invasive meningoccal disease Flashcards
what is meningitis
inflammation of the meninges (membranes) which cover the brain and spinal cord
what are the 3 layers of meninges
dura mater
arachnoid mater
pia mater
usual causes of meningitis
infection with
- bacteria
- viruses
- less common ones: fungi, protoza &other parasites
non infectious causes of meningitis
- medications eg antibiotics, NSAIDS
- cancers eg melanoma, lung cancer
- autoimmune diseases eg SLE, Behcets syndrome
differential diagnoses for acute bacterial meningitis
• Viral meningitis
• Fungal meningitis
• TB meningitis
• Drug-induced meningitis Loading…
• Sepsis from other causes
• Encephalitis – inflammation of the brain
• Brain abscess – collection of pus in the brain
• Subarachnoid haemorrhage
• Brain tumour
• HIV infection
what is invasive meningococcal disease
infection with NEISSERIA MENINGITIDIS
describe neisseria meningitidis
gram negative dipolococci
carried by 10-24% of population
humans are the only known reservoir
describe transmittion of neisseria meningitidis
by respiratory droplets/nano-pharyngeal secretions
usually requires either frequent or prolonged close contact
incubation period of neisseria meningitidis
2- 10 days
usually 3-4 days
2 main manifestations of neisseria meningitidis
meningitis - a localised infection of the meninges with ‘local’ symptoms
septicaemia - a systemic infection with widespread signs, and generalised organ damage
how many sero groups of neisseria mengitidis
12 sero groups based on the capsular polysaccharide
when is meningitis more prominently
winter
which is worse - bacterial or viral meningitis
viral
risk factors for invasive meningococcal disease
Extremes of age
• Immunocompromised (e.g. HIV) or immunosuppressed (e.g. chemotherapy)
• Asplenia/hyposplenia
• Cancer – people with leukaemia and lymphoma
• Sickle cell disease
• Organ dysfunction – e.g. liver or kidney disease
• Cranial anatomical defects
• Cochlear implants
• Contiguous infection - e.g. otitis media, sinusitis, mastoiditis, pneumonia
• Smokers
• Living in overcrowded households, college dormitories or military barracks
• People who have had contact with a case
• Travellers abroad to high risk area - increased risk of encountering the pathogen
classic symptoms of meningococcal meningitis
fever
stiff neck
headache
confusion
increased sensitivity to light
nausea and vomiting
babies symptoms of meningococcal meningitis
slow or inactive
irritable
vomiting
feeding poorly
bulging anterior fontanelle - soft spot of the skull
meningococcal septicaemia symptoms
- fever and chills
- fatigue
- vomiting
- cold hands & feet
- severe aches or pains in the muscles, joints, chest or abdomen
- rapid breathing
- diarrhoea
- nom blanching rash (petechiae)
- in later stage - a dark purple rash (purpura)
what happens if you press a glass against a petechiae rash
the rash does not fade if you press the side of a clear glass firmly against the skin
what can sepsis cause
Disseminated intravascular coagulation - the activation of coagulation pathways that results in formation of intravascular thrombi and depletion of platelets and coagulation facors
these clots cause arterial occlusionsleading to gangrene of extremities & auto amputations
natural history of disease
acute onset
fulminating infection - occurs quickly, escalates uickly
prolonged and persistent coccaemia (bloodstream infection)
surovioprs may have long term complications -eg deafness, amputations, seizures
what specimens do you take on hospital admission before initiating antibodies
blood sample for culture & PCR
CSK for microscopy, culture and PCR
for other localised infections - aspirate from sterile site for microscopy, culture and PCR
throat swab for culture
additional samples for enhanced national surveillance
why do you notify public health about the disease
To find out how the patient caught it
when do you notify
on suspicion
don’t wait for confirmation
what action can public health take
contract tracing
chemoprophylaxis
vaccination
alerting and informing close contacts and the public
define confirmed case for public health purposes
clinical diagnoses with lab confirmation (immediate pH action)
define probable case for public health purposes
clinical case with no lab confirmation, but meningococcal disease is most likely (immediate PH action)
define possible case for public health purposes
no lab confirmation and other diagnoses is equally likely (no immediate PH action)
define close contacts
- people living in the same household as the case
- anyone who slept overnight in the same household in previous 7 days
- other household members if case stayed overnight elsewhere in previous 7 days
- intimate kissing contacts in lass 7 days
what type of antibiotics is given
chemoprophylaxis
why are antibiotics given for meningitis s
to eradicate throat carriage
main type of antibiotic given
ciprofloxacin
single dose
doesn’t interact well with oral contraceptives
readily available
alternative antibiotic given
rifampicin
what happens if there is delayed report of a case
offer prophylaxis to household contacts up to 4 weeks after case became ill
what do you give for meningococcal conjunctivitis
prophylaxis
further public health actions
Contact school/nursery/university etc
Standard letter to warn and inform
Customised letter if unusual circumstances e.g. death
Offer leaflets
Offer information/support/helpline
Media handling
do we get cluster cases in this country
no its rare less than 5%
most cases are individual
what age range is most popular
teenagers / youths
outbreaks occur in schools/colleges
what does action depend on
attack rate
isolation of the same organism
establishing a link between cases
public anxiety
describe clusters in schools
Two probable or confirmed cases of the same type within 4 weeks
Need to define the risk group
Class, Year group, or Whole school
describe clusters in the community
Look for links
Define an at risk population
Calculate age-specific attack rates Loading…
No specific threshold, but look for a substantial increase
describe global epidemiology
Occurs sporadically, and in small clusters worldwide
Seasonal variation: October-May in Northern
Hemisphere Groups B&C most common in Europe and Americas
Group A most common in Africa and Asia
causes of epidemic meningitis s
• Dry season (Dec – Jun) dust laden winds
• Upper Respiratory Tract Infection (URTI) due to cold nights
• Decrease in “local immunity” in pharynx
• Overcrowded housing
• Large population displacements due to pilgrimages and traditional markets
• Herd immunity leads to cyclical epidemics
3 goals of WHO to defeat meningitis by 2030
Elimination of bacterial meningitis epidemics
Reduction of cases of vaccine-preventable bacterial meningitis by 50% and deaths by 70%
Reduction of disability and improvement of quality of life after meningitis due to any cause
4 types of vaccines for meningococcal
MenC conjugate vaccine
Hib/MenC conjugate vaccine
MenACWY quadrivalent conjugate vaccine
multi component protein vaccine (MenB)
immunisation schedule for meningococcal routine vaccination
8 weeks
16 weeks
one year
14 years
describe polysaccharide vaccines
- Polysaccharide vaccines give only short term (3-5 years) protection
• Polysaccharide vaccines will not evoke an immune response in children under 2 years
describe conjugate vaccines
Polysaccharide-conjugate vaccines are immunogenic across all ages. In infants and young children, conjugation increases the immunogenicity of the vaccines compared to polysaccharide only vaccines
• also prevents acquisition of carriage so interrupt transmission of meningococci to others and induces population protection
• Serogroup specific and do not provide any cross-protection against other meningococcal serogroups
describe meningitis B vaccine
Biologically difficult to produce. Antigenically similar to brain protein.
• In UK, multiple strains of serogroup B, so not easy to produce a “one size fits all” vaccine.
• Group B vaccine developed, given routinely for infants, but issues with uncertain effectiveness and high costs
• Not used in outbreaks
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