Unable to determine the source of an inexplicable outbreak of Elizabethkingia anopheles in Wisconsin and two other states, investigators are inviting the survivors of the infection to participate in focus groups and see if they can find a common link that preceded their illness.
“We want to get those that are still living face-to-face in groups and see if they can help each other bring some information to the surface,” says Gwen Borlaug, MPH, CIC, coordinator of the HAI Prevention Program in Wisconsin.
Updating the exhaustive but fruitless investigation recently at the APIC conference in Charlotte, Borlaug said the investigation continues though the number of cases appears to have peaked.
“At this point in the investigation, I think it is apparent that clues to the source of these infections are not found in the epidemiologic, clinical, environmental, or laboratory data that we have collected to date,” says. “We therefore need to expand our investigation methods.”
Active surveillance will continue, as E. anopheles is now a reportable condition in the state. That in itself is unusual, as the relatively obscure bacteria usually causes about five to 10 infections per state annually in the U.S.
“Whole genome sequencing is ongoing and that is going to help focus the epi-analysis toward patients with very closely related isolates,” she says.
As of June 16, 2016, the CDC confirmed 65 cases in three states with 20 deaths. With one case in Illinois and one in Michigan, the remaining 63 are in Wisconsin, which reported the first six cases between Dec. 29, 2015, and Jan. 4 of this year. The temporal and geographic pattern of the infections suggest west-to-east movement across southeast Wisconsin and the bordering areas of Michigan and Illinois. Though the common source of the outbreak remains unknown, two of the infections in Wisconsin were acquired in healthcare settings, Borlaug says.
“In terms of place of residence, 75% of the cases were living at home, 20% resided in nursing homes, and four patients were hospitalized at the time of their first positive culture,” she says. “Two of those cases had no signs or symptoms of infections and likely represent colonization. Those were incidentally identified in their hospital stay but two others represent healthcare associated infections.”
The cases don’t explain the outbreak, however, as no common source has been found despite an exhaustive investigation. The CDC has been assisting in an ongoing outbreak investigation that has included testing of water, soil, plants, food, and personal products in the search for a source of the genetically distinct strain of E. anopheles. Thirty-four isolates collected from other areas of the country do not match the infecting strain.
In addition, investigators have looked for common healthcare contacts in dialysis, dental settings, long-term care, and hospitals. With the exception of the two aforementioned nosocomial cases, there is no discernable pattern in healthcare contacts that would explain the majority of cases. The infections have primarily been in people with immune deficiencies and underlying health problems over the age of 65. The majority of the infections identified to date have been bloodstream infections, but some patients have had the bacteria isolated from other sites, including the respiratory tract and joints.
How exhaustive has the search been? Among the environmental sources tested have been neti pots, bird baths, marijuana, vacuum cleaner bags, leaf cuttings, and soil, Borlaug says. Among the food sources have been fish, as fish-fries are a common social event in Wisconsin, she adds. That led to questions about fish varieties and health — leads that had to be followed like everything else in the case.
“I didn’t know we had a state Fish Health Veterinarian,” she said.