Level 2 - Infections Flashcards
Definition of chicken pox?
- Highly infectious disease caused by herpes virus transmitted by air droplets
- VZV infection between 1-6yrs commonly —winter/spring
- Varicella is very infectious
Transmission of chicken pox? Infectious period?
- Transmission is by personal contact or droplet spread, with an incubation period (the time from becoming infected until symptoms appear) of 1-3 weeks
- Chickenpox is infectious from 1-2 days before the rash appears until the vesicles are dry or have crusted over, usually 5 days after the onset of the rash
What is Herpes Zoster?
- Herpes Zoster (shingles)
o a reactivation of the latent infection may occur -> vesicular lesions in the distribution of the sensory nerve. Increased risk in immunosuppressed
Epidemiology of chicken pox?
- Incidence is highest before 10 years of age
- > 90% of people older than 15 years of age UK are immune
- Peak incidence from March-May
Causes of chicken pox? Name a risk factor?
- Caused by varicella-zoster virus (VZV)
- Immunocompromised
Prodrome of chicken pox?
- Infection begins 2 days before vesicles appear
- Infection ends when last vesicle crusts over
Rash in chicken pox?
- Head and trunk rest of body.
- Red macules papulevesiclepustulecrusting
- Completely heal in 2wks
Other symptoms in chicken pox?
headache, anorexia, URTI (sore throat, coryza, cough), fever and itching
Investigations (when needed) for chicken pox?
Ex: Characteristic rash, its distribution and progression
Other: Serology (VZV IgM), vesicle fluid or electron microscopy
Management of chicken pox?
Usually self-limiting, symptomatic: Paracetamol, calamine lotion and chlorphenamine
School exclusion: 5 days from start of skin eruption
Antivirals: Acyclovir if severe, in babies and immunosuppressed
Human varicella zoster Ig recommended for high risk immunocompromised
Complications of chicken pox in pregnancy?
- Varicella in pregnancy can result in severe chickenpox
- Infection during 1st 28 weeks of pregnancy can lead to intrauterine infection and foetal varicella syndrome
Other complications in chicken pox?
- Secondary bacterial infection
o Due to staphylococcal/streptococcal leading to toxic shock syndrome or necrotising fasciitis - Encephalitis
o Cerebellitis, meningitis - Purpura fulminans
o Vasculitis in the skin due to cross-reactivity of antiviral antibodies - Immunocompromised can disseminate causing pneumonitis/DIC – fatal 20%
Define conjunctivitis? Classification?
- Redness and inflammation of conjunctiva (thin layer that covers front of eye)
- Hyperaemic vessels may be moved to sclera by pressure on globe
- Classified as infectious or non-infectious, and as acute (<4 weeks), chronic, or recurrent
What is allergic conjunctivitis?
o Associated with IgE antibodies or non-atopic
o Can be acute/chronic or seasonal (hayfever)
What is infectious conjunctivitis?
o Hyper-acute conjunctivitis is a rapidly developing severe conjunctivitis typically caused by infection with chlamydia
o Ophthalmia neonatorum (ON) is conjunctivitis occurring within the first four weeks of life
Can be infectious or non-infectious
Can be caused by Chlamydia trachomatis or Neisseria gonorrhoeae
Epidemiology of allergic conjunctivitis?
o 15-40% of children
Infectious aetiologies of conjunctivitis?
o Viral
Most common 80% adenoviruses
HSV, VZV, EBV, Coxsackie
o Bacterial
Streptococcus pneumoniae, Staphylococcus aureus and Haemophilus influenzae
Moraxella catarrhalis, Chlamydia trachomatis, and Neisseria gonorrhoea
Non-infectious causes of conunctivitis?
o Allergic, mechanical/irritative/toxic, immune-mediated and neoplastic
Symptoms of conjunctivitis?
- Eyes itch, burn, ‘gritty feeling’ and lacrimate
- Often bilateral with discharge sticking lids together
Explain different discharges in conjunctivitis?
- Discharge can be watery, mucoid, purulent depending on cause
o Bacterial purulent with sticking lids, may have lymphadenopathy
o Viral watery discharge and less, URTI
What happens to eye function?
- Acuity, pupillary responses, corneal lustre are unaffected
DDx of conjunctivitis?
- Acute glaucoma, Scleritis, Episcleritis, Keratitis, Uvitis, Iritis, Corneal ulcer, abrasion or foreign body
- Nasolacrimal duct obstruction
- Dry Eye
- Blepharitis
Investigations of conjunctivitis?
- Slit lamp examination if needed
- Gram staining and culture if gonococcal suspected
When is sticky eyes common? Management?
- Sticky eyes common in first few days of life
o Clean with saline
o Eye drops lubricating
Management of conjunctivitis? Bacterial?
Allergic?
Neonates?
Opthalmia neonatorum?
- Usually self-limiting and rarely causes loss of vision (resolves within 5-10 days)
- Bacterial Conjunctivitis
o Chloramphenicol topical drops (or fusidic acid drops) - Allergic Conjunctivitis
o Topical antihistamines
o Topical corticosteroids
o Cromoglycate eye drops - Neonates
o Treat with neomycin - Ophthalmia Neonatorum
o Gonococcal infection should be cultured and treated with 3rd generation cephalosporin given
o If chlamydia infection then treated with oral erythromycin
Complications of conjunctivitis?
- Keratoconjunctivitis
- Keratitis
- ON
o Corneal scarring, ulceration, visual impairment
What is a food allergy? Type of reactions?
- Immediate IgE-antibody allergic reaction to specific food antigens
- 70% have FHx of atopy
- Immunological reactions - both IgE (acute, often rapid, onset) and non-IgE-mediated (delayed and non-acute reactions)
- Food Intolerance – non-immunological hypersensitivity to specific food
Epidemiology of food allergy?
- Affects 5% of young people
- Incidence are rising
- Around 2% have cow’s milk protein allergy
Most common food allergens?
o Cow’s milk, egg, peanut, tree nut, fish, shellfish, wheat and soya
Questions to ask about the allergic reaction?
- Why they suspect an allergy?
- What foods do they feel are implicated?
- Symptoms that occur after eating?
- At what age and how much food is eaten to cause symptoms?
- How long do symptoms last?
- Worst reaction to ever happen?
- Family history of allergy?
Features of IgE mediated allergy?
Occurs 10-15 minutes after
Acute urticaria – localised or generalised
Acute angio-oedema
Oral itching, nausea, vomiting
Colicky abdominal pain
Nasal itching, sneezing, rhinorrhoea, allergic conjunctivitis
Cough, shortness of breath, wheezing and bronchospasm
Other signs of anaphylaxis, stridor, feeling of impending doom, cardiovascular collapse
Pruritis, erythema, diarrhoea and abdominal pain are common to both types
Features of Non-IgE Mediated allergy?
Atopic Eczema GORD Infantile colic Diarrhoea/Dysentery Pallor Faltered growth Pruritis, erythema, diarrhoea and abdominal pain are common to both types
What is cow’s milk protein allergy? Symptoms? Management in breast/bottle fed babies?
- Separate to colic and is either IgE or non-IgE mediated
- Causes colic symptoms, GORD, blood/mucus in stools, faltering growth
- In breastfed babies, completely exclude cows’ milk protein from diet
- In formula-fed babies, change to hypoallergenic extensively hydrolysed or amino acid formula
DDx of food allergy?
Cow’s milk protein, IBD, IBS
Investigations to identify food allergy?
Food Diary
If IgE mediated:
- Skin prick tests
- RAST or ELISA test (measures specific IgE antibodies)
Non-IgE allergies can be deduced from history and examination
- May need endoscopy and biopsy which will have eosinophilic infiltrates
- Exclusion of food under supervision of dietician
Management of food allergy?
Dietary - Avoid foods from diet Drug - Mild Reactions o Antihistamines - Anaphylaxis o Adrenaline (via auto-injector, Epipen) Cows’ milk protein allergy usually resolves during childhood
Definition of Epstein-Barr virus? Transmission? Pathology?
- Glandular fever is an infectious, usually self-limiting disease
- Virus has tropism for B lymphocytes and epithelial cells of pharynx
- Transmission via oral contact and majority of infections are subclinical
- EBV infection leads to a lifelong latent carrier state
Epidemiology of EBV?
- 50% of children will have detectable EBV antibodies by 5 years of age
- 90% of people will have antibodies by 25 years of age
Causative organism of EBV?
- Caused by the Epstein-Barr virus (EBV), a member of the human herpes virus family (hHV4)
Features of EBV?
- Long incubation period
- Most people are asymptomatic
- In most people, the disease is self-limiting and lasts 2–3 weeks
Symptoms of EBV?
o Fever o Malaise, myalgia, rigors, anorexia o Lymphadenopathy o Tonsillopharyngitis o Palatal petechiae o Hepatosplenomegaly o Maculopapular rash o Jaundice
DDx of EBV?
Streptococcal throat infection Leukaemia Cytomegalovirus Toxoplasmosis Acute viral hepatitis
Investigations of EBV?
- Blood film shows atypical lymphocytes
- FBC, lymphocytosis, heterophile antibody (Monospot) test
- Viral serology for IgM EBV
- LFTs
Management of EBV?
- Supportive
o Pain relief and paracetamol - If airway compromised, then corticosteroids could be used
- AVOID AMPICILLIN/AMOXICILLIN AS CAUSES MACULOPAPULAR RASH IN CHILDREN AFFECTED WITH EBV
Prognosis of EBV?
- Risk factor for Burkitt’s lymphoma, Hodgkin’s lymphoma, B-cell lymphoma and other cancers
Definition Kawasaki Disease?
Affects children <5
Known as mucocutaneous lymph node syndrome
Systemic vasculitis disease with coronary arteritis coronary artery aneurysms= most important complication (20-30%)
Epidemiology of kawasaki disease?
Commonest cause of acquired heart disease in children
Features of Phase 1: Acute (weeks 1-2)??
1) High temp (>38) lasting for >5days
2) Polymorphous rash (red-raised spots)
@genital area
trunk, arms, legs, face
3) Swollen glands in the neck
4) Dry, cracked lips and swollen tongue (strawberry)
5) Red fingers or toes – tender to touch
6) Red eyes- 94% conjunctival infection – non purulent
Features of Phase 2: Sub-Acute (weeks 4-6)??
1) Peeling skin from fingers and toes
2) Abdo pain, D&V, jaundice
3) Pus in urine
4) Drowsy, lethargic & headache
6) Joint pain and swollen
Classical features to make diagnosis of Kawasaki’s disease?
To make diagnosis: Fever for 5 days + 4 out of 5 of the following:
1) Conjunctivitis without pus
2) Cervical lymphadenopathy
3) Extremity changes – swelling of hands/feet and desquamation
4) Rash
5) Lips- red, cracking or strawberry tongue
Diagnosis of Kawasaki Disease?
Diagnosis can be made clinically
Bloods
- FBC - increased WCC, thrombocytosis, CRP and ESR raised
Urine
- MSU dipstick - pus
Lumbar puncture- CSF
ECG and echo to rule out CV comlications and aneurysm
Management of Kawasaki’s disease?
High dose IV immunoglobuilin 2g/kg within 10 days
Aspirin 30-50mg continued for at least 6 weeks
Corticosteroids - prednisolone -if IV-ImmunoGlobulin ineffective
Complications of Kawasaki’s disease?
- Coronary artery aneurysm can develop (20-30%)
- MI risk in 1st year
- Thrombosis
What virus causes measles?
- RNA paramyoxyviridae virus
- Highly infectious
Transmission of measles? Incubation and infectious period?
- Transmitted by droplets / direct contact
- Incubation period: 7-14 days
- Infectious 2d before symptoms and 4d after onset of rash
Epidemiology of measles?
- Peak age= <1 year (before immunisation) or older children that are not immunised
- Occurs typically in preschool children - peak in winter/spring
- Commonest in developing countries
- Rare due to MMR vaccine
Risk factors of measles?
- Not immunised, immunocompromised, contact!
Prodromal symptoms of measles? Rash?
- Prodrome of:
o Fever
o Conjunctivitis, coryza, cough, lymphadenopathy
o Koplik’s spots (grain like spots opposite lower molars and buccal mucosa) - Rash appears 3-4 days later usually behind ear and spreads to whole body
- Initially maculopapular but then blotchy and conflueunt, may desquamate in 2’ wk.
Investigations of measles?
- Clinical diagnosis confirmed by serology &/ or viral culture
- Blood Film
o Leucopenia, lymphopenia
Management of measles?
- Isolation
- Supportive – Antipyretics
- Notifiable disease to Health Board
- Immunocompromised
o Ribavirin - Immunised in MMR vaccine to prevent disease
Complications of measles?
o Otitis Media
o Pneumonia
o Diarrhoea
o Subacute sclerosing panencephalitis
Rare complications of measles?
o Encephalitis
o Subacute Sclerosing Panencephalitis
What is periorbital cellulitis?
- Infection of soft tissues anterior to orbital septum
Where is periorbital cellulitis more common?
- Common in young children
Causes of periorbital cellulitis? When is it more common?
- Commonly caused by sinusitis, facial insect bites, trauma, dental infections
- Most common pathogenic organisms are S. aureus, S. epidermidis, streptococci and anaerobe
- Unimmunised children can be due to H.influenzae type b
- Both conditions occur more commonly in the winter months
Symptoms of periorbital cellulitis?
- Fever
- Almost always unilateral
- Erythema
- Tenderness
- Oedema of the eyelid
- Absence of painful eye movements, diplopia and visual impairments distinguish from orbital cellulitis
DDx of periorbital cellulitis?
Orbital cellulitis
Conjunctivitis
Episcleritis
Scleritis
Management of periorbital cellulitis? How would you manage orbital cellulitis?
- Periorbital cellulitis - oral co-amoxiclav
- If orbital cellulitis - admit and need to do CT and LP to assess extent and exclude meningitis – IV Abx needed
