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In the UK, suspected and confirmed cases of viral haemorrhagic
fever (VHF) are managed according to the document produced by the Advisory
Committee on Dangerous Pathogens (ACDP) called the "Management
and Control of Viral Haemorrhagic Fevers" which was published in
1996 (1). As the name suggests, these are comprehensive guidelines.
The ACDP is currently reviewing the UK guidance in the light of the
experience gained from recent European cases to ensure that safety is
maintained while optimising provision of modern medical care for such
patients (2).
Transfer of patients from endemic areas into UK
People suffering from VHF should be treated in the
endemic area if the medical facilities in that country are favourable.
However, instances do arise when it becomes necessary to transport a
confirmed or suspected case to a non-endemic area and contingency plans
exist for this procedure. Air ambulances carrying suspected cases of
VHF (eg febrile patients from an endemic area) are required to inform
the port health authority at the airport before arriving in the UK.
Similarly, when patients become ill on a passenger flight into the UK,
port health should be informed. Patients suspected of being at high
risk of having a VHF should ideally be transported in the aeroplane
in a high security isolator and received into a high security ambulance
on arrival in the UK before transfer to an infectious diseases unit
with provision for high security isolation. There are two high security
infectious disease units (HSIDU) in the UK. One is at Coppett’s Wood
Hospital in London. The other is located at Newcastle General Hospital
in the north of England, to serve cases arriving in Scotland, the north
England and Northern Ireland. On average, less than one patient per
year is managed in such a unit. The highest volumes of air traffic occur
between endemic areas and London, so the most likely points of arrival
are Gatwick and Heathrow airports. In addition, London has several infectious
disease units to which such patients may be referred for investigation
of undiagnosed fever.
Management of suspected cases of VHF
Categorisation of risk
Pending confirmation of diagnosis, patients are categorised
as low, moderate, and high risk (table 1). The risk categorisation changes
as more information, or results of tests become available. All high
risk patients should be referred immediately to a HSIDU. Problems have
been identified with the case definitions since the guidance was developed
(3). As HSIDUs are not overwhelmed with referrals, it seems that most
clinicians do not follow the guidance exactly and many front-line clinicians
may not be aware of them. The case definitions may be simplified following
the current review of UK guidance.
Investigation of patients
Laboratory investigation should be minimised until
the diagnosis is established. The priority is to examine samples for
malaria as this is the likeliest diagnosis. Safe methods to conduct
these investigations are described in the memorandum.
Management of confirmed cases of VHF
UK guidance is that confirmed cases should be managed
in a high security isolator bed (Trexler unit). This requirement is
based on UK interpretation of European legislation on the control of
such dangerous pathogens (category 4) though Control of Substances Hazardous
to Health legislation. It is an engineering solution which contains
all infectious material by containing the patient (as well as waste
and other potential infectious materials). Such a unit therefore protects
everyone, in contrast to suited units which offer personal protection
to the wearer of the suit only. All personnel who would be expected
to use the facility should received regular training in its use (every
3 months is suggested). Use of containment measures which provide only
personal protection is acceptable under current legislation only if
there is no alternative way of managing a particular patient.
Laboratory aspects
Malaria should be ruled out using normal procedures
but other laboratory investigations should be postponed awaiting the
diagnosis. In patients in whom malaria diagnosis is not confirmed, blood
or serum samples should be sent to the Central Public Health Laboratory
(CPHL) at Colindale or ‰ ‰ the Special Pathogens Unit at the Centre
for Applied Microbiological Research (CAMR) for rapid molecular diagnosis
(PCR). Usually PCR results are available within 24 hours (4). Virological
confirmation of PCR results by serology and/ or viral isolation may
take up to one week. Laboratories and clinical centres sending samples
for VHF diagnosis are required to inform the receiving laboratory (CPHL/
CAMR) prior to the dispatch of samples. Details on handling, collection
and transport of specimens are given in the guidance.
Table 1 : Risk categorisation for VHF
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Risk category
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| Minimum |
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Febrile patients who have:
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Not been in known endemic areas before the onset
of illness
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Or
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Been in endemic areas (or in contact with a known
or suspected source of VHF) but in whom the onset of illness was
definitely more than 21 days after their last contact with any
potential source of infection
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Moderate
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Febrile patients who have:
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Been in endemic area during the 21days before
the onset of illness, but who have none of the additional risk
factors which would place him or her in the high risk category
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Or
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Not been in a known endemic area but who may
have been in adjacent areas or countries during the 21 days before
the onset of illness, and who have evidence of severe illness
with organ failure and/or a haemorrhage which could be due to
a VHF, and for which no alternative diagnosis is currently evident
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High
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Febrile patients who have been in an endemic
area during the three weeks before illness:
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And
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Lived in a house or stayed in a house for more
than 4 hours where there were ill, feverish persons known or strongly
suspected to have a VHF
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Or
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Took part in nursing or caring for ill, feverish
patients known or strongly suspected to have a VHF, or had contact
with the body fluids, tissue or the dead body of such a patient
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Or
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Are a laboratory, health or other worker who
has, or has been likely to have come into contact with the body
fluids, tissues or the body of a human or animal known or strongly
suspected to have a VHF
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Or
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Who were previously categorised as moderate risk
but who have developed organ failure and/or haemorrhage
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Or febrile patients who have not been in an endemic
area but during the three weeks before the illness they:
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Cared for a patient or animal known or strongly
suspected to have a VHF, or came into contact with the body fluids,
tissues or dead body of such a patient or animal
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Or
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Handled clinical specimens, tissues or laboratory
cultures known or strongly suspected to contain the agent of a
VHF
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Management of contacts
At the point where the diagnosis of VHF is suspected,
the physician must notify the designated local public health doctor
who is the proper officer for notification (generally the consultant
in communicable disease control or consultant in public health medicine
in Scotland). She/he will start to identify all the contacts awaiting
establishment of the diagnosis and organise provision of information.
Contacts should be categorised by level of risk (table 2). Only contacts
in categories 1 and 2 require monitoring if VHF is confirmed. They should
be monitored by taking their temperature twice daily for 21 days from
the date of last contact with the patient and reporting it to their
safety officer. The ACDP guidance does not mention use of ribavirin
prophylaxis, but this was offered to Category 1 contacts of the patient
with Lassa fever managed in England during 2000.
Communication
For public health officials and press officers, communication
is the greatest task. This takes place in the context of greater access
to information through media such as the Internet. Each confirmed case
of VHF generates tremendous anxiety in healthcare workers and in the
public and press briefings need to be prepared. Contacts of the patient
need full information about their risk. Local, regional and national
public health authorities, the Department of Health, the ministry of
health of the country in which the patient contracted the infection,
any organisations that transported the patient, the European Commission
and the World Health Organization all should be notified and have information
about the case.
Lessons learnt from recent cases
Many lessons are learnt following each case of VHF
(2,5). Firstly, it is clear that UK guidance on risk assessment of cases
is not always followed. As found in other countries, if the diagnosis
of VHF is not considered then diagnosis will be delayed, however detailed
are the case definitions. VHF cases are very rare, so it is a challenge
to maintain awareness amongst clinicians. In interpreting safety legislation,
the ACDP needs to find the right balance between exacting standards
of safety in management of an individual VHF case and practicability
for clinicians managing many febrile patients who have travelled to
endemic regions (3).
Table 2
Categorisation of contacts of a VHF case
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Category
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Description
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Category 1
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Direct contact (i.e. skin / mucosa with blood
/ bodily fluids of index case)
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Category 2
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Direct contact with the patient or specimens
from the patient but no direct contact with blood/bodily fluids
and appropriate precautions taken
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Category 3
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Spent time in areas the patient had been, but
no physical contact with patient/ bodily fluids / specimens
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Category 4
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Shared the same public space as the patient
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Category 5
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People who were in contact with those in categories
1 and 2.
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Communication is a vital task for clinicians and public
health specialists. It requires robust systems to ensure that information
reaches staff when large numbers working long shifts become involved
with caring for a patient. Safety officers need dedicated time for this
communication role. Current guidance requires active temperature monitoring
of contacts for at least 21 days. When the number of staff reaches 100,
this becomes a formidable communication task.
The Trexler unit is popular amongst staff trained in
its use and it is probably more congenial for patients to see their
carers’ faces than to be surrounded by staff in protective suits. Protective
suits limit the time staff can work to four hours, which means that
more staff are required to care for the patient. This presents a significant
problem for the UK National Health Service. However, providing modern
intensive care within a Trexler unit also presents a challenge.
Conclusions
VHF is rarely diagnosed in the UK, with two confirmed
cases between 1997 and 2000. The potential for such patients to come
to the UK is always present because tourists, aid workers and troops
travel regularly to and from the UK to endemic areas of the world. In
addition, VHF are amongst the agents that have potential to be weaponised.
Events since September 11 have underlined the importance of national
preparedness to contain and manage the deliberate release of infectious
diseases such as VHF.
Acknowledgement
Thank you to: Dr Barbara Bannister
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