As the weather starts to cool off and we head into the peak of tick season, we thought it would be a good time to review some information about fleas, ticks, and how to prevent them. Both fleas and ticks are capable of transmitting potentially serious diseases to your pets, some of which are zoonotic, or transmittable from animals to humans. Fleas commonly transmit the bacteria that cause cat scratch disease (Bartonella henselae) and tapeworms (Dipylidium caninum) that cause infestations in dogs, cats, and children who inadvertently ingest fleas from infested pets. In addition to these diseases, many dogs and cats (and some people) have allergies to flea saliva, which can cause severe itching and rashes that are prone to infections even after a single flea bite. As most of us are likely aware, ticks transmit Lyme disease (caused by Borrelia burgdorferi) as well as a number of other rickettsial diseases, and while you and your family won’t catch Lyme disease from your infected dog, you are certainly at risk of being bitten by a tick that hitched a ride into the house on your unprotected pet.
The life cycles of fleas and ticks are very different, and knowing a little something about them is important in order to know how to best control infestations by either one. Once an adult female flea jumps on to your dog or cat, she can start to lay eggs within 20-24 hours, and an average flea can lay as many as 40-50 eggs per day. Once the eggs are laid on the back on the host, they fall off into the environment within a few hours. From there, larvae will develop either in shaded areas outdoors or protected areas indoors, such as under furniture, in carpets, or on bedding. The speed at which larvae develop into pupae depends on temperature and humidity, but at typical room temperature pupae will emerge into adults within 8-13 days. At cooler temperatures when pupae are not stimulated by CO2 or mechanical pressure created by hosts walking nearby, they can remain in their cocoons for up to 50 weeks, ready to hatch and jump onto your pet when the environment is right. Once they emerge, the adult fleas find a host and immediately start to feed, starting the cycle all over again. In other words, it only takes one flea jumping onto an unprotected pet for a significant infestation to develop in a home. Keeping your pet on year-round flea preventative and killing that first flea jumps on is clearly a much better way to approach the potential problem than waiting until you see that flea, since she may have already dropped 50 soon-to-be adult fleas into your living room. If a flea infestation does develop, treating the home by cleaning all carpets, furniture, and bedding, as well as potentially spraying a flea-killing agent in the house, is critical in order to fix the problem.
Ticks develop and reproduce differently, and the most common species of hard ticks that we have here in the northeast are called “three-host” ticks. This means that each stage of development requires the tick to feed on a host animal, and most species will fall off of the host in between life stages only to have to find a new host to continue its development. Adult ticks can mate either on or off a host, depending on the species of tick. Once they mate, female ticks engorge themselves with a blood meal and fall off of the host in order to lay a large clutch of several thousand eggs before they die. Depending on the environmental conditions, it can be weeks to month before the six-legged tick larva hatches from the egg and goes to find a host of its own. Once it does, it feeds on the host’s blood for several days before falling off and molting into an eight-legged nymph, who will then find its own host animal and feed there for several days to a week. It is at either the larval or nymph stages that most ticks will become infected with the disease agents (such as the Lyme disease bacteria) that they keep with them until they molt into adults and are ready to transmit that disease to their host. As soon as the nymph is done feeding, it falls off of the host to molt into an adult, beginning the whole process over again. Most ticks need to be protected from drying out when they are not on a host animal, so they tend to thrive in years with lots of precipitation and high humidity – sort of like this year! Since temperature differences between the environment and host animals is one of the factors that allows tick to find their hosts, cooler fall temperature accentuate that difference and make it a lot easier for ticks to find us or the animals they want to feed on.
There are a number of both oral and topical flea and tick preventative options. Some of them contain added ingredients call insect growth regulators, so that in addition to killing any adult fleas or ticks that may be on your pet, they help break the life cycle of the parasite by interfering with reproduction and development of immature life stages. Please call our office to discuss the best preventative options for your pet, and see capcvet.org for more detailed information on flea and tick life cycles.