Brucellosis is a zoonotic pestilence caused by Brucella. The source of pestilence is infected livestock, primarily sheep, followed by cattle and pigs. Infection occurs through consuming milk or meat from infected animals, contact with sick animals, or via the respiratory tract and conjunctival membrane. The most commonly affected tissues are the liver, spleen, lymph nodes, lungs, and intestines.

bubble_chart Epidemiology

Resided in pastoral areas with a history of contact with diseased livestock (sheep, cattle, pigs) or consuming their milk or meat.

bubble_chart Clinical Manifestations

The severity of the illness and the duration of the course vary greatly. Generally, the onset is slow. Fever may persist for several weeks to months, with varying patterns, including undulant, remittent, continuous, or septic. The fever gradually rises and persists for 1 to several months, then gradually subsides, only to rise again after several days to 2 weeks, recurring cyclically. Without treatment, the fever can last for months. Along with fever, symptoms may include chills, weakness, profuse sweating, loss of appetite, weight loss, cough, arthralgia, neuralgia, diarrhea, or constipation. Enlargement of the liver and spleen, lymphadenopathy, joint swelling and redness, and rashes (light red maculopapular eruptions or petechiae) may also occur. Children often exhibit restlessness, headaches, and lethargy. Older children may develop orchitis. Central nervous system damage is possible but rare.

bubble_chart Auxiliary Examination

1. Etiological examinations should include blood or bone marrow cultures conducted before antibiotic treatment, which yield higher positive rates (approximately 80%). Other specimens such as cerebrospinal fluid, liver or lymph node puncture fluid, and urine can also be cultured for bacteria.
2. Serological tests
   1. Brucella agglutination test: A titer of 1:160 or higher is considered positive, and a rising titer during the course of the disease is more significant.
   2. Complement fixation test: This test becomes positive later in the disease course (a titer >1:8 is considered positive), typically after 3 cycles of day and night, but it has high specificity.
   3. Anti-human globulin test: A titer >1:80 is considered positive.
   4. Heat agglutination reaction: After heating the patient's serum and treating it with dimercaptoethanol or cysteine, a reduction in agglutination titer by 20–30% or more indicates natural infection. This test can differentiate between post-vaccination and natural infection serum agglutination reactions.
   5. Intradermal test: Used for epidemiological surveys. A positive result is indicated by local redness and induration with a diameter >2 cm 48 hours after intradermal injection, suggesting prior infection.

bubble_chart Treatment Measures

1. General treatment includes bed rest and a nutritious, easily digestible diet. Drink plenty of water and pay attention to fluid and electrolyte balance. Symptomatic treatment may be given for those with high fever, arthralgia, or neuralgia.
2. Pathogenic treatment
   1. Tetracycline or oxytetracycline (contraindicated in children under 8 years old) 30–40 mg/(kg·d), divided into 4 oral doses. The course of treatment is 3–4 weeks.
   2. Compound formula sulfamethoxazole (SMZ) at 50 mg/(kg·d), divided into 2 doses daily, for a course of 3–4 weeks.
   3. Streptomycin 25 mg/(kg·d), intramuscular injection, administered continuously for 3 weeks, followed by a 1-week break, then another 3-week course.
   4. Ampicillin 100 mg/(kg·d), intramuscular injection, administered continuously for 3 weeks, followed by a 1-week break, then another 3-week course.

bubble_chart Prevention

1. Do not drink raw milk or goat milk.
2. If sick animals are found, isolate them promptly and treat them thoroughly.
3. Those who have frequent contact with livestock should undergo preventive vaccination.