Infectious diseases in childrenMeningococcal disease
Meningococcal disease remains one of those diagnoses we are all afraid of missing, but in its early stages we may not recognise it. In this article we review the pathology, behaviour, presentation, management and mystery of meningococcal disease, and what you should do if you suspect it
eningococcal disease remains one of those diagnoses we are all afraid of missing. We know it kills children, and adults too, and we know it’s not always easy to spot, and we know it develops very quickly. We are right on all fronts.
The terrible dilemma though is that if we do see the disease early its signs can be nonspecific and we may not recognise it for what it is.
In this article we explain the signs and symptoms of meningococcal disease and discuss that dilemma and how to manage it.
We also explain the logic of NOT treating contacts, to enable you to explain this to anxious parents when there is a case in your area.
HOW COMMON IS IT?
Since the introduction of vaccination against meningococcus group C, invasive meningococcal disease has become less common. This is good news, and there is a possibility that a vaccine against the group B meningococcus will soon be introduced.
Invasive meningococcal disease is not confined to children: it can affect any age group. In 2011–12 there were 614 cases of invasive group B disease in the UK. While over half of these cases were in children under five years,1 the remainder were fairly evenly spread with a small peak in adolescents and young adults. In 2012 there were 29 cases of invasive Group C meningococcal disease, against which we have been vaccinating since 2000, down from a peak of 955 in 1998–99. Other types (W135 and Y) caused a further 115 cases. Most infections occur during winter and early spring.
The possibility of meningococcal disease should therefore still remain at the forefront of the mind of the practice nurse seeing children and indeed young adults with acute illness. The organism remains a major cause of death – particularly in the developing world. It remains the case that any child with a fever and a purpuric rash has meningococcal disease until proved otherwise.
HOW INFECTION OCCURS
The behaviour of the meningococcus is not well understood. It harmlessly colonises the nose in around 10% of the population, but in occasional individuals it becomes ‘invasive’ and causes serious illness.2
For this reason, meningococcal disease is not simply caught in a predictable manner by person-to-person contact. The organism can be passed on, through saliva or very close general contact, but the patient must also be susceptible (in a way we don’t clearly understand) before they will develop invasive disease.
The pathogen
Meningococcal disease is caused by the bacterium Neisseria Meningitidis, also called the meningococcus.4–6 There are at least 13 meningococcus subgroups – B and C were the most common in the UK before the vaccine was introduced.1,3 Now group B is most common, with C, W135 and Y accounting for most of the rest. Group A is rare in the UK but is the epidemic strain worldwide.
The three common presentations are meningitis alone (50%), septicaemia alone (10%) and the combination of the two (40%).
Meningitis occurs when the organism invades the cerebrospinal fluid and inflames the meninges. Apart from causing severe meningitis with fitting, this can result in permanent brain and central nervous system damage, nerve palsies and loss of limbs.
Septicaemia alone has the highest case fatality of the three presentations (20%). It causes disseminated intravascular coagulation (DIC). This is a condition in which multiple tiny clots form in small blood vessels, blocking blood flow to major organs. This becomes so widespread that it uses up all the body’s clotting factors, so the blood fails to clot at all and bleeding begins. This includes bleeding into the skin, which is the cause of the purpuric rash. Circulatory collapse and multi-organ failure quickly follow.
The meningococcus can also, less commonly, cause pericarditis or myocarditis, both of which have a grave prognosis. A pneumonia can occur with sepsis and shock, often with concurrent influenza, and occasionally other organs such as the eye (endophthalmitis or conjunctivitis) or the bones (osteomyelitis) can be infected.
The process of infection
About 10% of us carry one of the common strains of meningococcus. Carriage rates are lowest in young children – 2% – and highest in teenagers and military recruits (around 25%). Carriage of N.Lactamica, which is believed to confer protection, is highest in young children.2 The presence of this organism is one of the reasons why widespread use of ‘preventative’ antibiotics around a single case may actually be harmful. By wiping out the protective strains we could in fact increase some children’s vulnerability to the invasive disease.
Acquisition of meningococcus in the nose is followed by either a variable period of carriage (mean 9 months) or by invasive disease, which usually develops within a week or two. It is rare for carriers to develop invasive disease.
There is no reservoir other than humans, and the organism dies quickly outside a human host. Transmission is by droplet spread or direct contact from carriers or those in the early stages of the infection. It is not as easy to pass on as the common cold.
Invasive disease
The window of opportunity for treatment between the first signs of invasion and catastrophic and overwhelming disease can be short – a few hours or even less. It is essential therefore to be vigilant; this is a disease none of us ever wants to miss.6
RECOGNITION
Practice nurses will see meningococcal disease rarely but must retain a high index of suspicion.
The classical presentation is of an unwell patient with a non-blanching rash and signs of septicaemic shock and/or meningitis.
The characteristic purpuric lesions are irregular in size and outline, have a necrotic centre and may be extensive (purpura fulminans), making the diagnosis obvious. However, isolated petechiae may appear and it is important to search the whole body in good light for further marks.
A petechial or purpuric rash in a febrile patient is a medical emergency as there is a significant chance of invasive meningococcal disease. All such patients should be given penicillin and sent urgently to hospital.
However, the rash is not invariably present: while 80% of bacteriologically confirmed cases will develop purpura or petechiae, the rest have either a maculopapular rash (13%) or no rash (7%), and these patients may also develop severe disease.4,6
Classical symptoms of invasive meningococcal disease are given in Box 1. However, not all patients will display all these features – indeed they would represent very late stage disease.
Early features
Early on, when there is the greatest chance of making a difference, features may be nonspecific. Onset can be mild or sudden: at first the rash may be maculopapular and blanching, or there may be no rash at all. Sore throat is not uncommon and may mislead you into diagnosing an upper respiratory tract infection (URTI). There may be just one petechial spot.
Have a high index of suspicion. Put this disease through your diagnostic sieve. Whenever you see a febrile individual ask yourself why this does NOT seem to be meningococcus. Consider it EVERY time.
Certain signs are particularly important – most of the signs and symptoms listed in Box 1 are unusual in children with simple URTI. Be very alert to things you don’t normally see.
Don’t be afraid of being too cautious. It is better to suspect meningococcal disease in a hundred people than to miss it in one.
It is always important to empower parents to seek immediate help should the clinical situation worsen, by giving them information on symptoms and signs to watch for, including the tumbler test (Box 2), and promising immediate review if there is further concern.
INITIAL TREATMENT
Mortality and long term sequelae are significantly reduced by early antibiotic therapy.5,6 Get medical assistance if you suspect the disease. Give immediate penicillin (intravenous [IV] if possible) or intramuscular (IM) (quadriceps) while arranging transfer to hospital by the quickest available means.
Penicillin-resistant meningococcus is rare in the UK, but an alternative is cefotaxime 80mg/kg IV or IM, which covers other bacterial diagnoses.
In known penicillin anaphylaxis use cefotaxime or chloramphenicol.
Accompanying children to hospital
Occasionally the GP or nurse might opt to accompany an extremely sick child to hospital. On the way you should give oxygen (particularly if there are signs of shock) and be prepared to administer CPR, remembering that in very young children it is important not to hyperextend the neck, which can occlude the airway. If you feel able to obtain IV access, and this does not delay transfer, then IV fluids may help prevent circulatory collapse (in children, 20ml/kg bolus).
PUBLIC HEALTH IMPLICATIONS
Confirmation and Notification
Confirmation of disease usually takes place in hospital, so the hospital will notify the Consultant in Communicable Disease Control (CDC) who will advise on contact treatment and monitor case clustering.
If penicillin has been given then blood culture is rarely positive, but throat swabs are positive in 50% of cases. Antigen detection, serology and polymerase chain reaction (PCR) tests on blood and CSF may also confirm diagnosis, but many cases are unconfirmed.
Positive throats swabs of household contacts are likely to be the same strain as the index case, especially if it is a child, so you may find that the CDC department has swabbed family members to help identify it. It is important to explain to the family that this is to try to prevent them catching it to forestall feelings of guilt.
Box 4 suggests the kind of information the CDC will offer. Check before offering your own advice in case there are circumstances of which you are unaware.
Chemoprophylaxis and prevention of spread
Chemoprophylaxis and immunisation are offered to all appropriate contacts, and while the CDC will advise on whom to treat, it is helpful for GPs and practice nurses to know how decisions are taken, as surgeries are frequently inundated with calls from anxious parents wanting antibiotics after a case.
There is evidence of increased risk – around 1% chance of invasive disease – for those in the same household. This is highest for the first seven days, probably the result of a combination of increased rate of exposure and genetic susceptibility. The risk of linked cases outside the household is low. Outbreaks do sometimes occur in college halls of residence and army training camps.
Chemoprophylaxis aims to eliminate carriage from all close prolonged contacts and it is given to those who have been in the same household for one week prior to the illness.
There is no evidence that chemoprophylaxis prevents further cases in nurseries – this age group is also more likely to be carrying the protective N. Lactamica, so treatment could be counterproductive. Healthcare workers generally need prophylaxis only if they have given mouth-to-mouth resuscitation.
Prophylaxis should ideally be given within 24 hours of the index case presentation and is supplied by the admitting hospital. Rifampicin is the drug of choice. Penicillin does not consistently eradicate nasal carriage –the index case should also receive eradication treatment when able to take oral medication.7
Conjunctivitis
Eye swabs may occasionally grow virulent strains of meningococcus. This, like nasal carriage, is potentially invasive and should be notified and contacts treated in the same way.
VACCINATION
The meningococcal conjugate group C vaccine gives long-term immunity and is now in widespread use.
Meningococcal plain polysaccharide A&C vaccine is still available and has a 90% response, but there is little response to group C under the age of 18 months or to group A under 3 months. Immunity lasts only a few years – less in young children. It is still the most appropriate for travellers, where the danger is mainly from group A.3,8
A group B vaccine, Bexserol® has been developed and is licensed in the US and Europe. This is not a live vaccine. It does not currently form part of the vaccination schedule – its cost effectiveness has not yet been fully evaluated, but analysis continues in 2014 and a decision is expected later in the year. The Irish government is also considering its introduction into the routine schedule. At present its use is advised during outbreaks and to persons considered at high risk (e.g. those without spleens, or with complement deficiency).
At present others may obtain the vaccine on private prescription.
REFERENCES
1. Public Health England. Laboratory confirmed cases of invasive meningococcal disease 1998-2010. Available at: http://www.hpa.org.uk/webw/HPAweb&Page&HPAwebAutoListName/Page/1201094595391?p=1201094595391 accessed January 2014
2. Gold 21 R, Goldshneifer I, Lepow ML, et al. Carriage of Neisseria meningitidis and Neisseria Lactamica in infants and children. J Inf Dis 1978:137;112-21
3. Immunisation against infectious disease 1996:Update CMO1999.
4. Meningitis Research Foundation. Meningococcal disease. http://www.meningitis.org/disease-info/types-causes/meningoccal-disease
5. Hart CA, Thomson AP. Meningococcal disease and its management in children. BMJ. 2006 Sep 30;333(7570):685-90.
6. NICE. Bacterial meningitis and meningococcal septicaemia, NICE Clinical Guideline 102 (June 2010) Available at: http://guidance.nice.org.uk/CG102
7. Zalmanovici Trestioreanu A, Fraser A, Gafter-Gvili A, et al; Antibiotics for preventing meningococcal infections. Cochrane Database Syst Rev. 2011 Aug 10;(8):CD004785. http://www.ncbi.nlm.nih.gov/pubmed/21833949?dopt=Abstract accessed January 2014
8. Meningitis Research Foundation: A new meningitis vaccine. http://www.meningitis.org/menb-vaccine accessed January 2014
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