That bites: Spider causes big illness

Posted: Friday, September 19, 2003

Two weeks ago, when Kenai resident Sherri James noticed an unusual blemish on her abdomen while drying off after a bath, she had no idea exactly how big a mountain would grow from that molehill.

"It's been horrible, absolutely horrible," James said.

The blemish has since been identified as a venomous spider bite. The culprit is believed to be a hobo spider (Tegenaria agrestis), an arachnid with a potentially lethal bite.

It is quite common for the initial bite from a hobo spider to be painless. James said she never felt the spider's bite, but believes it to have been during the night while she was asleep. She found spider legs in her bed after she realized she had been bitten.

"It started out as just a red welt about the size of a pencil eraser," said James. By the next morning the red area had grown and was becoming painful. The center of the irritation also had developed into a hardened spot.

She went to her family physician, but the doctor was uncertain what was causing the irritation.

"By the next day I was sick, really sick" James said. "I had several flu-like symptoms and a migraine that drugs seemed to have no effect on. The irritation site on my abdomen had also started to blister."

By the next day, the blister had broken open and James continued to feel worse.

"The area looked like I had been burned and the red was still growing," she said.

The next day her symptoms continued, and the red area was beginning to look bruised. She went back to her doctor who immediately referred her to a surgeon Dr. M. Todd Boling, a board certified physician at Peninsula Surgical Clinic.

Boling immediately recognized the bite as having characteristics suspicious to a hobo spider bite.

He drained, cultured and cleaned the wound, but by the next day James felt even worse. Her migraine was crippling, and medicine for severe headaches wasn't working. Only later did James find out that headaches induced by hobo spider bites frequently are non-responsive to drugs.

She went back to Boling who started her on antibiotics, but by the next day her condition hadn't improved. She called Boling's office only to learn more bad news.

"They got the results of the culture back and the bite was causing a bacteria to grow that was resistant to the antibiotics I was on," said James. She was put on another antibiotic to combat the harmful bacteria.

By Monday morning her condition had yet to improve. James is considering surgery to remove the core section of the bite, which has turned black from tissue necrosis.

Hobo spider bites in fatty tissue are known to cause local lesions that become deep and extensive, sometimes taking up to two to three years to heal completely.

"I don't want to wait years for this thing to heal on its own, so cutting out the clot and cleaning it up may be the best thing for me," she said.

Also, in extreme cases of hobo spider bites, a condition can develop known as aplastic anemia. This is a bone marrow failure, which, although rare, is often fatal.

"I feel fortunate that I went and got it checked out quickly," James said.

What makes her bite even more unusual is that depending on who you ask, hobo spiders aren't known to exist in Alaska.

"It's possible they're here, but to our knowledge the hobo spider has never been positively identified anywhere in Alaska," said Louisa Castrodale, a veterinarian at the state of Alaska Office of Epidem-iology in Anchorage.

However, that doesn't mean that James wasn't bitten by a hobo spider.

"It just means we've never conclusively proven their existence here because we've never had anyone catch, identify and match a hobo spider to a bite they had," Castrodale said.

This is unfortunate since not only does this hinder positively identifying the species as existing in Alaska, but also the age and sex of the spider affects the amount and concentration of venom a spider injects during a bite. Keeping the spider can help determine the necessary course of treatment.

According to the state of Alaska Epidemiology Web site, hobo spiders are indigenous to western Europe and are believed to have been accidentally introduced to the Pacific Northwest in the 1930s. The introduction was likely a result of the arachnids stowing away in cargo.

The University of Alaska Fairbanks Cooperative Extension Service on Kalifornsky Beach Road said it has received a higher than average number of requests for spider identification this year.

"Because of the unusually warm and dry summer we've had there are lots of spiders this year," said Janice Chumley, integrated pest management technician.

"It's extremely difficult to positively identify them. I don't have the expertise," she said. "Generally though, they've been common orb weavers."

She said that because many characteristics of spiders resemble others, it is important for people trying to identify them to catch the whole spider, and not bring in just parts.

In cases involving a serious spider bite, Chumley said the specimen would be sent to Seattle for identification by experts.

Boling said Thursday that James has now caught what she believes is a hobo spider and she is sending it to Seattle for positive identification.

He said he has seen four or five bites this year that "were suspicious for hobo spider bites."

Without having actually seen the spider that did the biting, Boling said he cannot say the bites are "suspected to be from hobos."

"I can only say they have suspicious characteristics of bites from hobo spiders," he said.

He also said he has spoken with a physician in Homer, who reported a number of spider bites there this year that also were suspicious for hobos.

A hobo spider bite typically produces a black ring about the size of a silver dollar, according to Boling, and the wound develops an infection on top of the bite.

He said treatment for hobo bites "is conservative."

"They don't require surgery. The infection is treated with antibiotics."



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