When Cindy and I first moved to Gothenburg, we came in contact with fleas for the first time. I would take the dog to the river and we brought them back home. Well, a couple of years ago we again discovered fleas…on our cats! Not sure where they came from… probably the dog and the river again. So, now on the first of each month from April through November, we apply flea and tick medications to our animals (the dog gets it too).

Fleas are insects and they belong to the order “Siphonaptera” which translates as the “tube and wingless” insects. There are about 2,500 named species and all live by sticking their tube-shaped mouthparts through the skin, feeding on the blood of mammals or birds. With no wings they have to hop…and they do so impressively!

The life cycle of a flea is familiar. The female must have a blood meal before she can lay eggs, which then hatch one to 10 days later. The eggs hatch into larvae, which go through three life-stages, needing a blood meal for each stage. The larvae pupate about five to 20 days later. They can remain in the pupae for days or months depending upon the environment. They emerge from the pupae and immediately feed. Once fed, they start the life cycle over again. Like ticks and mosquitoes, the bite of the flea itself is irritating but not life threatening. It’s what’s in the bite.

Probably the most famous of the negative effects of flea bites is the Bubonic plague, also known as the “black death”. This is caused by a bacterium in the blood that is transmitted from rat to rat and from rat to humans via fleas. If it makes you feel any better, the plague is also deadly to the rats! The flea feeds on the blood of the rat or human and ingests the bacterium. It then bites another rat or human and spreads the disease.

It is believed that in 1346 the Mongols catapulted plague-diseased bodies over the walls of the city of Caffa thus spreading the disease within the city. The strategy worked and the people fled the city and carried the disease into Europe. Once there, the plague spread throughout Europe killing up to 60% of the people that came down with it. Almost half of all Europeans died from the plague and it took 200 years for the populations of the different European countries to recover to pre-plague numbers.

It wasn’t the last use of the disease in war. In WWII Japan dropped massive numbers of Bubonic plague infested fleas on over 70 Chinese cities resulting in up to 500,000 deaths! That is nearly twice as many as the Japanese that were killed in the atomic bombs dropped on Hiroshima and Nagasaki!

Most fleas only attack one or two animals. The rat fleas of the plague years obviously also fed on humans, and there are dog fleas and cat fleas. You would expect to find dog fleas on dogs and cat fleas on cats. However, one study done on the East Coast concluded that there are no dog fleas in America and that the fleas we find on our dogs are actually cat fleas…so I guess blaming the dog for bringing fleas into the house and infecting the cats might just be backwards…did the cats bring the fleas to the dog?