UNEXPLAINED DEATHS AND SEVERE ILLNESS IN
INJECTING DRUG USERS IN THE UNITED KINGDOM AND IRISH REPUBLIC:
APRIL TO JULY 2000
Unexplained outbreaks of illness may occur suddenly.
Effective investigation and control of such incidents usually
requires an alert health professional who raises the alarm. This
is followed by a co-ordinated public health response that has
to be rapid, multi-sectoral, and multi-agency, sometimes operating
at international, national and regional as well as local levels
of organisation. The current investigation of unexplained deaths
and severe illness in injecting drug users (IDUs), which is still
ongoing, is a potent example of the organisational challenge posed
by such incidents.
In early May of this year, a microbiologist
in a Glasgow hospital alerted local public health doctors to an
unusual and severe fatal illness in a number of injecting drug
users, that had not been seen previously. An intensive public
health investigation began in Scotland involving dozens of clinicians,
microbiologists, pathologists, and public health staff, working
closely with police and services for IDUs. By mid-May, between
20 and 30 cases had been recognised including 10 deaths.
The PHLS was kept informed about the evolving
outbreak in Glasgow and began providing reference and expert microbiological
support. In the third week of May, the PHLS asked Consultants
in Communicable Disease Control throughout England and Wales to
liaise with medical staff locally to see whether illnesses in
IDUs, similar to those in Scotland, were being seen. An "early
warning" was circulated to competent authorities throughout
the European Union to encourage active case finding in other countries.
These messages were reinforced through scientific updates in surveillance
bulletins that are disseminated widely.
By 30 June, investigators had identified 91
IDUs in Scotland (49), Ireland (19) and England (23) with injection-site
soft tissue inflammation and signs of severe systemic infection
resulting in hospitalisation or death; 40 (45 per cent) have died.
Recognition of separate clusters of cases in Dublin and North
West England have led to intense local investigations which complement
the ongoing national and international collaboration. Upon becoming
aware of the outbreak of unexplained illness, the Centres for
Disease Control (CDC) in the United States offered to assist the
investigators. The investigation became trans-Atlantic when this
offer was accepted.
A large number of different bacteria, most of
which are normally found on the skin or in the gut, were isolated
from the cases. Special laboratory efforts were required to rule
out anthrax infection as an IDU in Norway had died from this infection
earlier in the year. The features of the illness, however, suggested
an infection by a toxin producing bacteria in the muscle into
which heroin and been injected. Some of the clostridia family
of "anaerobic" bacteria, that require an absence of
oxygen to grow, can produce these powerful toxins. After many
days of painstaking work on specimens transported to PHLS reference
laboratories in Colindale and Cardiff and to the CDC in the US,
Clostridium novyi type A has been isolated from a number
of the cases. This particular bacterium can exist for years in
dust or soil as dormant spores that only become activated when
conditions are right.
The most likely source of infection seems to
be contaminated heroin but this hypothesis has yet to be confirmed.
Clinical, epidemiological, and laboratory investigations continue
to further characterise these illnesses, confirm the role of C.novyi
as the etiologic agent, identify risk factors for the syndrome,
and to suggest preventive measures. Surveillance activities to
identify additional cases in the United Kingdom and Ireland are
ongoing, and efforts to find cases in the rest of Europe or the
United States have been expanded.
The PHLS in England and Wales, and
the CDC in the United States are both providing reference and
research microbiological facilities for the investigating collaborators.
The PHLS together with public health
colleagues in the North West are co-ordinating clinical and epidemiological
investigations in England and Wales.
Greater Glasgow Health Board and
the Scottish Centre for Infection and Environmental Health are
co-ordinating clinical, epidemiological and microbiological investigations
The National Disease Surveillance
Centre and the Eastern Health Board are co-ordinating clinical,
epidemiological and microbiological investigations in the Irish
Case ascertainment in other EU countries
is being pursued through the EU Network for communicable diseases
and participants in the European Programme for Intervention Epidemiology
Training programme for field epidemiology.
Other groups contributing to the
investigation include local Police Services in England and Scotland,
the Home Office, the Drug Tsar's Office, Drug Information Services,
local Drug Action Teams, Centre for Applied Microbiology and Research,
Guy's and St Thomas' Medical Toxicology Unit.
This outbreak illustrates the constant threat
of communicable diseases and the importance of maintaining and
developing the capacity and expertise required to respond rapidly
when an infection emerges unexpectedly. In these circumstances
public health and microbiological resource have to be mobilised
rapidly so that bodies such as the PHLS should be resourced to
provide "surge capacity". Insofar as is possible it
is also essential to maintain and develop channels of communication
between all levels of those agencies that are likely to have to
work together in an investigation. Inter-agency collaboration
occurs best when there is mutual respect between highly professional
organisations that have a clear purpose that is readily understood
by the other agencies likely to become involved. Concerns about
patient confidentiality complicate data and information exchange
between laboratories and surveillance centres. There does not,
as yet, seem to be a simple solution that will ensure confidentiality
and yet allow daily exchange of updated information between several
centres in several countries. Appropriate health care professionals
in these exceptional circumstances should given consideration
to the use of patient name as a genuinely unique identifier.
Prepared by Drs Tamara Djuretic, Noel Gill,
Rob George, Public Health Laboratory Service.