Ten Alaskans were sickened by raw or undercooked walrus. A parasite was in the meat, CDC says.

The first sign came when a teenage girl from Gambell ended up in the hospital last summer. She was having trouble walking. She was weak and suffering with fever, rash and swollen, painful legs. Then her brother and father became ill. Then an aunt and uncle.

All of them had eaten raw or half-cooked walrus.

By this spring, there was a second outbreak, in neighboring Savoonga, where, as in Gambell, people rely on walrus as one of their basic foods.

People in the two rural Alaska villages on St. Lawrence Island eat more walrus than anywhere in the world, and in recent decades have not gotten sick like this — until now.

The Bering Sea island is far from mainland Alaska and affordable stores. The ocean and the land provide their food: walrus and whale, salmon and halibut, wild birds and wild greens.

Public health officials are using the serious and unusual outbreaks of illness from eating raw or undercooked walrus to call attention to the risks. Some people who ate the undercooked meat became infected with a parasite, the freeze-resistant Arctic trichinella roundworm species, a cousin of the one that infects pigs and bears.

The cautious message is intended to inform residents, not scare them away from a favorite nutritious food.

The U.S. Centers for Disease Control and Prevention last week featured the Alaska occurrences of walrus-triggered trichinosis in its Morbidity and Mortality Weekly Report. The state Public Health Division also outlined the risk.

"In areas where wild game species are harvested for subsistence, traditional methods of collecting, handling, preparing, storing, and consuming meat often have great cultural significance; however, some of these methods can be inconsistent with public health best practices," the CDC said.

[Special report: Stories from St. Lawrence Island]

The outbreaks mark the first since 1992 in which multiple Alaskans were sickened by walrus, according to state and federal epidemiologists.

In all, 10 people became ill, five in each village, from eating infected walrus that was raw, underboiled, or pan-fried to "medium doneness." Yet almost all the 1,500 people who live on the island eat walrus. Those who become sick need to seek help, public health officials stress.

Those who were part of the recent outbreaks showed up at village clinics and Native hospitals with muscle and joint pain, diarrhea, nausea and overall weakness. The parasitic infection also can lead to breathing problems, heart failure, neurological complications and difficulty coordinating movement. If large numbers of larvae are ingested, trichinosis can be deadly, according to the U.S. Geological Survey.

Vanquished from pork

No one is sure why a once-common parasitic illness almost vanished only to emerge anew. Before the recent outbreaks, Alaska had only seen one reported case in the preceding 23 years, the CDC said. Maybe there are changes in infection rates of walruses. Maybe changes in hunting due to diminishing sea ice is a factor. Maybe people are changing preparation and cooking methods, according to the CDC report.

The parasite that causes trichinosis used to be most prevalent in pork, but stricter laws and changes in commercial practices have generally eliminated it there. It still shows up in hunted wild boar as well as all kinds of bear, said Louisa Castrodale, a state epidemiologist involved in the recent studies of walrus-associated disease.

Polar bears, especially, carry the parasite, with 55-60 percent of those in Alaska infected, according to a 2013 study led by researchers with the University of Alaska Fairbanks. But people who eat polar bear usually boil it well.

Few walruses — 1 to 3 percent — are infected, and it doesn't seem to bother them or other wild animals, said Lori Quakenbush of the state Department of Fish and Game's Arctic Marine Mammal Program. The rate is so low that Fish and Game, U.S. Fish and Wildlife Service and Native partners didn't even look for trichinella during recent studies in 2012-14, and 2016.

Even if new tests found increasing rates, nothing would likely change in terms of the public health message to cook the meat, she said. It would be up to individuals to decide what to do.

"Would you take more or less of a chance of eating raw walrus if you had in a 1 in 100 chance (of becoming ill) vs. 5 in 100 chance?" Quakenbush said.

Hunters already are wary of what they call "carnivore walruses," which often were orphaned young and stayed alive by eating seal and other meat, not the usual walrus diet of clams and other mollusks, said Savoonga's Kenneth Kingeekuk, who serves on the Eskimo Walrus Commission, which works on walrus management issues on behalf of Alaska Natives.

Researchers aren't sure how walruses become infected with parasites, but one route could be through eating seal.

Those animals have oily skin and discolored tusks, and their meat is suspect, Kingeekuk said. Hunters don't target them, but if they find seal fur and bird feathers in a walrus stomach, "we start letting go of its meat. We put it all back in the water," he said.

Only the most recent meals will be in the stomach. Some other walruses can be infected too, Quakenbush said.

'Cook mine real good'

Since 1975, 241 trichinosis cases were reported in Alaska, and 227 of them were from wild nonporcine game, mainly walrus or bear, according to the CDC. Those walrus cases were from the past. Many public officials, including Castrodale, who has worked in Alaska epidemiology since 1999, had never before seen an outbreak.

"From our perspective it was just unique because we are so used to hearing about bears and illness," Castrodale said.

Health officials don't think they have missed cases. The parasite makes some people terribly ill, she said.

"It's not something you would sit at home and wait it out," she said.

Infected meat has cysts that contain larvae. When that meat is consumed, digestive acids dissolve the hard covering of the cyst and release the larvae, which then grow into worms that reproduce in the intestines. New larvae eventually undergo "a mass migration" through muscle that causes intense pain and discomfort, Castrodale said. The medication used to kill the worms, albendazole, is expensive and only somewhat effective, but essential, she said.

Drying, smoking and fermenting meat doesn't kill the trichinella roundworm. For the Arctic species, neither does freezing it. But cooking meat well-done will, according to health officials.

Many people in both villages still like their walrus half raw, just like many people in cities like steaks rare, said Richmond Toolie, a Savoonga walrus hunter who, along with his brothers, had successful hunting this year with seven walruses brought home for seven families.

But he doesn't do his that way, for worry of illness.

"I cook mine real good," he said. "We always cook it real good." Some complain it is overdone. He calls it well-done.

People in St. Lawrence Island villages also still consider fermented walrus calves a delicacy. They aren't cooked at all but are put on racks to slowly ferment.

Cultural factors

In the Gambell outbreak, the girl became ill Aug. 15, 2016, almost a month after she and family members ate raw and undercooked walrus. She was seen at the village clinic and in September was hospitalized at Alaska Native Medical Center.

More family members were diagnosed. Investigators weren't able to determine if all the meat came from the same animal, or who hunted it. State public health officials mobilized. They prepared a campaign of information about walrus-born trichinosis.

When the second outbreak occurred in Savoonga this May, health officials were working to circulate public service announcements.

In Savoonga, two neighboring households that hunted walrus together were sharing a meal that included walrus boiled for about an hour. The exterior was cooked. But "the interior remained undercooked or raw, which was the desired result; interviewed persons reported that many community members prefer the taste and texture of undercooked or raw walrus meat to that of fully cooked meat," the CDC report said.

The CDC urged public health officials to recognize the cultural importance of food preparation. Public health campaigns shouldn't tell people how to cook their food, but rather warn of the risks of undercooking meat like walrus, the CDC said.

That's the approach of the state public health campaign, which included posters and radio announcements, Castrodale said.

"We want to let people know that when you cook something, the risk of having a parasite in that meat product is going to be reduced," she said.

When people experience muscle and joint pain after eating those animals, they should see a doctor, the radio announcement said.

So much data is available and it can empower people, Castrodale said.

"Then they are in a position to weigh that and then decide for themselves," she said.