Brucellosis (Undulant fever) is known for relapsing fever in the chronic stage. It is an occupational disease of workers handling infected animals and their tissues, especially in Mediterranean countries, the Middle East, Africa, central Asia, Central & South America, India, and Mexico.

1,554 (US); 500,000 (Global)
Undulant fever; Malta fever; Mediterranean fever; Brucella abortus infection; B. mellitensis infection; B. suis infection; B. canis infection;
2-4 weeks (range of 5 days to 6 months); [CDC Travel]
Irregular fever with sweating, headache, arthralgias, myalgias, weakness, fatigue, and weight loss; [CCDM, p. 78]
Standard; "Not transmitted from person to person except rarely via banked spermatozoa and sexual contact. Provide antimicrobial prophylaxis following laboratory exposure." [CDC 2007 Guideline for Isolation Precautions]
Patients recover in 2-3 weeks in uncomplicated cases. The three forms are acute (<8 weeks), undulant (<1 year), and chronic (>1 year). Arthralgias are common in all forms. Both infectious and reactive arthritides occur. Bone involvement is also common. About 3% to 15% of patients have spondylitis, usually of the lumbar spine. Less than 1/3 of patients have lymphadenopathy and hepatosplenomegaly. Abnormal liver function tests are common in acute and undulant brucellosis. Gastrointestinal symptoms occur in up to 70% of patients. Anemia, leukopenia, and thrombocytopenia are common in the undulant form. Patients in endemic areas may have constipation. Travelers are more likely to present with diarrhea. Respiratory findings are rare. [ID, p. 164, 1362, 1717-20; PPID, p. 2753-7; Guerrant, p. 271-5; Merck Manual, p. 1580-1; Cohen, p. 1099] Two stockbreeders presented with high fever and severe exudative pharyngitis. [PMID 18397911] About 1/2 of patients have myalgia and difficulty walking. A maculopapular rash is an uncommon finding. [Harrison ID, p. 561-2] See "Arthritis, reactive."

The chronic form affects mainly older individuals and includes depression, eye disease, and CNS infections. About 10% of infected men develop epididymitis and/or orchitis. Endocarditis, usually involving the aortic valve, has been reported as one of the common causes of death in patients with brucellosis. Myocarditis and pericarditis are complications. Brucella is a common cause of uveitis in endemic areas. Neurobrucellosis (meningitis, encephalitis, brain abscess, myelitis, radiculitis, and neuritis) affects approximately 2% to 5% of patients. Guillain-Barre syndrome has been reported. Pancreatitis is rare. About 5% of patients have skin lesions including papules, ulcers, petechiae, and erythema nodosum. Chronic brucellosis is associated with hypergammaglobulinemia. [ID, p. 164, 1362, 1717-20; PPID, p. 2753-7; Guerrant, p. 271-5; Merck Manual, p. 1580-1, Cohen, p. 1099]

Brucellosis is a generalized bacterial infection characterized by irregular fever (undulant fever). It is an occupational disease for workers who handle infected animals and their tissues. Affected workers include farmers, hunters, veterinarians, butchers, and slaughterers. Airborne transmission occurs in animal stables and pens, slaughterhouses, and medical laboratories. A vaccine to prevent the disease in animals is available. Infections have been reported in cattle, swine, goats, sheep, dogs, coyotes, bison, elk, caribou, and deer. Transmission by raw milk and cheese and by contaminated meat has been reported. [CCDM, p. 78-80; Foodborne Illnesses. CDC. 4/16/04; ID, p. 1717] Humans may acquire infections from infected chickens or desert rats. [Merck Manual, p. 1580] Human-to-human transmission has been documented in 45 cases, including sexually transmision and by transfusion. [Cecil, p. 1949]
Culture; PCR; Paired sera--use agglutination assay for uncomplicated cases; [CCDM] Diagnostic: agglutination titer >1:160; Best to combine 2 tests (SAT & indirect Coombs; Brucellacapt & SAT; ELISA & Brucellacapt); [ABX Guide]
Global; Primarily an occupational disease, especially in Mediterranean countries, Middle East, Africa, central Asia, central and S. America, India, and Mexico; [CCDM]
  • >arthralgia
  • >fatigue, weakness
  • >fever
  • >fever, biphasic or relapsing
  • >myalgia
  • >relative bradycardia
  • E pharyngitis
  • G abdominal pain
  • G constipation
  • G diarrhea
  • G hepatomegaly
  • G liver function test, abnormal
  • G nausea, vomiting
  • H anemia
  • H hypergammaglobulinemia
  • H leukopenia
  • H lymphadenopathy
  • H splenomegaly
  • H thrombocytopenia
  • N confusion, delirium
  • N headache
  • N lethargy
  • N stiff neck
  • R cough
  • S lymphadenitis, acute
  • S papules or plaques
  • S rash (exanthem)
  • S ulcer of skin
  • X cystic or cavitary lesions
  • X hilar lymphadenopathy
  • X pleural effusions
  • *arthritis
  • *blindness
  • *bowel obstruction
  • *brain abscess or lesion
  • *cirrhosis
  • *cranial neuropathy
  • *encephalitis
  • *endocarditis
  • *epididymo-orchitis
  • *erythema nodosum
  • *glomerulonephritis
  • *hepatitis
  • *mediastinitis
  • *meningitis
  • *myelitis
  • *myocarditis
  • *osteomyelitis
  • *pancreatitis
  • *paralysis
  • *pericarditis
  • *peripheral neuropathy
  • *pneumonia
  • *pneumonitis
  • *rhabdomyolysis
  • *uveitis
  • *weight loss




Inhalation, Ingestion, Needle (Includes Drug Abuse), Scalpel or Transfusion, Skin or Mucous Membranes (Includes Conjunctiva), Animal Bite, Sexual Contact
Person-to-Person, Animal Tissue, Eating Contaminated Food, Eating Contaminated or Infected Meat, Eating Unpasteurized Milk or Cheese
Birds and Poultry, Cattle, Goats and Sheep, Cats, Deer, Elk and Antelope, Dogs, Horses, Rabbits, Rodents, Swine, Wild Animals
  • Consume unpasteurized milk/cheese
  • Eat undercooked meat or fish
  • Handle animal carcasses or placentas
  • Handle dog or cat (bite or scratch)
  • Handle domestic animals
  • Travel to endemic area
  • Victim--air release of infectious agents
  • Work in a medical or research lab
1. (US) Published in MMWR 2011: 79 cases; Estimated 1,554 cases in 1997; [Mead1999: PMID 10511517]
2. (Global) Estimated 500,000 new cases every year; [Gorbach, p. 106]