Unexplained Critical Illnesses and Deaths of Possible Infectious Etiology, 2007

Surveillance for unexplained critical illnesses and deaths of possible infectious etiology (UNEX) began in September 1995. Any case should be reported, regardless of the patient’s age or underlying medical conditions. A subset of cases (persons up to 49 years of age with no underlying medical conditions who died of an apparent non-nosocomial infectious process) are eligible for testing performed at CDC as part a special project. For cases not eligible for the CDC project, some testing may be available at MDH or CDC, at the physician’s request.

Sixty-four cases (39 deaths and 25 critical illnesses) were initially reported in 2007, compared to 45 cases in 2006. The cause(s) of illness subsequently were determined for 13 cases and were no longer considered unexplained. Among the remaining 51 cases, 15 presented with neurologic symptoms; 11 case-patients presented with respiratory symptoms; 10 presented with cardiac symptoms; seven presented with shock/sepsis; five presented with sudden unexpected death (SUD); one presented with gastrointestinal (GI) symptoms; one presented with a renal syndrome; and one had an illness that did not fit a defined syndrome. Case-patients with neurological symptoms were 1 to 76 years of age; those with respiratory symptoms ranged from 2 to 54 years of age; those with the cardiac case-patients were 8 days to 52 years of age; those with sepsis were 1 to 54 years of age; the case-patients with SUD were 1 to 53 years of age; the case-patient with GI symptoms was 16 years of age; the case-patient with renal symptoms was 39 years old, and the case-patient without a defined syndrome was 15 years of age. Nine patients with a cardiac syndrome, six patients with sepsis, five patients with respiratory symptoms, two patients with neurologic symptoms, and the patient with a GI syndrome died, as did the patient with a renal syndrome. Twenty-five patients resided in the metropolitan area, 14 case-patients resided in Greater Minnesota, and 12 case-patients were out-of-state residents hospitalized in Minnesota.

Nineteen cases were eligible for the CDC project (five cardiac, four respiratory, three sepsis, three neurologic, two SUD, the GI case, and the renal syndrome case). Specimens were obtained for testing at MDH or CDC for 14 cases. Probable etiologies were established for nine cases. Immunohistochemical (IHC) testing and a viral culture of the lungs were positive for influenza A from a 1 year-old who experienced sudden unexpected death. A viral culture and PCR test of a nasopharyngeal swab was also positive for influenza A. A 2-year-old had influenza A cultured from the lung and spleen and also had a culture and PCR test of the lung that were positive for group A streptococcus. A 10-month-old, a 4-year-old, and a 25 year-old male who died from myocarditis all had positive PCR tests for enterovirus from heart samples. A 44 year-old male who died with a respiratory syndrome had positive PCR tests of lung samples for Streptococcus pneumoniae. A 47 year-old male who died with a respiratory syndrome had IHC testing of a lung sample that was positive for S. pneumoniae. A 2 year-old who died with a respiratory syndrome had adenovirus type 2 isolated from a viral culture of a nasopharyngeal swab. A 3 year-old who died with shock/sepsis syndrome had a positive PCR test of blood for serogroup C Neisseria meningitidis.

Testing was also provided at MDH and/or CDC at the physician’s request for 18 of the 32 cases that were not eligible for the CDC project. Positive results were found for four of these cases. All four (a 2 year-old, a 3 year-old, a 17 year-old female, and a 40 year-old female) were hospitalized with culture-negative meningitis and had positive PCR tests of cerebrospinal fluid for serogroup C N. meningitidis.

Medical Examiner Surveillance

MED-X is a population-based surveillance program aimed at identifying all infectious disease related deaths that are investigated by medical examiners (MEs). There are three mechanisms in place for case finding. First, as part of the unexplained deaths surveillance (UNEX), MDH reviews all death certificates for deaths due to infectious causes. Second, MDH reviews all death investigation reports at the Minnesota Regional Medical Examiner Office (MRMEO) in Hastings. This office covers seven counties, including Carver, Chisago, Dakota, Houston, Fillmore, Goodhue, and Scott, which together make up 14.3% of the state population. Lastly, the ME offices actively report cases that have infectious causes or are suspicious for infectious causes and MDH collaborates with them to determine the cause of death. In some instances, these become UNEX cases and may have additional testing done at CDC.

In 2007, MED-X was expanded to include the Hennepin County Medical Examiner’s Office and the Midwest Regional Forensic Pathology Office in Anoka, in addition to the MRMEO. Additional counties covered by these two offices include Anoka, Crow Wing, Hennepin, Mille Lacs, Meeker, McLeod, Sibley, and Wright counties. The three ME offices together cover 48% of the state population.

MDH distributes specimen collection kits to the ME offices to help guide the number and type of specimens collected. These specimens are then tested at the facility laboratory or sent to MDH for testing. There were 15 kits distributed in 2007. Use of these kits has continued to improve the quality and number of specimens sent to MDH, which has increased our ability to determine a cause of death.

There were 104 MED-X cases in 2007, and 24 of these were also UNEX cases. Based on MRMEO data, the population-based rate of potential infectious disease related deaths as reported to medical examiners was 5,700 per 100,000 ME cases, which translates to 2,700 per 100,000 total deaths and 12 per 100,000 among the total population. The mean age of the case was 58 years, and 52% were female. The majority of cases were found through death investigation report review (78, [75%]). MEs reported 22 cases (21%), and four (4%) were found through death certificate review. The most common presenting symptom was pneumonia/upper respiratory infection, which was also the most common pathologic finding. In addition, there were 12 cases with myocarditis. Of the 104 cases, 35 (34%) were confirmed to be due to an infectious cause, 58 (56%) were possibly due to infectious cause, nine (9%) were determined to not be due to infectious cause, and two (2%) were unable to be determined. Pathogens that were identified as the cause of death included Streptococcus pneumoniae, Staphylococcus aureus and methicillin-resistant S. aureus, Group A Streptococcus, influenza A, enterovirus, Haemophilus influenzae, and prion disease. Other pathogens identified as possibly related to the cause of the death included Coxsackie virus, Group F Streptococcus, and adenovirus.

• For up to date information see>> Unexplained Deaths and Critical Illnesses
• Full issue>> Annual Summary of Communicable Diseases Reported to the Minnesota Department of Health, 2007