Update 11 a.m. Tuesday: The Alaska section of epidemiology reported Tuesday morning that an additional death in Fairbanks was not originally included in its data. The story has been updated to reflect four deaths due to group A strep infection, instead of three, as previously reported.

Original story:

A new strain of group A Streptococcus bacteria first identified in Fairbanks in early 2016 has caused an outbreak in Anchorage, mainly among the homeless population, a state health department official said Monday afternoon.

At least 28 people in Fairbanks and Anchorage have been hospitalized since the bacteria were identified, and four have died due to different invasive diseases, said Joe McLaughlin, state epidemiologist and chief of the Alaska section of epidemiology with the Department of Health and Social Services.

"This outbreak is a new strain that we've never seen before. So having this increased number of cases of group A strep is not atypical," McLaughlin said.

Group A Streptococcus bacteria can cause a wide range of infections, McLaughlin explained. Those range from less-severe strep throat and wound infections to potentially fatal toxic shock syndrome and necrotizing fasciitis, a quick-spreading bacterial skin infection that kills the body's soft tissue.

Every year in Alaska, about 60 to 90 people with invasive diseases from group A strep are identified, McLaughlin said. An invasive disease is one where germs enter normally germ-free parts of the body.

The outbreak is the largest since public health officials began doing surveillance on the bacteria in 2000, McLaughlin said.

The strain was first identified in early 2016 in Fairbanks. Ten people in the Interior community were hospitalized due to infection, and two died.

Those cases trickled in, with one or two a month. No new cases have been seen in Fairbanks in several months, McLaughlin said.

The strain was then identified in Anchorage in July, and an outbreak started in October, when the number of cases shot up, McLaughlin said. In Anchorage, 18 people have been hospitalized, two people have died, and another two cases are suspected, pending lab results.

Six of the Anchorage patients have developed necrotizing fasciitis. Two have developed toxic shock syndrome, a rare bacterial infection.

One person has lost an arm and another person lost "multiple digits," McLaughlin said. One had cellulitis — a bacterial skin infection — and the other had toxic shock syndrome.

Of the three people who have died in Alaska, one had toxic shock syndrome, another had sepsis, where bacteria enter the bloodstream, and the third had pneumonia, McLaughlin said. The fourth had a combination of sepsis, toxic shock syndrome, and nectotizing fasciitis.

People who are more susceptible to illness from group A strep tend to be the elderly, very young people and those with health complications, McLaughlin said. Many people have been "colonized" by the bacteria but may not get sick, he said.

"From data that have been published nationally, there can be a higher risk in certain racial demographic groups," McLaughlin said, including Native Americans. "It's unclear why that is," he said.

The cases in Alaska have mostly been middle-aged Alaska Native men, McLaughlin said, and many have stayed at Anchorage homeless shelters. Alcohol abuse is another common condition noted on medical charts, McLaughlin said.

Of the four who died, one was elderly, McLaughlin said. In Anchorage, one person was homeless but the second was not. All four who died were Alaska Natives, according to McLaughlin.

Group A strep has about 220 different strains. New strains are not commonly identified, McLaughin said. When they are, they are often associated with outbreaks, as people have not developed immunity to it.

At Brother Francis Shelter, staff has been prioritizing education on how to identify symptoms, said program director Lisa Caldeira.