Undulant fever, also known as brucellosis, is an infectious disease caused by bacteria belonging to the Brucella genus. This bacterial infection can affect both animals and humans, though humans are typically accidental hosts. The disease is characterized by a range of symptoms.
Transmission and High-Risk Groups
The infection spreads from animals to humans through several routes. A common way to contract brucellosis is by consuming unpasteurized dairy products, such as raw milk, cheese, or ice cream, from infected animals like goats, cattle, or sheep. Direct contact with infected animals or their bodily fluids and tissues also transmits the bacteria. This can occur through cuts in the skin or contact with mucous membranes when handling animals or their carcasses. Additionally, inhaling airborne bacteria poses a risk.
Certain occupations and activities place individuals at a higher risk of exposure to Brucella bacteria. Veterinarians, farmers, and ranchers are frequently exposed due to their close contact with livestock and potential exposure to animal secretions. Slaughterhouse workers and meat inspectors also face elevated risks from handling infected animal tissues and fluids. Laboratory personnel who work with Brucella cultures are at risk of inhalation exposure. Hunters may also be at increased risk when dressing game animals.
Characteristic Symptoms
The disease acquired the name “undulant fever” because the fever characteristically rises and falls in waves over days or weeks. People infected with Brucella bacteria often experience profuse sweating.
Beyond the fever and sweating, individuals commonly report severe fatigue. Headaches are a frequent complaint, alongside pain in the joints and muscles. Other symptoms may include loss of appetite, chills, back pain, and weakness. The incubation period for brucellosis typically ranges from one to three weeks, but it can extend to several months after exposure.
Diagnosis and Treatment
Diagnosing undulant fever typically begins with a doctor inquiring about a patient’s potential exposure history, including their occupation, recent travel, and dietary habits, especially concerning unpasteurized dairy. Confirmation of brucellosis involves specific laboratory tests. Blood tests are used to detect antibodies produced by the body in response to the Brucella bacteria.
Another method for definitive diagnosis is culturing the Brucella bacteria from samples such as blood or bone marrow. Once diagnosed, treatment involves a combination of antibiotics, as using a single antibiotic often leads to a high rate of relapse.
Patients are typically prescribed a regimen of two different antibiotics, such as doxycycline combined with rifampin, streptomycin, or gentamicin. This antibiotic combination is generally taken for a minimum of six weeks. Completing the entire course of medication is important to effectively eliminate the bacteria and prevent relapse or long-term complications.
Prevention Strategies
Preventing brucellosis primarily involves avoiding exposure to the bacteria from animal sources. A straightforward measure is to avoid consuming unpasteurized dairy products, including raw milk, cheese, and ice cream. Pasteurization is a heating process that destroys harmful bacteria in dairy products, making them safe for consumption.
For individuals in high-risk occupations, using personal protective equipment (PPE) such as gloves, goggles, gowns, and masks minimizes direct contact with infected animals, their tissues, or bodily fluids. Hunters should also use gloves when dressing wild game. Proper handling and cooking of meat from potentially infected animals, particularly game, further reduces the risk of transmission. Animal vaccination programs play a significant part in controlling the disease within livestock populations, reducing human infection risk.