“A Terrifying Wound of Rotting Flesh:” The American Spider with One Infernal Bite

Spiders are one of the trademarks of Halloween. But did you know that there is a spider in North America with venom that can destroy human flesh?

Brown recluse spider (Loxosceles recluse) is native to the USA and has established itself in numerous states, including Alabama, Arkansas, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Nebraska, Ohio, Oklahoma, Tennessee, and Texas.

The spider, which is considered among the most dangerous in North America, it has also been observed outside this range in other states. But these are usually isolated cases where people have inadvertently introduced brown hermits into those areas.

This species is common within its range and is often found in homes, but as the name suggests, they tend to stay hidden and are not aggressive, said Jerome Goddard, professor of medical entomology in Mississippi State University’s Department of Biochemistry, Molecular Biology and Entomology, and Plant Pathology, told Newsweek.

As a result, brown recluse bites are relatively rare, and when they do happen, it’s usually because the spider is trapped against the skin and feels threatened, for example if someone rolls onto the spider while they’re sleeping.

The venom of this spider can damage local tissues and cause various symptoms. In many cases, the bitten person does not experience any significant consequences.

“Reactions to a brown recluse bite can range from no reaction, to a mild red sore, to a scary rotting flesh sore,” Goddard said.

A brown recluse bite can feel like a pinprick and is usually painless until three to eight hours later, when it can become red, swollen and tender, according to Goddard.

The central area of ​​a brown recluse bite turns pale or blue over time, not red, Goddard said. After 24 hours have passed, intense pain may develop. Later, a black scab may appear and, eventually, the area around the site may decay and slough off in a process known as “necrosis”—or the death of body tissue—producing an ulcer.

Eventually, the edges of the wound become thickened and raised, while the central area is filled with scar tissue. Healing can take months, and the victim may be left with an indented scar.

“Their bites can produce nasty lesions that are slow to heal and leave unsightly scars,” Goddard said.

The primary component of brown recluse venom that causes skin necrosis is likely an enzyme called sphingomyelinase D, which breaks down fibrinogen (a clotting factor) and fibronectin (a protein that plays a role in tissue repair).

“Sphingomyelinase D also disrupts the structure of the basement membrane, which acts as a platform for cell growth,” Goddard said. “All of this leads to local tissue death.”

The proportion of brown recluse bites that result in necrotic wounds is not entirely clear because many of the bites I’ve reported are actually something else, such as a staph infection, according to Goddard.

But the entomologist said his best estimate is that about 10 to 50 percent of brown recluse bites result in some form of necrosis.

The lack of development of necrosis may be due to factors unique to the immune system of the person bitten.

“Or like venomous snakes, perhaps brown recluse spiders can deliver ‘dry’ bites where they retain or don’t inject much venom,” Goddard said.

In rare cases—perhaps less than one percent of incidents—brown recluse bites can lead to a potentially serious systemic illness about two to three days after the bite that affects the entire body.

This disease—known as “systemic loxocelism”—is characterized by anemia, blood in the urine, fever, rash, nausea, vomiting, and coma. In very rare cases, death has resulted from a systemic reaction to a brown recluse bite. Local necrotic wounds are not fatal.

The treatment The brown recluse bite is controversial and seems to be constantly changing, Goddard said.

“A specific antidote – or antivenom – has shown success in patients before the development of a necrotic lesion, but I don’t think it’s widely available,” he said. “Also, some brown recluse bites are unsightly, not leading to necrosis; therefore, treatment may not be necessary in these cases.”

Some studies have shown that applying ice to the bite site is effective. This may be because the activity of the necrotic enzyme sphingomyelinase D increases as temperature increases.

At one time, early, complete surgical excision of the bite site followed by skin grafting was recommended. But more recent evidence no longer supports wound excision as a treatment, according to Goddard.

Some scientists and doctors have reported success in treating an individual with a drug known as dapsone. But some evidence shows that this drug is completely ineffective.