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Flea Diseases

Flea Diseases Affecting Humans and Pets

Flea-Borne Diseases in Humans

According to a recent CDC statement, the number of illnesses caused by mosquito, tick, and flea bites tripled between 2004 and 2016. Though rare, the disease fleas most commonly spread is plague. Still, fleas can be difficult to control and remain a major cause of worldwide sickness.

Fleas may transmit diseases while taking a blood meal from a human or animal host or via contaminated fecal pellets. Some of the more commonly encountered flea-borne diseases affecting people worldwide include:

  • Plague – transmitted by the oriental rat flea in areas of the world where the rat flea vector and rats that harbor the disease are found.

  • Flea-borne typhus, also known as murine typhus – transmitted by the bacteria-infested feces of infected cat fleas when the bacteria enters the body at the time of a flea bite or from scratching the area of the bite.

  • Bartonellosis (cat scratch disease) – transmitted to humans from the bites of the oriental rat flea and cat flea.

  • Flea tapeworm – most often transmitted when children accidently eat an infected flea or come in contact with infected flea feces.

  • Tungiasis – a tropical ailment caused by the chigoe flea when it burrows into the skin and takes a blood meal. The bite of the chigoe flea often results in secondary infections and itching.

Risk of Infection

There is a risk of secondary bacterial infection if the skin where bites occur is not kept clean and disinfected. The more that bites are scratched, the more likely infection will result.

Flea Diseases Affecting Cats & Dogs

Some of the more common and serious flea-borne diseases affecting pets include:

  • The possibility of contracting plague from eating a plague-infested rodent

  • Getting murine typhus from an infected flea

  • Parasitic dermatitis caused by a pet’s allergy to flea saliva. The animal’s skin is itchy and inflamed and has rounded bumps where the flea bites. Given a situation where fleas are not controlled, the irritation may end up in hair loss and infection. Flea-related dermatitis is one of the most common disease problems brought on by fleas.

  • Cat scratch disease - Bartonella henselae in cats which is transmitted by cat fleas.

  • Flea tapeworm - Dipylidium caninum. An infection that forms in cats when they ingest an infected flea during grooming.

  • Anemia and iron deficiencies resulting from a large population of blood-feeding fleas.

Flea Allergy Dermatitis

Many cats and dogs bitten by fleas suffer only minor irritation. However, some pets are allergic to the cat flea bite and may experience severe itching. This condition is known as flea allergy dermatitis, or FAD. FAD is a skin disease afflicting dogs and cats and is caused by an allergic reaction to flea saliva. FAD is most prevalent on pets in summer when high temperatures provide ideal conditions for flea development and infestation, and pets are often spending more time outdoors.

The itching caused by FAD can result in dramatic hair loss, as well as open sores and scabs. Open wounds are then susceptible to secondary bacterial infections, which produce strange odors. In cats, the hind legs and area directly in front of the tail are most commonly affected first, while the rump and tip of the tail are affected first in dogs. Dogs are particularly sensitive in the flanks and thighs and will scratch most aggressively in these areas. Lesions may be present on the lower back and inner thighs of dogs with FAD. If allowed to progress, affected areas become pigmented.

The first step in treating FAD is the removal of all fleas from the pet. Many topical treatments are available to this end and vary in price and application method. Other medications may be administered orally and are available in specialty pet stores, through your veterinarian or pet specialist. Treatments differ for cats and dogs, so be sure to purchase the correct product and read the instructions carefully. Dogs and cats with FAD may also require treatment of secondary skin infections. Antibiotics and antifungal drugs are effective and can be obtained through your veterinarian.

Treating a pet infestation does not address an entire flea population. After administering the appropriate medication to your pet, ensure that your home and yard are free of fleas and that your pet does not frequent flea-infested areas. Clean all floors and bedding and consult a pest control professional to discuss further extermination options.


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