonomic overactivity in early phases (irritability, sweating, tachycardia)
- stiff neck
- Opisthotonus (arched back)
- Sardonic smile
- Board-like rigid abdomen
- periods of apnoea or upper airway obstruction
- Dysphagia

40
Q

Management of tetanus

A

Long lasting effects, 4-6 weeks of clinical symptoms
ICU management
- Penicillin and metronidazole (stop toxin production)
- Neutralisation of unbound toxin (human tetanus Ig)
- Active immunisation - does not confer immunity following recovery from acute illness (3 doses of DTP at least 2 weeks apart)
- Control muscle spasms (benzos, propofol, rocuronium etc.)
- Manage autonomic dysfunction (MgSulfate, beta blockers e.g. labetalol, atropine, clonidine, epidural bupivacaine)
- Airway management (early intubation, tracheostomy likely needed)
- Nutritional support
- VTE prophylaxis
- Physical therapy as soon as spasms ceased

41
Q

Tetanus prophylaxis

A

Tetanus vaccine to anyone who has completed only the primary series of immunisation or who received a booster over 5 years ago and has sustained a puncture wound
Tetanus toxoid AND tentaus immune globulin should be given to patients with puncture wounds who have received less than 3 doses of immunisation in the past or whose immunisation status is uncertain

Paediatrics (20 decks)

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