Cat Scratch Fever: What Owners Must Know

Most cat scratches heal without any fuss, and most never lead to an infection at all. Still, one particular infection is worth knowing about by name, because it explains a pattern many owners find puzzling: a scratch that seems to heal, followed days later by tender, swollen glands near the scratch. That infection is cat scratch fever, also called cat scratch disease. It is caused by a bacterium called Bartonella henselae, it is closely linked to fleas, and it is usually mild in healthy people. This guide explains how it spreads, what it looks like in people and in cats, when to seek professional advice, and the simple habits that lower the risk.

One reassuring fact comes first. The United States Centers for Disease Control and Prevention notes that most cat scratches do not result in cat scratch disease. A scratch alone is not a diagnosis, and this guide is not one either. It is general information to help you recognise a pattern early and know when to ask a professional.

What Is Cat Scratch Fever?

Cat scratch fever is a bacterial infection caused by Bartonella henselae. The bacterium is carried by fleas and is common in cats around the world, including healthy cats that show no signs of illness at all. Estimates quoted by public health sources put carriage at roughly 30 to 40 percent of domestic and shelter cats at some point in their lives, which sounds alarming until you pair it with the other half of the picture: most exposed people never become ill, and most cases that do occur are mild and settle on their own.

The name is slightly misleading, because the scratch itself is only part of the story. Fleas are the engine of the whole cycle. Infected fleas pass the bacterium among cats, and flea faeces, often called flea dirt, carry it. A cat that grooms itself can pick flea dirt up onto its claws and into its mouth, and that is how a later scratch or bite can pass the bacterium into a break in a person’s skin.

How Do Cats Pick It Up?

Cats most commonly become infected through flea bites. Kittens, stray cats, and cats living in warm, humid areas where fleas thrive are more likely to carry the bacterium, as are cats that roam outdoors or live with other cats that have fleas. Cats do not pass it directly to one another without fleas in the picture, which is why flea control sits at the centre of prevention.

Most infected cats show no symptoms at all, and that is normal. A small number may run a brief fever, seem lethargic for a few days, lose appetite, or develop swollen lymph nodes. More serious effects, such as inflammation affecting the eyes or other organs, are uncommon. Because healthy cats so often carry the bacterium silently, public health guidance does not recommend routinely testing or treating a cat for Bartonella henselae unless the cat is actually sick. Your vet can advise on what, if anything, is right for your cat.

How Do People Pick It Up?

People usually become infected after being scratched by a domestic or feral cat, especially a kitten, when the scratch is contaminated with flea faeces. An infected cat that bites, or licks an open wound, can also pass the bacterium on. Direct spread from flea faeces alone, without a scratch or bite, is not considered a usual route, and direct spread from an infected flea bite to a person has not been proven. Person to person spread is not the pattern described for this infection; the route runs from cat to person.

Age and health shape the risk. Children under 5 and people with weakened immune systems are more likely to develop serious illness if infected, which is why the prevention habits below matter most in households with young children or anyone whose immune system is suppressed. For those households, public health guidance even suggests avoiding cats under one year old and avoiding stray or sick cats, a point worth discussing with your doctor before bringing a new kitten home.

Symptoms in People

Symptoms usually appear within 3 to 14 days of the scratch or bite. The earliest sign is often a small red bump, blister, or scratch mark at the site that may feel warm or tender. The most distinctive feature follows: lymph nodes near the scratch become swollen and tender, and they can stay swollen for weeks or even months. Other symptoms can include fever, headache, fatigue, muscle aches, stomach cramps, nausea, and loss of appetite.

In healthy people the illness is typically mild and self limiting, often resolving within 2 to 4 weeks without specific treatment, though swollen nodes may take longer to settle fully. That slow fade is one reason owners sometimes worry: a gland that is still enlarged a month later can feel wrong even when it is following the usual course. If a node keeps growing, becomes very painful, bursts, or is joined by a fever that will not settle, that is a reason to seek medical advice rather than wait it out.

Symptoms in Cats

As noted above, most cats with Bartonella henselae show no signs at all, so a lack of symptoms in your cat says nothing about whether the bacterium is present. When signs do appear, they may include fever, tiredness, reduced appetite, or swollen lymph nodes, and they are usually brief. Eye inflammation, mouth inflammation, and other less common signs have also been reported in cats, which is another reason any cat that seems persistently unwell deserves a vet visit rather than a guess at home.

How Is It Diagnosed?

In people, diagnosis usually starts with the story: a recent scratch or bite, followed by a bump at the site and swollen nodes nearby. Blood tests that look for antibodies, and occasionally other laboratory tests, can support the diagnosis, but testing is not automatic. Public health sources note that there are no widely available over the counter lab tests for this infection in people, and people are rarely tested unless symptoms are more severe or prolonged.

In cats, a blood test can reveal the bacterium, but a positive result in a healthy cat does not automatically mean treatment is needed. Guidance from veterinary public health sources is clear on this point: antibiotic treatment is recommended only for pets that show clinical symptoms. If your cat is well, testing and treating are generally not recommended, so ask your vet rather than requesting a test on the strength of an article alone.

Treatment

For healthy people, treatment is often not needed beyond good wound care, and the infection resolves on its own. When treatment is given, it usually involves antibiotics prescribed by a doctor, for example in cases where symptoms are prolonged, nodes are very painful, or the person is in a higher risk group. The choice of antibiotic and the length of treatment are medical decisions, so this guide deliberately does not name doses or courses.

For cats, treatment follows the same conservative principle. Cats without symptoms are generally not treated, while a sick cat may receive antibiotics and flea control from its vet to prevent reinfection. Never give a cat a human antibiotic, and never use a flea product meant for dogs on a cat: some dog products contain permethrin, which must never be used on cats.

Prevention: The Habits That Matter Most

• Keep your cat on vet approved flea prevention all year round, even if your cat lives indoors, since fleas can still find their way inside.
• Wash your hands promptly after handling, petting, or playing with cats, and wash any scratch or bite at once with soap and running water.
• Play gently and avoid rough play, especially with kittens, whose play scratches are the most common route of exposure.
• Trim your cat’s claws regularly and keep cats indoors and away from stray cats where possible.
• Do not let a cat lick an open wound, and cover scratches or wounds with a bandage.
• Do not pet or pick up stray or feral cats, and talk to your doctor before adopting a kitten if someone in the household has a weakened immune system.
• Declawing is not recommended as a way to prevent this infection.

Flea control deserves emphasis because it breaks the cycle at its source. Without fleas moving the bacterium among cats, the chain that ends in a contaminated scratch largely stops. Vacuuming carpets and washing bedding also help in a household that is dealing with an active flea problem, alongside the vet approved product for the cat itself.

Myths and Misunderstandings

A common worry is that every scratch from a cat means infection. It does not: most scratches do not result in cat scratch disease, and ordinary wound care is the right response to most minor scratches. Another misunderstanding is that a healthy cat that carries the bacterium must be treated or rehomed. Public health guidance says the opposite for healthy cats: keep the cat, control its fleas, and practise the hygiene habits above. A third myth is that flea dirt itself infects people directly through skin contact. The recognised route is a scratch or bite that carries contaminated flea dirt into a break in the skin.

When to Seek Medical or Veterinary Advice

• A scratch or bite that becomes increasingly red, warm, swollen, or painful, or that develops pus.
• Swollen lymph nodes that keep growing, are very painful, burst, or do not settle over several weeks.
• Fever, headache, or fatigue that lingers or worsens after a scratch or bite.
• Any symptoms after a scratch or bite if you are pregnant, have a weakened immune system, or care for a child under 5 who was scratched.
• A cat that is feverish, lethargic, off its food, or showing swollen nodes or eye problems.

When in doubt, seek advice early. A short call to your doctor or vet can settle whether a symptom fits the usual mild pattern or needs a closer look, and it costs far less worry than watching and waiting.

Frequently Asked Questions

Can I get cat scratch fever from a flea bite directly?

Direct spread from an infected flea bite to a person has not been proven. The recognised route is a scratch or bite from an infected cat that carries flea faeces into a break in the skin.

Should my healthy cat be tested for Bartonella?

Routine testing and treatment of a healthy cat is not recommended. Testing is generally reserved for cats that are actually sick, and your vet can advise whether it is appropriate.

Do I need antibiotics after a cat scratch?

Most scratches need only thorough washing with soap and water. Antibiotics are a medical decision for confirmed or more serious cases, so contact your doctor if symptoms develop or the wound worsens.

Are kittens more risky than adult cats?

Yes, kittens are more likely to carry the bacterium and to scratch during play, so gentle play, hand washing, and flea prevention matter most with young cats.

Can cat scratch fever come back?

Reinfection is possible while fleas remain in the household, which is why year round flea control matters even after an episode has settled.

This article is general information for cat owners. It is not veterinary advice and it is not a substitute for professional care. If you are worried about a scratch, a bite, or any symptom described here, contact your doctor, and contact your vet if your cat seems unwell.