A SERIOUS INFECTION INCIDENT LASSA FEVER
IN LONDONMARCH 2000
On 6 March 2000, an aid worker returned to the
UK from Sierra Leone with suspected Lassa Fever, a rodent virus
that is endemic in Eastern Sierra Leone. It causes a serious illness
that in some cases results in extensive haemorrhaging and death.
He was initially admitted to the Hospital for Tropical Diseases
in London and after three days was transferred to Coppetts Wood
Hospital where he died on 23 March. This is the fifth case of
Lassa Fever to be imported into the UK since 1976.
Events of this nature may occur at any time
without warning. The occurrence of a single incident or of an
outbreak of a serious life-threatening infection, requires a rapid
response from a number of agencies acting in concert. Co-ordination
and public health leadership combined with expert microbiology
is therefore key in effectively controlling the incident and preventing
transmission and adverse outcomes. The most recent case of Lassa
Fever came to the notice of the Public Health Laboratory Service
(PHLS) through the PHLS Communicable Disease Surveillance Centre
(CDSC) on-call system on a Thursday evening, and the diagnosis
was made late on the Friday evening at the PHLS Central Public
Health Laboratory. The Incident Control Team had to convene rapidly
over the weekend. Further confirmatory testing was undertaken,
potential contacts of the patient were identified and interviewed,
all relevant national, local and international agencies were informed;
plans were formulated for patient care, and for prevention and
control of the infection; roles of responsibility were delegated,
with clear lines of accountability; press officers from the main
health agencies were involved and consulted on media briefing.
By Monday the plans were operational with smooth co-operation
between the various agencies and an established forum, the Incident
Control Team, for decision making.
With these kinds of infection, without rapid
co-ordinated action there is the danger that the infection will
be transmitted to health care workers, and to the public. The
clinical diagnosis of Lassa Fever is rarely obvious (it was not
in this case) and so rapid laboratory diagnosis is essential for
early recognition. This is a hazardous infection requiring P4
containment which needs to be undertaken at a national reference
laboratory. There is also the potential to provoke excessive and
inappropriate public anxiety, thus emphasising the need to work
proactively and responsibly with the press and other media to
convey a balanced and honest level of risk to the public. Both
these contingencies require senior experienced people to establish
lines of communication and accountability among the many agencies
There may be potential international implications.
In cases of Viral Haemorrhagic Fevers or other highly infectious
diseases, it is important to alert the country of origin as the
case may signal an outbreak and/or contacts of the case may need
to be traced. Transport agencies may need to be informed as an
infected person may have returned to the UK on public transport
exposing other passengers to risk of infection. This would necessitate
public health agencies tracing contacts at risk. (This did not
apply in the recent case of Lassa Fever where the patient was
flown back by air ambulance so that the risk was known to staff
who took the necessary precautions.)
A wide range of agencies are involved in every
incident. However, for every incident the players will vary. In
the Lassa Fever incident there was extensive involvement of UK
national and local organisations, as well as overseas organisations.
The PHLS took the lead in this incident. Other agencies involved
included the Department of Health, the Department for International
Development, two acute NHS Trusts, the Chief Medical Officer,
the Regional Director of Public Health, the Health and Safety
Executive, a number of District Health Authorities, authorities
at Heathrow airport, a number of GPs, the Intercounty and London
Ambulance Services, several agencies in Sierra Leone including
the Ministry of Health, the World Health Organization, the European
Commission, Centers for Disease Control and Prevention USA, the
air ambulance in Switzerland and the Swiss Ministry of Health.
Whatever the nature of the incident, it is important
to have an extant plan which can be adapted. The PHLS is well
placed to offer the expertise and skills to take the co-ordinating
role, having both public health skills, corporate knowledge and
In the event of a major infectious disease/health
incident there is a surge in the need for experienced professional
staff at senior and more junior levels and a need for secretarial
and other administrative support. The increased support may need
to be sustained for substantial periods of time and may apply
to a number of the organisations involved. In the Lassa Fever
incident over 90 contacts were spread over three hospital sites.
The largest resource input from PHLS was the public health component
requiring input from six consultants and three senior registrars,
with additional public health support from the host district health
authority. However it was also necessary to immediately provide
expert virology in a secure laboratory and the provision of daily
virological investigation to support patient management. The surge
capacity of public health was stretched to its limit. Most public
health input was located on one site; optimally there should have
been support on all three sites as clinicians were not able to
give the public health advice and support needed.
It is important that key senior people are accessible
in all the relevant agencies at all times and that contact details
for the persons on duty are available. Difficulty was experienced
in contacting senior officers at the European Commission out of
hours though communications were good with WHO in Geneva.
PHLS has the strength of combining public health,
laboratory and clinical virological skills. It has a tried planning
strategy and good corporate knowledge to achieve a rapid co-ordinated
reaction where multiple organisations and agencies are involved.
It is important in the future that there is sufficient surge capacity
and resource management capacity to deal effectively with major
incidents. The PHLS would also be able to make a significant contribution
to incidents involving suspected or actual deliberate release
of biological and chemical agents where the need for rapid action,
mobilisation of resources and expert combination of laboratory
and public health skills would be similar to those in this incident.
It is important to have centres with corporate
knowledge, that will be well placed to respond to other future
incidents, be they natural or deliberate.
Prepared by Drs Margie Meltzer, Natasha Crowcroft
and David Brown, Public Health Laboratory Service.