What is Brucellosis?

Brucellosis is the main source of infection in China, with lambs receiving by herders or veterinarians. Fur, meat processing, milking, etc. can be infected through the skin and mucous membranes, eating sick animal meat, milk and dairy products can be transmitted through the digestive tract. Does not produce lasting immunity, and re-infection is not uncommon.

Brucellosis epidemiology

Source of infection

Sheep are the main source of infection in China, followed by cattle and pigs.

2. Ways of transmission

Herdsmen receive lambs as the main route of infection, and veterinary veterinarians are also susceptible to infection. In addition, peeling cattle and sheep skins, shearing wool, milking, cutting virus meat, slaughtering sick animals, children playing sheep, etc. can be infected, and the bacteria enter the human body from the damaged skin at the contact. Laboratory staff can often be infected by bacteria from the skin and mucous membranes. The bacteria can enter the body from the digestive tract when eating raw milk, dairy products and uncooked diseased animal meat. In addition, germs can also infect through the mucous membranes of the respiratory tract, the conjunctiva of the eye, and the mucous membranes of the sexual organs.

3. Susceptible people

The population is generally susceptible to brucella.

Clinical manifestations of brucellosis

The clinical manifestations of this disease are varied. As far as individual patients are concerned, their clinical manifestations can be very simple, showing only local abscesses, or being complicated and involving several organs and systems simultaneously. Sheep and swine brucellosis are mostly severe, and the symptoms of cattle are mild, and some cases may not have fever. Sheep's disease is most common in China. The natural course of untreated people is 3 to 6 months (average 4 months), but it can be as short as 1 month or as long as several years. The course of disease can generally be acute and chronic, and the acute phase of cattle is often not obvious. The incubation period is 7 to 60 days, usually 2 to 3 weeks. A few patients develop the disease months or more after infection. Most of the infected people in the laboratory became sick within 10-50 days. Human brucellosis can be divided into subclinical infections, acute and subacute, chronic infections, localized and recurrent infections.

1. Subacute and acute infections

Approximately 10% to 30% of patients have sudden onset. A few patients have prodromal symptoms for several days, such as weakness, insomnia, low fever, appetite, upper respiratory tract inflammation, and so on. The main clinical manifestations of the acute phase are fever, sweating, fatigue, arthritis, and orchitis.

(1) The thermal type is most common in the relaxation type. Although the wavy type only accounts for 5% to 20%, it is the most characteristic. Its fever is 2 to 3 weeks, followed by 3 to 5 days to 2 weeks. After the heat period, the heat rises again, so the cycle fluctuates and becomes a wave shape; most patients have only 2 to 3 waves, even as many as 10 or more. Other heat types include irregular types and persistent low fever.

(2) Hyperhidrosis is a prominent symptom of this disease, which is more common than other febrile diseases. Sweating often occurs late at night in the early morning when the heat drops suddenly, and most patients feel weak and weak.

(3) Joint pain often makes the patient to groan and pain, which can involve one or several joints, mainly large joints such as condyles, hips, knees, shoulders, wrists, elbows, etc., can be migratory in the acute phase. The pain is tapered, and analgesics are generally ineffective. Some patients have red and swollen joints and purulent sides. Local swellings such as bursitis, tenosynovitis, and periarthritis are also common. Muscle pain is more common in the thighs and buttocks on the sides, which can cause cramping pain.

(4) Orchitis is also one of the characteristic symptoms of brucellosis, which is caused by the involvement of testes and epididymis, most of which are unilateral and can be as large as goose eggs with obvious tenderness.

(5) Minor symptoms include headache, neuralgia, hepatosplenomegaly, and lymphadenopathy. Rash is rare.

2. Chronic infection

The characteristics are: There are many complaints, especially night sweats, headaches, myalgias and joint pains, and fatigue, chronic low fever, chills or chills, gastrointestinal symptoms, such as poor appetite, diarrhea, constipation, etc. May also have insomnia, depression, irritability, etc., easily diagnosed as neurosis. Remaining symptoms in the acute phase, such as back pain, arthralgia, sciatica, marked fatigue, night sweats, low levels of delay for many days, etc. Fixed and stubborn joint pain is more common in sheep, and suppurative complications are more common in pigs.

Brucellosis test

Surrounding blood

The white blood cell count is normal or slightly low, and the lymphocytes are relatively or absolute increased. The rate of erythrocyte sedimentation increased during the acute phase and was higher during the chronic phase. Anemia is unclear, only seen in severe patients or those with delayed lesions.

2. Bacterial culture

It takes a long time to give up after 4 weeks without growth. The positive rate of bone marrow culture is higher than that of blood, especially in the chronic phase. The positive rate of blood culture in acute stage sheep patients can reach 60% to 80%.

3. Immunological test

(1) The test method of serum agglutination test is to directly detect the antibody of lipopolysaccharide antigen, and the titer is 1: 160. It is positive, but it can also be positive after injection of vaccinated vaccine. A fold increase or more indicates a recent brucella infection.

(2) Enzyme-linked immunosorbent assay (ELISA) The positive rate of this method is higher than the agglutination test, and the sensitivity of detecting IgM and IgG is similar. Because the antibodies of chronic patients are of the IgG type, this method can be used for the diagnosis of both acute and chronic patients. Recently, avidin ELISA has been used, which is more sensitive than ELISA.

(3) 2-mercaptoethanol (2-ME) test This method can detect IgG and is used to identify natural infections and bacterial immunity. After 1 month of natural infection, the agglutination in the body is mainly IgG (originally IgM type), the IgG is resistant to 2-ME; and the lectin within 3 months after bacterial immunization is IgM Lord, can be destroyed by 2-ME.

(4) Supplementation test Supplementation antibody is also IgG, and the effect of the third week of the disease can exceed 1:16. The positive rate of this test is higher than the agglutination test, and the specificity is also high, but it appears later than the agglutination test.

(5) Human globulin test Patients can still produce an incomplete antibody. Although the latter can bind to the antigen, it is not visible to the naked eye. When anti-human globulin immune serum is added to the antigen-incomplete antibody complex, a directly visible response occurs. Incomplete antibodies appear early and disappear later, so they can be used for the diagnosis of patients with acute and chronic phases. In view of the complicated operation of this method, it is only applicable to suspicious patients with negative agglutination test, and the titer> 1:80 is positive.

(6) Intradermal test The brucetin skin test is a delayed hypersensitivity reaction, and the results are observed for 24 to 48 hours. Those with only local redness and no lumps were negative, and those with local redness and hardness of 2-6 cm in diameter were positive. The positive rate of skin test within 6 months is very low, and almost 100% of patients in chronic stage are positive or strongly positive.

(7) Other immune tests There are reverse passive hemagglutination tests, radioimmunity tests, indirect immunofluorescence tests, etc., which are not suitable for general use due to the complicated operation.

4. Other inspections

Cerebrospinal fluid examination is suitable for patients with meningitis, cerebrospinal fluid cells (lymphocytes) increased, protein increased, the rest are normal. Cardiac power production can show the director of the new period of PR, myocardial damage, low voltage and so on. X-ray examination of bones and joints showed soft tissue calcification, strong bone repair response with little damage, and narrowing of intervertebral discs and intervertebral spaces. Changes in liver function and EEG are non-different.

Brucellosis diagnosis

Diagnosis can be confirmed based on epidemiological clinical characteristics and related examinations.

Brucellosis treatment

Acute infection

(1) General therapy and symptomatic therapy Patients should rest in bed, pay attention to water, electrolytes and nutritional supplements, and give adequate amounts of vitamins B and C, as well as a digestible diet. People with high fever can apply antipyretic analgesics at the same time. Adrenal cortex hormones (hormones) can help improve the symptoms of blood disorders, but must be combined with antibiotics, the course of treatment is 3 to 4 days. Some people think that infection affects the central nervous system and long-term testicular swelling and pain, there are indications for the use of hormones.

(2) Antibacterial treatment Rifampicin is effective for this disease. It is advisable to combine tetracycline with streptomycin in sheep and pig infections.

2. chronic infection

It is generally believed that the combination of tetracycline and streptomycin has a certain course of treatment, but the course of tetracycline should be extended to more than 6 weeks, and streptomycin is preferably 4 weeks. Surgical drainage can be performed for purulent lesions.