The importance of Hib immunisation in infancy and high-risk groups
Although routine Hib immunisations have significantly reduced the number of infants contracting Hib meningitis Dr Siba Paul and Dr Lilias Lamont advise community practitioners they should remain vigilant.
Dr Siba Prosad PaulMBBS, DCH, MRCPCH ST4 in Paediatrics, Great Western Hospital, Swindon Honorary Paediatric Registrar, St Richard's Hospital, Chichester
Dr Lilias Susan LamontMRCP, FRCPCH Consultant Paediatrician, St Richard's Hospital, Chichester
The incidence of Haemophilus influenzae type b (Hib) invasive disease has declined significantly in the United Kingdom since the introduction of routine Hib immunisation. However life-threatening Hib infections such as meningitis and epiglottitis may still occur, especially in the unimmunised and immigrant children. A case of Hib meningitis is a reminder that the threat of invasive Hib disease has not been totally eliminated.
Early diagnosis and treatment of bacterial meningitis (including Hib meningitis) is essential to prevent death and serious neurological sequelae. Health visitors play a vital role in encouraging parents to have their children immunised without any avoidable delays and in providing reliable information as necessary to back up this advice. Enquiring about immunisation status of all children new to a practice and addressing any omissions, should be routine; immigrant children (and their parents) may be particularly vulnerable and more likely to be inadequately immunised.
■ Haemophilus influenzae B meningitis is rare in the post-vaccination era, especially in the industrialised world
■ However Hib meningitis can still occur, particularly in unimmunised and immigrant children
■ Clinical suspicion of meningitis should be followed by a lumbar puncture in a clinically stable child
■ Treatment of Hib meningitis is likely to combine intravenous antibiotics and high dependency care
■ Long term follow up should include immunisation, hearing tests and developmental checks
■ Health visitors can facilitate immunisations for immigrant children and instances where parents refuse vaccination by counselling and providing information
The recent death of a young female university student from meningitis, shortly after feeling unwell, highlighted the fact that meningitis is still a dangerous and frightening illness. Meningitis has a reputation for spreading rapidly if not contained quickly, particularly in busy environments like schools and colleges, where groups of people cluster together. About 50 different types of bacteria can cause meningitis in children, although the main types are Meningococcus, Pneumococcus, Haemophilus influenzae type b (Hib), group B Streptococcus, Mycobacterium tuberculosis, Escheria coli and Listeria monocytogenes1,2. Hib was the leading cause of bacterial meningitis in children until the Hib conjugate vaccines were introduced2. Hib is particularly vicious as it can cause a range of serious invasive illnesses including meningitis, pneumonia, pericarditis, epiglottitis, septic arthritis and cellulitis3.
Identification of high-risk children
Although health care practitioners will rarely see an infant presenting with a case of Hib meningitis, they should be suspicious of this in non-immunised or immigrant children from developing countries. We describe the case below of a previously healthy seven week-old infant, who presented with fever and being non-specifically unwell, who was found to have a Hib meningitis. Figure 1 highlights the coverage of Hib vaccination in the world and this will help in identifying at risk immigrant children where Hib vaccination may not be routinely available. HH, a seven-week-old Caucasian male infant, was born at term by Caesarean section with a birth weight of 4.3 kg. He was formula fed, with no history of travel outside the UK. He presented to the hospital with a 24-hour history of high temperature up to 38.5°C, blanching rash, decreased feeding and had not opened his bowels for five days.
The initial observations showed a heart rate of 132/min, respiratory rate of 32/min, axillary temperature of 36.9°C and a saturation of 99% in air. He was found to be alert with good tone and a soft anterior fontanelle. The rest of his clinical examination was otherwise normal. Blood investigations were done and he was admitted for observation. A glycerine suppository administered rectally helped in passing soft faeces. The blood investigations showed haemoglobin of 9.1gm/dl, white cell count of 8.3x109/cu.mm and a C-reactive protein (CRP) of 6mg/L. His urine sample showed no evidence of infection. A few hours after admission, HH spiked a further temperature of 38.8°C and was found to be irritable. In view of this, a lumbar puncture was done; cerebrospinal fluid (CSF) sample showed a white cell count of 53/cu.mm, red cell count <1/cu.mm and gram stain did not show organisms. The CSF glucose was 2.7mmol/L against a blood glucose of 6.6mmol/L (normal value: CSF glucose levels should be ≥2/3rd of blood glucose) and protein of 0.65gm/dl (normal for age). The CSF analysis showed strong evidence of meningitis and HH was commenced on intravenous (IV) antibiotics and fluids. He was managed in the paediatric high dependency area. The temperature settled after 72 hours of starting antibiotics. CSF results confirmed Hib on a Latex Agglutination Test, however the CSF culture was reported as negative. The blood culture was reported to be negative after five days. In view of the CSF findings and in co-relation with the clinical picture, HH was treated as a case of Hib meningitis with IV Cephalosporins 3rd generation4. His mother was also offered a course of prophylactic antibiotics.
HH is currently being followed by a paediatric consultant and remains under the care of a health visitor. He is now up-to-date with his immunisations and is reported to be doing well, achieving expected milestones. A subsequent hearing test was also reported as normal. A discussion with his mother at a later stage revealed that she was born at a period when Hib vaccination had not yet been introduced in the UK. The infant therefore was unlikely to have transitory protection against Hib due to maternal antibodies offered by immunisation of mothers5.
In 1933, Fothergill and Wright described a relation between age and the occurrence of meningitis due to Hib6. They also demonstrated that serum bactericidal activity to Hib was associated with protection from infection and their observations guided the vaccine production in the 1970s and 1980s7. Since 1939, all the cases of Hib meningitis had been recorded in the Greater Helsinki area and this provided an opportunity to the epidemiologists to study the impact of Hib vaccination on invasive Hib diseases10. The Hib vaccination was introduced in the UK in 19922,8,9.
Typical presentation of meningitis (illustrative case)
An eight-month-old infant presented with a one day history of high fever, irritability and refusing to feed. She was previously well and healthy and reported to have been fully immunised. The initial assessment revealed that the infant was pyrexial with increased heart and respiratory rate, not moving the neck (ie. neck stiffness) and covered her eyes with her hands when bright light was shown to her eyes (ie. photophobic). There was no rash noted. A provisional diagnosis of meningitis was made and the infant was admitted for close observation and management. Infants less than 3 months of age should have a full septic screen if there is a suspicion of sepsis or meningitis11. Blood investigations showed raised infection markers such as white cell count and C-reactive protein. The lumbar puncture showed evidence of meningitis. IV antibiotics were started and close monitoring was done in the high dependency area. The CSF culture grew Meningococcus serogroup B. The fever and irritability settled within 48 hours of admission and the infant was treated with a 10 day course of IV antibiotics. The family was offered Rifampicin prophylaxis. A hearing test was organised at discharge and she was found to be well at the clinic review eight weeks later. Studies have shown that only 11 per cent of patients presenting with a nonblanching petechial rash, actually had a meningococcal infection. It should be noted that non-blanching rash is only one of the criteria and not all rashes are associated with meningococcal meningitis or sepsis20
Positive effects of the Hib vaccination programme
Before the introduction of the Hib vaccination in 1992, Hib was one of the major cause of childhood bacterial meningitis, especially in the under-5s2. Since its introduction, cases of Hib meningitis in children under five years have dropped by 99 per cent from about 800 cases per year to 12 cases per year in 2008. This compares favourably with figures in the US, where Hib meningitis now occurs in < 2 per 100,000 children12. The beneficial effect of Hib vaccinations is demonstrated in Figure 2 and also reflects the impact of the pilot booster dose of Hib vaccination introduced in 200313. Currently four doses of Hib immunisation are offered to all children in the UK at two, three and four months and a booster at around 12 months of age2. It's worth noting that the booster dose of Hib vaccination was only formally introduced to the UK in September 20062 and this resulted in better coverage of protective immunity in children13. Splenectomised children are at higher risk of overwhelming sepsis following an infection with an encapsulated micro-organism (eg. Hib, Pneumococcus)14 and should preferably be vaccinated before splenectomy14.
Immunising all the children is also important for herd immunity; this will help in protecting the immunocompromised children (eg. those on chemotherapy, long term steroids for conditions such as nephrotic syndrome and those with congenital immune deficiencies); as well as children before they get immunised, as would have been in this case of a seven-week-old boy16. Prognosis8,12. The overall mortality from Hib meningitis is approximately three to five per cent. Fifty per cent of individuals with Hib meningitis will have some neurologic sequelae, which includes partial to total sensorineural deafness, developmental delay, language delay, behavioral abnormalities, language disorders, impaired vision, mental retardation, motor problems, ataxia, seizures, and hydrocephalus. Approximately six per cent of individuals with Hib meningitis experience permanent sensorineural hearing loss. Role of health care providers in immunisation uptake Health visitors in the UK, routinely provide immunisation information for parents, whereas general practitioners and practice nurses administer the vaccines15. Health visitors also play a vital role in providing information to parents, as well as ensuring that a child is actually taken for the immunisations and any missed doses are rearranged16.
Crucially they are also well placed to identify "at risk" groups and individuals, such as immigrant children recently moved into the catchment area (who may not have received any immunisations at all) and the children of parents who seem averse to immunisation. The latter's parents may cite reasons such as a fear of adverse events as a consequence of immunisation, moral reasons, alternative methods of protection, practical issues and personal experience of previous immunisations16,17. Some facts about invasive Hib2,6,13 disease are presented in Table 1 and this may help convince a non-compliant parent in reconsidering their decision not to agree to their child being immunised.
Signs and symptoms of meningitis (NICE 2010)19
● Unwell looking child, toxic or in a moribund state
● Altered mental state, decreased consciousness or change of behaviour
● Refusing to eat or drink
● High fever
● Neck stiffness
● May present with spreading petechial or purpuric rash (see Figure 3)
● Signs of shock (eg. prolonged central capillary time)
● Raised or tense anterior fontanelle
The following strategies are helpful during the health visiting consultation to maximise vaccine uptake and to ensure that children who suffered from meningitis receive further adequate care2,8,16,17,18.
1) Provide information about the immunisation to the new parents
2) Check the personal child health record (the"Red book") about the vaccines actually being Administered
3) Identify immigrant children who may have moved into the area
4) Emphasise the need for vaccine administration in children whose parents choose not to immunise their child.
5) Identify splenectomised children and arrange for vaccinations against encapsulated organisms such as Pneumococcus, Hib, etc. (post trauma, children with sickle cell disease and are new immigrant, etc.). Immunising all children will build up the herd immunity and help in protecting immunocompromised children.
6) Where a case of Hib has occurred, check to see if vaccinations of the child and other siblings within the family are up-to-date
7) Conduct regular developmental follow ups to ensure the child after the episode of meningitis continue to achieve milestones.
This case illustrates the importance of being aware of the Hib meningitis in infants, even though we see it much less nowadays, due to the success of the Hib immunisation. However, it may still be seen in unimmunised children or children who are recent immigrants and early treatment can avoid mortality and long-term morbidity. We hope this case report heightens awareness about this rare but important infection in children.
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