HEALTH RISKS AND ACTION YOU SHOULD TAKE

When Bitten By A Rat

Rats have a well deserved reputation for carrying risks to the health of humans. Their most famous (or rather infamous) period in history was their role in the spread of Bubonic Plague ("The Black Death") in the middle ages. This was estimated to have killed about a third of all adult humans in Europe - including 30,000 of the then 70,000 population of London. The first cases known in England were recorded on the Dorset coast! The rats were carriers of the true culprits - the plague was actually spread by the fleas living on them. Health Risks

Rat bites can become locally infected from any common bacteria present in the environment just like any wound, however there are other diseases and infections specific to rats : Leptospirosis is the most common zoonosis (a disease spread to humans from animals) in the world and caused by a spiral-shaped bacteria - Also known as Weils' disease if severe, Leptospirosis was first recognised in sewer workers in the 19th century. Infection occurs by physical contact with infected water or rat effluent which explains why the sewer workers were affected. The disease initially causes mild and non-specific flu like symptoms of chills, muscular aches and weakness but can progress to a more severe form including meningitis, liver failure (jaundice) and kidney failure which while dramatic are usually temporary and fully recoverable with use of antibiotics and specialist treatment. However death can occur if treatment is very delayed or unavailable such as in some areas of the third world. Leptospirosis is uncommon in the UK but is occasionally seen in people who come into close contact with rats or contaminated water either through their job or recreation. I have only seen one case in my 8 years as a doctor - the patient was a teenager who had accidentally fallen into one of Birmingham's fine canals.

Rat Bite Fever is another infectious disease transmitted in the mouth or urine of an infected rodent. Despite the name, humans do not need to be bitten by the offending animal - contact with water contaminated by rat urine can be enough to contract the disease. Although the bacteria is different, the early symptoms are very similar to leptospirosis. Rat bite fever can be suspected from recent activities, detected by blood tests and treated with great success by penicillin.

Rats have occasionally been thought to carry and spread rabies. This is in fact not the case. While any mammal could theoretically harbour the disease, rabies is almost unheard of in rodents. Worldwide rabies is carried by domestic cats and dogs, and in the wild mainly by bats. The UK has had just one case of rabies in the last 100 years which came from a bite from a wild bat - the victim was a bat conservationist ironically enough.

What To Do

If bitten by a rat the first course of action is to allow the wound to bleed freely initially then rinse thoroughly with clean water. Sterile medical saline is ideal but clean tap water is fine. If still bleeding after several minutes, a clean gauze or bandage can be applied with pressure to stop the bleeding and cover the wound. Stitching of animal bites is almost never needed unless a large tear of skin, and even then any stitching would normally be delayed for days until it is clear there is no infection present.

As bite wounds tend to implant bacteria deep into the tissue layers, cleaning of the wound is often not enough to prevent infections so prophylactic (preventative) antibiotics are required. Antibiotics are particularly important for bites to the hand from any mammal (including dog, cat, human) as these tend to be much more prone to infection and subsequent complications. It is wise to start antibiotics within 24 hours in order to prevent infections, and if an appointment to see your own GP is not available that day, a telephone consultation with your doctor will usually be sufficient in order for a prescription to be made available. At this time it is also worth discussing your tetanus status, and arranging to go to your GP practice for a booster within the next week if required.

Dr. Mike Farrell

Archive Winter 2004 | next

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