Brucellosis

Brucellosis

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• Brucellosis

ILRI/Stevie Mann

Villager and calf share milk from cow in Rajasthan, India

©
Credits

 

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Key facts

• Brucellosis is found globally and is a reportable disease in most countries
• The disease causes flu-like symptoms, including fever, weakness, malaise and weight loss
• Person-to-person transmission is rare
• Brucellosis is a bacterial disease caused by various Brucella species, which mainly infect cattle, swine, goats, sheep and dogs

Brucellosis is a bacterial disease caused by various Brucella species, which mainly infect cattle, swine, goats, sheep and dogs. Humans generally acquire the disease through direct contact with infected animals, by eating or drinking contaminated animal products or by inhaling airborne agents. Most cases are caused by ingesting unpasteurized milk or cheese from infected goats or sheep.

Brucellosis is one of the most widespread zoonoses transmitted by animals and in endemic areas, human brucellosis has serious public health consequences. Expansion of animal industries and urbanization, and the lack of hygienic measures in animal husbandry and in food handling, partly account for brucellosis remaining a public health hazard.

 

Who is at risk? 

Brucellosis is found globally and is a reportable disease in most countries. It affects people of all ages and both sexes. In the general population, most cases are caused by the consumption of raw milk or its derivatives such as fresh cheese. Most of these cases are from sheep and goat products.

The disease is also considered an occupational hazard for people who work in the livestock sector. People who work with animals and are in contact with blood, placenta, foetuses and uterine secretions have an increased risk of contracting the disease. This method of transmission primarily affects farmers, butchers, hunters, veterinarians and laboratory personnel.

Worldwide, Brucella melitensis is the most prevalent species causing human brucellosis, owing in part to difficulties in immunizing free-ranging goats and sheep.

Human-to-human transmission is very rare.

 

Prevention and control

Prevention of brucellosis is based on surveillance and the prevention of risk factors. The most effective prevention strategy is the elimination of infection in animals. Vaccination of cattle, goats and sheep is recommended in enzootic areas with high prevalence rates. Serological or other testing and culling can also be effective in areas with low prevalence. In countries where eradication in animals through vaccination or elimination of infected animals is not feasible, prevention of human infection is primarily based on raising awareness, food-safety measures, occupational hygiene and laboratory safety.

Pasteurization of milk for direct consumption and for creating derivatives such as cheese is an important step to preventing transmission from animals to humans. Education campaigns about avoiding unpasteurized milk products can be effective, as well as policies on its sale.

In agricultural work and meat-processing, protective barriers and correct handling and disposal of afterbirths, animal carcasses and internal organs is an important prevention strategy. 

 

Treatment and care

Brucellosis typically causes flu-like symptoms, including fever, weakness, malaise and weight loss. However, the disease may present in many atypical forms. In many patients the symptoms are mild and, therefore, the diagnosis may not be considered. The incubation period of the disease can be highly variable, ranging from 1 week to 2 months, but usually 2–4 weeks.

Treatment options include doxycycline 100 mg twice a day for 45 days, plus streptomycin 1 g daily for 15 days. The main alternative therapy is doxycycline at 100 mg, twice a day for 45 days, plus rifampicin at 15mg/kg/day (600-900mg) for 45 days. Experience suggests that streptomycin may be substituted with gentamicin 5mg/kg/daily for 7–10 days, but no study directly comparing the two regimes is currently available. The optimal treatment for pregnant women, neonates and children under 8 is not yet determined; for children, options include trimethoprim/sulfamethoxazole (co-trimoxazole) combined with an aminoglycoside (streptomycin, gentamycin) or rifampicin.

WHO response

WHO provides technical advice to member states through provision of standards, information and guidance for the management of brucellosis in humans and animals. The Organization works to support the coordination and sharing of information between the public health and animal health sectors. In collaboration with the Food and Agricultural Organization of the United Nations (FAO), the World Organisation for Animal Health (OIE) and the Mediterranean Zoonoses Control Programme (MZCP), WHO supports countries in the prevention and management of the disease through the Global Early Warning System for Major Animal Diseases (GLEWS).  

---

 

Brucellosis – Symptoms & causes

Overview

Brucellosis is a bacterial infection that spreads from animals to people. Most commonly, people are infected by eating raw or unpasteurized dairy products. Sometimes, the bacteria that cause brucellosis can spread through the air or through direct contact with infected animals.

Signs and symptoms of brucellosis may include fever, joint pain and fatigue. The infection can usually be treated with antibiotics. However, treatment takes several weeks to months, and the infection can recur.

Brucellosis affects hundreds of thousands of people and animals worldwide. Avoiding raw dairy products and taking precautions when working with animals or in a laboratory can help prevent brucellosis.

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Symptoms

Symptoms of brucellosis may show up anytime from a few days to a few months after you’ve been infected. Signs and symptoms are similar to those of the flu and include:

• Fever
• Chills
• Loss of appetite
• Sweats
• Weakness
• Fatigue
• Joint, muscle and back pain
• Headache

Brucellosis symptoms may disappear for weeks or months and then return. Some people have chronic brucellosis and experience symptoms for years, even after treatment. Long-term signs and symptoms may include:

• Fatigue
• Recurrent fevers
• Inflammation of the inner lining of the heart chambers (endocarditis)
• Joint inflammation (arthritis)
• Arthritis of the spinal bones (spondylitis)
• Arthritis of joints where the spine and pelvis connect (sacroiliitis)

When to see a doctor

Brucellosis can be hard to identify, especially in the early stages, when it often resembles other conditions, such as the flu. See your doctor if you develop a rapidly rising fever, muscle aches or unusual weakness and have any risk factors for the disease, or if you have a persistent fever.

Causes

Brucellosis affects many wild and domestic animals, including:

• Cattle
• Goats
• Sheep
• Pigs and wild hogs
• Dogs, especially those used in hunting
• Deer
• Elk
• Bison
• Caribou
• Moose
• Camels

A form of brucellosis also affects harbor seals, porpoises and certain whales.

The most common ways that bacteria spread from animals to people are by:

• Eating raw dairy products. Brucella bacteria in the milk of infected animals can spread to humans in unpasteurized milk, ice cream, butter and cheeses. The bacteria can also be transmitted in raw or undercooked meat of infected animals.
• Inhaling contaminated air. Brucella bacteria spread easily in the air. Farmers, hunters, laboratory technicians and slaughterhouse workers can inhale the bacteria.
• Touching blood and body fluids of infected animals. Bacteria in the blood, semen or placenta of an infected animal can enter your bloodstream through a cut or other wound. Because normal contact with animals — touching, brushing or playing — doesn’t cause infection, people rarely get brucellosis from their pets. Even so, people who have weakened immune systems should avoid handling dogs that are known to have the disease.

Brucellosis normally doesn’t spread from person to person, but in a few cases, women have passed the disease to their children during birth or through their breast milk. Rarely, brucellosis may spread through sexual activity or through contaminated blood or bone marrow transfusions.

Risk factors

While brucellosis is rare in the United States, it is more common in other parts of the world, especially:

• Southern Europe, including Portugal, Spain, Turkey, Italy, Greece, Southern France
• Eastern Europe
• Mexico, South and Central America
• Asia
• Africa
• The Caribbean
• The Middle East

Occupations at higher risk

People who work with animals or who come into contact with infected blood are at higher risk of brucellosis. Examples include:

• Veterinarians
• Dairy farmers
• Ranchers
• Slaughterhouse workers
• Hunters
• Microbiologists

Complications

Brucellosis can affect almost any part of your body, including your reproductive system, liver, heart and central nervous system. Chronic brucellosis may cause complications in just one organ or throughout your body. Possible complications include:

• Inflammation of the inner lining of the heart chambers (endocarditis). This is one of the most serious complications of brucellosis. Untreated endocarditis can damage or destroy the heart valves and is the leading cause of brucellosis-related deaths.
• Arthritis. Joint inflammation is marked by pain, stiffness and swelling in the joints, especially the knees, hips, ankles, wrists and spine. Inflammation of the joints in your spine (spondylitis) or the joints linking the lower spine and pelvis (sacroiliitis) can be particularly hard to treat and may cause lasting damage.
• Inflammation and infection of the testicles (epididymo-orchitis). The bacteria that cause brucellosis can infect the epididymis, the coiled tube that connects the vas deferens and the testicle. From there, the infection may spread to the testicle itself, causing swelling and pain, which may be severe.
• Inflammation and infection of the spleen and liver. Brucellosis can also affect the spleen and liver, causing them to enlarge beyond their usual size.
• Central nervous system infections. These include potentially life-threatening illnesses such as inflammation of the membranes surrounding the brain and spinal cord (meningitis) or inflammation of the brain itself (encephalitis).

Prevention

To reduce the risk of getting brucellosis, take these precautions:

• Avoid unpasteurized dairy foods. In recent years in the United States, few cases of brucellosis have been linked to raw dairy products from domestic herds. Still, it’s best to avoid unpasteurized milk, cheese and ice cream, no matter what their origin. If you’re traveling to other countries, avoid all raw dairy foods.
• Cook meat thoroughly. Cook a whole cut of meat until it reaches an internal temperature of 145 F (63 C) and let it rest for at least three minutes — a medium doneness. Cook ground meat to 160 F (71 C) — well done. Cook all poultry, including ground poultry, to 165 F (74 C). When traveling outside of the United States, avoid undercooked meats.
• Wear gloves. If you’re a veterinarian, farmer, hunter or slaughterhouse worker, wear rubber gloves when handling sick or dead animals or animal tissue or when assisting an animal giving birth.
• Take safety precautions in high-risk workplaces. If you work in a laboratory, handle all specimens under appropriate biosafety conditions. Slaughterhouses should also follow protective measures, such as separating the killing floor from other processing areas and use of protective clothing.
• Vaccinate domestic animals. In the United States, an aggressive vaccination program has nearly eliminated brucellosis in livestock herds. Because the brucellosis vaccine is live, it can cause disease in people. Anyone who has an accidental needle stick while vaccinating an animal should be treated.

Brucellosis

Brucellosis

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• Brucellosis

ILRI/Stevie Mann

Villager and calf share milk from cow in Rajasthan, India

©
Photo

Key Facts

• Brucellosis occurs worldwide and is notifiable in most countries.
• The disease causes flu-like symptoms including fever, weakness, malaise and weight loss.
• Human-to-human transmission is rare.
• Brucellosis is a bacterial disease caused by different types of Brucella that infects mainly cattle, pigs, goats, sheep and dogs.

Brucellosis is a bacterial disease caused by different types of Brucella that mainly infect cattle, pigs, goats, sheep and dogs. Human infection usually occurs through direct contact with infected animals, ingestion of contaminated animal products, or inhalation of airborne pathogens. Most cases are caused by drinking unpasteurized milk from infected goats or sheep, or cheese made from such milk.

Brucellosis is one of the most common animal-borne zoonoses, and in endemic areas, human brucellosis has serious public health implications. Expansion of animal husbandry and urbanization, as well as lack of hygiene measures in animal husbandry and food processing, partly explain the fact that brucellosis continues to pose a threat to public health.

Who is at risk?

Brucellosis is distributed throughout the world and is subject to registration in most countries. It affects people of all ages and both sexes. In the general population, the majority of cases are caused by the consumption of raw milk or products made from it, such as fresh cheese. Most of these cases are caused by the consumption of sheep and goat milk and products made from it.

This disease is also considered as an occupational risk for people working in the livestock sector. People who work with animals and come into contact with their blood, placenta, fetuses and uterine secretions are at increased risk of infection. This mode of transmission primarily affects farmers, butchers, hunters, veterinarians and laboratory workers.

Worldwide Brucella melitensis is the most common Brucella species causing human brucellosis, due in part to the difficulty of immunizing free-ranging goats and sheep.

Human-to-human transmission is rare.

Prevention and control

Brucellosis prevention is based on surveillance and prevention of risk factors. The most effective prevention strategy is to eliminate infection in animals. In areas with a high prevalence of enzootics, it is recommended to vaccinate cattle, goats and sheep. In low-prevalence areas, serological and other tests and culling of livestock may also be effective. In countries where prevention of infection in animals by vaccination or destruction of infected animals is not possible, prevention of infection in humans relies mainly on awareness-raising, food safety, occupational health and laboratory safety measures.

Pasteurizing milk for direct consumption and making products such as cheese is an important step in preventing animal-to-human transmission. Educational campaigns to prevent the manufacture of products from unpasteurized milk can be effective, as can marketing policies for such products.

In the field of agriculture and meat processing, an important prevention strategy is the provision of protective barriers, as well as the correct handling and disposal of placentas, carcasses and internal organs of animals.

Treatment and care

Brucellosis usually causes flu-like symptoms, including fever, weakness, malaise, and weight loss. However, the disease can manifest itself in many atypical forms. Because many patients have mild symptoms, the disease may go undiagnosed. The incubation period of the disease can vary widely – from one week to two months – but usually ranges from two to four weeks.

Treatment options include doxycycline 100 mg twice daily for 45 days in combination with streptomycin 1 g daily for 15 days. The main alternative therapy is doxycycline 100 mg twice daily for 45 days in combination with rifampicin at 15 mg per kg of body weight per day (600-900 mg) for 45 days. Experience shows that streptomycin can be replaced by gentamicin at a rate of 5 mg per 1 kg of body weight per day for 7-10 days, but to date there have been no studies directly comparing these two regimens. The optimal treatment for pregnant women, newborns, and children under 8 years of age has not yet been determined; possible treatment options for children include trimethoprim/sulfamethoxazole (cotrimoxazole) in combination with an aminoglycoside (streptomycin, gentamicin) or rifampicin.

WHO activities

WHO provides technical advice to Member States by providing standards, information and guidelines for the control of brucellosis in humans and animals. The organization promotes coordination and information exchange between the public health and animal health sectors. In collaboration with the Food and Agriculture Organization of the United Nations (FAO), the World Organization for Animal Health (OIE) and the Mediterranean Zoonotic Disease Program (MZP), WHO is supporting countries to prevent and treat the disease through the Global Early Warning System on Major Animal Diseases (MCAD).

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• Brucellosis in humans and animals
  Food and Agriculture Organization of the United Nations, World Health Organization and World Organization for Animal Health
• WHO
  

  Brucellosis: symptoms, diagnosis, treatment

  In contact with animals or with thermally unprocessed products of animal origin, there is a risk of infection with brucellosis. This infectious disease affects many human organs and systems and easily becomes chronic with frequent relapses.

  General information about infection

  The causative agent of brucellosis is the bacterium Brucella, the main reservoir for which are domestic and wild animals and birds. Human infection occurs through contact with an infected animal. Ways of transmission of brucellosis – small wounds on the skin or mucous membranes, the digestive tract when eating animal products, the respiratory tract when inhaling air with infected dust.

  Human infection is possible only from an animal. The existence of tick-borne brucellosis has not been proven – so far not a single case of transmission of this infection through tick bites has been recorded.

  Brucella can be found not only in the body of animals, but also on their fur, in milk and even in frozen meat, as well as in the soil, where they enter with the feces of animals. The bacterium is excellently adapted to adverse conditions, remaining viable at low temperatures and in the absence of moisture from one and a half months to six months. However, it dies within half an hour when heated to 60 ° C, and when boiled, it is destroyed instantly. Therefore, eating animal products after heat treatment is completely safe.

  Symptoms of disease

  Between the penetration of bacteria into the body and the appearance of the first signs of brucellosis, at least a week passes, sometimes the incubation period lasts up to two months, but its most frequent duration is two weeks. Symptoms develop gradually and include:

  • severe increase in body temperature up to 38-39°C, accompanied by chills and fever;
  • increased sweating, especially during nocturnal sleep;
  • a sharp decline in strength, a feeling of weakness;
  • the appearance of pain in the joints of the limbs, tingling in different parts of the body.

  The listed symptoms of brucellosis can be undulating in nature: gradually increase and intensify, then decrease and disappear for a while. The disease is systemic in nature and affects the human musculoskeletal system, nervous system and reproductive organs, provoking the development of concomitant ailments.

  Pathogenesis

  The development of brucellosis in humans goes through several stages.

  1. Lymphogenic – bacteria penetrate the lymphatic system and occupy the lymph nodes with the lymph flow, without leading to their enlargement.
  2. Hematogenous drift – having penetrated into the circulatory system, bacteria release toxins that act on nerve fibers through the blood.
  3. Acute brucellosis – with the bloodstream, bacteria penetrate into the tissues of various organs, forming secondary foci of infection in the form of granulomas, and sometimes inflammatory abscesses.
  4. Exofocal contamination – new foci of infection appear, an allergic reaction to unfavorable factors develops in the body, chronic brucellosis is formed, which lasts for several years with numerous relapses;
  5. Residual effects – the final stage of the disease, which is characterized by deformation of the bone tissue and joints, allergic manifestations and disorders of the nervous system, which are usually irreversible.

  After the end of the disease, the patient develops temporary immunity, the duration of which is from six months to five years, after which the person can again become infected.

  Infection detection

  The technique for diagnosing brucellosis is well developed and is based on laboratory tests aimed at identifying the pathogen, which include:

  • general blood test;
  • biochemical blood test;
  • bakposev biomaterials;
  • serological examination;
  • blood test for detection of antigens;
  • PCR test for Brucella DNA;
  • testing for antibodies to Brucella.

  In addition, to detect pathological changes in the patient’s body, ultrasound and x-ray studies of damaged organs may be needed.

  How to treat brucellosis

  Antibiotics are prescribed for the treatment of acute brucellosis. When the disease becomes chronic, these drugs cease to be effective, immunoglobulins with anti-brucellosis antibodies and vaccines with killed bacteria have a much more pronounced effect. Supportive and strengthening therapy is important – ultraviolet irradiation sessions, taking vitamin complexes, etc. When an allergic reaction occurs, antiallergic drugs are prescribed. During the recovery period, a visit to balneological resorts with radon and sulfur-radon waters is shown.

  How to prevent disease

  Unfortunately, the development of an effective long-acting vaccine that prevents the development of infection in humans has proved impossible. However, subject to simple measures to prevent brucellosis, it is quite possible to avoid the disease. For this you need:

  • boil or pasteurize milk before eating;
  • avoid dry-cured meat products;
  • follow the rules of hygiene, wash hands after contact with animals, agricultural workers wear protective gloves;
  • to vaccinate livestock, since a brucellosis vaccine for animals has long been developed, and in countries that practice blanket vaccination of livestock, this disease has practically disappeared.

  In case of contact with an infected animal, it is necessary to monitor the state of health for at least six months, periodically taking tests for the presence of bacteria in biomaterials.

  Frequently Asked Questions

  Is brucellosis transmitted from person to person?

  Medicine excludes the possibility of transmission of brucellosis from person to person, since the bacterium cannot enter the body by airborne droplets or by contact. There are some data on the ways of brucellosis infection of infants through mother’s milk and fetus from a pregnant mother.

  Why is brucellosis dangerous for humans?

  Brucellosis is a severe infection, the main danger of which is the negative impact of the toxin released by bacteria on human organs and systems. The most common complications are endocarditis, the main cause of death from this infection, arthritis leading to deformation of the joints and bones, inflammation of the reproductive organs, liver and spleen, and infections of the nervous system.