Lecture 38: Fever in Children or Fever & Rash Vaccine Preventable Disease

Question 1

What are the different types of Vaccines?

Answer 1

1) Live Attenuated Vaccines

Live attenuated vaccines are made out of either live viruses or live bacteria

2) Inactivated Vaccines

Inactivated vaccines are made out of either whole viruses or bacteria, or fractions of either.

• Fractional vaccines are either protein-based or polysaccharidebased.
  
  • Protein-based vaccines include toxoids (inactivated bacterial toxin) and subunit/subvirion products
  • Recombinant vaccines
  • Polysaccharide-based vaccines are composed of pure cell-wall polysaccharide from bacteria
  • Conjugate polysaccharide vaccines are those in which the polysaccharide is chemically linked to a protein

Question 2

What type of information is required when taking a vaccination history?

Answer 2

Immunisation up to date (UTD). What does that mean? I want detail!

• Need to know schedule & the age they actually got their needles
• Where were they born, have they been overseas or had someone caring from them from overseas
• Is there an outbreak at the moment?

Question 3

Describe the schedule of vaccination for Measles

Answer 3

Regular 2 dose schedule 15 months and 4 years with live attenuated viral vaccine

Question 4

Describe Measles

Answer 4

Measles is highly infectious

• Prodrome (early symptoms) 2-3 days of fever, conjunctivitis, coryza (acute inflammation of mucous membrane of the nasal cavities), Kopliks spots
• Characteristic rash day 3-7, most unwell at time of rash

Complications are common:

• 10% secondary infection (ear infection, pneumonia, croup)
• 1/1000 encephalitis (15% die, 25-35% long term damage)
• Rarely subacute scelerosing panencephalitis (SSPE) 7-10 years later, which is a degenerative fatal nervous system disease from persistent measles infection

Question 5

Describe the infant vital signs

Answer 5

Infant BP: 80-100 and 55-65

Question 6

Bacterial meningitis is caused by…

Answer 6

• Streptococcus pneumoniae
• Neisseria meningitidis
• Haemophilus influenzae type b (now rarely seen due to vaccination)

Question 7

What are the features that allow us to differentiate between the 3 bacteria that can cause mengingitis?

Answer 7

Bacterial meningitis is caused by:

• Streptococcus pneumoniae
  
  • ​Gram positive
  • Cocci
• Neisseria meningitidis
  
  • ​Gram negative
  • Cocci
• Haemophilus influenzae type b (now rarely seen due to vaccination)
  
  • Gram negative
  • Bacilli

Question 8

Describe Polysaccharides (sugar coating around bacteria) and vaccines

Answer 8

Young children (age < 2years) produce very weak antibody responses to polysaccharide antigens

Poor immunological memory to polysaccharide antigens

Therefore these bacterial vaccinations use connjugate vaccines.

Question 9

Describe Conjugate Vaccines

Answer 9

Conjugate vaccines are 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 <2 years of age

Good production of memory cells

Question 10

Describe Haemophilus Influenzae Type B bacteria

Answer 10

Haemophilus Influenzae Type B

A serious disease almost eradicated by immunisation in the developed world. It is Gram-negative rod.

• Typed by capsule.
• Type b is most important and prior to vaccination caused 95% of H. flu serious disease

Question 11

Describe the HiB vaccine

Answer 11

Induces antibody to PRP capsule, protects against invasive disease

Initial, HiB vaccines were unconjugated and poorly immunogenic.

Conjugate vaccines are now available. It is PRP polysaccharide 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%

Conjugate HiB Vaccine In NZ

Conjugate HiB introduced in 1994. Given at 6 weeks, 3 months, 5 months and 15 months

• Still occasional cases. Most children who developed invasive HiB disease since 2000 have been incompletely or unimmunised.
• Prior to Hib vaccine, 1/350 NZ children developed invasive type B infection

Question 12

Describe the features of Streptococcus Penumoniae

Answer 12

Streptococcus pneumoniae colonises nasopharynx 5-10% of adults, 20-40% children at any one time

Invasive disease is common in children <5 years, especially <2 years and adults >65 years. Worldwide responsible for million deaths/year for children <5 years.

• Bacteraemia, pneumonia, bacteraemia
• Otitis media, sinusitis

Streptococcus pneumoniae is Gram-positive coccus

• Polysaccharide external capsule
• 90+ serotypes have been identified based on different capsular polysaccharides
  
  • Therefore trying to make a vaccine against all the serotypes is hard.
• Capsule plays essential role in escape from phagocytosis

Question 13

Describe Invasive Pneumoccal Disease

Answer 13

Invasive Pneumococcal Disease (IPD)

Invasive pneumococcal disease (IPD) is pneumococci isolated from usually sterile sites, e.g. cerebrospinal fluid (meningitis), blood (bacteraemia) or pleural space/lung tissue (pneumonia)

• In children, major cause of mortality and morbidity < 2 yrs. Most common bacterial cause of otitis media.
• For all age groups, commonest cause of bacterial pneumonia. Meningococci and pneumococci most common causes of bacterial meningitis.

Question 14

Describe the features of Streptococcus Penumoniae Vaccines + who you give it to.

Answer 14

Strep. pneumoniae vaccine is a polysaccharide vaccine ($20). It contains _capsular polysaccharid_e from each of the 23 most common infecting serotypes

• Used in splenectomy, immunosuppressed, chronic illness
• Elderly (>65 years recommended not funded)
• Not useful in those younger than 2 years of age

Question 15

Describe Neisseria Meningitidis

Answer 15

As for Hib and pneumococci, polysaccharide capsule is an important virulence factor

N. meningitidis is an exclusive human pathogen transmitted by droplets from colonized upper respiratory mucosal membranes.

• 12 serogroups based on capsular polysaccharide: A, B, C, 29E, H, I, K, L, W135, X, Y, and Z.
• 90% of cases of meningitis are caused by strains belonging to serotypes A, B and C (occasionally W135, Y).
• All three serotypes can cause epidemics.
  
  • NZ meningococcal epidemic started in 1991
  • Serogroup B is majority of infections (subtype P1,4)
  • Menz B vaccine is introduced mid 2004

Question 16

What are the current Meningococcal Vaccines that are available now

Answer 16

Meningococcal Vaccines

Both purified capsular polysaccharides and c_onjugate protein vaccine_s made for serogroups _A, C, W135 and Y, t_he same principles as for Hib and pneumococcal glycoconjugates

• Meningococcal C conjugate vaccine is on the schedule in Australia and UK, available to buy in NZ
• New MenB vaccine available in UK/US (to buy)

Question 17

Describe the MenzB vaccine in NZ

Answer 17

MenzB Vaccine

The vaccine is made out of outer membrane inside capsule. Two outer membrane proteins (Por A and Por B) are main components of MenZ B vaccine.

Antibodies to these proteins can cause complement activation and phagocytosis

Question 18

A 6 month old Chinese/Samoan baby girl is brought in as she has a fever of 39°C. She has been u_nwell for 2 days_, has a rapid pulse and has not had a wet nappy for 24 hours

What are the differentials?

Answer 18

• Recognise the signs and symptoms of vaccine preventable disease including measles, pertussis meningococcal and pneumococcal disease
• Recognise rashes commonly associated with infection