Brucellosis is a human-animal infectious disease caused by the bacterium Brucella abortus. In humans, it is characterized by prolonged fever, excessive sweating, arthralgia, orchitis, and ovarian inflammation. The disease is widespread, almost all over the world. The disease was once prevalent in the pastoral areas of Inner Mongolia, northeast and northwest China, and has been disseminated in other northern regions. After a person is infected with brucellosis, the incubation period is generally 7 to 60 days, with an average of 2 weeks. Few patients can be up to several months or more than 1 year. The clinical manifestations of the disease are complex and varied, with symptoms varying in severity and severity, showing multi-organ lesions or limited to a particular local area. Clinically, the disease is generally divided into two types: acute and chronic.
1. Etiology
B. burgdorferi infects domestic animals first, the clinical manifestations of domestic animals are not obvious, but pregnant females are very likely to cause abortion or stillbirth, the amniotic fluid, placenta, secretions containing B. burgdorferi, especially infectious. The bacterium is found in the skin, urine and feces, and milk. The bacteria can be excreted for more than 3 months. People can be infected by contact with livestock, by taking contaminated milk and meat, by inhaling dust containing bacteria or by entering the conjunctiva of the eyes. The age of onset is mostly above 30 years old.
After the bacterium enters the body from the damaged skin and mucous membrane or digestive tract or respiratory tract, it is firstly engulfed by phagocytes and enters the lymph nodes, where it can sometimes survive and grow and multiply to form foci of infection, and after about 2 to 3 weeks it can enter the blood circulation and produce bacteraemia. After that, it grows in the reticuloendothelial system such as liver, spleen and bone marrow to form new foci of infection, and can repeatedly break through the cells into the blood circulation many times, then again cause bacteraemia and clinical acute symptoms, manifested as an average of 2 to 3 weeks of fever, every interval of about 3 days to 2 weeks, fever and repeatedly, producing waves of fever, so called wave fever.
At the same time, B. burgdorferi contains endotoxin and the bacterium itself can cause allergy and various allergic lesions in human body. Bone and joint lesions occur more often in about six months, and less often earlier. B. burgdorferi osteomyelitis is a local manifestation of hematogenous B. burgdorferi infection in the bone and joint. Any bone can be involved, but spondylitis is the most common. Joint lesions often invade large joints, hip arthritis is most common.
2, the transmission route
Cattle, sheep and pigs are the main natural hosts of the bacterium, and the bacteria can be transmitted to humans through the skin, gastrointestinal tract, respiratory tract and conjunctiva.
3.Pathological changes
The damaged tissues are not only liver, spleen, bone marrow and lymph nodes, but also bone, joints, blood vessels, nerves, endocrine and reproductive system; not only interstitial cells but also parenchymal cells of organs are damaged. The most significant lesions are those of the monocyte-phagocyte system. The main pathological changes of the lesions are: (1) exudative degenerative necrotic changes, mainly in the liver, spleen, lymph nodes, heart, kidney, etc., with plasmacytic inflammatory exudation, interspersed with a little cellular necrosis; (2) proliferative changes, lymphatic and monocyte-phagocytic proliferation, especially significant in the early stage of the disease. It is often diffuse and later often accompanied by fibroblast proliferation; (3) granuloma formation is seen in the foci of granulomas composed of epithelioid cells, macrophages and lymphocytes, and plasma cells. Granulomas further undergo fibrosis and eventually cause sclerosis of tissues and organs. The three pathological changes can alternate and develop sequentially from the acute phase to the chronic phase. For example, in the liver, plasma inflammation with parenchymal cell degeneration and necrosis can be seen in the acute phase; subsequently, it turns into proliferative inflammation, forming epithelioid granulomas in the liver lobules, and then fibrous tissue proliferation, resulting in mixed or atrophic cirrhosis.
4 .Clinical manifestations
1) Acute phase
The onset of the disease is slow in 80% of the cases, and the symptoms are often repulsive, and its performance is similar to that of a heavy cold. General malaise, fatigue, reduced food intake, headache, myalgia, irritability or depression, etc. It lasts for 3 to 5 days.
In 10% to 27% of patients, the onset of the disease is acute, with chills and high fever, excessive sweating, and wandering arthralgia as the main manifestations.
Typical cases have a wave-like fever, in which the body temperature increases day by day at the beginning, reaches a peak and then slowly decreases, with a fever duration of about 2 to 3 weeks, with an interval of several days to 2 weeks, and then the fever starts again, repeatedly several times. In addition to this fever type, other types of fever include flaccid fever and retention fever.
Excessive sweating is one of the prominent symptoms of the disease, with sweating dripping at night or in the early morning when the fever subsides. There are also patients who do not have a high fever or are in the interval of fever but still sweat a lot, and the sweat smells sour. Most of them feel weak after sweating, and may even be deficient due to heavy sweating.
More than 76% of patients have arthralgia, which goes hand in hand with fever. The pain is cone-like or dull, and those with severe pain resemble rheumatism, and they toss and moan, but the degree of joint pain does not parallel the pathological changes. The lesions mainly involve large joints, such as hip, shoulder and knee, single or multiple, asymmetric, with localized redness and swelling. It may also present as synovitis, tenosynovitis, and periarthritis. Rarely, it is manifested as septic arthritis. In the acute phase, the pain is mostly wandering, while in the chronic phase, the lesion is fixed and the pain is fixed in certain joints. Muscle pain is also present, especially in the lower limb muscles and gluteal muscles, and in severe cases it is spasmodic.
In addition, there is also orchitis and epididymitis is one of the common symptoms in male patients, mostly unilateral. Individual cases may have syringomyelia and pyelonephritis. Female patients may have ovarian inflammation, endometritis and painful breast swelling. However, it is less common in humans to cause miscarriage.
2 ) Chronic phase
The chronic phase usually develops from the acute phase, or it can gradually become chronic from asymptomatic infections or mild cases without a history of acute disease. The symptoms of the chronic phase are not obvious, but there are also typical and diverse manifestations. The active chronic phase has the manifestations of the acute phase, but may also have prolonged low-grade fever or no fever, fatigue, headache, unresponsiveness, depression, neuralgia, and arthralgia, usually limited to a particular part, but in severe cases the joints are tonic and deformed.
Some patients report a lot of symptoms and lack of signs, similar to neurosis; others show multi-organ and systemic damage, such as constant and indefinite dull pain in skeletal muscles, repeatedly and persistently, and some develop into joint ankylosis, muscle contracture, deformity, and paralysis in late stages. The nervous system manifests as neuritis, radiculitis, and cerebrospinal meningitis. In the genitourinary system, there may be orchitis, epididymitis, ovarian inflammation, endometritis, etc.
In the chronic phase, the symptoms and signs are relatively stable, and the dysfunction is only aggravated by climate change and overexertion. However, physical exhaustion, malnutrition and anemia after prolonged illness.
5.Auxiliary examination
The X-ray findings are similar to those of septic infection. Bone changes on X-rays gradually appear only after 1 to 2 months of disease onset and are characterized by bone repair with little destruction. In the spine, two to three vertebrae are often involved, with narrowing of the vertebral space and bone destruction at the vertebral margins, but significant bone growth. Gradually, the bone destruction is replaced by irregular dense new bone, the vertebral body edges form significant bony redundancies, the anterior longitudinal ligament calcifies, the vertebral body may fuse, and there are inflammatory changes in the small joints, from widening to narrowing and fusion of the gap. Paravertebral abscesses are often seen, and in the sacroiliac joint there is often bilateral osteoporosis, widening of the gap and irregular destruction, surrounding sclerosis, and rare dead bone, which can eventually fuse.
The serum agglutination test and complement binding test are highly specific, and patients are mostly positive. In epidemiological screening, intradermal test is mostly used, but the positive rate is very low within 6 months of onset, while 100% of chronic patients are positive.
6.Differential diagnosis: clinically, it should be differentially diagnosed with heavy cold, rheumatism, neurosis and other diseases.
7.Therapeutic measures
Brucella burgdorferi is mostly used in combination with tetracycline and streptomycin, also available with compound sulfonamide plus streptomycin. Recently, it is believed that rifampicin and doxycycline combined treatment, treated well rarely relapse. Because the bacillus brevis is multiplying in the reticuloendothelial cells, the drug is difficult to reach, so the effect is slow after the drug, but it is appropriate to relapse, to long time, multi-course combination of drugs. In some cases, due to late detection or misdiagnosis, there are sequelae such as joint deformation, tendon atrophy, liver cirrhosis, disability or sterility.
The most effective drug in the acute stage is tetracycline, 0.25~0.5g/time, 4 times a day. Take 4 weeks for a course of treatment. After stopping for 1 week, the drug can be used again for 1 to 2 courses according to the condition. Streptomycin can be added if necessary.
8.Disinfection measures
Bacteria can survive for several months in dry soil and weeks to months in dairy products, fur or water. Bacteria are sensitive to light, heat and chemicals such as 3% bleach and lysol, and can be killed in a few minutes to 20 min. Physical disinfection method can be used or the use of common disinfectants can be sterilized, such as 3% bleach solution.
9.Preventive measures
The fundamental measures are to control and eliminate the epidemic of brucellosis among animals, to cut off the transmission route and to vaccinate the population. 9.1 Management of infectious sources
Strengthen the management of sick animals and find that the affected animals should be isolated in special pastures. Sick people should be isolated in time until the symptoms disappear, and the excrement and pollutants of patients with positive blood and urine cultures should be disinfected.