Endemic Diseases Caused by Rats - Plague, Rat Bite, Salmonellosis (Download PDF)

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  • An infectious disease.
  • Caused by the bacterium Yersinia pestis.
  • Found usually in found in small mammals and their fleas.
  • Disease transmission occurs between animals via their fleas and as it is a zoonotic bacteria.
  • Can also transmit from animals to humans.
  • A case-fatality ratio of 30 %- 100 % if left untreated.
Human Plague and the Countries Reporting


Bubonic Plague

  • Most common form of plague.
  • Caused by the bite of an infected flea.
  • The plague bacillus, Y. pestis enters at the bite travelling through the lymphatic system to the nearest lymph node where it replicates itself.
  • Cannot be transmitted from human to human.

Septicaemic Plague

  • Infection spreads through the bloodstream.
  • May result from flea bites.
  • Direct contact with infective materials through cracks in the skin.
  • Y. pestis in the blood spreads at the advanced stages.

Pneumonic Plague

  • Lung-based plague.
  • Most virulent and least common form of plague.
  • Untreated pneumonic plague has a case-fatality ratio close to 100 % .


  • Sudden onset of fever
  • Chills
  • Head and body-aches
  • Weakness
  • Vomiting and nausea

Preventive Measures

  • Informing people about the zoonotic plague՚s presence in the environment.
  • Advice regarding taking precautions against flea bite.
  • Not to handle animal carcasses.
  • Health workers should also avoid direct contact with infected tissues or close exposure to patients with pneumonic plague.

Rat Bite Fever (RBF)

  • A zoonotic disease.
  • Caused by Streptobacillus bacteria.
  • Found in the mouth of apparently healthy rats and mice.
  • The wound often gets healed between 2 to 10 days (before the symptoms begin) after the bite in case of bites and scratches.
  • Death can be caused incase the ill person do not seek medical attention and treatment.

People are infected through:

  • Bites or scratches from rodents.
  • May also become ill after eating contaminated food or drink.
  • Close contact with rodents.


  • Chills
  • Headche
  • Vomitting
  • Arthritis
  • Reddish brown rash


  • Antibiotic treatment is effective.
  • Immediately cleaning and disinfecting wounds.
  • Promptly seeking medical attention after any rodent bite or scratch.


  • Commonly associated with poor hygiene.
  • Inadequately cooked food.
  • Can also be acquired from rodents.
  • Found in the faeces of many animals including wild and pet rodents.
  • Infection spreads by people who do not wash their hands after contact with rodent droppings.
  • Also spreads if food, drink or eating utensils are contaminated with rodent droppings.
Salmonella Infection
Salmonella Outbreak

Leptospirosis - Weil՚s Disease

  • Also known as Weil՚s disease.
  • Caused by the bacteria Leptospira.
  • Carried by rodents and other wild animals.
  • Infection is through contact with:
  • Water
  • Food
  • Soil containing urine from an infected animal.
  • The infection can be prevented by avoiding contact with water that might be contaminated with animal urine.
Leptospirosis - Weil՚s Disease
Leptospirosis - Weil՚s Disease

Q Fever Rickettsial Disease

  • An acute or chronic disease.
  • Caused by a number of related bacteria of the genus Rickettsia.
  • Blood-sucking parasite vectors.

Causes and Transmissions

  • Workers whose occupations bring them in close contact with farm animals or their products.
  • Transmission is usually by inhalation of infected aerosols.
  • Can also be contracted by ingesting infective raw milk.


  • Fever
  • Headache
  • Malaise
  • Interstitial pneumonitis
  • The incubation period averages 18 to 21 days (range 9 to 28 days)

Prevention and Treatment

  • Vaccines are effective.
  • Vaccination protect people with occupational risk such as slaughterhouse and dairy workers, rendering-plant workers, herders, farmers) .
  • To identify preexisting immunity to Q fever, Prevaccination screening with skin and blood tests should be done.
  • Incase of acute Q fever primary treatment is doxycycline 200 mg po once followed by 100 mg po bid until the patient improves.
  • In case of endocarditis, treatment needs to be prolonged typically for at least 18 months.

- Published/Last Modified on: April 6, 2020

Health, Environment/Ecology, Down-to-Earth

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