Four Alaskans have died this year in an outbreak of invasive strep bacteria that has mostly affected the homeless and Alaska Natives in the state’s two largest cities, State epidemiologist Joe McLaughlin said Tuesday.

There have been 28 confirmed hospitalization cases of a new strain of Group A Streptococcus bacteria, starting with 10 cases in Fairbanks earlier this year and, more recently, 18 cases in Anchorage, he said.

Among the total, 15 involved homeless people in Anchorage and two homeless people in Fairbanks.

Two of the deaths occurred in Fairbanks and two in Anchorage.

Another three probable cases in Anchorage have not been confirmed.

All four of the deaths were of Alaska Natives. McLaughlin said studies have shown that American Indians and Alaska Natives are at increased risk of invasive disease. That’s when bacteria moves into normally sterile parts of the body.

Also more susceptible are the elderly, young children, people with compromised immune systems and other factors, including alcohol abuse.

McLaughlin emphasized that the people counted all had invasive cases, which can lead to death or serious illness, including sepsis, pneumonia and toxic shock syndrome. Those generally would not include simple strep throat.

“People with strep throat don’t have what we would call invasive disease,” McLaughlin said. “Now, people with strep throat can develop invasive disease.”

The strain is new to the state, according to McLaughlin, who noted it was previously seen in the Middle East. There are more than 220 strains of Group A strep, and Alaska sees between 60 and 90 cases each year, including deadly ones.

“This is the first time this particular strain of Group A strep has been identified in Alaska,” McLaughlin said. “We’re not aware of other states that have seen this particular strain of Group A strep circulating in their communities.”