Rat-Bite Fever: Symptoms, Causes, Treatment

What are the symptoms of rat-bite fever?

Rat-bite fever (RBF) is an infectious disease that can occur after a bite or scratch from an infected rodent, such as a rat, or after handling rodents without being bitten. It is caused by two different bacteria: Streptobacillus moniliformis (common in the United States) and Spirillum minus (common in Asia). The symptoms can vary depending on the type of bacteria causing the infection, but common symptoms generally include:

Symptoms of Rat-Bite Fever Caused by Streptobacillus moniliformis (more common in the U.S.):

• Fever: A high fever, often accompanied by chills, usually develops within 3 to 10 days after exposure.
• Rash: A red, bumpy rash may develop, often on the hands and feet, but it can spread to other parts of the body. The rash may be flat or raised and can sometimes be itchy.
• Joint Pain: Pain and swelling in the joints (polyarthritis) are common and can affect multiple joints. This is often accompanied by muscle pain (myalgia).
• Headache: A severe headache may occur, along with other flu-like symptoms such as fatigue and malaise.
• Vomiting and Nausea: Gastrointestinal symptoms, including vomiting, nausea, and abdominal pain, may also be present.
• Ulcers at the Bite Site: In some cases, an ulcer may develop at the site of the bite or scratch.

Symptoms of Rat-Bite Fever Caused by Spirillum minus (common in Asia):

• Recurrent Fever: The fever in this type of rat-bite fever tends to be recurrent, coming and going over several days or even weeks.
• Rash: A rash, similar to that caused by Streptobacillus moniliformis, may develop, often accompanied by swollen lymph nodes.
• Ulcers at the Bite Site: The bite or scratch site may develop into an ulcer, and surrounding tissues may become red and inflamed.
• Lymphadenopathy: Swelling of the lymph nodes, particularly near the site of the bite, is common.

General Symptoms:

• Chills and Excessive Sweating: These are common and can occur intermittently.
• Generalized Weakness: Patients may feel generally weak or fatigued.
• Complications: If left untreated, rat-bite fever can lead to serious complications such as endocarditis (inflammation of the heart valves), meningitis, pneumonia, and, in rare cases, death.

Summary:

Rat-bite fever typically presents with fever, rash, joint pain, and, depending on the type of bacteria, recurrent fever, ulcers at the bite site, and swollen lymph nodes. The symptoms usually appear within a few days to weeks after exposure to an infected rodent. Early recognition and treatment are important to prevent complications.

What are the causes of rat-bite fever?

Rat-bite fever is caused by two different types of bacteria, depending on the geographic region:

1. Streptobacillus moniliformis: This bacterium is primarily found in the United States and is responsible for most cases of rat-bite fever in this region. It is part of the normal flora in the mouths of rats.
2. Spirillum minus: This bacterium is more commonly found in Asia and is responsible for cases of rat-bite fever in that region. It is also present in the mouths of infected rodents.

The infection is typically transmitted to humans through:

• Rat Bites or Scratches: Direct contact with the saliva of an infected rat through a bite or scratch.
• Handling Infected Rodents: Direct contact with the saliva or excrement of infected rodents.
• Contaminated Food or Water: In rare cases, ingesting food or water contaminated with the bacteria from rat saliva or feces.

Transmission:

• Rodents as Carriers: Rodents, particularly rats, are the primary carriers of the bacteria. The bacteria are often present in the rodents’ saliva and can be transmitted through bites or scratches.
• Environmental Contamination: The bacteria can be present in environments where infected rodents live, including their nests or areas contaminated with their urine or feces.

What is the treatment for rat-bite fever?

The treatment for rat-bite fever involves antibiotics to address the bacterial infection. The choice of antibiotics can depend on the specific bacteria causing the infection. Here’s a general overview of the treatment approach:

Antibiotic Treatment:

• For Streptobacillus moniliformis-related Rat-Bite Fever:
• Penicillin: Often the antibiotic of choice. It is effective in treating the infection caused by this bacterium.
• Alternative Antibiotics: If the patient is allergic to penicillin or if the infection is severe, other antibiotics such as doxycycline or tetracycline may be used.
• For Spirillum minus-related Rat-Bite Fever:
• Doxycycline: Commonly prescribed for infections caused by Spirillum minus.
• Alternative Antibiotics: Erythromycin or other macrolides may also be used, particularly if the patient cannot tolerate doxycycline.

Supportive Care:

• Pain and Fever Management: Over-the-counter pain relievers and fever reducers, such as acetaminophen or ibuprofen, can help manage symptoms.
• Wound Care: Proper cleaning and care of the bite or scratch wound to prevent secondary infection.
• Hospitalization: In severe cases, or if complications arise, hospitalization may be necessary for more intensive treatment and monitoring.

Summary:

The primary treatment for rat-bite fever involves antibiotics tailored to the specific bacteria causing the infection. Penicillin is commonly used for infections caused by Streptobacillus moniliformis, while doxycycline is preferred for Spirillum minus. Supportive care and proper wound management are also important in the overall treatment plan.