Fleas

Flea bites: how to recognize them, relieve them and know if there are fleas at home

What a flea bite looks like

A flea bite is a small red dot, 2 to 5 millimeters across, with a darker speck in the center where the insect's mouthparts went in. The itching is intense from the start. The location gives it away: ankles, the tops of the feet and the lower legs, because the flea lives on the floor and jumps as high as it can reach, about 20 centimeters. If you sleep with the dog, also on the forearms and waist.

The bites usually come in groups of 2 or 3 in a line or a triangle, sometimes described as "breakfast, lunch and dinner". In children and sensitive people the welt can be bigger, with a tiny blister on top.

Flea, mosquito, bed bug or spider: how to tell them apart

The four get confused because they all cause red, itchy welts. These clues sort out most cases:

• Flea: small dots with a dark center, grouped, on the ankles and legs; they appear at any time of day and itch right away. There is a pet, or there was one.
• Mosquito: a bigger welt, swollen and pale in the center, on its own, on any exposed part of the body. You felt or saw the mosquito, and it happens mostly at dawn and dusk.
• Bed bug: 3 to 5 welts in a straight line or zigzag, on the face, neck, arms and back, that appear when you wake up. Never during the day in the yard. It has its own guide in how to recognize a bed bug bite.
• Spider: a single lesion, not in a group, with swelling and pain more than itching. Almost always on the hands or feet, after reaching into a box or putting on a shoe that had been stored away.

What to do about the bite

The first step is to wash with soap and water to remove the flea saliva left on the skin, which is what causes the reaction. Then local cold: a towel with ice or a wet cloth for 10 minutes reduces the swelling and stops the itching for a while. If the itching keeps you from sleeping, take an over-the-counter antihistamine (loratadine or cetirizine) for adults; for children, check the dose with the pharmacist. A 1% hydrocortisone cream also helps.

See a doctor if any of these happen: the bite becomes warm, hard, has pus or a red streak that spreads (that is a bacterial infection and needs antibiotics); if hives appear all over the body, the lips swell or there is difficulty breathing (an allergic reaction, get care immediately); or if a young child has dozens of bites and a fever.

The white sock test to confirm fleas

Put on long white socks, up to the knee, and walk slowly for 5 minutes through the suspicious areas: the room where the dog sleeps, the living room rug, along the edge of the sofa, the hallway. Drag your feet so the floor vibrates. Then check the socks in good light: adult fleas are dark brown dots 2 to 3 millimeters long, flattened from side to side, that jump if you touch them. On white they are easy to see.

If you want to check the dog, run a fine comb at the base of the tail over a sheet of white paper: you will see the fleas and the "flea dirt", black specks that turn reddish when wet because they are digested blood.

Why they bite even without a pet

The answer is in the pupa stage. The flea larva spins a sticky cocoon that gets covered in dust and hides in floor cracks, under baseboards, inside carpets and at the base of furniture. Inside, the fully formed adult flea can wait for weeks or months without eating, until it detects heat, carbon dioxide and above all vibration. That is why, when people move into a house that was empty, their footsteps wake hundreds at once and on the first night everyone wakes up bitten.

The other sources when you have no pet of your own are the neighbors' cats that sleep in your yard or in the ceiling, opossums (zorros pelones) that walk across the roofs of almost the entire GAM, rats in the attic and, in areas near pastures, cattle. Their fleas fall into the yard and the porch, and from there they come inside. It is not a lack of cleanliness.

The flea life cycle: why treating only the dog isn't enough

The adult fleas you see on the dog are only 5% of the population. The rest is in the environment. A female lays up to 40 eggs a day on the animal, and since the eggs don't stick, they fall wherever it walks and rests: its bed, the sofa, the car, the lawn. From there come larvae, then pupae, and from the pupa the adult that goes looking for the dog again or, if the dog isn't there, for you.

That is why the classic story happens: a spot-on treatment and a bath for the dog, and ten days later it is full of fleas again. The floor kept producing new ones. In the rainy season, from May to November, the full cycle can be completed in three weeks. Treating the animal is half the job. The other half is the house. We have a broader guide in fleas and ticks in homes with pets.

What to do in the house

• Vacuum thoroughly, every day for two weeks: rugs, along the walls, under beds and sofas, between the cushions, and the car if the dog rides in it. Throw the bag out right away.
• Wash at 60 °C everything you can: the dog's bed, blankets, sheets, sofa covers, small rugs. Whatever can't be washed hot goes in the dryer for 30 minutes on high.
• Yard and garage: mow the lawn, clear out piled-up leaves, and check the shady spots with loose soil where the dog lies down. The larvae don't survive in the sun: the problem spots are the dark, damp ones.
• The animal, the same day: the spot-on, pill or collar the veterinarian prescribes. And repeat it as directed, not just once.

With only a few fleas, this may be enough. If the bites continue after two weeks, or the house was empty and they came out en masse, there are already too many pupae for the vacuum.

When to fumigate and how much it costs

Professional flea treatment applies an insecticide with an insect growth regulator to floors, edges, under furniture, the yard and the spots where the pet sleeps. The regulator prevents eggs and larvae from becoming adults, which is what vacuums and spot-on treatments can't achieve. You can go back into the house one hour after the application, pets included. If you have questions about your dog or cat during fumigation, we explain it in is fumigation safe for pets.

Price: house or apartment up to 100 m², ₡39,900; up to 200 m², ₡49,900; over 200 m², ₡59,900. VAT included and no travel fee in the GAM. If you have not fumigated in the last 6 months, it takes two applications and the second one is charged; the 30-day check only applies once the plan is complete. The date is confirmed by WhatsApp in less than an hour. More about the service in flea and tick control.

Frequently asked questions

How long does a flea bite itch?

Between two and four days for most people. If you scratch a lot it can last longer and leave a scab. If it goes beyond a week or becomes warm and has pus, a doctor should see it.

Do dog fleas bite people?

Yes. The cat flea (Ctenocephalides felis), which is the one that lives on dogs and cats in Costa Rica, bites people when it can't find the animal or when there are many of them. It doesn't stay living on you; it bites and drops off.

Why am I getting flea bites if I don't have a pet?

Flea pupae can wait for months inside their cocoon in carpets, floor cracks and under furniture. They wake up with heat and the vibration of footsteps. It is typical when you move into a house that had a dog, or when cats or opossums get into the yard or the ceiling.

Is it safe to treat for fleas with the dog in the house?

Yes, with the right preparation: the pet goes out during the application and comes back after the re-entry time, which is one hour. That same day it is a good idea to give it the flea treatment from the veterinarian to break the cycle on both sides.