Director: David Fiess, MPA Phone: (260) 449-7459 FAX: (260) 449-7460 Email:
Location: 2242 Carroll Rd, Fort Wayne, IN 46818 Hours: 8 a.m. to 12 p.m. and 1 to 4:30 p.m., Monday - Friday
Meet the Staff: Josh Blauvelt, BS, CHHS, Asst. Director; Tom McCue, BS, Env. Health Specialist II; Francis Koch, Env.Technician; Trina Riecke, Lead Case Manager; Cindy Wable, Lead Case Coordinator/Env. Technician; Pat De Haven, Secretary Seasonal Mosquito Technicians

Rats & Mice - Biology & Diseases


We all agree commensal rodents are good for nothing.  In fact, the word "commensal" means these rodents live off humans without returning anything of worth.  The Norway rat (Rattus norvegicus) and house mouse (Mus musculus) are the prevailing rodent species found in Allen County.

The rat's tail is shorter than the head and body.  The ears are close to the body and do not cover the eyes when bent forward.  The eyes are small and the nose and muzzle are blunt.

Rats usually live in underground burrows, but will inhabit wall voids.  They feed on garbage, meat scraps, cereal grains, vegetables, and cat and dog food.  Rats will dig undigested food out of cat and dog feces and eat it.

Mice tail size equals the length of the body, which averages about 4 inches.  The ears are big and nose is pointed.  Mice live for about year. 

Mice fear rats, so you may have one or the other; not both.  Rats will eat mice.


  • Droppings and urine trails left wherever they travel, especially in corners
         Rat droppings look like little footballs
         Mouse droppings look like pieces of rice
  • Dark smears and rub marks on baseboards as they move throughout their territories
  • Footprints and tail drags in dusty areas
  • Gnaw marks on wooden surfaces, especially door corners
  • A distinctive, musky odor
  • House pets may become agitated because they hear gnawing, digging, running and fighting


Rats and their fleas are capable of transmitting a variety of human diseases.  Mice are also capable of transmitting disease, while also contributing to asthma conditions.

  • Asthma is triggered in humans by many things, rodent hair and urine included.
  • Hantavirus is carried and transmitted by the deer mouse through its urine, droppings, and saliva.
  • Human Lymphocytic Choriomeningitisis a rodent-borne viral infectious disease that causes serious neurological problems.  It is primarily carried by the house mouse, but hamsters in contact with wild mice at a pet store can also carry the disease.
  • Leptospirosis (Weil's disease) is contracted through water or food contaminated with the urine of infected rats.
  • Plague, a disease carried by a bacterium called Yersinia pestis, is known to exist in the western United States, South America, Africa and Southeast Asia.  Humans are infected by the bite of the Oriental rat flea.
  • Rat-bite Fever is rare in the United States.  It is caused by the bite of an infected rat.
  • Salmonellosis is a bacterial food-borne illness.  It is transmitted when rodents contaminate food or working surfaces where food is prepared.
  • Typhus is transmitted to humans by infected rat fleas, usually Xenopsylla cheopis, the Oriental rat flea.  The flea will defecate while sucking blood and contaminate the bite site.



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Photo Gallery

Click thumbnail to see large image.
  • Trina Riecke, Lead Case Manager, conducts a developmental assessment of a lead-poisoned child.
  • Lucky the Lead Free Lemur is a mascot of the Childhood Lead Poisoning Prevention Program.  He appears at health fairs and other events to promote lead prevention.
  • This engorged American Dog Tick was pulled off a human.  To prevent tick attachment, wear light-colored clothing, long pants with the bottoms placed into the top of socks, and apply a DEET-product to your clothing.  Check your clothing and body after exiting a high grass or wooded area.
  • De-rimmed tires breed mosquitoes and can provide drinking water for rats.  Culex species, ones that can carry WNv, and Ae. triseriatus, carrier of LaCrosse Encephalitis, use tires as a habitat when in the larval form.  The sun heats the black rubber allowing for increased mosquito production, even when it is cool out.  Tires should be properly disposed of or covered to prevent mosquito breeding.
  • A female Culex mosquito laying an egg raft, which can consist of 200-300 eggs.
  • A blood sample to be tested for lead is taken from a capillary in the tip of the finger.
  • Mold needs water to grow.  Remove the water source and there won't be a mold problem.
  • The American dog tick is the largest tick in Indiana and can carry Rocky Mountain Spotted Fever.
  • Children enjoy meeting Lucky the Lead Free Lemur.
  • Sticky traps are a great tool to catch cockroaches.
  • Trina Riecke educates a citizen about how to maintain a healthy and safe home.
  • Rats like to eat grease, as can be seen in the pan on the stove.
  • Educating the public on Vector-borne diseases is an on-going effort.
  • Ae. triseriatus, a carrier of LaCrosse Encephalitis, lays her eggs in treeholes and containers.
  • Mosquito larvae
  • Cockroach infestation in kitchen cabinet.
  • Mosquitofish can be placed into ornamental ponds to eat mosquito larvae.  The fish only get to be an inch in length.
  • Un-maintained swimming pools are perfect for breeding the mosquitoes that can carry West Nile virus.
  • Double whammy for mosquito breeding - uncovered boat with un-rimmed tire in it.
  • Notice the pop can the rats tried pulling into a burrow.
  • This rat ate poison bait stored in a secure station.
  • Bed bugs do not transmit diseases, but their bites can become infected if scratched too much.
  • Radon is the second leading cause of lung cancer. Free radon test kits are available at the Fort Wayne-Allen County Department of Health.
  • Ingredients taken from a meth lab that was found in a house.
Did You Know?

Mosquitoes are not affected by ultrasonic devices.