Common Diseases Spread by Fleas and Ticks

Kate Barrington
by Kate Barrington

When these pests leave their mark on your pet, it may cause more than a minor irritation. They carry Lyme disease, rabbit fever… and even the plague! We’ve got fleas and ticks to thank for spreading these diseases.

When it comes to keeping your pet healthy, you probably understand the importance of taking your pet to the vet once or twice a year. You may also know that feeding your pet a healthy diet will help to keep him healthy as well. But what about pest control? Many pet owners overlook the importance of flea and tick prevention, as they don’t realize that these pests can actually transmit some serious diseases.

Common Tick-Borne Diseases

Lyme Disease

The most common tick-borne disease in the United States is Lyme disease. This disease can produce symptoms including fever, loss of appetite, and lethargy. If left untreated, Lyme disease sometimes leads to severe kidney disease.

American Canine Hepatozoonosis (ACH)

Another disease carried and spread by ticks is American Canine Hepatozoonosis (ACH). This disease is caused by the ingestion of a tick – that’s right; it isn’t caused by tick bites! ACH can lead to a severe, sometimes fatal infection, which produces symptoms like high fever, stiffness, pain, weight loss, and muscle wasting. Even if your dog recovers, he may still require treatment for several years after.

Related: What’s The Difference Between Fleas and Ticks?


A common tick-borne disease found in cats is called cytauxzoonosis, and symptoms may include depression, anemia, high fever, jaundice, and difficulty breathing. Unfortunately, treatments are largely ineffective and death can occur as little as seven days after contraction.


Another dangerous tick-borne disease is tularemia, sometimes called rabbit fever. This disease affects cats more than dogs and it can lead to depression, loss of appetite, mild fever in dogs or high fever, swollen lymph nodes, and abscesses in cats. There is no vaccine for this disease but it can be treated with antibiotics.

Anaplasmosis or Dog Tick Fever

Transmitted by a bite from an infected deer tick or brown dog tick, anaplasmosis is an infection of the bloodstream. Symptoms of infection may begin to surface anywhere from 1 to 7 days after infection. They include vomiting, loss of appetite, diarrhea, malaise, fever, coughing, nosebleeds, labored breathing, joint pain and lameness, and seizures.

Dogs that have been diagnosed will be prescribed a course of antibiotics and can see signs of improvement as soon as 24 to 48 hours they start medication.

Rocky Mountain Spotted Fever

A more commonly recognized tick-borne disease, Rocky Mountain Spotted Fever is carried by the American Dog Tick, Brown Deer Tick, and the Rocky Mountain Wood Tick. Symptoms will start to show in 2 to 14 days after being bit by a tick carrying the disease.

The most common symptoms include loss of appetite, abdominal pain, vomiting, diarrhea, cough, nosebleeds, eye or nose discharge, swelling of the face or legs, fever, joint pain and lameness, and enlarged lymph nodes. Approximately one-third of dogs that are infected will go on to experience symptoms related to the central nervous system which include weakness, balance problems, lack of coordination, or seizures.

Fortunately, following early diagnosis most dogs respond well and will start to show improvement within 24 to 48 hours of starting antibiotic treatment. If the disease is allowed to progress untreated, it is more likely to result in severe complications that may not respond to treatment.


A disease that can infect both dogs and people, babesiosis is an infection of the red blood cells by the protozoal parasite. It is most common in the southern states and is most often seen in racing greyhounds and pit bull terriers. Signs of an infection include aches and pains, fever and chills, lethargy, loss of appetite, dark-colored urine, heart murmur or rapid heart rate, pale skin, or jaundice.

The prognosis for a dog diagnosed with babesiosis will depend on what areas of the body have already been affected. Those that are considered recovered may relapse in the future and are considered to be sub-clinically infected moving forward.  

Diseases Spread by Fleas

Flea Allergy Dermatitis

One of the most common problems caused by fleas is called flea allergy dermatitis. Flea bites can cause irritation and swelling at the site of the bite but, in cases of flea allergy dermatitis, the reaction is much stronger. This condition is caused by an allergic reaction to the flea’s saliva, not just to the bite itself. Symptoms may include hot spots and extreme itching.

Murine Typhus

While this disease isn’t overly common in North America, it has been reported in the hot, humid climates of Texas and Southern California. Most often carried by rats, murine typhus can be transmitted to cats. Luckily for the cats that come in contact, they are merely carriers and show no signs or symptoms. Unfortunately, the same can’t be said for the humans that these cats return home to.

The most common signs of murine typhus in humans include nausea, vomiting, stomach pain, body aches, fever and chills, loss of appetite, cough, or rash. If it’s left untreated, it can progress to the point of causing damage to important organs in the body such as the liver, kidneys, lungs, heart, and brain. At this stage, it can be fatal.

Cat-Scratch Disease

Another potential problem caused by fleas is called cat-scratch disease. About 40 percent of cats will carry this disease at some point in their lives and it is transmitted from one cat to another by fleas. Cat scratch disease generally doesn’t harm the cat but it can cause fatigue, headaches, and fever in humans.

Related: Top 10 Flea and Tick Prevention Tips

The Plague

Another disease spread by fleas is the plague. This is the same disease that killed roughly 30 percent of the European population during the Middle Ages and it can still affect pets today, though it is uncommon in humans. This disease can cause fever, swollen lymph nodes, and even sudden death.


Fleas can also carry tapeworms. If your dog ingests a flea that is carrying tapeworms he can become infected and may experience symptoms of weight loss, irritation, and vomiting. Tapeworms can be passed to humans if infected fleas are brought to the house. This is most common in young children due to their tendency to put everything in their mouths.

Flea and Tick Prevention

As you now know, fleas and ticks can spread some dangerous diseases. Fortunately, flea and tick prevention is actually fairly simple. Treating your dog or cat with a topical flea and tick preventive every month is generally enough to keep these pests at bay. Keep in mind that fleas and ticks can affect your dog at any time of year, even during the winter when you might think that this is not the case. The key to protecting your pet against dangerous diseases is to be consistent about your flea and tick prevention methods. Stay up to date with topical preventives and have your dog checked for ticks and fleas at his routine vet visits. If you suspect a problem with fleas or ticks, contact your veterinarian immediately.

Kate Barrington
Kate Barrington

Kate Barrington is the loving owner of two cats (Bagel and Munchkin) and a noisy herd of guinea pigs. Having grown up with golden retrievers, Kate has a great deal of experience with dogs but labels herself a lover of all pets. Having received a Bachelor's degree in English, Kate has combined her love for pets and her passion for writing to create her own freelance writing business, specializing in the pet niche.

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