Unexplained Critical Illnesses and Deaths of Possible Infectious Etiology, 2001
Surveillance for unexplained critical illnesses and deaths of possible infectious etiology in Minnesota began in September 1995 as part of the EIP. MDH requests that any cases of unexplained critical illness or deaths that appear to have possibly infectious causes be reported, regardless of the patient's age or underlying conditions. A subset of reported cases (i.e., persons 1-39 years of age with no serious underlying conditions who died of apparent non-nosocomial infectious processes) will be eligible for testing performed at CDC as part of the core surveillance project. For cases who are not eligible for enrollment in the CDC project, some testing may be available at CDC and MDH, at the physician's request.
Thirty-five possible cases were reported in 2001, compared to 17 cases in 2000; the increase may be attributed partially to heightened awareness among providers and broader active surveillance activities related to bioterrorism concerns at the end of the year. Providers subsequently determined causes of illness for 15 cases. Two deaths remain unexplained, but there was no evidence to suggest infectious causes for either case.
Of the remaining 18 cases, 10 presented with respiratory symptoms, five with neurologic symptoms, and three with shock/sepsis. The respiratory cases ranged from 1 to 64 years of age; the neurologic cases were 18, 36 (2 cases), 40, and 59 years of age, and the sepsis cases were 56, 60, and 78 years of age. Three patients with respiratory syndromes and one patient with a neurologic syndrome died. Nine respiratory case-patients, two neurologic case-patients, and one sepsis case-patient resided in the seven-county Twin Cities metropolitan area; the remaining cases resided in greater Minnesota, except for one neurologic case-patient who was a Wisconsin resident hospitalized in Minnesota. One case, the death of a 1-year-old with a respiratory syndrome, was eligible for inclusion in the CDC project. Autopsy specimens were sent to CDC; preliminary tests have not identified an etiology.
CDC has proposed that each EIP site carry out hospital-based, syndrome-specific surveillance projects in addition to the core project involving surveillance for unexplained deaths. Projects studying critical illnesses and deaths due to unknown causes of meningoencephalitis and respiratory failure may begin at several hospitals in Minnesota later this year.