| Statistics in Meningitis: Their Meaning and Use |
 Meningitis and meningococcal disease are notifiable separately and since 1968 it has been compulsory to notify suspected, as well as confirmed cases. Notifications encompass all suspected cases whatever the organism believed to have caused the disease.
It is up to the attending physician to give notification to the relevant public health authority, through the consultant for communicable disease control.
This data contributes to disease surveillance as well as enhancing the speed with which outbreaks and epidemics can be identified. Awaiting confirmation of a suspected case takes time and delays prompt intervention with chemoprophylaxis for close contacts.
Figures relating to notifiable disease encompass all suspected and confirmed cases of meningitis and meningoccocal septicaemia.
Figures relating to confirmed cases include only those incidences of meningitis and meningoccocal disease that have been confirmed by laboratory testing.
The incidence of a disease is the rate at which it occurs within a population during a specified time and is worked out proportional to the population size (ref. Table 1). However, figures quoted for incidence are usually only an approximate measure of the frequency at which a disease occurs, as there will nearly always be cases that go unreported.
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Incidence of Meningococcal Disease amongst
Countries in Western Europe 1998/9
(Source: 'Surveillance of Bacterial Meningitis in Europe 1998/9', PHLS)
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Table 1 (click to enlarge)
There are two types of incidence data. Crude incidence gives the disease rates for a population as a whole without subdivision (ref. Table 1).
Specific incidence data is broken down by demographics such as age, sex, or geographical location. It may also be broken down by serogroup. For example, following the introduction of the C vaccine it was important to examine its impact in terms of incidence of that strain (ref. Figure 1)
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Figure 1 (click to enlarge)
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