9 Diseases Caused by House Rats: Types, Symptoms, Diagnosis & Treatment

House rats are the carrier of several diseases that result in severe sickness and, in a worse case, death. Among the diseases transmitted by direct contact are rat bites, while disposing of infected dead rats, inhaling dust and consuming foods and drinks contaminated with infected rats’ urine, hair, saliva and faeces. Diseases caused by rats can also be transmitted indirectly by parasites like fleas, ticks and mites that live on the infected rodents.

Rats have a common association with both nature and humans. An instance is the 14th-century bubonic plague, better known as ‘black fever. Since then, this rodent family has been a potential carrier of fatal diseases.

Here is the list of 9 diseases caused by rats to humans.

Symptoms

Nearly 38% of Hantavirus infections lead to death. Commonly the signs of Hantavirus appear within 1 to 5 weeks (incubation period). Fatigue, fever, muscle pain, diarrhoea, nausea and abdominal pain are some of the early symptoms of this disease caused by rats. The signs of HPS that spread throughout the body are

• Lung congestion
• Fluid accumulation in the lungs 
• Breathlessness

Diagnosis

As the early Hantavirus symptoms are similar to influenza, it is difficult to diagnose the infection. Regardless, if individuals with frequent rodent exposure experience fever, breathlessness and fatigue, they must seek medical assistance at the earliest opportunity.

Treatment

Unfortunately, there is no definitive vaccine, drugs or treatment for Hantavirus. However, identifying the early symptoms and immediate medical aid in the intensive care unit may improve the survival chances from severe HPS.

Rats, along with other rodents like mice, voles etc., transmit this acute zoonotic disease through their aerosolized excrements. Various Hantavirus species use rodents as the carrier of Haemorrhagic Fever with Renal Syndrome (HFRS).

Symptoms

HFRS has acute flu-like signs, including headache, high fever and vomiting. However, depending on the severity, patients can have symptoms like

• Hypotensive Shock-Like SOB, 
• Diaphoresis, 
• Palpitations
• Confusion

Diagnosis

The diagnosis in patients with a clinical history similar to HRFS requires various laboratory examinations. A positive serologic test report confirms the disease. Further, doctors recommend immunohistochemical staining and microscope examination and proof of Hantavirus RNA sequences in blood or tissue to recognise this infection.

Treatment

Supportive care, including optimal hydration with electrolytes such as sodium, potassium and chloride and maintenance of oxygen level and blood pressure, are the mainstay treatment for the disease. At times, dialysis is required to restore severe fluid overloading. Furthermore, an early dose of an antiviral drug named intravenous ribavirin has shown positive results to control the infection.

This is also an acute zoonotic viral disease transmitted by multimammate rats (Mastomys natalensis). These rats shed the Lassa virus in urine and faces and contaminate food and other objects.

Symptoms

Mild fever, common malaise, headache and weakness are some of the early symptoms of Lassa fever. However, infected individuals may also exhibit severe signs like-

• Haemorrhaging in eyes, gums or nose
• Respiratory complications
• Vomiting tendency
• Swollen face
• Chest, back and abdominal pain and shock

A few neurological symptoms of Lassa fever include hearing disability, tremors and encephalitis, and in a worse condition, multi-organ failure and eventually death within 2 weeks.

Diagnosis

Lassa fever is commonly diagnosed with enzyme-linked immunosorbent serologic assays (ELISA). Besides, the reverse transcription-polymerase chain reaction (RT-PCR) test detects the disease early.

Treatment

Ribavirin antiviral drug has shown effective results in curing the infection if taken at an early stage. Patients should also be kept under supportive care to maintain accurate fluid and electrolyte, oxygenation and blood pressure to avoid complications.

This is a bacterial infection caused by Leptospira interrogans bacterium. Rodents like rats, mice etc., are the vectors of this bacteria that live in their kidneys and contaminate soil and water through urine.

Symptoms

Apart from fever spiking to 104°F, other common signs of this bacterial infection are-

• Muscle pain
• Headache
• Vomiting
• Diarrhoea
• Jaundice 
• Skin rash

Diagnosis

The most effective way to diagnose this bacterial infection is through serological tests such as-

• Microscopic Agglutination Test (MAT) for detecting serovar-specific antibodies
• Solid-phase assay to identify Immunoglobulin M (IgM) antibodies

Treatment

Doses of antibiotics like penicillin or doxycycline are recommended at an early stage of Leptospirosis. Nonetheless, patients with severe symptoms require intravenous antibiotics for quick recovery.

This neurological disease caused by rats and mice are -

• Aseptic meningitis- inflammation of meninges, a membrane that surrounds the brain and spinal cord)
• Encephalitis- Inflammation of the brain
• Meningoencephalitis- inflammation of both the brain and meninges

Lymphocytic choriomeningitis virus, found in the saliva, urine, and faeces of infected mice and rats, causes Lymphocytic Chorio-Meningitis (LCM).

Symptoms

The onset of these viral infection signs occurs within 8 to 10 days after coming in contact with the virus. The early symptoms include-

• Fatigue
• Muscle pain
• Fever
• Loss of appetite
• Nausea
• Headache
• Vomiting

After recovering these symptoms, an infected individual can have signs, including-

• Meningitis (neck stiffness, headache and fever)
• Encephalitis (drowsiness, sensory disorders like paralysis, confusion)

Diagnosis

Acute conditions in humans can be detected by isolating the virus from cerebrospinal fluid. Additionally, the immunofluorescent antibody test and ELISA are 2 other effective ways to diagnose LCM disease.

Treatment

Anyone with LCM symptoms should be admitted to a hospital under supportive care, depending on the seriousness. Moreover, ribavirin is effective against such viral diseases.

Though the Yersinia pestis bacteria are responsible for the plague, rats are the amplifying factor of the disease. It is transmitted to rats through fleas present on their bodies and infects humans through a bite, inhalation of respiratory droplets of another infected person and contact with contaminated materials. Primarily, there are 2 types of clinical forms of plague- bubonic and pneumonic.

Symptoms

Patients infected with plague bacteria develop acute febrile disease after 1 to 7 days of incubation. A few common symptoms are-

• Headache
• Body aches
• Fever
• Tremor
• Nausea
• Vomiting

Diagnosis

One of the effective ways to detect the plague is identifying Y. pestis bacteria from a blood or sputum sample. Another potential diagnosis is a laboratory approved rapid dipstick test.

Treatment

Antibiotics like enterobacteria (gram-negative rods) and supportive therapy are essential for patients with the pneumonic plague at the early stage.

Rat-bite fever or RBF is a severe disease caused by Streptobacillus moniliformis or Spirillum minus bacteria found in rats’ urine, saliva, and faeces. Besides, rat bites and scratches are the other possible causes.

Symptoms

RBF signs and symptoms depend on the type of bacterial infection. The symptoms of streptobacillary RBF are-

• Rash near the rat bite
• Joint and muscle pain in the lower abdomen
• Nausea
• Sudden fever (on and off for several weeks)
• Sore throat
• Vomiting

However, the spirillary RBF develops similar symptoms other than hard or soft lymph nodes and inflammation near the bite.

Diagnosis

Medical practitioners detect the clinical variants of rat-bite fever in 2 ways.

• For streptobacillary RBF, doctors look for joint pain and culture blood or joint fluid.
• For spirillary RBF, doctors assess, look for swollen lymph nodes and determine blood or infected tissue samples.

Treatment

Both the RBF variants are treated with amoxicillin, penicillin, erythromycin, or doxycycline.

Symptoms

A few common signs of Salmonella infection are-

• Cramps in stomach
• Blood in stool
• Cold
• Fever
• Diarrhoea
• Headache
• Vomiting
• Stomach upset

Diagnosis

Experts culture blood or stool samples to diagnose Salmonellosis.

Treatment

This is one of the fatal diseases caused due to rats affecting the eyes, skin, lungs and lymph nodes. The rodents are the vector of Francisella tularensis and transmit the bacterium through bites and direct exposure.

Symptoms

Based on the site of infection, Tularemia has 6 clinical variants with a distinctive set of signs and symptoms. They are-

• Ulceroglandular Tularaemia (most common)
  • Skin ulcer (usually forms at the site of the infection)
  • Swollen lymph glands
  • Headache
  • Fever
  • Shivering
  • Exhaustion
• Glandular Tularaemia (same as Ulceroglandular, except for skin ulcers)
• Oculoglandular Tularaemia (affects eyes)
  • Eye redness
  • Eye Pain
  • Swelling and discharge from eyes
  • Ulcer inside eyelid
  • Light sensitivity
• Oropharyngeal Tularemia (affects mouth, throat and digestive tract)
  • Throat pain
  • Fever
  • Ulcer inside mouth
  • Abdominal pain
  • Diarrhoea
  • Vomiting
  • Inflamed tonsils
  • Swollen lymph nodes (neck)
• Pneumonic Tularemia
  • Dry cough
  • Chest pain
  • Breathlessness
• Typhoidal Tularaemia (rare and fatal)
  • High fever
  • Muscle aches
  • Sore throat
  • Enlarged spleen
  • Vomiting
  • Diarrhoea
  • Enlarged liver
  • Pneumonia

Diagnosis

Tularemia is a rare disease with symptoms similar to other diseases caused by rats. The best way to identify the infection is through blood tests. One can also opt for a chest X-ray for pneumonia detection.

Treatment

One of the effective treatments of Tularaemia is gentamicin (antibiotic) injection shot directly into muscle or vein. Streptomycin is also a reliable cure for the disease. In addition, doctors prescribe oral antibiotics like doxycycline or ciprofloxacin for fast results.

There are 3 simple preventive measures to control the diseases caused by rats, including-

• Sealing all entry holes, including cracks, crevices and holes to prevent rats and mice from entering.
• Trapping is a permanent solution to keep diseases caused by rats at bay.
• Cleaning and disinfection of the rodent-infested area are essential to keep the diseases caused by rats at bay. Individuals must be cautious while cleaning such areas and wear masks and gloves to avoid contamination.