I received an email warning about bananas from Costa Rica carrying the necrotizing fasciitis virus. The email states the FDA is aware of this and at least 15,000 Americans are affected. Can the virus graft itself on banana skins or any other type of produce? Is this a joke? A hoax?

Ed

I have heard about this rumor, and I can assure you that it is false. It is such a hardy rumor that the U.S. Centers for Disease Control (CDC) addressed it recently and also declared the rumor to be false. No cases of necrotizing fasciitis associated with eating bananas have been reported to the CDC.

Let me first explain what necrotizing fasciitis is and why people do not develop the infection from eating bananas, or any food for that matter. Necrotizing fasciitis is a severe infection of the skin and deeper tissues. (Fascia is fibrous tissue that separates muscle from the overlying fat and skin.) In necrotizing fasciitis, this fascia becomes infected and the tissue dies (becomes necrotic). That allows the infection to spread even deeper and to other adjacent tissues very quickly.

The most common cause of necrotizing fasciitis is Group A streptococcus, or Streptococcus pyogenes. In the lay press, this is often referred to as the "flesh-eating virus," though it is actually a bacterium, not a virus. This is the same strep bacterium that causes simple skin infections (cellulitis) and strep throat. However, in the cases of necrotizing fasciitis, the strain (variety) of bacterium is more virulent (more capable of causing disease), and it makes toxins that can rapidly destroy tissue. Most cases of necrotizing fasciitis occur when virulent streptococci penetrate the skin after minor injury.

Strep, including the virulent strains, can be found in the environment, but it is usually spread from person to person. This is why there are outbreaks of strep throat in classrooms and military barracks. Strep can also be spread from a patient with necrotizing fasciitis to another person. When a patient enters the hospital with necrotizing fasciitis, he or she is usually isolated from other patients, and special precautions are taken to avoid spreading the bacterium to others.

As to the banana rumor, experts believe that any strep that came in contact with the surface of a banana would not survive long and would be unlikely to get under the skin of a banana to the edible part. Even if it did, eating food contaminated with strep would be unlikely to result in any skin infection at all. There have been outbreaks of severe streptococcal infection after ingesting foods. This has occurred with Streptococcus pyogenes, but it is much more common with other streptococcal species. In these outbreaks, however, strep throat, not fasciitis, has been the usual manifestation of illness.