Examining the upsurge of meningococcal disease in Malta

Charles Meilaq traced Mark Muscat, of the Statens Serum Institute's Department of Epidemiology in Copenhagen, Denmark where he is the coordinator of the European surveillance network for vaccine-preventable diseases. Dr Muscat perused his interest on meningococcal disease in Malta that started when he was still working at the then Department of Public Health.

Mark Muscat is in Malta to present his work on measles in Europe and also on meningococcal disease in Malta at the 7th Malta Medical School Conference which commences tomorrow. The conference is a multidisciplinary meeting, and papers and posters will be presented relating to clinical work and research that are carried out locally by graduates of the Malta Medical School. A number of eminent Malta Medical School graduates working abroad were invited to give plenary lectures.

Tapping briefly the history of the meningococcal disease in Malta, Dr Muscat said that, since the mid-1990s, the disease has acquired prominence in Malta on account of its resurgence after three decades of negligible reported cases.

What causes the disease?

Dr Muscat said it is caused by bacteria commonly referred to as meningococci and manifests itself as meningitis, as a generalised infection spreading through blood (septicaemia) or as both.

"Although most cases recover from the disease, it remains a serious and life-threatening illness. In a few cases the disease progresses rapidly to death. Indeed, few infections can cause the social stress that occurs when meningococcal disease enters a community."

A scientific article, published last month in the Journal of Medical Microbiology, describes a study led by Dr Muscat on the occurrence of meningococcal disease in Malta between 1994 and 2007.

Dr Muscat remarked that he and his colleagues at the Infectious Disease Prevention and Control Unit, the University of Malta, the Directorate of Health Information and Research, the Bacteriology laboratory at Mater Dei Hospital and the Meningococcal Reference Laboratory in Manchester, UK, analysed the 233 cases of meningococcal disease notified to the Maltese health authorities during the 14-year period.

What were the ages of those affected and has the disease claimed any fatalities?

Dr Muscat said the average age of the notified cases was 14 years and 165 (70 per cent) were below 20 years of age. The disease claimed the lives of 28 patients giving an overall case fatality rate of 12 per cent. Collectively, he remarked, the number of cases peaked in late winter/early spring and again in summer.

"This is unlike the seasonal pattern observed in other European countries where the disease occurs mostly in winter."

Dr Muscat said the upsurge of the disease became noticeable in 1996, placing Malta among the countries with the highest incidence for the disease in Europe during the same period.

"There is no single clear explanation for this resurgence. However, other countries have reported increased occurrence following the introduction of new strains of meningococci into their populations," he added.

Meningococci are classified into various strains or serogroups. Laboratory investigations carried out on 114 cases showed that, in Malta, serogroup B formed the largest proportion (76 per cent) as in the rest of Europe, followed by serogroup C (16 per cent). A particular strain of serogroup B identified as B:4:P1.19,15 has dominated Malta during the study period.

Of the total cases, 137 (59 per cent) were confirmed and 30 (13 per cent) were classified as probable. However, 66 cases (28 per cent) had no laboratory evidence of the disease and were classified as possible.

Dr Muscat said doctors are, therefore, recommended to submit clinical specimens not only for laboratory confirmation of cases, but also for the identification of the meningococcal strains causing the disease.

Continuous monitoring of the predominant strains would support the use of immunisation to prevent and control the disease, if found to be vaccine-preventable.

Dr Muscat said vaccines against specific meningococcal serogroup B strains that were also found in Malta have been licensed for use elsewhere or are under trial. However, it is the eventual development of vaccine against serogroup B strains for universal use that would be a major public health tool to control meningococcal disease in Malta.

What are the main methods of control?

"Until safe and effective vaccine for universal use is found, the main methods of control remain the early treatment of cases and the prevention of secondary cases. The latter public health measures primarily involve the identification of close contacts and the administration of appropriate antibiotics."

Dr Muscat developed particular interest in the disease in 1998 when the number of cases notified to the then Department of Public Health increased rapidly.

"It can be a devastating disease killing within hours, leaving family members and friends completely distraught," said Dr Muscat, a former principal medical officer of the same department. He saw then the need of a support group for relatives and friends of meningococcal disease victims to provide additional information, counselling and to encourage contact with other affected families.

"The dissemination of accurate information to the public about the disease is also important to allay widespread public alarm following a case of meningococcal disease in a community, particularly if death occurs. Raising awareness aims for early recognition and treatment that if timely can save lives," concluded Dr Muscat.