Meningitis, MMR and flu vaccines

Question 1

Meningococcal- spread and characteristics of disease

Answer 1

Before the 1990s, Hib was the leading cause of bacterial meningitis
Bacteria transmitted from person to person by droplet infection of respiratory or throat infections, bacteria can be carried in the pharynx, average incubation period is 4 days

Question 2

Bacterial meningitis

Pneumococcal subunit vaccine

Answer 2

Cases of bacterial meningitis and septicaemia have halved in the past 25 years but there are still new cases in the UK every day
Pneumococcal subunit: vaccine against infection, contains polysaccharides from capsule conjugated to carrier proteins

Question 3

Meningococcal Meningitis

Answer 3

Even diagnosed early with adequate therapy, 5-10% of patients die typically with 24-48 hours of onset
May result in hearing loss, brain damage or learning disability in 10-20% of survivors
Watch out for tiny red or brown pin prick mark, which can change into larger red or purple blotches or blood blisters

Question 4

MMR

Answer 4

Measles- viral illness transmitted by droplet infection, can cause pneumonia, convulsions and encephalitis
Mumps- viral illness with swelling of parotid glands in neck, complications include meningitis and encephalitis
Rubella- maternal rubella infection in first eight weeks of pregnancy results in foetal damage in 90% of cases

Question 5

Measles

Answer 5

Before introduction of measles vaccine in 1968, around 100 children a year in England and Wales died from measles
MMR vaccine in 1988 with coverage >90%, notifications of measles fell progressively and spread of measles effectively halted by the mid 1990s

Question 6

MMR vaccine controversy

Answer 6

Scientific misconduct triggered health scare in 1998, MMR vaccination rates in UK decreased to 80%
In 2008 measles was declared endemic in England and Wales
Hundreds of thousands of children in the UK remain unprotected

Question 7

Predicted increases in complications with 10% fall in uptake

Answer 7

Measles: 100 cases of convulsions, 20 cases of encephalitis, 4 deaths
Mumps: 100 meningitis/ encephalitis, 800 deafness
Single vaccines may lead to poor uptake- in Japan single componenet vaccines, 79 deaths reported 1993-1997

Question 8

Myxoviruses

Answer 8

RNA core, a protein shell and a lipid membrane
Two glycoproteins: Haemagglutinin (H)- assists viral entry into the cells of the respiratory epithelium
Neuraminidase (N): facilitates release of new virions from infected cells

Question 9

Myxovirus serotypes

Answer 9

Serotype A viruses are the main human pathogen associated with epidemics and pandemics, since 1977 the commonly circulating subtypes are H1N1 and H3N2
Further variation within individual strains
Combinations of these proteins possible: 144
An individual may not have immunity against different strains of the same subtype

Question 10

Influenza- epidemics and pandemics

Answer 10

Influenza virus serotype A has a marked capacity to mutate- antigenic drift and antigenic shift
Pandemic is an epidemic of an influenza virus that spreads on a worldwide scale and infects a large proportion of the human population, may occur 2-4 times every century
Antigenic shifts associated with pandemics e.g. Spanish flu 1918-1920

Question 11

Pandemics

Answer 11

The 1918 flu pandemic was an unusually deadly influenza pandemic, the first of the two pandemics involving the H1N1 virus
It infected 500 million people across the world, including remote Pacific islands and the Arctic resulting in the deaths of 50 million

Question 12

Tamiflu

Answer 12

Oseltamivir phosphate = tamiflu

Neuraminidase enzyme competitive inhibitor

Question 13

Tamiflu action

Answer 13

Neuraminidase is essential for release of the virus from its host, with its activity being to hydrolyse the sialic acid end of molecule present on the surface of host cell membranes»> essential for virus mobility as it prevents aggregation of the virus and release from host cell membranes
Tamiflu is a sialic acid analogue, binds to active site of meuraminidase, prevents enzyme from carrying out activity
Hameagglutinin then binds, trapping the virus and preventing its spread

Question 14

Influenza vaccines

Answer 14

Who traditionally receives the flu vaccine: pregnant women, 65 and over, children who have previously been in hospital with a chest infection, anyone in a residential or nursing home, main carers, those with a chronic chest condition, heart condition, liver disease, kidney disease, diabetes, lowered immunity due to a disease or treatment, chronic neuro condition

Question 15

Flu vaccine serotypes

Answer 15

Vaccines tailored to the circulating serotypes of the flu virus
WHO predicts which serotypes will be in circulation
Surveillance 110 laboratories in 79 countries and four reference centres

Question 16

Flu vaccine for adult population

Answer 16

Killed- given by subcutaneous injection, manufactured from virus stock grown in chicken embryos
Vaccine effectiveness does not rapidly wane, however considerable antigenic drift from year to year in the circulating strains, so there is a need to immunise each year to cover the circulating virus

Question 17

Flu vaccine for children

Answer 17

Complications- bronchitis, pneumonia, middle ear infection, death
Live attenuated- nasal administration of six strains produced in VERO cells by genetic technology
Nasal spray flu vaccine is more effective than the injected flu vaccine in healthy children and avoids needle administration