Rabbit Fever: Symptoms, Types, Causes and Treatment

Rabbit fever—scientifically known as tularemia—is a rare but potentially severe disease that can affect both animals and humans. With its roots in the natural world but implications for public health, understanding rabbit fever is crucial not only for clinicians but also for anyone who spends time outdoors or works with animals. This article provides a thorough overview of rabbit fever, exploring its symptoms, various types, underlying causes, and best approaches for treatment. Drawing on the latest research, we aim to demystify this complex disease and empower readers with essential knowledge.

Symptoms of Rabbit Fever

When rabbit fever strikes, its symptoms can be varied and sometimes misleading. Recognizing these signs early can be life-saving, especially since the disease can progress rapidly. The illness may mimic other infections, making prompt identification crucial for effective treatment and prevention of complications.

Symptom	Description	Severity	Source
Fever	Sudden onset, often high-grade	Moderate–Severe	2 3
Ulcers	Skin sores at infection entry point	Mild–Severe	2 3
Swollen Glands	Enlarged, tender lymph nodes	Moderate	2 3
Sore Throat	Pain, difficulty swallowing	Mild–Moderate	2
Eye Irritation	Redness, swelling, discharge	Mild–Moderate	2
Cough	Especially in pneumonic tularemia	Severe	2 3
Gastrointestinal	Diarrhea, abdominal pain	Mild–Severe	2

Table 1: Key Symptoms of Rabbit Fever

Common Early Symptoms

The first signs of rabbit fever typically include a sudden onset of high fever, chills, and general malaise. These flu-like symptoms may be accompanied by headache, muscle aches, and fatigue. Because tularemia can present in various forms, the exact combination of symptoms depends on how the bacteria entered the body and which organs it affects 2 3.

Skin and Lymph Node Involvement

In the most common form—ulceroglandular tularemia—patients develop a skin ulcer at the site where the bacteria entered (often a tick or insect bite), followed by swelling of nearby lymph nodes. These nodes can become very tender and may sometimes suppurate (form pus) 2 3.

Eye, Throat, and Respiratory Symptoms

• Oculoglandular tularemia involves the eye, leading to redness, swelling, and discharge, often accompanied by preauricular lymph node swelling.
• Oropharyngeal tularemia is characterized by severe sore throat, mouth ulcers, and swelling of neck glands.
• Pneumonic tularemia presents with cough, chest pain, and difficulty breathing. This form is particularly severe and can be life-threatening if not treated promptly 2 3.

Gastrointestinal Manifestations

Some patients develop gastrointestinal symptoms such as abdominal pain, vomiting, and diarrhea, especially in the oropharyngeal form. These symptoms can sometimes be confused with other gastrointestinal infections, making diagnosis challenging 2.

Types of Rabbit Fever

Tularemia is a master of disguise, presenting in several clinical forms depending on the route of infection. Understanding these types helps guide diagnosis and treatment, as well as predict potential complications.

Type	Main Features	Route of Infection	Source
Ulceroglandular	Skin ulcer, swollen lymph nodes	Insect/animal bite	2 3
Glandular	Swollen lymph nodes, no ulcer	Insect/animal bite	2 3
Oculoglandular	Eye involvement, preauricular swelling	Eye contact	2
Oropharyngeal	Sore throat, GI symptoms	Ingestion	2 3
Pneumonic	Cough, chest pain, breathing trouble	Inhalation	2 3
Typhoidal	Generalized, severe systemic illness	Variable	2

Table 2: Clinical Types of Rabbit Fever

Ulceroglandular Tularemia

This is the most common form, accounting for the majority of cases. It typically arises after a tick, deer fly bite, or handling of infected animals. A skin ulcer forms at the point of entry, and regional lymph nodes become swollen and painful. Fever is almost always present 2 3.

Glandular Tularemia

Similar to the ulceroglandular type but without a visible skin ulcer, glandular tularemia can make the diagnosis more difficult. Swelling of the lymph nodes is the key feature 2 3.

Oculoglandular Tularemia

This form results from the bacteria entering through the eye, either via contaminated fingers or splashes. It leads to conjunctivitis (red, painful eye) and swelling of nearby lymph nodes 2.

Oropharyngeal Tularemia

Acquired by ingesting contaminated food or water, this form manifests as sore throat, mouth ulcers, tonsillitis, and often gastrointestinal upset. It can sometimes progress to more severe forms if not treated quickly 2 3.

Pneumonic Tularemia

One of the most serious forms, pneumonic tularemia develops when the bacteria are inhaled, either from contaminated dust or aerosolized particles. It causes cough, chest pain, and difficulty breathing, and can progress rapidly to respiratory failure if untreated 2 3.

Typhoidal Tularemia

This rare form does not have a clear site of entry and presents as a severe, generalized illness with high fever, prostration, and often sepsis. It carries a higher risk of complications and death, especially if diagnosis is delayed 2.

Causes of Rabbit Fever

At its core, rabbit fever is a zoonotic disease—a disease transmitted from animals to humans—caused by the bacterium Francisella tularensis. But the path from nature to human infection is complex, involving multiple reservoirs and modes of transmission.

Cause	Description	Example/Vector	Source
Bacterium	Francisella tularensis	All cases	1 2 3
Animal Contact	Handling infected animals (hares, rabbits)	Hunting, trapping	2 3
Arthropod Bite	Tick, deer fly, mosquito bites	Outdoor exposure	2 3
Inhalation	Breathing contaminated dust/aerosols	Farming, landscaping	2 3
Ingestion	Eating/drinking contaminated food/water	Untreated water, game	2 3

Table 3: Causes and Transmission of Rabbit Fever

The Bacterium: Francisella tularensis

Rabbit fever is caused by Francisella tularensis, a highly infectious, gram-negative bacterium. There are several subspecies, with varying degrees of virulence and geographic distribution. Type A strains, found mainly in North America, are the most virulent, while type B strains are more common in Europe and tend to cause milder disease 1 2 3.

Animal Reservoirs

Wild mammals, especially rabbits, hares, and rodents, serve as the primary reservoirs. Outbreaks often follow epizootics—large die-offs among these animals—which can increase the risk of human exposure. Domestic animals such as cats can also become infected and transmit the disease to humans 2 3.

Vectors: Arthropods

Ticks, deer flies, and occasionally mosquitoes can acquire the bacteria from infected animals and transmit it to humans through bites. Tick bites are one of the most common transmission routes in endemic areas 2 3.

Environmental Routes

Humans can become infected by inhaling dust contaminated with animal carcasses or excreta, especially during activities like mowing, farming, or landscaping. Contaminated water sources and improperly cooked game meat also pose risks 2 3.

Special Considerations: Bioterrorism

Due to its high infectivity and ease of aerosolization, F. tularensis is classified as a Category A bioterrorism agent. This highlights the importance of awareness and preparedness among healthcare providers and public health authorities 2 3.

Treatment of Rabbit Fever

Rapid, effective treatment is essential for rabbit fever. While the disease can be severe, especially in its pneumonic and typhoidal forms, early intervention with appropriate antibiotics leads to excellent outcomes in most cases.

Treatment	Indication	Effectiveness	Source
Gentamicin	Severe cases	High; first-line	2
Streptomycin	Severe cases	Effective, alternative	2
Doxycycline	Mild–moderate cases	Effective	2
Ciprofloxacin	Mild–moderate cases	Effective	2
Prevention	Vaccine, avoidance	Experimental/variable	1 2
Homeopathy	Supportive, limited	Unproven, controversial	5

Table 4: Treatment Options for Rabbit Fever

Antibiotic Therapy

• Gentamicin is the preferred first-line treatment for severe tularemia, especially in hospitalized patients. It is highly effective when administered promptly 2.
• Streptomycin is another effective option, historically considered the gold standard but less widely available.
• For milder cases, fluoroquinolones (like ciprofloxacin) and tetracyclines (like doxycycline) are commonly used, often on an outpatient basis 2.
• Treatment duration typically ranges from 10 to 21 days, depending on severity and response.

Supportive Care

Patients may require hospitalization for intravenous fluids, oxygen therapy, and monitoring, especially if they have pneumonic or typhoidal forms. Early diagnosis and intervention are key to preventing complications and death 2.

Experimental and Alternative Approaches

• Vaccination: Research in animal models, such as New Zealand White rabbits, has shown promise for live attenuated vaccines delivered by aerosol, which may offer strong protection in high-risk settings. However, no vaccine is yet available for general human use 1.
• Homeopathy: Experimental studies in rabbits have tested ultra-high dilutions of homeopathic remedies for fever management. While some reduction in fever was noted, these findings are limited by small sample sizes and lack of robust evidence. Such approaches cannot replace antibiotics in treating tularemia 5.

Prevention Strategies

• Avoid handling sick or dead wild animals.
• Use insect repellent and wear protective clothing in tick-infested areas.
• Ensure food and water are properly cooked and treated.
• Public health measures and laboratory awareness are essential, especially in outbreak or bioterrorism scenarios 2 3.

Conclusion

Rabbit fever, or tularemia, is a complex and potentially severe zoonotic disease with a wide range of symptoms, types, causes, and treatments. Awareness and early intervention are crucial for successful outcomes.

Key takeaways:

• Symptoms: Range from high fever and lymph node swelling to ulcers, cough, sore throat, and gastrointestinal issues, depending on the form 2 3.
• Types: Six main clinical types, each linked to different routes of infection and varying in severity 2 3.
• Causes: Caused by Francisella tularensis, transmitted via contact with animals, arthropod bites, inhalation, and ingestion 1 2 3.
• Treatment: Requires prompt antibiotic therapy; gentamicin for severe cases, doxycycline or ciprofloxacin for milder cases. Vaccines are experimental; alternative therapies are unproven 1 2 5.
• Prevention: Focuses on animal and environmental control, personal protection, and heightened awareness among clinicians and the public 2 3.

By understanding the multifaceted nature of rabbit fever, individuals and health professionals can better recognize, prevent, and treat this serious but manageable disease.