Since May 1995 the California Emerging Infections Program has
been conducting surveillance for critical illness or deaths
from a potentially infectious cause occurring in previously
healthy persons in San Francisco, Alameda, and Contra Costa
Surveillance for Unexplained Deaths (SUDs)
We are interested in learning about any previously healthy patients
less than 50 years of age who have died from an unexplained
illness that appears to have been caused by an infectious agent.
To identify emerging pathogens that may be causing serious illness.
Much of the impetus for this approach comes from the 1993 experience
in New Mexico with the hantavirus pulmonary syndrome. Two mysterious
cases presented to the same physician who contacted others in
the area; an investigation was begun, the pathogen found, and
the reservoir identified within six weeks of the first case presentation.
We hope our approach will be useful in early identification of
newly emerging or re-emerging pathogens and will enhance the public
health infrastructure in investigating and responding to cases
and clusters of unexplained deaths of public health importance.
An unexplained death
is defined by the following criteria:
-Age: <50 years
-Previously healthy, without severe underlying illness or immunosupression
(e.g., no AIDS, cancer,
-Hallmarks of infection (abnormal white blood cell count, fever)
seen within 48 hours before death
-Preliminary testing has not revealed a cause
Previously healthy 35
year old who presents with hypotension, fever, and respiratory
failure, then died; no etiology confirmed.
How to Report
health professionals to contact the California UNEX Project upon
encountering a patient who fits the above criteria. Timely reporting
ensures collection of optimal clinical specimens, which are crucial
for our ability to aid in disease diagnosis.
Our staff will
gather clinical and epidemiologic information (presenting syndromes,
travel and exposure histories, etc.) and ensure that sera and
other pertinent clinical specimens are sent to the California
Department of Public Health (CDPH) Viral and Rickettsial Disease
Laboratory and to the Centers for Disease Control and Prevention.
Patients with biopsy or autopsy specimens will be given highest
laboratory specimens are critical to providing diagnoses for these
illnesses. Useful specimens include body fluid specimens and tissues.
Multiple samples from all major organs are preferred. Fresh frozen
tissue is a valuable adjunct to fixed and/or embedded tissue;
however, if specimens are limited, fixed tissue should take first
priority. Pathology reports, even preliminary ones, are valuable
to our analysis.
and research level testing will be performed at CDPH, the CDC,
and collaborating laboratories.
What we have found:
Since May 1995, 76 fatalities
have been investigated by UNEX. The median age of included fatal
cases was 24 years (range 7 days to 81 years), and 39 (51%) were
female. Autopsies were performed on 66 cases (87%).
of cases presented with either a respiratory (37%) or neurologic
(22%) syndrome (Table 1). Laboratory testing was performed at
the Viral and Rickettsial Diseases Laboratory (VRDL) at the California
Department of Public Health (CDPH), CDC, and several collaborating
laboratories. An etiology was determined in 27 of the 72 cases
(38%) which had adequate specimens for evaluation (Table 2). Common
pathogens were found to be responsible for most of these "mystery"
illnesses, although one fatal case of hantavirus was found in
a resident of Contra Costa County, an area not known to have endemic
hantavirus, and Clostridium sordellii has been associated with
toxic shock in four women who underwent medical abortion (M. Fischer,
et al., 2005, “Fatal toxic shock syndrome associated with
Clostridium sordellii after medical abortion”,
NEJM 353: 2352-2360.)
1. Primary Syndromes for California Cases of Unexplained Death,
05/01/1995 - 06/30/2005
Number of Cases (%)
Table 2. Putative
Etiologies for Fatal CA UNEX Cases: 05/01/1995 - 06/30/2005 (N=27)
||Agent (# of cases)*
||Arenavirus (White Water Arroyo)
||Enterovirus (Echovirus 30)
||Hantavirus (Sin Nombre)
||Herpes simplex virus type 1
||Influenza A (3)
||Parainfluenza virus type 1 (2)
|Sepsis/Multi-organ failure (9)
||Clostridium sordellii (4)
||Group A Streptococcus (2)
||Influenza A/S. aureus
||E. coli O157:H7 toxin type 2
||Adenovirus type 11
|Blood Cell Dyscrasia (1)
* One case
per etiology, unless otherwise noted<br>
** Abbreviations: IHC=immunohistochemistry, PCR=polymerase chain
EIA=enzyme immunoassay, IEM=immunoelectron microscopy
For more information about UNEX, follow the links below.
Unexplained Deaths and Critical Illnesses Site
Unexplained Critical Illnesses and Deaths Project
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