Fever and Rash; Vaccine Preventable Disease Flashcards
What types of Vaccines do we use
What do you need to ask the parents in terms of a vaccine-preventable disease history?
What is this? what are the signs and issues of this disease?
Measles! (highly infectious)
- 2-3days of fever, conjunctivis, coryza, Kopliks spots (in mucosa of cheek, hard to find)
- Characteristic rash day 3-7, widespread and diffuse, most unwell at time of rash
- Complications commone; 10% get secondary infection (ear, pneumonia, croup)
- 1/1000 encephalitis (15% die, 25-35% long term damage
- Rarely SSPE: 7-10 years later; degenerative fatal NS disease from persistent measles infection
When do we vaccinate for measles
At 15 months then a booster at 4 years, as 10% of people don’t seroconvert on the first dose. Therefore we need the second dose to ensure >95% of people are immune
Do we still get measles outbreaks?
Yes, although the last epidemic was 1991, we still yes small outbreaks, mainly in people who either
- are not vaccinated
- or only had one dose!
2013: Lots in Waikato and Auckland, spread quickly accross the country
What is this rash indicative of
Purpura rash, that is indicative of Meningitis.
Meningicoccal Spesis
Spinal Fluid shouldn’t have WBC in it.
87% polymorphs (neutrophils)
Low Glucose: As glucose is what’s required for bacteria to survive, low glucose indicated infection
Gram negative coccobaccili: Grew Haemophilis influenza
Seizures in the first 48hrs of hospitalisation
Day 3 Head CT: bilateral extra axial collections and meningeal enhancement consistent with meningitis; ‘empiema’
Follow up: long course of IV AB’s
What is Bacterial meningitis and what is it caused by?
Meningitis: inflammation of the meninges (membrane) surrounding the brain
Bacterial meningitis caused by:
- S. pneumoniae***
- N. meningitidis
- Haemophilis influenzaae type b now rarely seen due to vaccination
- Different pathogens occur at different ages: eg newborn babies; Grp B streptococcous, gram negatives*
- also Viral agents (herpes simplex and enterovirus) and Tuberculosis*
What is the main part that is targetted of the different pathogens from the meningitis vaccines
They all have a distinctive sugary capsule coating that is the immunogenic part of them.
Why are polysaccharide vaccines not very good?
Polysaccharides have weak immunogenicity so we (especially young children age <2yrs) produce very weak antibody responses to polysaccharide antigens
We have poor immunological memory to polysaccharide antigens
How have polysaccharide vaccines been revolutionised?
But the introduction of Conjugate vaccinations
- Taking the long polysaccharide sugar chains on the capsule of the bacteria, taking them off and conjugating them into something more immune stimulating.
- Conjugate sugar to a protein and the IS will remember that life-long!!
Describe Conjugate Vaccines!
- Polysaccharide attached to a carrier protein
- taken up by B cells
- Carrier protein digested and antigen presented to helper T cells
- Converts a T-cell-independent carbohydrate antigen into a T-cell-dependent antigen
- Good immunogenicity in those 2yrs of age
- Good production of memory cells
How has conjugate vaccination helped Haemophilus influenza and what is HI?
A serious disease almost eradicated by immunisation in the developed world
- Gram-neg rod
- Typed by capsule
- Tybe b most important and prior to vaccination caused 95% of H.flu serious disease
Hib Vaccine
- Induces antibody to PRP capsule, protect against invasive disease
- Initial HiB vaccines were unconjugated and poorly immunogenic
- Conjugate vaccines now available
- PRP polysachareide linked to immunogenic protein
- Effective in young infants
- Reduces or eliminates nasopharyngeal colonisation
- If vaccine uptake is >80% invasive disease is virtually eliminated in a population
- Protective efficacy of vaccine >98%
- Given at 6 weeks, 3 months, 5 months and 15 months
- Still a few cases and most of these have been incomplelety or unimmunised
Streptococcus pneumoniae is a causative agent of Meningitis. Describe it as a bacteria
- Colonises the nasopharynx 5-10%of adults, 20-40% children at any one time
- Gram + coccus with a polysaccharide external capsule
- has >90 serotypes of capsular sugar which makes it really hard to vaccinate for! Causes escape of phagocytosis
- Invasive disease common in children <5yrs especially <2yrs and adults >65yrs
- Bacteraemia, sinusitis
- otitis media, pneumonia
- worldwide responsibility for million deaths/yr for children <5yrs
For many years, we used the polysaccharide vaccine ($20), what is this and why is it shit?
- Contains capsular polysaccharide from each of the 23 most common infecting serotypes
- used in splenectomy, immunosuppresed, chronic illness
- poorly immunogenic, doesn’t cause a big response, BUT for people with a poor immune system
- elderly (>65yrs recommended not funded)
- NOT useful in those younger then 2yrs; because you don’t have the ability to respond!
so the conjugate vaccine is finding immunogenic protein carrier (toxoids) and conjugating them to polysaccharides; these became part of the vaccine scheme in 2008
What’s the prominent age group of meningitis patients?
Adolescent disease; mainly all <1yr, a smaller peak at 1-4yr
What are the main anti-vaccine arguments?
