Rats! Keep these rodents far away

You know we have an abundance of wildlife on Kauai; some of it is wonderful, some of it is less wonderful. Today’s column is about the health risks that rats pose to us and what we can do to protect ourselves from the diseases that they carry. Rats carry more than 40 harmful diseases and have been thought to have taken more human lives in the last 10 centuries than all the wars and revolutions combined.

Rats carry deadly diseases which can be transmitted to humans by various common ways. The most common ways rats can transmit disease include bites and scratches, rat urine infecting open sores, dead rats in water sources, infecting human food with droppings, and indirectly by mites and slugs.

There are over 40 different diseases that rats can transmit but there are six more common ones on Hawaii. They are: rat lung worm disease, Salmonellosis, rat-bite fever, Weil’s disease (Leptospirosis), Hantavirus Pulmonary Syndrome and Murine Typhus.

Rat lung worm disease is a deadly parasite carried by rats in their hearts, much the same as dogs carry heartworm disease.

Dog heartworm does not infect humans; however, rat feces can infect snails and slugs with the parasite, when they eat rat feces.

People are then infected when they eat raw infected snails or slugs or lettuce, fruit or other vegetables that are infected by the snails or slugs. The common symptoms of rat lung worm disease include a tingling in the skin, a stiff neck, vomiting, headaches, nausea and fever.

The disease can lead to permanent disability and coma and in some extreme cases cause Eosinophilic Meningoencephalitis, leading to death — although that is rare. More likely is permanent brain and nervous system damage.

The obvious way to avoid contracting this disease is to avoid eating raw slugs and snails, and monitor children when they are playing in the yard so that they don’t either.

Wash all veggies and salad components thoroughly before consuming. Snails and slugs can be very small and hide in lettuce folds. Wash your hands after gardening and put out rat bait as well as snail and slug bait to control vermin around your garden and property.

Salmonellosis is a bacterial illness carried by domestic pet rats as well as wild rats. It is transmitted to humans through contact with rat urine and feces and causes gastrointestinal problems such as stomach cramps, fever and diarrhea. In mild cases, people may recover in a week, but in more severe cases, the infection can spread through the entire body through the bloodstream.

Rat-bite fever is usually contracted when a rat bites or scratches a person, although it can also be contracted through contact with rat feces, or urine on open sores. There are two types of rat bite fever.

One is Streptobacillary wherein one presents with a fever, joint and muscle pain, a rash and vomiting and the other is Spirillary wherein one presents with a rash, swollen lymph nodes and a recurring fever.

Weil’s disease (Leptospirosis) is caused by a common bacteria that many rats carry. Humans infected with Weil’s disease show muscle aches, fever, rash, vomiting, and headaches and it can result in liver and kidney damage as well as cardiovascular problems. It is caused when our mucous membranes come in contact with contaminated rat feces or urine.

Hantavirus Pulmonary Syndrome is a fatal disease carried by rats and transmitted to humans by saliva, droppings or urine. Humans can also contract the disease through breathing in the aerosolized virus, which may be from urine, droppings or rotting rat carcasses.

Although the disease is somewhat rare, it is serious. This disease is usually carried by roof rats or Norway rats, which we have on Kauai. The first signs of the disease can be mistaken for the flu and can lead to deadly breathing difficulties. When cleaning up a rodent infestation, spray the area with disinfectant, use gloves and a respirator to avoid any airborne particles.

Murine Typhus is transmitted to humans by rat fleas. Much like the bubonic plague (the Black Plague) transfer occurs when fleas from rats bite humans. The Black Plague killed millions (75 million) of people in the middle ages up to the 1800s, but Murine Typhus typically is reported in Hawaii only five or six times a year. In 2002, we had 47 cases and this high number underlines the constant need for community education to prevent rat originating diseases.

Both Murine and the Black Plague fall under the category of an indirect disease, carried by a vector such as a flea, mite or tick rather than a direct disease carried by contact with the rat or its body fluids or feces.The rat has been and continues to be one of the most damaging invasive species in Hawaii. Rats are also a potential cause of allergens. Their droppings, their dander and hair can cause people to sneeze and experience allergic reactions.

Rat control measures include the application of zinc phosphate oat bait to grasslands and pasture areas believed to be infested with rats. Zinc phosphate is repellent to birds and other species but not to rats. It is considered a single dose poison.

Rat trapping and environmental assessments including rodent proofing, community education and the application of insecticides to reduce the flea and mite population are important measures. As well, it is important to clean up rat infested areas and remove access to possible food or shelter.

When using poisons to eradicate rats, it is important to protect your children and domestic animals from accidental contact. Rats typically do not become bait shy, which means that they will return to the bait, such as warfarin, if it doesn’t kill them the first time.

Live safe!


Dr. Jane Riley, EdD., is a certified personal fitness trainer, nutritional adviser and behavior change specialist. She can be reached at janerileyfitness@gmail.com, (808) 212-8119 cell/text and www.janerileyfitness.com.


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