Infections and Immunity 2 Flashcards
What is conjunctivitis?
Inflammation the conjunctiva (thin membrane which covers the sclera of the eyes and the inside of the eyelids)
What are some causes of bacterial conjunctivitis?
Staph aureus Strep pneumoniae H influenzae Morazella catarrhalis Pseudomonas aeruginosa Gonococcal Chlamydial
What does neonatal conjunctivitis within the first 48hrs, with purulent discharge and swelling of the eyelids suggest?
Gonococcal conjunctivitis
How is gonococcal conjunctivitis managed?
IV cephalosporin
How is chlamydial conjunctivitis in a newborn diagnosed and treated?
Specific monoclonal antibody test performed on conjunctival secretions
PO erythromycin / topical tetracycline
What are some causes of viral conjunctivitis?
Adenovirus (most common)
HSV
HZV
Molluscum contagiosum
How is allergic conjunctivitis managed?
Topical mast cell stabilisers
Antihistamines
Topical steroids (specialist)
How does viral conjunctivitis present?
Red eye, usually generalised, often bilateral
Irritation, grittiness and discomfort typical (not significant pain)
Clear, watery discharge with mucoid component
NO PHOTOPHOBIA
NO CHANGE IN VISUAL ACUITY
What does marked pain, photophobia and possibly decreased visual acuity suggest?
Uveitis
These symptoms suggest deeper inflammatory conditions of eye
Esp in those with ‘conjunctivitis’ not responding to conventional treatment and those with previous episodes
How do scleritis and episcleritis present?
Unilateral with localised injection and aching (episcleritis) or intense boring pain (scleritis)
What is the management of bacterial conjunctivas?
Chloramphenicol or fusidic acid drops
What is the management of viral conjunctivitis?
Symptomatic
Self-limiting
What is the discharge like in conjunctivitis that is:
1) Viral
2) Bacterial
3) Allergic
1) Viral - watery / sticky
2) Bacterial - thick yellow / green
3) Allergic - watery / clear / no discharge
What are some advantages of breastfeeding for:
a) Baby
b) Mother
Advantages to baby
• Antibodies - especially from rich colostrum in first few days
• Attachment with mum
• As baby grows, the composition of the milk changes to suit the baby
• Reduces risk of allergies, infections, eczema
• Reduce risk of obesity, CVD, diabetes, certain cancers
• In short term, reduces risk of neurodevelopmental problems
Advantages to mother
• Faster uterine involution (oxytocin stimulates uterine contractions) - reduces risk of PPH
• Earlier return to pre-pregnancy weight - burns 500kcal/day
• Lactational amenorrhoea providing natural contraception - 98% effective if fully breastfeeding for up to 6 months post-partum
• Improved bonding with infant
• Reduced risk of ovarian, breast, endometrial cancer and cardiovascular disease and osteoporosis
• Reduced costs and reduced time - more convenient
What is colostrum?
Colostrum (thick, yellow fluid) = the first milk produced during late pregnancy until 3-4 days post-partum, which is rich in proteins and immunoglobulins that play important part in gut maturation and immunity for infant
What are some CI to breastfeeding?
- Galactosemia in infant - autosomal recessive defects in enzymes that metabolise galactose
- HIV infection
- Cocaine use
- Active TB or varicella infection - but can give expressed breast milk instead
- Herpes simplex breast lesions (but if no lesions, encourage breastfeeding)
- Drugs - tetracyclines (teeth staining), chemotherapy, cytotoxics, lithium, methotrexate, amiodarone
What is the time frame of the weaning process?
0-6 months - breast or formula milk only
6 months - Introduce solid foods such as pureed and finger feeds
7-9 months - give more soft feeds before milk feeds. Encourage finger feeding. Give fruit juices in a cup
9-12 months - mash food with a fork. 3 meals / day, at least one with family
1 year and over - undiluted cow’s milk in a cup
What is the difference between food allergy and food intolerance?
Food allergy = immunologically mediated reaction to food allerges
- Acute, rapid onset usually IgE
- Delayed and non-acute usually non-IgE
Food intolerance = vague term requiring specific explanation
What investigations are done for food allergy?
Food diary
Psysician-supervised oral food challenged
Skin-prick testing
Food-specific serum IgE testing
Concordance between results of skin prick testing and serum IgE levels is not always good and thus both need to be carried out
How are serum-allergen specific IgE measured?
Enzyme-linked immunosorbent assay (ELISA) and fluorescent enzyme immunoassay (FEIA) tests
Only available for a some foods and v expensive
What are some classic foods involved in allergy?
Milk Eggs Fish and seafood Peanuts Sesame Tree nuts Soy beans Wheat Kiwi fruit
What are some examples of non-IgE mediated food allergy?
1) Food protein induced enterocolitis
2) Eosinophilic oesophagitis and gastroenteritis
3) Coeliac disease (not strictly an allergy)
How does food protein induced enterocolitis present?
Projectile committing, diarrhoea and FTT in first few months of life
Cows milk and soy protein formulas are usually responsible
How does eosinophilic oesophagitis and gastroenteritis present?
Nausea, abdo pain, reflux and FTT
No response to antacids
Eosinophilia may be found on FBC or at GI biopsy
What is the management of food allergy and intolerance?
Food avoidance (inc breastfeeding mothers)
Dietician referral
Drug therapy:
Antihisatmine for mild symtoms
Oral sodium cromoglicate
Corticosteroids
Medical emergency identification bracelet
EpiPen (IM) in severe respiratory symptoms or anaphylaxis
Injection immunotherapy (desensitisation) successfully sued for pollen and insect venom allergies (but risky for food)
What is the prognosis of food allergy?
Most children grow out of allergies
1/3rd adults and children lose their clinical reactivity to food allergens after 1-2 years of food elimination diets
Which foods is sensitivity rarely lost?
Peanuts
Seafood
Fish and tree nuts
What are some examples of GI enzyme deficiency leading to food intolerances? (2)
1) Lactose intolerance
2) Congenital sucrose-isomaltase deficiency
What are some common food additives and chemicals in food that can cause pharmacological food intolerance reactions?
1) Artificial food colours / preservatives
2) Glutamates including monosodium glutamate
3) Salicylates
4) Caffeine
What causes infectious mononucleosis?
aka glandular fever
Epstein-barr virus (90%)
Rarely CMV
How does infectious mononucleosis present?
Prodrome of flu-like illness for 3 days
1) Low-grade fever
2) Malaise
3) Pharyngitis
4) Cervical lymphadenopahty
Occasionally:
5) Hepatotosplenomegally
6) Jaundice
What investigations are done for infectious mononucleosis?
Triad:
1) FBC - WCC shows lymphocytosis (lymphocytes account for 80-90% WBC)
2) Blood films - more than 10% lymphocytes atypical
3) Serology - positive agglutination test (monospot test) for EBV (or CMV)
How long do symptoms last of infectious mononucleosis?
Self-limiting but can last months
What is contraindicated in infectious mononucleosis?
Amoxicillin as will cause a maculopapular rash in EBV infection
Does the monospot test have high or low sensitivity?
Low sensitivitiy
False positives in lymphoma and hepatitis
What else may be found when investigating infectious mononucleosis?
Raised LFTs
Mild thromobocytopenia
Raised IgM and IgG early in disease
What is the management of infectious mononucleosis?
Supportive
Pt with splenomegaly should avoid contact sports for 1 months and avoid alcohol
What are some complications of infectious mononucleosis?
GI / abdo:
- Hepatitis
- Splenomegaly
- Splenic rupture
CNS:
- Aseptic meningitis
- Encephalitis
- Guillan-Barre syndrome
Post-viral tiredness
Also:
- Lymphoma
- Orchitis
- Myocarditis
- Pneumonia
What is the pathophysiology of infectious mononucleosis?
Virus infects B lymphocytes in pharyngeal lymphoid tissue then spreads to the rest of the lymphoid system
What is the incubation period of infectious mononucleosis?
4-8 weeks
What is EBV also associated with?
Burkitt’s lymphoma
B-cell lymphoma
MS
What is Kawasaki disease?
Idiopathic self-limiting systemic vasculitis
What age group does Kawasaki disease most commonly affect?
6 months - 5 years
M>F
Children of which origin are most commonly affected by Kawasaki disease?
Asian esp Japanese and Chinese
Kawasaki disease is the most common cause of what in the developing world?
Acquired childhood heart disease
It has taken over from rheumatic fever
What are the characteristic features of Kawasaki disease? (6)
CRASH and burn
Conjunctivitis - bilateral and dry
Rash - widespread non-vesicular
Adenopathy - cervical LN >1.5cm
Strawberry tongue - inflammation of mucous membranes of mouth, lips, tongue
Hand - erythema, swelling and desquamation
Burn = prolonged fever of 39 degrees or more (5 or more days)
(or echocardiographic evidence of coronary artery aneurysms)
May not all be present at the same time
What are some other features of Kawasaki disease? (7)
1) Lethargy
2) Urethritis and sterile pyuria
3) d&v
4) Abdo pain
5) Myalgia
6) Arthralgia
7) Arthritis
Describe the type of rash and its course in Kawasaki disease
Polymorphic exanthema
Comes on within 3-5 days of onset of fever
What investigations are performed for Kawasaki?
No diagnostic test for condition - diagnosis made clinically
FBC - leukocytosis, neutrophilia, raised ESR and CRP (in acute phase)
Platelets elevated and marked thrombocytopenia in 2-3rd weeks
LFTS - elevated transaminases and bilirubin
Urinalysis - sterile pyuria
Abdo US - gallbladder distension
ECG - conduction abnormalities
How is Kawasaki managed?
Hospital admission
Aspirin
- One of the few cases in which aspirin is indicated in a child due danger of Reye’s syndrome
- 30-50mg/kg/day divided QDS
- For at least 6 weeks
- Reduces risk of thrombus
IV immunoglobulin
- 2g/kg as a single infusion over 12 hours
- Give in first 10 days (or much less effective)
What is the follow up management of Kawasaki disease?
Children who receive IvIg should have live vaccines (eg MMR) delayed for 3-11 months
Follow up echocardioloogy to determine if there have been any coronary artery complications
List some ddx of Kawasaki disease
Bacterial = strep / staph infection Viral = adenovirus / enterovirus / measles infection Others = drug reaction / SJS
What are some complications of Kawasaki disease? What is the mortality?
Coronary artery aneurysms (20-30%)
Coronary thrombosis
MI
Dysrhythmias
4% mortality
What causes measles?
Paramyxovirus
Leading cause of vaccine-preventable childhood mortality in the world
Is measles contagious?
One of the most contagious infectious diseases
NB is a notifiable disease
How is measles transmitted?
Airborne via respiratory droplets
These can spread to surfaces and the virus can remain transmissible for up to 2 hours
What is the incubation period of measles?
10-12 days
Infectivity lasts from 4 days before until 4 days after the rash appears
How does measles present?
Rash + 3 x C’s (cough, coryza and conjunctivitis)
1) Rash for at least 3 days
2) Fever for at least 1 day plus at least one of:
- Cough
- Coryza
- Conjunctivitis
3) Prodrome: 2-4 days with fever, cough, runny nose, mild conjunctivitis and diarrhoea
4) Koplik spots
5) Rash = morbilliform
+/- high fever and nonproductive cough
+/- swelling around the eyes and photophobia
Child ill and irritable (miserable disease) unlike other infectious diseases
What are Koplik spots?
Pathognomonic
On buccal mucosa
Small, red spots each with a bluish-white speck (like a grain of rice) in centre
Present in 60-70% during prodrome and for up to 2-3 days after rash disappears
Where does the rash first appear in measles?
Morbilliform = measles-like
Maculopapular rash
First on forehead and behind ears, then spreads to neck and spreads, involving trunk and finally limbs, over 3-4 days
Fades after 3-4 days
Leaves behind brown-discolouration (+/- fine desquamation)
How is measles confirmed?
Laboratory diagnosis:
- Salaviary swab or serum sample for measles-specific IgM within 6 weeks of onset
- RNA detection in salivary swabs
How is measles managed?
Uncomplicated measles is usually self-limiting and treatment is symptomatic - paracetamol, ibuprofen, fluids
Stay at home to limit spread
Monitor carefully for complications
What are some respiratory complications of measles?
Respiratory:
- Bronchopneumonia
- Giant cell pneumonitis
What are some neurological complications of measles?
Neurological = 3 different encephalitic diseases:
- Acute demyelinating encephalitis
- Subacute sclerosing panencephalitis (SSPA) occurs 4-10yrs after attack and characterised by slow progressive neurological degeneration
- Measles inclusion body encephalitis
What are some GI complications of measles?
GI:
- Diarrhoea
- Hepatitis
- Hypocalcaemia
What are some obstetric complications of measles?
Potentially fatal pneumonitis
Greater risk of miscarriage, prematurity an low birth weight (but not congenital malformation)
What are some other complications of measles?
Vitamin A deficiency and blindness
- Those with boardlerline vitA should be given a high dose vit A
Immunodeficiency
Acute OM
How is measles prevented?
MMR vaccine at 12 months
What is periorbital cellulitis?
Aka preseptal cellulitis
Infection of eyelid and surrounding skin anterior to the orbital septum
Alarming
What are the usual causes of periorbital cellulitis?
Staph aureus
H influenza type B
Staph epidermidis
Anaeorbes
What may periorbital cellulitis occur secondary to in older children?
Paranasal or dental abscesses
URTI and sinusitis
How does periorbital cellulitis present?
Often systemically unwell with:
- Acute onset of swelling, redness, warmth and tenderness of eyelid
- Eyelid oedema in the absence or orbital signs such as gaze restriction or proptosis
- Fever, malaise, irritability
- Ptosis
What features increase suspicion of orbital cellulitis?
Decreased visual acuity Proptosis External ophthalmoplegia Temp >37.5 Leuckocytosis
How is periorbital cellulitis investigated?
Clinical diagnosis
FBC may show leukocytosis
CT of sinuses and orbit +/- brain
MRI can help confirm cavernous sinus thrombosis
How is periorbital cellulitis managed?
Emergency referral to hospital - all children with suspected preseptal cellulitis should be considered to have orbital cellulitis until proven otherwise
ie repeated exams normal, good response to abx, normal CT
PO co-amoxliclav
- should show improvement within 24-48hrs
Possible IV ceftriaxone until response seen
What are some complications of periorbital cellulitis?
Progression of infection to orbital cellulitis
Lagophthalmos (inability to completely close eyelids)
Lid abcess
Cicatricial ectropion
Lid necrosis
What can orbital cellulitis lead to?
Untreated periorbital cellulitis may develop into orbital cellulitis with:
- Evolving ocular proptosis
- Limited ocular movement
- Decreased visual acuity
Rarely:
- Intracranial abscess formation
- Meningitis
- Cavernous sinus thrombosis
What is prophylactic management of peri-orbital cellulitis?
Prophylactic abx eg chloramphenicol for surgical and accidental trauma to eyelid
- QDS to clean wound for one week
Hib vaccine
What features do HIV infected infants usually present with?
Immunodeficiency:
- FTT
- Diarrhoea
- Candidiasis
- Hepatosplenomegaly
- Severe bacterial infections
What severe bacterial infections may affect HIV infected infants? (6)
1) Pneumonia
2) Septicaemia
3) Persistent pulmonary infiltrates
4) Pneumocystis jiroveci pneumonia (PCP)
5) TB
6) Systemic candida
How is HIV diagnosed in children?
Detection of HIV antibody = very specific and sensitive
However, passive maternal transplacental IgG obscures diagnosis in young infants as antibody may still be measurable up to 18 months in uninfected clinically well infants
Thus in children <2yrs, detection of HIV antigen is required to confirm diagnosis
How is HIV managed in children?
Antiviral drugs
Prophylactic abx
Viral vaccines
Where necessary, immune serum globulin
What is the prognosis of babies born to HIV-positive mothers?
20-30% become HIV positive themselves
How is vertical HIV transmission prevented?
Administration of combination antiretroviral therapy including zidovudine to HIV-infected pregnant women
Delivery by CS
At birth infant should receive zidovudine for 4 weeks
Avoid breastfeeding
List 3 AIDS defining conditions in a HIV +ve child
1) Lymphocytic interstitial pneumonitis
2) PCP
3) Candida oesphagitis
What is rubella? When is it concerning?
aka German measles
Mild illness and rash may not even be noticed
Concerning if it is contracted in first trimester
How may a fetus be affected if the mother contracts rubella in the first trimester of pregnancy?
Fetal death Congenital heart disease Mental retardation Deafness Cataracts
How does rubella present? What is the incubation period?
Rash appears in tiny macule on face and trunk and works its way down the body, lasts 2-3 days
- Suboccipital LN
(+/- generalised lymphadenopathy)
Generally well
+/- fever
Incubation period is 14-21 days
What are some complications of rubella?
Thrombocytopenia
Encephalitis
Arthritis (rare)
Devastating effects on fetus
