Active Tracing and Monitoring of Contacts Associated With the First Cluster of Ebola in the United States.

BACKGROUND: Following hospitalization of the first patient with Ebola virus disease diagnosed in the United States on 28 September 2014, contact tracing methods for Ebola were implemented. OBJECTIVE: To identify, risk-stratify, and monitor contacts of patients with Ebola. DESIGN: Descriptive investigation. SETTING: Dallas County, Texas, September to November 2014. PARTICIPANTS: Contacts of symptomatic patients with Ebola. MEASUREMENTS: Contact identification, exposure risk classification, symptom development, and Ebola. RESULTS: The investigation identified 179 contacts, 139 of whom were contacts of the index patient. Of 112 health care personnel (HCP) contacts of the index case, 22 (20%) had known unprotected exposures and 37 (30%) did not have known unprotected exposures but interacted with a patient or contaminated environment on multiple days. Transmission was confirmed in 2 HCP who had substantial interaction with the patient while wearing personal protective equipment. These HCP had 40 additional contacts. Of 20 community contacts of the index patient or the 2 HCP, 4 had high-risk exposures. Movement restrictions were extended to all 179 contacts; 7 contacts were quarantined. Seven percent (14 of 179) of contacts (1 community contact and 13 health care contacts) were evaluated for Ebola during the monitoring period. LIMITATION: Data cannot be used to infer whether in-person direct active monitoring is superior to active monitoring alone for early detection of symptomatic contacts. CONCLUSION: Contact tracing and monitoring approaches for Ebola were adapted to account for the evolving understanding of risks for unrecognized HCP transmission. HCP contacts in the United States without known unprotected exposures should be considered as having a low (but not zero) risk for Ebola and should be actively monitored for symptoms. Core challenges of contact tracing for high-consequence communicable diseases included rapid comprehensive contact identification, large-scale direct active monitoring of contacts, large-scale application of movement restrictions, and necessity of humanitarian support services to meet nonclinical needs of contacts. PRIMARY FUNDING SOURCE: None.

Addressing needs of contacts of Ebola patients during an investigation of an Ebola cluster in the United States - Dallas, Texas, 2014.

The first imported case of Ebola virus disease (Ebola) diagnosed in the United States was confirmed on September 30, 2014; two health care workers who cared for this patient subsequently developed Ebola. Since then, local, state, and federal health officials have continued to prepare for future imported cases, including developing strategies to identify and monitor persons who have had contact with an Ebola patient. This report describes some of the needs of persons who were contacts of Ebola patients in Texas. It is based on requests received from contacts in the course of daily contact tracing interactions and on how those needs were met through community partnerships. Meeting the needs of contacts of the Ebola patients was essential to successful contact tracing, which is critical to interrupting transmission. Although a formal needs assessment of contacts was not conducted, this report provides important information for preparing for an importation of Ebola. Anticipating the nonclinical needs of persons under public health surveillance includes addressing potential concerns about housing, transportation, education, employment, food, and other household needs. Ensuring necessary supports are in place for persons who are asked to refrain from entering public venues can impact their willingness to comply with voluntary and mandated quarantine orders. Engagement with a wide range of community partners, including businesses, schools, charitable foundations, community and faith-based organizations, and mental health resources would enhance public health emergency preparedness for Ebola by readying resources to meet these potential needs.

Ebola virus disease cluster in the United States--Dallas County, Texas, 2014.

Since March 10, 2014, Guinea, Liberia, and Sierra Leone have experienced the largest known Ebola virus disease (Ebola) epidemic with approximately 13,000 persons infected as of October 28, 2014. Before September 25, 2014, only four patients with Ebola had been treated in the United States; all of these patients had been diagnosed in West Africa and medically evacuated to the United States for care.

The 2012 West Nile encephalitis epidemic in Dallas, Texas.

IMPORTANCE: After progressive declines over recent years, in 2012 West Nile virus epidemics resurged nationwide, with the greatest number of cases centered in Dallas County, Texas. OBJECTIVE: To analyze the epidemiologic, meteorologic, and geospatial features of the 2012 Dallas West Nile virus epidemic to guide future prevention efforts. DESIGN, SETTING, AND PATIENTS: Public health surveillance of Dallas County, an area of 2257 km2 and population of 2.4 million. Surveillance data included numbers of residents diagnosed with West Nile virus infection between May 30, 2012, and December 3, 2012; mosquito trap results; weather data; and syndromic surveillance from area emergency departments. MAIN OUTCOMES AND MEASURES: Incidence and age-adjusted incidence rates of West Nile neuroinvasive disease (WNND), daily prevalence of emergency department visits for asthma and skin rash, and Culex quinquefasciatus species-specific vector index (an estimate of the average number of West Nile virus-infected mosquitoes per trap-night). RESULTS: The investigation identified 173 cases of WNND, 225 of West Nile fever, 17 West Nile virus-positive blood donors, and 19 deaths in 2012. The incidence rate for WNND was 7.30 per 100,000 residents in 2012, compared with 2.91 per 100,000 in 2006, the largest previous Dallas County outbreak. An unusually rapid and early escalation of large numbers of human cases closely followed increasing infection trends in mosquitoes. The Cx quinquefasciatus species-specific vector index predicted the onset of symptoms among WNND cases 1 to 2 weeks later (count regression ß = 2.97 [95% CI, 2.34 to 3.60]; P < .001). Although initially widely distributed, WNND cases soon clustered in neighborhoods with high housing density in the north central area of the county, reflecting higher vector indices and following geospatial patterns of West Nile virus in prior years. During the 11 years since West Nile virus was first identified in Dallas, the log-transformed annual prevalence of WNND was inversely associated with the number of days with low temperatures below 28°F (-2.2°C) in December through February (ß = -0.29 [95% CI, -0.36 to -0.21]; P < .001). Aerial insecticide spraying was not associated with increases in emergency department visits for respiratory symptoms (ß = -4.03 [95% CI, -13.76 to 5.70]; P = .42) or skin rash (ß = -1.00 [95% CI, -6.92 to 4.92]; P = .74). CONCLUSIONS AND RELEVANCE: Large West Nile virus epidemics in Dallas County begin early after unusually warm winters, revisit similar geographical distributions, and are strongly predicted by the mosquito vector index. Consideration of weather patterns and historical geographical hot spots and acting on the vector index may help prevent West Nile virus-associated illness.