Just a non-HCV "general interest" article I came across, regarding a small, rare, but nasty disease outbreak in Wisconsin area, mostly in the average 77 year old age bracket (earlier this year). But serious outcomes for a high percentage of infected. Probably 63 cases. Possibly a 29% death rate. This outbreak would be of some concern for anyone, but especially so for those in the age bracket and those with pre-existing chronic disease. 

Source of Elizabethkingia Outbreak Eludes Investigators

Caroline Helwick   November 01, 2016

 An epidemiologic investigation into the recent outbreak of Elizabethkingia infection in Wisconsin underscores the importance of statewide infection surveillance systems and highlights challenges faced by epidemiologists trying to track down the source of such rare infections.

"This is the largest reported outbreak of Elizabethkingiainfections, and the source of the outbreak strain of E anophelisremains unknown," said Lina Elbadawi, MD, from the Bureau of Communicable Diseases at the Wisconsin Division of Public Health in Madison and the Office of Public Health Preparedness and Response at the Centers for Disease Control and Prevention (CDC).

Dr Elbadawi described the epidemiologic investigation conducted by the Wisconsin Division of Public Health and the CDC here at IDWeek 2016.

Elizabethkingia anophelis is a rare aerobic Gram-negative bacillus that can be isolated in soil, water, and sink drains. It is intrinsically multidrug-resistant and opportunistic and causes severe infections in people who have underlying medical conditions. The three species associated with human illness  E anophelis, E meningoseptica, and E miricola  are hard to distinguish phenotypically.

On January 5, 2016, the Wisconsin Division of Public Health notified the CDC that six E anophelesbloodstream infections had been identified in residents of four counties in the preceding 13 days. Four isolates had indistinguishable patterns on pulsed-field gel electrophoresis (PFGD), but the CDC confirmed them to be E anophelis. A joint investigation ensued, during which many more cases emerged.

Identifying Clusters

Infection preventionists and clinical laboratories began to watch for cases involving Elizabethkingia and its former genera, Flavobacterium and Chryseobacterium. In searching for other clusters, epidemiologists looked at neighboring states, the nationwide Emerging Infections Network, and other programs in which outbreaks have been described.

"Rapidly established statewide retrospective and prospective surveillance techniques were critical to case-finding efforts," Dr Elbadawi explained.

An isolate of E anophelis from any clinical specimen collected on or after November 1, 2015, with a PFGD pattern matching that of the outbreak was considered to be a case.

The outbreak was found to be characterized by tight geographic clustering, community onset, and occurrence in older adults with comorbidities.

The medical records of each case-patient were reviewed to identify all healthcare encounters in the 30 days before collection of the first positive specimen. A Charlson comorbidity score was assigned to each patient, and epidemiologists interviewed each patient or a proxy about community exposures and potential sources and modes of transmission.

"We tested numerous potential community-associated and healthcare-associated sources," reported Dr Elbadawi. Sources of interest included, but were not limited to, personal contacts, animals, personal-care products (such as lotions, shampoos, and oral care products), food, water, the facility in which the patient resided, and environmental factors.

The clinical isolates underwent extensive laboratory testing. Water and other environmental samples were cultured, as were medical and personal-care products. For the household and healthcare contacts of each patient, cultures were taken at several sites on the body.

High Fatality Rate

The vast majority of the infections appeared to have occurred in the 2-month period from February to April 2016. Sixty-three case-patients lived in 12 southeastern Wisconsin counties, and three lived in neighboring states.

The median age of the Wisconsin case-patients was 77 years (range, 19 - 101), 56% were male, and the median Charlson score was 3.5 (range, 3 - 5). Most initial specimens were collected at the patients' private residences (75%), but 13% were collected in assisted-living facilities, 6% in long-term care facilities, and 6% in acute care facilities. In most of the initial positive specimens (89%), the isolate was identified in the blood.

In the Wisconsin cohort, 34% of the infections were associated with soft tissue, 33% with the lungs, and 13% with the urinary tract; 5% of the case-patients showed no evidence of infection. Sequelae were often serious, and 29% of the patients died, possibly as a result of the infection.

Looking for Source of Transmission

Case-patients had encounters at 47 healthcare facilities, but no facility had more than seven encounters in common with another facility, which eliminates any one facility as the cause of infection.

Municipal water, which came from 27 different systems, was used by 80% of the patients.

Surveillance cultures from 15 household contacts and 182 healthcare contacts were negative for E anophelis.

In the 30 days before specimen collection, most patients had at least one healthcare exposure; 43% of these were hospital admissions, and 14% were for hemodialysis. No common intravenous medications or compounded products were identified.

The investigators analyzed 31 personal-care products, 38 water samples, and 61 water-associated biofilm swabs from 12 residences and assisted-living facilities. At five acute care facilities, they sampled water and sink drains.

All healthcare and personal-care products, tap water, and water-associated biofilm samples tested negative for the outbreak strain of E anophelis, with the exception of one sample of tub water that contained bedding from an infected patient.

"All 41 medical products we tested were also culture-negative for E anophelis," Dr Elbadawi reported. These included alcohol swabs, single-exposure products, and products related to dialysis and other procedures.

"Food history interviews did not identify any food reported more frequently than expected," she said, "and there was no common food distributor among five long-term care facilities and no common personal-care products or brands identified among the majority of patients."

Obstacles Facing Investigators

A number of factors that limited the search for answers highlight the challenges faced by investigators of outbreaks.

"The high case-fatality rate and advanced age of the patients required broad use of proxy interviews, and recall was a limitation among surviving patients," said Dr Elbadawi. "Also, among the earliest cases, prolonged time from diagnosis to the completion of the interview made it hard to ascertain exposure.

"Despite extensive data and the numerous means used to collect it, we were also unable to determine the incubation interval for these illnesses, which has been a challenge during previous Elizabethkingiainvestigations as well," she added.

"I applaud the efforts of these investigators trying to get to the bottom of this relatively rare disease," said Scott Fridkin, MD, senior advisor in the Division of Healthcare Quality Promotion at the CDC. "They approached it from many directions, but it's relatively rare, and there is difficulty with recall of exposures."

The case-fatality rate is high largely because this organism infects mostly people with chronic and recurrent illnesses. They "go in and out of the healthcare setting," which makes it hard to pinpoint sources, he told Medscape Medical News. "It may also be a community-based disease."

The CDC provided guidance to healthcare providers in Wisconsin on how to recognize and empirically treat the infection. Although Elizabethkingia infections are rare, many infectious disease physicians have seen it, Dr Fridkin explained.

Dr Elbadawi and Dr Fridkin have disclosed no relevant financial relationships.

IDWeek 2016: Abstract LBA_9. Presented October 29, 2016.