Summary about Disease
Undulant fever, also known as brucellosis, is an infectious disease caused by bacteria of the genus Brucella. These bacteria primarily infect animals like cattle, sheep, goats, pigs, and dogs. Humans typically contract the disease through direct contact with infected animals, consuming unpasteurized dairy products, or inhaling contaminated aerosols. The disease is characterized by fluctuating (undulating) fever, hence the name.
Symptoms
Brucellosis presents with a wide range of symptoms, making it difficult to diagnose. Common symptoms include:
Fever (often fluctuating, with periods of remission)
Sweats (often profuse, especially at night)
Fatigue and malaise
Headache
Muscle and joint pain
Loss of appetite
Weight loss
Enlarged lymph nodes
Enlarged spleen and/or liver Less common symptoms can include:
Endocarditis (inflammation of the heart lining)
Meningitis (inflammation of the brain and spinal cord membranes)
Arthritis (inflammation of the joints)
Orchitis (inflammation of the testicles)
Depression
Causes
Undulant fever is caused by bacteria of the Brucella genus. The most common species affecting humans are *Brucella melitensis* (goats and sheep), *Brucella abortus* (cattle), *Brucella suis* (pigs), and *Brucella canis* (dogs). Transmission occurs through:
Direct contact with infected animals: Handling infected animals, their tissues, or body fluids (e.g., during slaughtering, butchering, or assisting with animal births).
Ingestion of unpasteurized dairy products: Consuming raw milk, cheese, or other dairy products from infected animals.
Inhalation of contaminated aerosols: Breathing in airborne bacteria in environments such as slaughterhouses or laboratories.
Rarely, through person-to-person transmission: This is extremely uncommon, but can occur through breastfeeding or sexual contact.
Medicine Used
Treatment for brucellosis typically involves a combination of antibiotics for several weeks to months. Common antibiotics used include:
Doxycycline
Rifampin
Streptomycin or Gentamicin (often used in combination, especially for severe cases) The specific antibiotic regimen and duration will depend on the severity of the infection, the specific Brucella species involved, and the patient's overall health. Relapses can occur, so follow-up monitoring is crucial.
Is Communicable
? Brucellosis is primarily a zoonotic disease, meaning it's transmitted from animals to humans. Person-to-person transmission is very rare. However, it can occur in some circumstances, such as through breastfeeding from an infected mother to her infant or rarely through sexual contact. Transmission through blood transfusions or organ transplants is also theoretically possible, but extremely uncommon.
Precautions
Preventing brucellosis involves several precautions:
Pasteurize dairy products: Always consume pasteurized milk, cheese, and other dairy products. Pasteurization kills Brucella bacteria.
Use protective gear when working with animals: Wear gloves, masks, and eye protection when handling animals, especially during slaughtering, butchering, or assisting with animal births.
Vaccinate animals: Vaccination of livestock is a crucial control measure in areas where brucellosis is endemic.
Cook meat thoroughly: Ensure meat is cooked to a safe internal temperature to kill any potential bacteria.
Avoid drinking untreated water: If in an area where water contamination is possible, boil or treat water before drinking.
Educate: Educate farmers, veterinarians, and the general public about the risks of brucellosis and preventive measures.
Laboratory safety: Implement strict biosafety protocols in laboratories working with Brucella to prevent accidental exposure through inhalation.
How long does an outbreak last?
The duration of an outbreak depends on several factors, including the source of the infection, the effectiveness of control measures, and the promptness of diagnosis and treatment.
Individual Infection: Without treatment, brucellosis can become chronic and persist for years. With appropriate antibiotic treatment, symptoms usually improve within a few weeks, but treatment duration can be several weeks to months to prevent relapse.
Community Outbreak: An outbreak in a community or livestock can last weeks to months if the source is not identified and controlled quickly. Effective control measures, such as identifying and culling infected animals, pasteurizing dairy products, and educating the public, are essential to shorten the duration of an outbreak.
How is it diagnosed?
Diagnosis of brucellosis typically involves a combination of:
Clinical evaluation: Assessing the patient's symptoms and medical history, including potential exposure to infected animals or unpasteurized dairy products.
Blood tests:
Serological tests: Detect antibodies to Brucella bacteria in the blood (e.g., Brucella agglutination test, ELISA). A rising antibody titer suggests active infection.
Blood culture: Attempts to grow Brucella bacteria from a blood sample. This is the gold standard for diagnosis, but can be time-consuming and may have low sensitivity.
Bone marrow aspiration: In some cases, bone marrow may be sampled for culture and analysis.
Other tests: Depending on the symptoms, other tests may be performed to rule out other conditions or assess the involvement of specific organs (e.g., spinal fluid analysis if meningitis is suspected, echocardiogram if endocarditis is suspected).
PCR (Polymerase Chain Reaction): PCR tests can detect Brucella DNA in blood or other tissues, providing a faster diagnosis than culture.
Timeline of Symptoms
The incubation period for brucellosis (the time between exposure and the onset of symptoms) is typically 5 days to several months, but is most commonly 2-4 weeks. The timeline of symptoms can vary greatly:
Acute phase: Symptoms develop gradually over several days or weeks. This phase is characterized by fever, chills, sweats, fatigue, muscle aches, and headache.
Subacute phase: If the acute phase is not treated, the symptoms may persist or fluctuate. Some symptoms may improve temporarily, only to return later.
Chronic phase: In some cases, brucellosis can become chronic, with symptoms lasting for months or even years. Chronic symptoms may include fatigue, joint pain, depression, and other nonspecific complaints. Complications such as endocarditis or neurological involvement can also occur.
Important Considerations
High Index of Suspicion: Due to the non-specific nature of brucellosis symptoms, a high index of suspicion is needed, especially in individuals with a history of exposure to animals or unpasteurized dairy products, or those living in or traveling to endemic areas.
Differential Diagnosis: Brucellosis symptoms can mimic those of other infectious diseases (e.g., influenza, malaria, typhoid fever) and non-infectious conditions. A thorough evaluation is necessary to rule out other possible diagnoses.
Treatment Adherence: Completing the full course of antibiotic therapy is crucial to prevent relapse and the development of chronic brucellosis.
Reporting: Brucellosis is a reportable disease in many countries, and healthcare providers are required to report confirmed cases to public health authorities.
Veterinary Public Health: Brucellosis is a classic example of a veterinary public health issue, emphasizing the importance of collaboration between human and animal health professionals to control and prevent the disease. Control of brucellosis in livestock is essential to reducing the risk of human infection.
Pregnancy: Brucellosis infection during pregnancy can lead to miscarriage, premature labor, or congenital infection of the newborn.