Surveillance for Unexplained Deaths and Critical Illnesses Due to Possibly Infectious Causes, United States, 1995-1998

Abstract

Population-based surveillance for unexplained death and critical illness possibly due to infectious causes (UNEX) was conducted in four U.S. Emerging Infections Program sites (population 7.7 million) from May 1, 1995, to December 31, 1998, to define the incidence, epidemiologic features, and etiology of this syndrome. A case was defined as death or critical illness in a hospitalized, previously healthy person, 1 to 49 years of age, with infection hallmarks but no cause identified after routine testing. A total of 137 cases were identified (incidence rate 0.5 per 100,000 per year). Patients’ median age was 20 years, 72 (53%) were female, 112 (82%) were white, and 41 (30%) died. The most common clinical presentations were neurologic (29%), respiratory (27%), and cardiac (21%). Infectious causes were identified for 34 cases (28% of the 122 cases with clinical specimens); 23 (68%) were diagnosed by reference serologic tests, and 11 (32%) by polymerase chain reaction-based methods. The UNEX network model would improve U.S. diagnostic capacities and preparedness for emerging infections.

Evaluation of the surveillance system for undiagnosed serious infectious illness (USII) in intensive care units, England, 2011 to 2013

“…As in this study, where the majority (7/22) of USII cases had respiratory illness, surveillance from Taiwan also found that respiratory syndromes were most common, accounting for 59% of cases [17]. Respiratory syndromes were also the second most common presentation for the US system, accounting for 26% of cases, although this was closely preceded by neurological presentations (29%) [18]. The latter were less common among our cases.…”

“…To our knowledge, there have been only two similar surveillance systems [17,18] described previously in the literature although these were not specifically developed for mass gatherings.…”

A new surveillance system for undiagnosed serious infectious illness for the London 2012 Olympic and Paralympic Games

“…Our annual rate is comparable to that reported in the literature from similar surveillance systems in the United States and Taiwan, despite methodological differences such as the inclusion and exclusion criteria and the extent of laboratory investigations. In Taiwan, 0.12 cases per 100,000 population were reported in 2000-05 [8] and in the United States, 0.5 cases per 100,000 population (range: 0.3-2.3 per 100,000 population) were reported during 1995-98 [4]. The majority of USII cases in our pilot study were reported in the first three months of surveillance.…”

“…Examples, including the international spread of severe acute respiratory syndrome (SARS) and the influenza A(H1N1)pdm09 pandemic, illustrate that new and emerging infections can spread through major transport hubs in a matter of days [2,3]. Such new and emerging diseases can pose difficulties in diagnosis and may present as undiagnosed serious infectious illness (USII) [4]. These could be missed by traditional surveillance, necessitating the development of new infectious disease surveillance systems.…”

“…Additional objectives were to estimate the annual rate of cases of USII and to develop a system that was both feasible and acceptable to participating clinicians. This surveillance is based on similar systems for detecting cases of new and emerging infections established previously in the United States [4,7] and Taiwan [8]. The HPA-based USII surveillance is part of a range of enhanced existing and new surveillance systems, including syndromic surveillance in primary care, Olympic venues and emergency departments, put in place for the 2012 London Games [9,10].…”