Tularemia: A Rare but Critical Disease You Need to Know About

Tularemia in Children: Key Symptoms, Diagnosis, and Treatment

Imagine an 8-year-old boy visiting his pediatrician for the third time in just over a week. Despite being prescribed antibiotics, his fever persists—often reaching 104°F—and his neck swelling is still as pronounced as it was on the first visit. The anxious parents explain that their child’s condition doesn’t seem to be improving, and they want answers. After revisiting the patient’s chart, the pediatrician considers alternative diagnoses that could explain the boy’s persistent fever and lymphadenopathy. Among the possibilities, one stands out: tularemia—a rare, zoonotic infection that may be the root cause of his symptoms.

Tularemia, caused by the bacterium Francisella tularensis, is often overlooked due to its rarity, yet it is an emerging concern, especially given its increasing incidence in the United States. This potentially life-threatening disease is nationally notifiable in the U.S., meaning health professionals are required to report cases to public health authorities for tracking and surveillance. While tularemia is uncommon, understanding its symptoms, transmission routes, and appropriate treatments is crucial for timely diagnosis and effective management.

What is Tularemia?

Tularemia is a highly infectious zoonotic disease primarily caused by Francisella tularensis, a Gram-negative bacterium. This pathogen is capable of causing a wide range of clinical manifestations, depending on the route of infection. With an average of 200 cases reported annually in the United States, tularemia may not be commonly encountered, but its significance cannot be understated. The Centers for Disease Control and Prevention (CDC) reports that between 2011 and 2022, a total of 2,462 cases of tularemia were recorded in the U.S., marking a 56% increase compared to the previous decade (2001-2010).

Notably, the disease tends to be more prevalent in children aged 5-9 years, as well as older men and individuals from American Indian or Alaska Native communities. Although tularemia can occur throughout the year, most cases (78%) begin during the warmer months, from May to September, when people are more likely to encounter infected vectors like ticks and deer flies.

Transmission and Risk Factors

Tularemia is primarily transmitted to humans through the bite of an infected arthropod, such as ticks or deer flies. However, Francisella tularensis can also spread through direct contact with infected animals or animal tissues, particularly rabbits, rodents (like prairie dogs), and muskrats. Pet store hamsters have also been linked to human tularemia outbreaks, demonstrating the risk even small animals may pose. While insect bites and animal contact are the most common modes of transmission, tularemia can also be contracted through inhaling aerosolized particles or consuming contaminated food or water.

In the United States, ticks are the primary vector, and deer flies also contribute to its transmission. Outbreaks have even been documented when infected animal carcasses are inadvertently aerosolized by farming equipment like lawnmowers or tractors running over the remains of animals such as rabbits or muskrats.

Clinical Manifestations of Tularemia

Tularemia’s clinical features are diverse and largely dependent on the route of exposure. The most common form of the disease, ulceroglandular tularemia, results from bites or direct contact with infected animals. Symptoms typically include the formation of an ulcer at the entry site, often accompanied by enlarged, tender lymph nodes (lymphadenopathy). This presentation is particularly common in children.

Other manifestations of tularemia include:

1. Conjunctival Tularemia: This occurs when the bacteria enter the body through the eyes, causing symptoms like conjunctivitis and preauricular lymph node swelling.
2. Oropharyngeal Tularemia: Often resulting from ingestion of contaminated food or water, it is associated with a sore throat, mouth ulcers, tonsillitis, and swollen lymph nodes in the neck.
3. Pneumonic Tularemia: The most severe form of the disease, this occurs when bacteria are inhaled or spread to the lungs from other body parts. Pneumonic tularemia is marked by symptoms such as cough, chest pain, and difficulty breathing, and it can be fatal if left untreated.

Diagnosing Tularemia

Given the wide variety of clinical symptoms, diagnosing tularemia can be challenging, especially in areas where the disease is rare. In the case of the 8-year-old boy, the pediatrician suspected ulceroglandular tularemia after finding a poorly healing 1-cm ulcer on his left occiput, which was consistent with a tick bite or animal exposure. The clinical findings, combined with the boy's fever and swelling, led the pediatrician to suspect tularemia.

A definitive diagnosis is made through serologic testing, which detects antibodies or antigens for Francisella tularensis. In the boy's case, the serologic test confirmed the diagnosis, and appropriate treatment was promptly started.

Treatment of Tularemia

The treatment of choice for tularemia in children is gentamicin, which is administered intravenously or intramuscularly. This antibiotic has proven efficacy in treating Francisella tularensis infections and is considered safe for pediatric use. Ciprofloxacin is an alternative, though it is not FDA-approved for this indication in children. Early diagnosis and timely antibiotic treatment are crucial in preventing complications, especially in severe forms like pneumonic tularemia.

Reporting and Preventing Tularemia

As a nationally notifiable disease, cases of tularemia must be reported to local and state health departments, which then transmit the data to the CDC. This surveillance system is vital for monitoring the incidence of tularemia, identifying trends, and implementing preventive strategies.

Preventive measures include using Environmental Protection Agency-registered insect repellents to protect against ticks and deer flies. Individuals who handle animals, particularly wild rodents or rabbits, should wear gloves to minimize the risk of direct contact with infected tissues. Furthermore, proper cooking of game meat and precautions during activities such as hunting, trapping, and skinning animals are essential to prevent exposure to Francisella tularensis.

Conclusion

While tularemia remains a rare disease, its potential for severe clinical consequences makes it important for healthcare providers to be vigilant in considering it as a differential diagnosis. Early recognition of tularemia, especially in areas where it is more common, can lead to rapid treatment and better outcomes. As this case highlights, tularemia is still a relevant public health concern, and understanding its transmission, symptoms, and treatment protocols is critical in managing this rare but serious disease.