Download Meningitis in service-age personnel

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Clinical
Meningitis in service-age personnel
Surg Lt R Miller, Surg Cdr K Houlberg
Abstract
The incidence of meningitis is declining in the UK population largely due to increased availability of vaccinations against
the most common bacterial strains. Acute bacterial meningitis, however, is a life-threatening condition and distinguishing it
from more benign causes of headache and fever is difficult in an operational environment due to limited access to diagnostic
tests. Despite medical advances, the case fatality rate in the United Kingdom in adults with invasive meningococcal disease
is 10.5%. Acute bacterial meningitis presents with the classical triad of fever, neck pain and altered mental state in less than
half of adults, and in the initial course of the disease it frequently mimics common viral illnesses. The aim of this article
is to discuss the recognition and management of meningitis with special emphasis on the deployed military environment.
Introduction
Meningitis is a serious infectious disease that, despite
modern Western intensive care and antibiotics, can have
a mortality rate of up to 10% (1). Early recognition and
prompt management of the condition is vital to reduce
mortality. However in its initial phase, meningitis often
presents similarly to a common viral illness (2). Given the
often remote and isolated nature of military operations,
it is important that medical personnel can accurately
differentiate meningitis from more benign conditions and
ensure patients receive prompt treatment and transfer to
specialist care facilities.
Meningitis is predominantly caused by viral or bacterial
invasion leading to inflammation of the meninges and
underlying cerebrospinal fluid (CSF). The term meningism
or a meningitic picture refers to symptoms of meningeal
irritation, which commonly include headache, photophobia
and neck stiffness (3). Viral meningitis is the most common
cause but is thought to be under-reported in the United
Kingdom (UK). The incidence of viral meningitis in
European studies is 7.6 per 100,000, largely secondary to
herpes and enteroviruses (4).
Most common bacterial causes of meningitis in adults (2):
1. Streptococcus pneumonia – known as pneumococcal
meningitis.
2. Neisseria meningitidis – known as meningococcal
meningitis.
Haemophilus influenza B meningitis has been largely
eradicated in adults due to the longstanding childhood
vaccination schedule. Listeria monocytogenes is more
common in those over 50, and is extremely serious in
pregnancy, so antibiotic choice should be adjusted in these
patients to cover this (5).
Meningococcal meningitis is further classified according
to its serogroup; to date, twelve capsular groups have
been identified (3). In England in 2013-14, 67% of cases
of meningococcal disease were serogroup B (1). The
serogroup is significant as vaccinations are widely available
against A, C, W135 and Y. A vaccine against serogroup B
has recently become available and there is controversy over
the UK Government’s delaying its introduction into the
routine childhood vaccination schedule due to discussions
with the manufacturer over cost (6). The ‘MenB’ vaccine
is currently only available to high-risk individuals, for
example asplenic patients (3). Meningococcal serogroup is
also relevant to prognosis; serogroup B had a case fatality
rate (CFR) of 4% in 2013/2014, whereas serogroup C had
a CFR of 15% (1).
Meningitis in its acute bacterial form is not only of concern
due to its high fatality rate; it is also a cause of significant
morbidity. Severe cases often leave patients with serious
long-term disabilities, for example seizures and neurological
deficits such as deafness, global cognitive issues and
memory loss. In one study of adults with communityacquired bacterial meningitis, seizures occurred in 17%.
Seizures were more common in pneumococcal meningitis
and those with a focal lesion (7). Rarely, if septicaemia
develops, peripheral gangrene may ensue, necessitating
amputation of digits or even limbs (8).
J Royal Naval Medical Service 2015, Vol 101.1
Service personnel, especially recruits, are at a higher risk of
contracting meningococcal disease. Biselli et al found the
reported incidence in recruits to be four to ten times that of the
general population. This is attributable to diverse geographic
backgrounds and crowded living conditions (9). Large
outbreaks of meningococcal disease in United States (US)
recruits during the late 1960s followed mass mobilisation
of troops for the Vietnam conflict. These risk factors are
shared with new university students; recommendations for
management of contacts in universities in the US are based
on data from military recruits (10).
The incidence of meningococcal disease also varies around
the world. During the dry season (December-June) in the
‘meningitis belt’ of sub-Saharan Africa, periodic epidemics
can lead to an incidence of 1,000 per 100,000 population
per year, predominately meningococcal serogroup A (see
Figure 1) (11). Even during non-epidemic periods, the rates
are several times higher than the UK at 5-10 per 100,000
(11). As a result of this high incidence, crowding and
diverse geographic origins, meningococcal vaccination
against serogroups A, C, W and Y is mandatory for religious
pilgrims to Saudi Arabia for the Hajj and Umrah (3) and
may be offered to all service personnel travelling to high
risk areas in accordance with latest guidance.
The rates of meningococcal disease reported to Public
Health England have decreased from 3 per 100,000
in 2004/2005 to 1 per 100,000 in 2013/2014 (1). It
predominately affects infants and children, although 40%
of cases in 2013/14 were amongst adults aged 20 and over.
Meningococcal meningitis is more common over winter
months; a third of all cases were reported between January
and March 2014 (1). Preceding Influenza A infection has
also been identified as a risk factor (12). Of note, although
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the overall CFR in England was 6%, among those over 25
the rate was 10.5% (1).
Clinical picture and diagnosis
Acute bacterial meningitis classically presents with a
triad of fever, neck stiffness and altered mental state.
This ‘typical’ presentation, however, only occurs in 44%
of patients in a prospective study of cases. Two or more
of headache, neck stiffness, fever and altered mental state
were present in 95% of cases (2). The key to diagnosis is a
high index of suspicion. Meningococcal septicaemia may
present without meningism and, therefore, this diagnosis
should be considered in any patient with signs of sepsis. A
non-blanching petechial rash, known as a ‘meningitic rash’
is strongly suggestive of meningococcal septicaemia but
may be difficult to see in dark-skinned individuals. It can be
demonstrated with the glass test (see Figure 2 below) (13).
Symptoms and signs of meningitis
The symptoms and signs of meningism are listed in Box
1. Box 2 lists additional features that may suggest a severe
infection and may warrant senior review and management
in critical care. In addition, a patient presenting with any of
the features in Box 3 also requires critical care review and
a Computed Topography (CT) of the head prior to Lumbar
Puncture (LP), as these patients may be developing raised
Intracranial Pressure (ICP) (14).
The differential diagnosis to be considered includes other
causes of a pyrexial illness (adding malaria if the patient
has travelled to an endemic area): intracranial abscess, subarachnoid haemorrhage, encephalitis and brain tumour.
Clinical investigations may help distinguish between
potential causes; however, a high clinical suspicion must
prompt early empirical treatment (12).
Figure 1. The Meningitis Belt of Sub-Saharan Africa.
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Clinical
Figure 2. The Glass Test showing a typical non-blanching petechial/purpuric rash.
Headache
Fever
Neck stiffness (absent in 30%)
Photophobia
Altered mental state
Kernig’s sign (lying supine with hips fully flexed –
passive knee extension elicits pain/resistance
Brudzinski’s sign (lying supine, patient asked to lift up
head – patient flexes hips)
Generalised petechial or purpuric rash that does not
blanche with pressure (see Fig 2)
Box 1. Signs and symptoms of meningism.
Rapidly prgressing rash
Respiratory rate <8 or >30 per minute
Heart rate <40 or >140 bpm
Prolonged capillary refill time > 4 seconds
Box 2. Features that may prompt senior review and management
in critical care.
Glasgow Coma Scale score <12, or fluctuating conscious level or fall >2 points
Focal neurological signs
Persistent seizures
Bradycardia with hypertension
Papilloedema
Box 3. Features that may indicate raised ICP.
Providing there are no signs of raised ICP and it does not
delay treatment, a LP should be performed and the CSF
analysed to determine the cause. Of course, this may not
be possible in a Role 1 setting. The typical CSF findings
in infectious meningitis are detailed in Table 1(4). CSF
analysis may be normal early in the disease so the LP may
have to be repeated. The findings may also be affected if
antibiotic treatment was commenced prior to LP.
A CT scan can also be used to identify the source of the
infection: for example, mastoiditis or a dural defect
predisposing to meningitis (15).
Box 4 lists additional further investigations that should be
considered for any patient with meningitis as these tests
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Cause of White blood cell
Predominant cell type
CSF: serum glucose
meningitis
count (x106 cells/l)
(normal ≥0.5)
Viral
50-1000
Mononuclear (may be >0.5
neutrophilic early in course)
Bacterial
100-5000
Neutrophilic (mononuclear <0.5
after antibiotics)
Tuberculous 50-300
Mononuclear
<0.3
Cryptococcal 20-500
Mononuclear
<0.5
Protein (g/l)
(normal 0.20.4)
0.4-0.8
0.5-2.0
0.5-3.0
0.5-3.0
Table 1. Typical CSF findings in meningitis.
Full Blood Count
C-Reactive Protein
Coagulation screen
Blood culture
Whole blood Polymerase Chain Reaction (PCR) for
N.meningitis
Blood glucose
Arterial blood gases
Chest radiograph
Urine, stool and nasal swab culture
Box 4. Further investigations that may be considered in cases of
suspected meningitis.
may aid the diagnosis, help to determine the severity of the
condition, and help to exclude the differentials (12).
raised ICP, shock or respiratory failure, a LP should be
performed prior to initiating antibiotics. If a LP cannot be
performed within 30 minutes, then antibiotics should be
given immediately (14).
CSF analysis can then be used to determine the infective
cause and treatment adjusted accordingly with specialist
microbiological advice. Clinical Guidelines for Operations
(CGOs) advise for empirical treatment of suspected
bacterial meningitis that Ceftriaxone 2g 12 hourly should
be initiated prior to CSF culture results. If the patient is
penicillin-allergic then Meropenem 2g IV can be given
8-hourly. If the patient is considered at risk of penicillinor cephalosporin-resistant pneumococcal infection (for
example, current inpatients or patients with recent hospital
stays) it is recommended that Linezolid 600mg IV 12
hourly is added pending CSF culture and sensitivity results
(16).
Clinical management
In the Role 1 or pre-hospital environment, the priority
is to rapidly identify and arrange transfer of the patient
to secondary care as an emergency. Patients should be
assessed using an Airway-Breathing-Circulation (ABC)
approach with particular attention paid to neurology (14).
The airway should be secured, high flow oxygen given
and intravenous (IV) access established. If the patient
has a clinical picture consistent with meningococcal
septicaemia and a ‘meningitic rash’, then they should be
given 1.2g Intramuscular (IM) or IV Benzylpenicillin prior
to transfer. If the patient has a history of anaphylaxis to
penicillin or if giving the antibiotic would delay transfer,
then Benzylpenicillin should not be given (16).
If a bacterial pathogen has been identified, in particular
in pneumococcal meningitis, and appropriate antibiotic
treatment is initiated, then corticosteroids (Dexamethasone
0.15mg/kg QDS for four days) may be given with or just
after the first dose of antibiotic (14).
If urgent transfer to hospital or a Role 2 care facility is
not possible, then patients should be managed with IV
Ceftriaxone 2g twelve-hourly, fluid resuscitation and
supportive treatment. If the patient shows signs of raised
ICP (see Box 3) then patients should have careful volume
restriction and be nursed with 30˚ head elevation (14).
Management of contacts
All causes of meningitis in the UK should be reported to
the Consultant in Communicable Disease Control (CCDC)
or Public Health specialist. If meningococcal disease is
suspected or confirmed, the CCDC will complete contract
tracing (17). Antibiotic prophylaxis should be offered to all
individuals with prolonged close contact with the patient
in the preceding seven days before symptoms developed,
for example those living in the same household, sharing a
Once transferred to hospital patients should be examined
for features of raised ICP and septic shock. If there is no
Raised ICP, septic shock and respiratory failure indicate
a severe cases of meningitis that will require immediate
empirical treatment with IV Ceftriaxone 2g until culture
and sensitivities are available, along with critical care
management including intubation, ventilation, inotropic/
vasopressor support, careful fluid balancing and good
glycaemic control (14). Throughout their care, all patients
require careful monitoring and repeated review.
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kitchen, dormitory or partners. In a service environment,
those sharing a mess deck or accommodated in barracks with
the patient should be treated. Antibiotic chemoprophylaxis
should be started as soon as possible, ideally within 24
hours. Contacts of a case of N. meningitidis may be given
a stat dose of Ciprofloxacin 500mg whereas those exposed
to Haemophilus Influenzae B require a 4 day course of
Rifampicin 600mg.
In addition, contacts of a patient with meningococcal disease
serogroup A, W135 or Y infection should be offered the
quadrivalent conjugate vaccine. Contacts with serogroup
C who were only immunised in infancy or completed the
course more than one year previously, may be offered a
booster MenC vaccine dose (17).
Management of viral meningitis
Viral meningitis may only be diagnosed in a hospital
environment, based on CSF analysis excluding other
infective causes, and is generally managed supportively
with antipyretics, analgesics, hydration and nutritional
support. There is increasing evidence that aciclovir early
in the clinical course may be beneficial in treating herpetic
meningitis. If Herpes simplex encephalitis is suspected
then IV aciclovir should be started promptly. Although
generally more benign, all cases of viral meningitis should
be reported and followed up as necessary as patients may
develop long-term neuropsychiatric complications (4).
Occupational considerations in the Royal Navy and UK
Armed Forces
Ideally, early appropriate occupational management
of service personnel should limit exposure to invasive
bacterial meningitis through timely immunisation against
the majority of bacterial causes, noting that those who spent
their childhood years outside of the UK may not have been
previously vaccinated. When operating abroad, medical
personnel should monitor travel health websites such as
National Travel Heath Network and Centre (NaTHNaC)
to identify epidemics and assess the risk to their patients
accordingly.
Meningitis of any cause is a serious disabling condition
that will leave patients unfit for any work initially. The
prognosis in viral meningitis is generally excellent. Patients
usually make a full recovery, generally within ten days, and
may well be able to return to work after this time (4).
Occupational prognosis in bacterial meningitis depends on
the pathogen and adverse signs such as severe neurological
impairment on presentation. Pneumococcal disease has the
worst prognosis (18). Counterintuitively, patients presenting
Clinical
with meningococcal septicaemia with meningitic signs
have a better prognosis than those without.
Patients should be assessed on an individual basis,
depending on their diagnosis and any residual deficits, and
their Joint Medical Employment Standard (JMES) adjusted
accordingly. Any permanent neurological deficit, in
particular hearing loss or seizures, may well trigger referral
to the Regional Consultant in Occupational Medicine and
thence to the Naval Service Medical Board of Survey.
Patients should also be considered with their occupational
role in mind and specialist referral may be considered for
individuals such as divers or aircrew (19).
Conclusions
Meningitis is a serious medical condition that requires
prompt recognition and treatment. Although more commonly
secondary to a viral infection, bacterial meningitis has a
high CFR, so all cases should be managed as bacterial until
proved otherwise, and transferred to secondary care. The
incidence of bacterial meningitis is declining rapidly due to
increasing immunity rates and new vaccinations covering
the majority of bacterial causes. However, it is important
to consider at-risk populations: the unvaccinated, recruits
accommodated in crowded conditions and those operating
in parts of the world where meningitis incidence is much
higher.
Bacterial meningitis only presents with the classic triad of
fever, neck stiffness and altered mental state in less than
half of the adult population, so it is important to have a
high index of suspicion and initiate treatment in the Role 1
environment in patients with fever, neck stiffness, headache
or global reduced consciousness. All Role 1 facilities
should have Benzylpenicillin available to be given IM
without delay in patients with features of meningococcal
disease prior to transfer.
In the hospital environment, the severity of the condition
should be assessed using an ABC approach. Patients with
a meningococcal septicaemia picture or raised ICP should
not have an LP and should be managed in critical care.
More stable patients should have an LP and the CSF sent
for analysis to determine the cause. All patients should
receive Ceftriaxone 2g IV as a priority.
All cases should be reported to CDCC, and for those with
bacterial meningitis contact tracing should be undertaken,
with chemoprophylaxis given to those at risk of exposure.
It is important to follow up all patients and to consider longterm sequelae, which may affect occupational disposal.
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Authors
Surgeon Lieutenant R Miller
HMS Sultan Medical Centre
[email protected]
Surgeon Commander K Houlberg