- Prophylaxis of contacts is only indicated when meningococcal or Hib disease (rare) is the "probable" (most likely) or "confirmed" diagnosis (see Case definitions). It is not necessary in e.g. suspected viral cases being treated "just in case". Always discuss with CCDC/Public Health. Prophylaxis is not necessary in pneumococcal and viral meningitis.
Rationale for giving or witholding meningococcal chemoprophylaxis
Before you can understand the reason for giving meningococcal chemoprophylaxis to some, and withholding it from others, you need to understand the following:
- Meningococcal carriage is common. At the end of the first term at university over a third of students will be carriers. Carriage comes and goes, and most people will carry the bug from time to time. But, despite this, meningococcal disease remains uncommon. So, becoming colonised with the bug is obviously a prerequisite (necessary cause) for getting disease, it is far from being sufficient cause, as the vast majority of people who become colonised never get ill with meningococcal disease.
- We know some of the answers as to why people get ill. Many have had a recent upper respiratory tract infection, which may increase their susceptibility (but as meningococcal disease is seasonal, and tends to occur most at times of the year when URTIs are most common, this is a very poor predictor of disease). There are various other known associations with disease, with smoking being one of the strongest. But as so few people get the disease the absolute risk associated with risk factors is very small.
- More important risk factors include:
- Recent case in a close household contact;
- Various immune deficiencies. (The fact that some of the immune deficiencies are familial could - at least in part - explain the increased risk in household contacts, as these are likely to be family members.)
- Given that meningococcal carriage is common, and disease uncommon, there are two principle hypotheses to explain why a few individuals who are colonised by meningococci go on to get ill while most don't:
- They are more-than-usually susceptible, either as a result of some chronic immunodeficiency, or as the result of some recent challenge, such as a viral infection.
- They have been exposed to a more-than-usually virulent strain of meningococcus. (The Group C strain that was circulating in the 1990s was particularly virulent, with a far higher illness:carriage ratio, for example. Other groups may carry the same, or similar virulence factors.)
- We also know that people who have carried a strain of meningococcus for five-seven days are extremely unlikely to get ill with that strain; and that
- Most people who get ill with meningococcal disease have, if you can trace the source, caught it from a sexual partner or close household contact who has been carrying the same strain.
Rationale for giving chemoprophylaxis
- The primary reason for giving chemoprophylaxis is the hypothesis that the person who got ill has acquired a more-than-usually virulent strain carried by a healthy carrier who is their close household contact or sexual partner. (Possibly the strain has evolved to become more virulent after that person was infected.) The purpose of chemoprophylaxis is thus to eliminate this hypothetically more virulent meningococcal strain from the healthy carrier, to ensure that they do not transmit it to anybody else. Since it is most likely that the case acquired the disease from a close household contact or sexual partner, there is no point in treating anybody else.
- A secondary reason for prescribing chemoprophlyaxis is based on the hypothesis that a contact might have been recently infected, and is in the incubation period between colonisation and illness. (This is the rationale used for treating a very few healthcare workers).
Rationale for witholding chemoprophylaxis
Colonisation with one bacterium provides protection against colonisation by related species. (This is sometimes known as "competitive inhibition". If a contact has been colonised for 5 days or more by a meningococcal strain, or a related organism such as Neisseria lactamica, this will provide them with some protection from new, potentially virulent strains. If there is a more virulent strain circulating, eradicating this protective carriage may, it is hypothesised, increase their risk to acquiring, and becoming ill with, the new strain.
(Of course, as with any drug, there is also a risk of adverse reactions.)
So on balance...
The theoretical benefits and harms of prophylaxis described above need to balanced when deciding whether to prescribe for any specific individual.
It is generally considered that there is a small-but-definite benefit of chemoprophylaxis to household contacts and sexual partners; but that the risks of harm outweigh the benefits for wider contacts.
- Notify promptly all suspected cases of meningitis or meningococcal septicaemia. This is the legal duty of the doctor who makes or suspects the diagnosis. Doing so by phone to the Consultant in Communicable Disease Control or health protection unit (or equivalent) or on call Public Health Specialist may be best. After 11pm notify next day.
- The CCDC or public health practitioner on-call will discuss with you who (if anybody) needs to be defined as a "contact" for the purpose of chemoprophylaxis.
- Unless there are clear local protocols for the prescription of chemoprophylaxis, this should usually only be done after discussion with the local CCDC. In meningococcal cases prescribe chemoprophylaxis (see BNF S5.1, Table 2) for "close household contacts" – those living in the same household as the case in the 7 days before onset. Advise household contacts that they are at increased risk of meningitis. Give advice on early symptoms and reinforce advice by giving a leaflet on meningococcal disease. Prescribe rifampicin for the case to clear nasopharyngeal carriage at the same time as household contacts or as soon as possible afterwards, certainly before discharge (not necessary if treated with ceftriaxone or other drug listed as suitable for chemoprophylaxis in BNF).
- In Hib cases the need for prophylaxis should be discussed with the CCDC or on-call Public Health Specialist. Indications for prophylaxis and drug regimes differ from those for meningococcal prophylaxis.
- The The CCDC or public health practitioner on-call will arrange for any contacts who do not live with the case to receive chemoprophylaxis, and for later immunisation of all close contacts if indicated, and will ensure information is disseminated to appropriate local schools, work places and General Practitioners, and is responsible for early detection of clusters and outbreaks of disease.
- Staff only require prophylaxis if they meet the criteria in "Contacts who should be offered chemoprophylaxis".
- Vaccination is recommended for those who should be offered chemoprophylaxis but only if:
- the strain of meningococcus is confirmed to be a vaccine-preventable strain, and
- the contact is not already covered against that strain. (Increasingly, people will have received conjugate vaccine, and will have long-term protection against group C meningococcal disease.)
- The Meningitis Research Foundation MRF has an excellent, 24-hour, nurse-run help line. Cases, their relatives, staff, and any others who are concerned about meningitis or meningococcal disease can call this line. The number – and leaflets from the MRF and/or the National Meningitis Trust (see Meningitis exernal links) – should be available in hospitals, and given out liberally.
- Bacterial meningitis
- Meningitis case definitions
- Meningitis charities
- Meningitis checklist
- Meningitis chemoprophylaxis
- Meningitis prevention
- Viral meningitis
- ↑ Control and Prevention of Meningococcal Disease: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recommendations and Reports. February 14, 1997 / 46(RR-5);1-51
- ↑ Guidelines for the Management of Airline Passengers Exposed to Meningococcal Disease. CDC. 2005. Accessed 25 July 2007
- ↑ Exposure to Patients With Meningococcal Disease on Aircrafts ---United States, 1999--2001. MMWR Weekly. June 15, 2001 / 50(23);485-9