Outbreak of emm26.3 Group a Streptococcus Invasive Disease Among Individuals Experiencing Homelessness— Alaska, 2016

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Wednesday, June 7, 2017: 11:30 AM
400C, Boise Centre
Anna Rose Frick , Alaska Department of Health and Social Services, Anchorage, AK
Emily Mosites , Centers for Disease Control and Prevention, Anchorage, AK
Prabhu Gounder , Centers for Disease Control and Prevention, Anchorage, AK
Louisa J Castrodale , Alaska Department of Health and Social Services, Anchorage, AK
Karen M. Rudolph , Centers for Disease Control and Prevention, Anchorage, AK
Tolulope Adebanjo , Centers for Disease Control and Prevention, Atlanta, GA
Jennifer Adebanjo , Centers for Disease Control and Prevention, Atlanta, GA
Chris Van Beneden , Centers for Disease Control and Prevention, Atlanta, GA
Debby Hurlburt , Centers for Disease Control and Prevention, Anchorage, AK
Tammy Zulz , Centers for Disease Control and Prevention, Anchorage, AK
Tom Hennessy , Centers for Disease Control and Prevention, Anchorage, AK
Michael G. Bruce , Centers for Disease Control and Prevention, Anchorage, AK
Joseph B McLaughlin , Alaska Department of Health and Social Services, Anchorage, AK
Audio File Recorded Presentation
BACKGROUND:  Group A Streptococcus (GAS) can cause severe invasive disease. In February 2016, we detected an increase in invasive GAS (iGAS) cases near Fairbanks, Alaska caused by a rare M protein gene (emm) subtype, emm26.3. By August 2016, cases of emm26.3 iGAS infection were detected in homeless persons using services provided by Shelter A in Anchorage, Alaska. We investigated the outbreak to prevent further cases and characterize the epidemiology of emm26.3 iGAS.

METHODS:  We defined a case of invasive disease as isolation of GAS emm26.3 from a normally sterile site in an Alaska resident from February 2016 to March 2017. We reviewed medical charts, interviewed cases, and referred contacts for antibiotic chemoprophylaxis. In December 2016, we cultured oropharyngeal and skin swabs from guests at Shelter A and referred emm26.3 carriers for chemoprophylaxis. Severe disease continued to occur in December and January. In February 2017, we launched a mass chemoprophylaxis campaign using single dose azithromycin at six facilities providing homeless services. We collected risk factor data, oropharyngeal swabs, and wound swabs at the time of the antibiotic intervention. In March 2017, we repeated the swabbing and survey process at the same facilities.

RESULTS:  We identified 51 iGAS emm26.3 cases as of March 1, 2017; 11 occurred in Fairbanks and 40 in Anchorage. The majority (n=39, 76%) occurred among Alaska Native persons and 38 (75%) occurred among persons experiencing homelessness. Most patients had a history of alcoholism (76%) and presented initially with cellulitis (55%). Associated diagnoses included sepsis (51%), necrotizing fasciitis (27%), and streptococcal toxic shock syndrome (STSS) (10%). Four (8%) patients died. Of the 137 Shelter A guests who were cultured in December, 6 (4%) were colonized with emm26.3 GAS in their oropharynx; in February 2017, 12 of 289 participants (4%) were carrying emm26.3 in the oropharynx or wounds. A single dose of azithromycin was administered to 394 individuals across 6 facilities. After the intervention, 4 of 298 participants (1%) were carrying emm26.3 GAS.

CONCLUSIONS:  This ongoing emm26.3 iGAS outbreak has disproportionally impacted Alaska Native persons experiencing homelessness and alcoholism, and has resulted in a high proportion of cases experiencing necrotizing fasciitis and STSS. Due to the numerous challenges associated with controlling the spread of GAS infection in this population, a community-based chemoprophylaxis strategy was undertaken to address this outbreak. The results of this intervention are forthcoming.

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