Eurosurveillance - Volume 7, Issue 3, 01 March 2002

Viral haemorrhagic fevers (VHF) have attracted the attention of the medical world and general public for many reasons, some based in reality and more on misinformation. They are amongst the highest profile infections in the public mind, because they are thought to be highly infectious and to kill most of their victims in a dramatic way (1,2). To add to the intrigue, mysteries remain about the source of some of the viruses involved. They emerge and re-emerge in many countries, most recently Ebola in Uganda in 2000 (3) and Gabon in 2001/02 (4), and Congo Crimean Haemorrhagic Fever (CCHF) in Kosovo (5) and Pakistan in 2001 (6). Large outbreaks have affected populations in endemic areas, living mainly in inaccessible areas or refugee camps where living conditions are very difficult. Poorly resourced medical facilities have played a role in amplifying transmission and infection control measures have been difficult or virtually impossible to establish. These viruses are likely to remain a threat until the reservoir is identified and as long as endemic areas are afflicted with ecological change, poverty and social instability. Recent events since September 11 2001 remind us of their potential to be used as weapons, and that fear can present a risk to public health.

Within the past decade, Ebola haemorrhagic fever (EHF) has been recognised for the first time in four countries. Our understanding of the epidemiology, clinical aspects, laboratory diagnosis and control measures for EHF has improved considerably as a result of the outbreaks in these countries and the re-emergence that has occurred in another. The coordinated international responses to several of the large EHF outbreaks serve as models for controlling epidemics of other communicable diseases. This report is a chronological overview of the EHF outbreaks in Africa during the past decade, including the recent epidemics in Gabon and the Republic of the Congo, and highlights new discoveries and some of the remaining challenges.

Patients suffering from viral haemorrhagic fevers must be handled specifically. The clinical diagnosis of these diseases in the initial stage is difficult because early symptoms are non specific. In Germany, specific diagnosis is available at two diagnostic centres with biosafety level 4 facilities. Five high security infectious disease isolation units for patient care are available in Munich, Leipzig, Hamburg, Berlin, and Frankfurt. In addition, a corresponding number of centres of competence are established to offer support and advice to the hospitals initially treating the patients and to the local public health officers. The decentralisation of these centres of competence is recommended to allow for more timely and reactive responses to VHF epidemic threats.The risk categorisation for contacts has proved to be very useful in practice.

Over the past years, there have been very few imported cases of VHF in Switzerland: one confirmed and four suspected cases of Ebola fever in Basel in 1994, two suspected cases of Ebola and Lassa fevers in Lausanne in 2000, and in the same year, six suspected cases of Lassa fever in Geneva. Given the considerable diversity in the management of patients with suspected or confirmed VHF, national guidelines are needed, as well as the establishment of a national reference centre.

In the UK, suspected and confirmed cases of viral haemorrhagic fever are currently managed according to the 1996 Guidance of the Advisory Committee on Dangerous Pathogens, which describes an approach to the risk categorisation of suspected cases. It also provides guidance on patient management including transfer, laboratory investigations, infection control, and monitoring of contacts based on the risk assessment. Confirmed cases are managed in bed isolators ("Trexler units"), two of which are available in high security infectious disease units in the UK. This guidance is under review and may change. Recent experience has shown that communication and reassurance for health care workers and the public are major tasks in managing such cases.

Two cases of Lassa fever have been reported in the Netherlands since viral haemorrhagic fevers became notifiable diseases in 1978. In 1980, an expatriate from Burkina Faso who was not seriously ill was confirmed by laboratory tests after his discharge from hospital. The second case occured in 2000: the patient died on the 11th day of admission to hospital. The problems we faced in the management of this case and the contact investigation - more than one hundred contacts - highlighted the need for national recommendations in the Netherlands.

The UK Public Health Laboratory Service hosted a meeting in London during November 2000 to discuss the management of Lassa fever following the four cases which had occurred in 1999/2000. Participants were invited because they had recent clinical or laboratory experience of managing cases of Lassa fever or had been involved in public health aspects of a case of this infection. The meeting was closed to enable free and frank discussion of confidential matters. This is a report of the general issues and recommendations which arose from the discussion.