Brucella (infectious disease)



Overview

Definition

Brucellosis is a systemic infectious disease of veterinary and human origin caused by Brucella infection, which is a legal Class B infectious disease and a legal occupational disease in China.

Brucella is the causative agent of the disease, using animals as the source of infection, and can cause disease in animals and humans, divided into 6 biological species and 19 biotypes, of which 4 species can cause disease in human beings, including Brucella in sheep species, Brucella in cattle species, Brucella in pig species and Brucella in canine species.

Brucella can survive for a long time in the natural environment and is sensitive to physical disinfection methods and commonly used chemical disinfectants. Heating to 60 ℃ or exposure to sunlight for 10 to 20 minutes, or 3% bleach clarifying solution for a few minutes, can kill the bacteria.

Classification

According to the type of pathogenic bacteria, it can be divided into sheep species brucellosis, bovine species brucellosis, porcine species brucellosis, canine species brucellosis, etc. The prevalent in China is mainly sheep species brucellosis, followed by bovine species brucellosis.

Incidence

Epidemic situation

It has been reported in the literature that the number of new cases of brucellosis worldwide exceeds 500,000 per year.

From 2004 to 2010, 164,752 new cases were reported in mainland China. 59,056 cases were reported in 2015, with an incidence rate of 4.34/100,000 cases.

Regional distribution

The disease can occur all over the world, mainly in the Mediterranean coastal countries, the Middle East, India, Central Asia and Central and South America.

In China, it occurs mostly in pastoral areas such as Inner Mongolia, Northeast and Northwest, and there are also disseminated cases in northern agricultural areas.

More cases occur in pastoral areas than in agricultural areas, and more cases occur in agricultural areas than in cities.

Time distribution

The disease can occur throughout the year, mostly in the breeding season of domestic animals (late spring, early summer).

Population distribution

Commonly found in veterinarians, herders, slaughter workers, meat and fur processing plant workers and other occupational groups.

It is more common in young adults, and is more common in males than females.

Causes

Causes

Brucellosis is caused by Brucella infections, and there are three basic conditions that lead to epidemics.

Infectious agents

The main source of infection is animals suffering from brucellosis, including sheep, cattle, pigs and dogs. The secretions, excretions, runoff products and milk of diseased animals contain a large number of brucellae, which is the most dangerous infectious source for human beings.

The feces, urine and milk of brucellosis patients also contain Brucella, which is also infectious, but is less likely to be transmitted from person to person.

Routes of transmission

Direct or indirect contact: direct contact of broken skin or conjunctiva with brucellosis-affected animals or their secretions, excretions, runoff, fur, carcasses, etc.; indirect contact with the environment and objects contaminated by brucellosis.

Gastrointestinal transmission: consumption of raw milk and dairy products, undercooked meat, etc. contaminated with Brucella.

Respiratory transmission: inhalation of aerosols with Brucella.

Other ways: The disease can also be transmitted by flies, ticks and other vectors, but it is rare.

Susceptible population

The population is generally susceptible, mostly veterinarians, herders, slaughter workers, meat and fur processing plant workers.

Susceptibility factors

Work in close contact with livestock and related products.

Engaging in activities such as farming and herding in areas where brucellosis is endemic.

Symptoms

The incubation period is usually l to 3 weeks, with an average of 2 weeks, and in some patients the incubation period can be as long as several months.

Acute phase

Acute phase refers to the course of the disease within 6 months.

Fever

The main manifestation is wave-like fever (typical characteristics), that is, the patient’s body temperature gradually rises, after 2 to 3 days the temperature rises to 39 ℃ or more, and then gradually drops to normal after 2 to 3 weeks, and then gradually rises again after 3 to 5 days of normal temperature, and so on and so forth.

Some patients may show low fever (mostly occurring in the afternoon and evening) and irregular fever (body temperature is variable in height and duration).

It is often accompanied by chills, headache and other symptoms.

Weakness

Weakness, easy fatigue, depression, even bedridden.

Almost all patients have this symptom, so this disease is commonly called “lazy man’s disease”.

Excessive sweating

Severe sweating, which can soak through clothing and bedding.

Muscle and joint pain

Generalized muscle pain and pain in the affected joints, usually in the lumbar spine, hip joints, knee joints and other large joints.

Enlargement of liver, spleen and lymph nodes

Enlarged liver may be palpable under the ribs on the right side.

When lying on the right side and flexing the left lower limb, the enlarged spleen can be touched under the rib cage on the left side, and there may be pain and induration when pressed.

There may be enlarged lymph nodes in the neck, armpit, groin (thigh root), which may appear as hard, painless, pushable, non-combined lumps.

Other symptoms

A variety of forms of rash may appear, such as red blotchy rash, maculopapular rash, and hives.

It may be accompanied by symptoms such as bloating and loss of appetite.

Chronic phase

The chronic phase refers to a disease that has not resolved for more than 6 months and may develop from the acute phase or may present directly as a chronic episode.

Fever, excessive sweating, fatigue, muscle and joint pains, etc., similar to those in the acute phase, may occur in the chronic phase, but they are atypical.

Complications

Diseases of the genitourinary system

In men, orchitis and epididymitis may occur, and there may be testicular pain and swelling.

In women, ovaritis and endometritis may occur, with symptoms such as lower abdominal pain and increased leukorrhea. In severe cases, it may cause infertility, and in pregnant women, miscarriage, preterm labor and stillbirth may occur.

Blood system diseases

Such as anemia, thrombocytopenic purpura, etc., there may be pale, fatigue, fatigue, dark purple patches of varying sizes on the skin and mucous membranes and other symptoms.

Eye lesions

Such as uveitis, optic neuritis, optic disc edema and corneal damage, etc., most commonly seen in chronic brucellosis, may have symptoms such as redness of the eyes, eye pain, photophobia, tearing, decreased visual acuity, and dark spots in the visual field.

Neurological diseases

Such as meningitis, meningoencephalitis, myelitis, polyneurogenic neuropathy, etc. There may be symptoms such as severe headache, vomiting, neck stiffness, numbness and weakness of limbs, and paralysis.

Cardiovascular system diseases

Such as endocarditis, myocarditis, pericarditis, aortitis, etc., there may be symptoms such as palpitation, chest tightness, chest pain, irritability, dyspnea, cyanosis (blue lips and fingernails).

Respiratory system diseases

Such as bronchitis, bronchopneumonia, etc., there can be fever, cough, sputum, shortness of breath and other symptoms.

Psychological

Mostly seen in patients with chronic brucellosis, such as anxiety, depression and other psychological disorders.

Consultation

Department of Medicine

Orthopedics

Active medical consultation is recommended in the presence of pain in large joints such as lumbar spine, hip and knee. After diagnosis, the patient should be referred to the Department of Infectious Diseases for further treatment.

Department of Infectious Diseases

If you have a high fever, especially the typical fluctuating fever, accompanied by joint pain and profuse sweating, and you are in a pastoral area or engaged in animal husbandry related work, it is recommended that you consult a doctor promptly.

Preparation for medical treatment

Consultation: registration, preparation of information, common problems

Tips for seeking medical treatment

Avoid taking fever-reducing drugs or antibiotics by yourself before seeking medical treatment, so as not to affect the doctor’s judgment of the condition.

For patients with fever, physical cooling can be prioritized, such as applying cold compresses to the forehead and wiping hands, feet and armpits with warm water.

Preparation Checklist for Doctor’s Visit

Symptom Checklist

Particular attention should be paid to the time of onset of symptoms, special manifestations, etc.

Is there high fever? What is the highest degree? Is the fever persistent?

Is there profuse sweating? How long has it lasted?

Are there any joint pains? Which joints?

Are there any large lumps anywhere?

When did the symptoms appear?

List of medical history

Has there been any visit to a pastoral area?

Has there been any contact with secretions, feces, runoffs, etc. of animals with brucellosis?

Has there been any long-term use of medications such as glucocorticoids, immunosuppressants, etc.?

Checklist

Examination results in the past six months, which can be brought to the doctor’s office

Laboratory tests: blood test, C-reactive protein, erythrocyte sedimentation rate (ESR), etc.

Imaging tests: bone and joint X-ray, magnetic resonance imaging (MRI), etc.

Medication List

Medications used in the last 3 months, if there is a box or package, you can bring it with you to the doctor’s office

Antipyretic and analgesic: ibuprofen, acetaminophen

Antibiotics: levofloxacin, doxycycline, cefotaxime, rifampin, streptomycin

Diagnosis

Diagnosis is based on

Medical history

Close contact with brucellosis-affected animals, their secretions, feces, runoff, and milk prior to onset of illness.

Residence or travel in areas where brucellosis is endemic.

Clinical manifestations

There is fever (mostly typical wave fever), malaise, excessive sweating, muscle and joint pains, enlarged liver, spleen and lymph nodes.

Laboratory Tests

Blood count and erythrocyte sedimentation rate

It can find out whether there is anemia, acute infection, etc.

Decreased hemoglobin (Hb) suggests the presence of anemia.

Erythrocyte sedimentation rate (ESR) is accelerated, suggesting possible acute infection.

Immunologic Tests

Serum agglutination test

Plate agglutination test: mainly used for initial screening. Positive results of Tiger Red Plate (RBPT) or Plate Agglutination Test (PAT) suggest possible infection.

Test tube agglutination test (SAT): a titer of 1:100 (++) and above or a disease duration of more than 1 year with a titer of 1:50 (++) and above; or a history of Brucella vaccination within six months with a titer of 1:100 (++) and above is positive, suggesting recent infection. False positives may occur.

Complement binding test (CFT)

A widely used diagnostic tool, but not suitable for mass screening.

A titer of 1:10 (++) and above is considered positive.

Antiglobulin test (Coomb’s test)

Complicated to perform and only suitable for suspected patients with negative coagulation test.

A titer of 1:400 (++) and above is considered positive.

Pathogenetic examination

Blood, bone marrow, joint fluid, cerebrospinal fluid, urine, lymphatic tissue, etc. are taken as specimens for bacterial isolation and culture, and bacterial growth and colony characteristics are observed and identified.

Bacterial isolation culture is positive for Brucella, which has diagnostic value.

The positive rate of blood, bone marrow and joint fluid is higher in acute stage and lower in chronic stage.

Diagnostic criteria

Brucellosis can be diagnosed if there is a history of epidemiologic exposure, clinical signs and symptoms of brucellosis, and positive serum agglutination test, complement binding test and antiglobulin test, or positive blood culture for Brucella.

Suspected diagnosis

The diagnosis is suspected if two of the following criteria are met.

Medical history: close contact with brucellosis-affected animals, their secretions, excretions, runoffs and milk before the onset of the disease, or living or traveling in a brucellosis-endemic area.

Clinical manifestations: fever (mostly typical wave fever), malaise, excessive sweating, muscle and joint pains, enlarged liver, spleen and lymph nodes.

Clinical diagnosis

Suspected diagnosis and positive plate agglutination test.

Confirmed Diagnosis

The diagnosis is confirmed by any one of the following conditions.

Suspected diagnosis or clinical diagnosis, and any one or more of the test tube agglutination test (SAT), complement binding test (CFT), or antiglobulin test is positive (Note: the results of the above tests need to be interpreted by a professional).

Suspected diagnosis or clinical diagnosis, and Brucella abortus is obtained by pathogenetic examination.

Hidden infection

History of the above, meeting the criteria of immunologic and pathogenetic tests for confirmation of the diagnosis, but without clinical manifestations.

Differential diagnosis

Typhoid fever and paratyphoid fever

Similarities: both may present with fever and hepatosplenomegaly.

Differences: Typhoid fever and paratyphoid fever are mainly characterized by persistent high fever, indifference, and rose rash on the skin, which do not conform to the typical undulant fever of brucellosis, and there are no manifestations of muscle and joint pains, excessive sweating, and so on. They can be differentiated on the basis of history and laboratory tests.

Rheumatic fever

Similarities: Both may present with fever and wandering joint pain.

Differences: Rheumatic fever may also present with rheumatic nodules and erythema, and rarely with hepatosplenomegaly. It can be differentiated on the basis of history and laboratory tests.

Rheumatoid arthritis

Similarities: Both may present with joint pain.

Differences: Rheumatoid arthritis has a history of rheumatic fever and is often associated with cardiac damage. It can be differentiated on the basis of laboratory tests.

Other

Brucellosis should be distinguished from tuberculosis and sepsis in the acute phase, and from other joint damaging diseases and neurological disorders in the chronic phase, based on history and laboratory tests.

Treatment

General treatment

Rest: patients should rest in bed to reduce physical exertion and promote recovery. Those with splenomegaly should reduce their activities to prevent splenic rupture.

Reasonable diet: Drink plenty of water, high-calorie, multi-vitamin, easy-to-digest diet.

Antipyretic: Physical methods can be used to lower the temperature for those with high fever, and antipyretic drugs can be applied for those with persistent high fever.

Analgesia: If there is severe pain in joints, analgesics can be applied.

Application of glucocorticosteroids: If there is testicular inflammation, glucocorticosteroids such as prednisolone can be applied for a short period of time.

Antibacterial treatment

The principle of treatment is early, combined, adequate amount and full course of medication, and prolong the course of treatment if necessary, in order to prevent recurrence and change from acute to chronic stage.

The medication regimen varies from person to person and will be formulated by the doctor according to the patient’s age, clinical stage, pregnancy or not, and the presence of complications.

Commonly used drugs are tetracyclines (e.g. doxycycline), rifamycins (e.g. rifampicin), but also quinolones (e.g. ciprofloxacin, levofloxacin), sulphonamides (e.g. sulphamethoxazole and metronidazole combination), aminoglycosides (e.g. streptomycin, tobramycin), and third generation cephalosporins (e.g. cefotaxime).

Chinese medicine treatment

Brucellosis belongs to damp-heat paralysis of Chinese medicine, which can be treated internally and externally, or both internally and externally.

Internal treatment: first identify the symptoms, and then apply the Chinese herbal formula with additions and subtractions.

External treatment: including acupuncture, fumigation, hot omelet and tattoos, etc., which can relieve the local pain symptoms.

Special reminder: all drugs should be applied according to the doctor’s prescription, avoid self-medication or changing the dosage.

Prognosis

Cure

Generally, the prognosis is good, and patients in the acute stage can be cured after standardized treatment, while some patients without timely or standardized treatment can be turned into the chronic stage.

Some patients without timely or standardized treatment may turn into chronic stage. The disease has a tendency to heal itself. However, patients who do not receive antimicrobial therapy, the case fatality rate of 2% ~ 3%.

The disease can recur, and after receiving antimicrobial therapy, about 10% of patients experience recurrence, which often occurs 3 to 6 months after the end of the initial treatment.

In women, cure has little effect on fertility.

Hazards

Symptoms such as fever, fatigue, excessive sweating, muscle and joint pain can occur, affecting normal work and life.

It can cause complications in many systems such as blood, nerves, cardiovascular, urogenital, respiratory and other systems, which are life-threatening in serious cases.

Pregnant women with the disease may suffer from miscarriage, preterm labor and stillbirth if they do not receive timely antimicrobial treatment.

Daily

Daily Management

Dietary management

Drink plenty of water.

A high-calorie, multi-vitamin, easy-to-digest diet is recommended.

Avoid oily, cold, spicy and stimulating food, such as fatty meat, raw fish, chili, onion, ginger and garlic.

Eat more foods rich in vitamins, such as fresh vegetables, melons and fruits.

Prohibit drinking alcohol.

Life management

Pay attention to rest and avoid exertion.

Maintain sufficient sleep time and avoid staying up late.

Quit smoking.

Psychological support

Pay attention to mental health, release pressure in time, avoid anxiety, depression, excessive tension and other bad emotions.

Patients and their families should have a correct understanding of brucellosis, change the wrong perception of the disease, and establish confidence in curing the disease.

Prevention

Comprehensive measures centered on vaccination of domestic animals should be taken for prevention.

Control of infectious sources

Excreta (mainly urine) of brucellosis patients need to be strictly sterilized.

Excreta of diseased animals and carcasses of sick and dead animals should be buried deeply or cremated.

Animals from brucellosis-endemic areas need to be isolated and quarantined.

Do vaccination of healthy animals to avoid mutual infection among animals.

Cut off the transmission pathway

In brucellosis endemic areas, protect yourself from direct skin contact with sick animals.

Use Pasteurization (or pasteurization for short) or boiling for milk and dairy products.

Meat should be cooked before consumption.

Strict disinfection should be carried out on the runoff products of sick animals, places contaminated by sick and dead animals and their skins, and water sources.

Avoid frequent visits to places with high human and animal traffic. Slaughterhouses need to be supervised by a veterinarian.

Protecting at-risk groups

People in areas where brucellosis is endemic should be better protected by wearing protective gear when coming into contact with sick animals and washing their hands with disinfectant or soapy water after work.

Veterinarians, stockbreeders, slaughter workers, fur processing plant workers and other high-risk groups should be vaccinated. Vaccination is valid for 1 year and should therefore be reinforced annually.

People in areas where brucellosis is endemic should be vaccinated 2 to 4 months before lambing.