We know that the average household cockroach is ferrying around a boatload of germs on its body on any given day. We also know that, at least in the lab, cockroaches can transmit those diseases to people. However, cockroaches don’t transmit disease directly into our blood stream through a bite like mosquitoes or ticks, but are what we call passive or “mechanical” disease vectors. In other words, they can transfer bacteria and other disease organisms carried on their bodies to our food or food surfaces.

Cockroaches Specialize in Down and Dirty

Think about the cockroaches’ lifestyle, where they live, and what they do. Like house flies and blow flies, cockroaches do not hesitate to walk  across poop, and even feed on it. They sometimes live inside sewer systems, after all, and they’re only there because they want to be (see Yes, There Are Cockroaches in Your Sewer System!). You can imagine the variety of human diseases that can be cultured from a city sewer. The situation escalates when cockroaches interact with people, when they crawl out of the dumpster or the sewer and into our homes and then walk across our kitchen counters.

The design of a cockroach’s body helps in disease transmission. A cockroach’s legs are covered with short spines that pick up bacteria as it walks across less than desirable surfaces. Their constantly moving antennae pick up germs, too. They also eat contaminated food or feces and transfer disease organisms as they poop randomly or when they vomit.

Food Poisoning is the Most Likely Result

Salmonella, E. coli, and other bacteria that cause food poisoning or gastroenteritis are the primary germs known to be spread by cockroaches (see Cockroaches in Your Food!). But cockroaches can also carry many other nasty germs such as plague, dysentery, typhoid fever, leprosy, even urinary tract infections. Almost any cockroach tested could be found to be carrying at least one disease organism on its body, but how real is the risk of a cockroach actually transmitting a disease to a person?

Cockroach transmission of diseases has been shown in the laboratory but proving transmission in the real world is problematic. Occasional localized outbreaks of hepatitis or typhoid have been attributed to the presence of disease-carrying cockroaches, but not directly proven. Perhaps it’s a testimony to our bodies’ ability to resist germs that cockroach-related disease outbreaks are not more common. That’s why it’s concerning that cockroaches in some hospitals have now been found to harbor antibiotic-resistant bacteria.

Then there’s the fact that cockroaches are a proven cause of allergies and asthma attacks, particularly among children…but that’s another story. Read about it in The Cockroach – Asthma Connection.

Photo Credit : ric_k | BY SA