THURSDAY, July 14 (HealthDay News) -- Misinformation about venomous spiders and spider bites often leads emergency department and primary care physicians to falsely blame the eight-legged creatures for "necrotic" skin lesions, new research indicates.

Necrotic lesions are those in which the tissues of the body die due to a lack of blood and oxygen, and the condition is irreversible.

The report pointed out that necrotic lesions on the skin are typically not the result of spider bites and often have more common causes, such as staph infections or Lyme disease, which is caused by bacteria carried by deer ticks.

As a result of these misdiagnoses, many patients are being given unnecessary antivenom and are not receiving appropriate treatment in a timely fashion, which puts their lives at risk, warned the authors of the Seminar, published online July 14 in The Lancet.

At the same time, the authors, Dr. Geoffrey Isbister from the University of Newcastle in New South Wales, Australia, and Hui Wen Fan from Instituto Butantan in Sao Paulo, Brazil, also stated that venomous spider bites, such as from the brown recluse spider, are not being recognized fast enough because symptoms do not appear immediately.

Although there are more than 41,000 species of spider, most spider bites are harmless and do not require treatment. The team concluded that additional research should focus on the reporting of definite cases of spider bites to help avoid causing potentially dangerous allergic reactions to antivenom in patients, and to help doctors properly diagnose and treat necrotic lesions.

More information

The U.S. Centers for Disease Control and Prevention provides more information on venomous spiders.