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close this bookCerebrospinal Meningitis Epidemics and Surveillance Systems in the Sudan, Ethiopia and Chad (Centre for Research on the Epidemiology of Disasters, 1990, 40 p.)
close this folderI. INTRODUCTION
close this folder1. Context
View the document(introduction...)
View the document1.1. Study Background
View the document1.2. Objectives of the Study

1.1. Study Background

In Africa, meningococcal A meningitis constitutes a serious health problem causing high mortality and morbidity. Of all causes of cerebro-spinal meningitis, meningococcal meningitis is the most disturbing for the international community in that this infection is characterized by epidemics which create emergency situations not only in the country where the epidemic occurs, but also in the neighbouring countries and beyond.

The semi arid region south of the Sahara and south of the equator has been referred to as the “meningitis belt”.1 In this area, endemo sporadic infections (more than 25 cases per 100.000) occur annually in the dry season, while large scale epidemics appear at longer intervals.

1L. Lapeysonnie; La Mngite Cbrospinale en Afrique. Bull. Wld. Hlth. Org. 28 Suppl. 1963

In 1983, an Experts Consultation held in Marseille, France, emphasized the importance of effective surveillance. It recommended that bacterial meningitis, categorized by specific etiology if possible, was to be reported by all countries. Surveillance was designated to serve two main purposes for the control of epidemic meningococcal disease:

- the detection of the onset of an epidemic and activation of the appropriate response.
- the evaluation of control measures.

Since then two problems have been identified in this context:

(i) The prediction of an outbreak (warning systems)

The analysis of time and geographical trends of an epidemic could be a useful tool towards the prediction of outbreak and consequently for its control.

Until 1950 there were clear “waves” from eastern to western Africa.1 Although, today this trend is not as obvious, it is still considered by many to be an expected pattern. For instance, the strain responsible for the current epidemic in Ethiopia, Sudan and Chad had been first observed in Saudi Arabia2, 3 and from there spread towards the East.

1L. Lapeysonnie; La Mngite Cbrospinale en Afrique. Bull. Wld. Hlth. Org. 28 Suppl. 1963

2M. Achtman Molecular epidemiology of epidemic bacterial meningitis. Max-Plank-Institut fekulare genetik. to be published in Reviews of medical microbiology, 1, 1990.

3P. Moore and coll. Intercontinental spread of an epidemic group A neisseria meningitidis strain. The Lancet, July 29, 1989.

A definitive answer to this question could be proposed through a systematic, analysis of historical data on epidemics. In particular, the analysis should be undertaken on smaller units of settlements (i.e., district or provincial levels) and not at country levels.4 A large geographical unit of measurement is likely to disguise or misrepresent the nature of the spread. A preliminary examination of national data reported to WHO does not reveal any definable geographical pattern. A study on more detailed data for smaller areas would avoid the artifact of the political divisions and permit a better analysis to test the geographical trend hypothesis from small areas to others.

4M.Rey. Mngite cbrospinale au Niger. Rapport de mission. Juin 1972

(ii) The Surveillance System

Even though the epidemiological surveillance of infectious diseases in Africa has improved and a vaccine now exists, the situation has not changed very much since Lapeysonnie's description in 1963. An epidemic is usually recognized only when it is underway, with vaccinations starting well after the onset.

At regional and inter-national level there is a lack of early recognition and communication of an on coming outbreak and no warning system linking one area to the next.

Repeated emergencies created by uncontrolled epidemic meningitis in Africa and the recognised risks of future incidents encourage changes in procedure. It is generally admitted today that surveillance efforts to detect meningococcal meningitis early should be heightened in sub-Saharan Africa and appropriate measures taken to ensure an early response to epidemics. International cooperation for surveillance of epidemics and coordination of relief efforts will be necessary for additional epidemic occurrence.