I took a surprisingly enjoyable course in medical entomology as an undergrad at Ohio State University. Admittedly, decades later, the only things I remember from that course are that only four of the 4500 species of cockroaches are classified as pests: the German, Asian, American, and Oriental cockroaches.
The majority of cockroach species live in their natural habitats in woods, tropical forests, or deserts, but these four have taken up residence with humans and have become serious pests. They may have distinctly cosmopolitan names, but it is believed that they all started in Africa. Their mouths can chomp through cardboard, cloth, or paper to reach food. They contaminate everything they touch with their feces.
Dissemination of disease has not been well documented, but they are undeniably transporters of bacteria, viruses, fungi, and parasites. A review of the literature indicates that cockroaches have been accused of spreading leprosy, cholera, and more recently, the HIV virus. Multiple studies of the bacteria associated with or in cockroaches also have demonstrated a host of bacteria and parasites pathologic to humans. They are dirty, repulsive little bugs that feed on filth.
One of the first things I learned when we moved to the South was that cockroaches love temperate and hot climates. These nocturnal partiers love to hide in warm, dark places. Living proof is the number of patients I see presenting with cockroaches in their external ear canals. The prospect of something with spiny little legs and fluttering wings moving around in one’s external ear canal is enough to cause the most stoic among us to cringe.
Nevertheless, I recently had one young man present with a cockroach that had been in his ear for an entire week. It could have been worse: a cockroach was once discovered during a routine screening colonoscopy. (Endoscopy 2010;42[Suppl 2]:E209.) Removal of the dead, decaying carcass from my patient was piecemeal and not easy. (Click here and here to see videos of removal.)
The problem with the retrieval process is that the external ear canal is extremely sensitive and total anesthesia comes at an expense: multiple painful injections in an extremely sensitive area. Anesthesia of the ear can be attempted with bupivacaine or lidocaine injections, but the four-point injection at the external canal seems like torture of sorts. (See illustration below from Roberts & Hedges, Clinical Procedures in Emergency Medicine, 6th edition, Philadelphia: Saunders/Elsevier, 2014.) Attempts to anesthetize the ear with an otic solution containing antipyrine and benzocaine or viscous lidocaine are also less than ideal because topical medications have only minimal benefit.
What do you do when the cockroach or any insect in the ear is still alive? Some of the interventions you think would work actually don’t. Microscope oil, 2-4% lidocaine, viscous lidocaine, mineral oil, EMLA cream, and ethanol all work within 60 seconds. Auralgan, isopropanol, water, succinycholine, and hydrogen peroxide do not work.
My experience with cockroach extractions is that the cockroach always seems to come out piecemeal. Your forceps will bring out legs, thorax, etc., in various sequences. Removal techniques with catheter irrigation can also work. Make sure the catheter is inserted deep into the canal and past the insect. This ensures that the fluid will push out the culprit.
A little known fact is that cockroaches bite and can cause physical harm. (Int J Dermatol 2014;53:e277; Am J Forensic Med Pathol 1997;18:177; Int J Dermatol 1997;36:90.) I first saw evidence of that several years ago when a handicapped 45-year-old woman presented with abdominal pannus skinfold injuries reportedly from the family of German cockroaches found lining her underwear. She noticed the cockroaches in the drawstring of her underwear, and her family identified the species based on Internet pictures. The patient subsequently developed four abscesses that drained. She cleaned them out with hydrogen peroxide, salt water, and bleach. She took antibiotics donated by a friend because the redness was worsening. (See video.) Knowing that cockroaches are omnivores willing to nibble on human skin elevates their repulsiveness considerably.