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Phase 2a - ICS > Invasive Meningococcal Disease > Flashcards

Invasive Meningococcal Disease Flashcards

1
Q

Definition of meningitis

A

Inflammation of the meninges which cover the brain and spinal cord (dura mater < arachnoid mater < pia mater)

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2
Q

Meningitis can be caused by:

A

Infection or by non infectious causes (rarer).

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3
Q

Infectious meningitis is usually caused by:

A

Bacteria - meningococcus or pneumococcus.

Viruses - coxsackievirus, echovirus, herpes virus, mumps virus, influenza, HIV etc.

Other: fungi, protozoa, and other parasites.

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4
Q

Non infectious causes of meningitis:

A

Medications - ABx (amoxicillin, trimethoprim), carbamazepine, lamotrigine, NSAIDs, ranitidine.

Cancers - melanoma, lung-, breast CA, lymphoma, leukaemia.

Autoimmune disease: SLE, Behcet’s syndrome (=BV inflammation throughout the body).

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5
Q

What are some of the differential Dx for acute bacterial meningitis?

A
  • Viral meningitis
  • Fungal meningitis
  • TB meningitis
  • Drug-induced meningitis
  • Sepsis from other causes
  • Encephalitis – inflammation of the brain
  • Brain abscess – collection of pus in the brain
  • Subarachnoid haemorrhage
  • Brain tumour
  • HIV infection
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6
Q

What is the causative agents of invasive meningococcal disease?

A

Infection with Neisseria meningitidis.

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7
Q

What are the characteristics of N. meningitidis?

A

Gram-negative diplococci.

Carried by 10-24% of the population.

Humans are only known reservoir.

Transmission by respiratory droplets/ naso-pharyngeal secretions.

Incubation period 2-10 days, usually 3-4 days.

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8
Q

What are the two manifestations of IMD?

A

Meningitis: localised infection of the meninges with ‘local’ symptoms.

Septicaemia: a systemic infection with widespread signs, and generalised organ damage.

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9
Q

How many serogroups of N. meningitidis are there?

A

12 - based on the capsular polysaccharide.

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10
Q

What are the six serogroups that cause the majority of disease?

A

A B C W X Y

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10
Q

Which are the vaccine preventable serogroups?

A

A B C W Y

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11
Q

How many cases of meningitis are there in a year?

A

9 million worldwide

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11
Q

Where is the highest concentration of infections?

A

In the sub-Saharan countries.

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11
Q

What are the numbers of bacterial and viral cases?

A

2500 bacterial (less likely to kill)
6500 viral (most likely to kills).

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12
Q

What is the fatality % and what does it depend on?

A

4-15% and depends on geographic location.

More prevalent during the winter.

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13
Q

How is N. meningitidis transmitted?

A

Transmitted by aerosol, droplets, or direct contact with secretions from the upper respiratory tract. Transmission usually requires either frequent or prolonged close contact.

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14
Q

Who are most commonly affected?

A

Commonly affects extremes of age (<2 months and >60 years) because of impaired or waning immunity. Another spike in incidence is also seen in adolescence and early adulthood (due to close contact/ social mixing?)

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15
Q

What are the risk factors of meningitidis?

A
  • 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
16
Q
A
17
Q
A
18
Q

What are the symptoms of meningococcal meningitis?

A

Fever

Stiff neck

Headache

Confusion

Increased photophobia

Nausea and vomiting

19
Q

How does meningitis present in babies?

A
  • Slow or inactive
  • Irritable
  • Vomiting
  • Feeding poorly
  • Have a bulging anterior fontanelle (the soft spot of the skull)
20
Q

Brudzinski’s neck sign

A

Reflexive flexion of the knees and hips following passive neck flexion.

While the pathophysiology for the hip/knee flexion is not completely understood, the theory is that hip and knee flexion occurs as an involuntary reflex to compensate and help reduce meningeal irritation. Passive neck flexion causes spinal cord movement and stretching of the meninges, resulting in pain for patients with meningitis. The thinking is that the involuntary hip/knee flexion occurs to create maximal relaxation of the meninges, reducing pain.

21
Q

What are the symptoms of meningococcal septicaemia?

A
  • Fever and chills
  • Fatigue
  • Vomiting
  • Cold hands and feet
  • Severe aches or pain in the muscles, joints, chest, or abdomen
  • Rapid breathing
  • Diarrhoea
  • Non blanching rash (petechiae)
  • In the later stages, a dark purple rash (purpura)
22
Q

Describe petechiae

A

Rash does not fade if you press the side of a clear glass firmly against the skin.

The rash can be harder to see on brown or black skin:

Check paler areas, such as the palms of the hands, soles of the feet, roof of the mouth, tummy, whites of the eyes or the inside of the eyelids.

23
Q

Describe purpura and DIC

A

Sepsis can cause Disseminated Intravascular Coagulation (DIC) – the activation of coagulation pathways that results in formation of intravascular thrombi (clots) and depletion of platelets and coagulation factors.
These clots can cause arterial occlusions leading to gangrene of extremities & auto-amputations (spontaneous detachment of an appendage from the body).

24
Q

Natural history of meningitis

A
  • Acute onset
  • Fulminating infection (death can occur rapidly) 5% in meningitis, 22% in septicaemia.

Prolonged and persistent coccaemia.

Survivors may have long term sequelae (deafness, seizures, motor deficit, amputations).

25
Q

Making the diagnosis of meningitis

A

Specimen should be collected ideally before initiating ABx treatments (but treatment should be started before Dx).

  • Blood culture and PCR
  • CSF for microscopy, culture and PCR
  • Aspirate from sterile sites
  • Throat swab for culture
  • Acute serum for enhanced surveillance.
26
Q

Is meningitis a notifiable disease?

A

Legal requirement to report it to regional UKHSA.

27
Q

What is needed to prevent further cases?

A

Contact tracing

Chemoprohylaxis

Vaccination

Alerting and informing close contacts and the public.

28
Q

What are the three forms of cases?

A

Confirmed (by lab). Immediate action.

Probable case (no lab confirmation, but meningococcal disease is most likely). Immediate action.

Possible (no lab diagnosis and other diagnosis is equally likely). No immediate action.

29
Q

Management of contacts

A

Close contacts are identified as :
* People living in the same household as the case

  • Anyone who slept overnight in the same household as the case in previous 7 days
  • Other household members if case stayed overnight elsewhere in previous 7 days
  • Intimate kissing contacts in last 7 days
30
Q

Describe the chemoprophylaxis:

A

ABx is given to eradicate throat carriage!

Ciprofloxacin (all age groups, even in pregnancy). Single dose, does not interact with oral contraceptives, readily available.

Rifampicin (alternative).

31
Q

In what time frame does the vaccination has to be offered?

A

In cases caused by vaccine preventable strains, vaccination would be expected to reduce the long-term risk of disease in close contacts within a week.

32
Q

Clusters

A

Rare <5% cases occur in clusters.
Most common in teenagers/youths.
Outbreaks occur in schools/colleges.

Action depends on:
Attack rate
Isolation of the same organism
Establishing a link between cases
Public anxiety

33
Q

What is the requirement for clusters in school?

A

Two probable or confirmed cases of the same type within 4 weeks.

34
Q

Global epidemiology

A

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.

35
Q

MenAfriVac

A

New conjugate Men A vaccine -> delivered to 284 million people, affordable 40c per dose.

36
Q

What are the causes of epidemic meningitis (Africa)?

A

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

37
Q

What are the three goals of the WHO towards a world free of meningitis?

A

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.

38
Q

Meningitis vaccines

A

Men A&C polysaccharide (travel to Africa).

Men C conjugate introduced into routine childhood schedule in 1999.

Also used for close contacts of confirmed Group C disease.

Quadrivalent Men ACWY – advised for the Hajj and close contacts of W135 or Y disease.

New Men B vaccine. 4CMenB protein vaccine (Bexsero®, GSK) In 2013, a four-component protein-based meningococcal B (4CMenB) protein vaccine (Bexsero®) was licensed authorised for children and adults in Europe. The vaccine is estimated to protect against 66-88% of MenB strains in England and Wales (Parikh et al., 2017). 4CMenB has been very effective in preventing MenB disease in infants and toddlers since its implementation into the UK national infant immunisation programme in September 2015 (Ladhani et al, 2020). 4CMenB can also protect against infection by sero groups other than MenB (Ladhani et al, 2021).

39
Q

Polysaccharide vaccines

A

Polysaccharide vaccines give only short term (3-5 years) protection.

Polysaccharide vaccines will not evoke an immune response in children under 2 years.

40
Q

Conjugate vaccines

A

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.

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.

41
Q

Meningitis B vaccine

A

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.

Phase 2a - ICS (43 decks)

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