Brucellosis

Brucellosis (Malta fever, Gibraltar fever, Mediterranean fever, undulating fever, Bang's disease, Bruce's disease, melitococcosis, melitococcosis) is a zoonotic infectious disease with multiple mechanisms of pathogen transmission, characterized by fever, damage to the musculoskeletal system, nervous system, and genitals.

Brucellosis is caused by Brucella sp. Initial symptoms of brucellosis include an acute febrile illness with few or no local signs. The disease subsequently progresses to a chronic phase, which is characterized by recurrent fever, weakness, sweating, and vague pain. Diagnosis of brucellosis is based on culture (usually blood). Optimal treatment of brucellosis requires the administration of two antibiotics - doxycycline or trimethoprim-sulfamethoxazole in combination with streptomycin or rifampin.

ICD-10 codes

• A23. Brucellosis.
  • A23.0. Brucellosis caused by Brucella melitensi.
  • A23.1. Brucellosis caused by Brucella abortus.
  • A23.2. Brucellosis caused by Brucella suis.
  • A23.3. Brucellosis caused by Brucella canis.
  • A23.8. Other forms of brucellosis.
  • A23.9. Brucellosis, unspecified.

What causes brucellosis?

Human brucellosis is caused by Brucella species: Brucella abortus (from cattle), B. melitensis (from sheep and goats), and B. suis (from domestic pigs). B. canis (dogs) causes sporadic infections. The most common sources of infection are domestic animals and raw dairy products. Cases of brucellosis have also been reported in elk, bison, horses, moose, Canadian deer, hares, chickens, and desert rats.

Brucellosis is acquired through direct contact with the secretions or excrement of infected animals, or by consuming raw milk or dairy products containing viable organisms. The disease is rarely transmitted from person to person. Brucellosis is more common in rural areas, where it is an occupational disease of meatpacking workers, veterinarians, farmers, hunters, and livestock breeders. Brucellosis is rare in the United States, Europe, and Canada, but has been observed in the Middle East, Mediterranean regions, Mexico, and Central America.

What are the symptoms of brucellosis?

Brucellosis has an incubation period that varies from 5 days to months, averaging 2 weeks. The onset may be sudden. Symptoms of brucellosis include chills and fever, severe headache, joint and lower back pain, general weakness, and in some cases diarrhea.

Brucellosis may progress gradually, with mild prodromal weakness, muscle pain, headache, and back and neck pain. All of this is accompanied by an increase in evening temperature. As the disease progresses, body temperature rises to 40-41 C, after which it gradually decreases to normal or close to normal values, which is accompanied by profuse morning sweats. In typical cases, intermittent fever lasts for 1-5 weeks, followed by a 2-14-day remission, when the symptoms of brucellosis are weak or absent. In some patients, fever may be intermittent. In other patients, the febrile phase recurs one or more times in waves (undulations), with remissions lasting months to years between them.

After the primary febrile phase, anorexia, weight loss, abdominal and joint pain, headache, back pain, weakness, irritability, insomnia, depression, and emotional instability may occur. Constipation is common. Splenomegaly occurs, and lymph nodes may be slightly to moderately enlarged. Up to 50% of patients have hepatomegaly.

Patients with acute uncomplicated brucellosis usually recover within 2-3 weeks of illness even without treatment. Some patients develop subacute, intermittent, or chronic forms of the disease. Complications of brucellosis are rare but include serious illnesses such as subacute bacterial endocarditis, meningitis, encephalitis, neuritis, orchitis, cholecystitis, liver suppuration, and osteomyelitis.

How is brucellosis diagnosed?

Brucellosis is diagnosed by drawing blood for culture. Growth of the organism may take more than 7 days, so the laboratory should be alerted to the possibility of brucellosis. Acute and convalescent serum samples should be collected separately, 3 weeks apart. A 4-fold increase in IL and a titer of 1/160 or higher in acute serum are considered diagnostic, especially if there is a history of exposure and characteristic clinical findings. The white blood cell count remains normal or may be decreased in the acute phase. Relative or absolute lymphocytosis is observed.

How is brucellosis treated?

In acute cases of the disease, the patient is contraindicated to exertion and is recommended bed rest during attacks of fever. In cases where antibiotics are prescribed, combination therapy is preferable. Doxycycline 100 mg orally twice a day for 3-6 weeks in combination with streptomycin 1 g intramuscularly every 12-24 hours for 14 days reduces the frequency of relapses. Children under 8 years of age are prescribed trimethoprim-sulfamethoxazole in combination with either intramuscular streptomycin or oral rifampin for 4-6 weeks. Acute musculoskeletal pain, especially arising along the spine, may require the use of analgesics.

Brucellosis can be prevented by pasteurizing milk. A brucellosis vaccine is also available. Cheese made from unpasteurized milk that is stored for less than 3 months may be contaminated. People handling livestock or butchering animal carcasses should wear goggles and rubber gloves and protect broken skin from contact. In the United States and some other countries, programs are required to detect infection in animals, destroy infected animals, and vaccinate young seronegative cattle and swine. Immunity after human infection lasts an average of 2 years.

What is the prognosis for brucellosis?

Brucellosis has a favorable prognosis. Adequate treatment of brucellosis promotes complete recovery. In acute uncomplicated brucellosis, clinical symptoms of brucellosis disappear in 2-3 weeks, but treatment should be continued for 6 weeks or more. Relapses of the disease occur in 5% of cases. Fatal outcomes are rare. Disability is possible as a result of severe lesions of the musculoskeletal system and central nervous system.