Fleas are bloodsucking parasitic insects that live on pets, livestock, and humans. Human fleas (Pulex irritans) are relatively uncommon, and the species most likely to bite humans is the cat flea (Ctenocephalides felis) or the rat flea (Xenopsylla cheopis).
They are small, 1–4 mm in length, and blackish-brown. Although wingless, fleas are still capable of taking giant leaps, jumping to a height of several meters. Adult fleas feed on only blood and are capable of living long periods without feeding. Fleas most often bite people around the legs and the ankles. The flea injects allergenic saliva after piercing the skin with its mandibles. The bites, which are usually felt immediately, become increasingly irritated and may remain sore, and/or itchy for as long as a week. Itching may be generalized or just at the site of the bites.
Flea bites produce a variety of effects, ranging from a transient raised, red skin lesion to prolonged symptoms that may last for years depending on the sensitivity of the person bitten. Children aged younger than 10 are generally more sensitive than older people, as people tend to become desensitized by repeated exposure over time. Flea bites in children produce an allergic reaction in which recurrent or chronic small red bumps occur on the exposed skin areas. Patients with hypersensitivity may also develop bullous reactions.
What should I Look For?
Flea bites usually occur around the ankles and lower leg area. Other common locations for flea bites are around the waist, in armpits, and in the creases of the elbows and behind the knees.
A flea bite appears as a small single papule that is flat, firm, and surrounded by a single red halo. The papule blanches when pressure is applied. Flea bites may show signs of bleeding. The area of skin affected may increase over time, or the rash may spread to a different area.
Flea bites can sometimes evolve into persistent bite reactions.
When a subsequent exposure to fleas leads to additional bites, itching and swelling may occur at the sites of prior bites. Some people are more sensitive to fleas than others. It can sometimes appear that the fleas are “picking on” one individual in a household but not on others.
If flea bites have occurred indoors, all sources must be treated for effective flea control. Carpets, pet bedding, and all rooms should be thoroughly vacuumed, and pets should be treated separately.
The primary goal of treatment is to relieve the itching, which can be achieved by the following:
- Burrow's solution compresses applied to the bites
- Calamine lotion to which 0.25% menthol may be added by the pharmacist
Prescription strength mid or high -potency topical corticosteroids can alleviate the severe itch.
Antihistamines may be prescribed for the relief of the itching.
- Diphenhydramine hydrochloride (Benadryl®) – 25, 50 mg tablets or capsules, 25–50 mg nightly or every 6 hours as needed
- Cetirizine hydrochloride (Zyrtec®) – 5, 10 mg tablets, 5–10 mg per day
The source of the flea infestation should also be treated. Flea control of pets includes the following:
- Oral flea medication (available for dogs but not for cats)
- Monthly topical spot-on products
- Flea collars
Flea control at home may be regulated by the following measures:
- Bedding should be clean and laundered regularly.
- Bedrooms should be vacuumed regularly, especially in the corners underneath the beds.
- The indoor environment can be sprayed with a chemical used for flea infestation such as methoprene.
- Pets should be kept clean and regularly checked by a veterinarian.
- A professional exterminator may be needed