Overview
Brucellosis is a bacterial infection caused by Brucella species, gram-negative bacteria that primarily infect livestock including cattle, goats, sheep, pigs, and dogs. The four species most commonly responsible for human disease are Brucella melitensis (from goats and sheep, the most common and most severe), Brucella abortus (from cattle), Brucella suis (from pigs), and Brucella canis (from dogs).
Brucellosis is a zoonotic disease , it is transmitted from animals to humans. Unlike typhoid fever, which spreads person-to-person through the fecal-oral route, brucellosis has no person-to-person transmission in ordinary circumstances. Humans are infected through three main routes: consuming unpasteurized dairy products (raw milk, unpasteurized cheese, fresh butter) from infected animals; direct contact with infected animal tissues, blood, urine, or placentas through broken skin or mucous membranes; and inhalation of aerosolized particles in slaughterhouses or veterinary settings.
In Ghana, brucellosis is endemic and disproportionately affects communities involved in livestock rearing, dairy farming, veterinary work, and slaughterhouse operations. It is considered a neglected tropical disease with significant underreporting because it is frequently misdiagnosed as malaria or typhoid fever. The WHO estimates brucellosis causes approximately 500,000 new human infections annually worldwide, with the true burden likely much higher due to underdiagnosis.
The incubation period ranges from one week to several months, typically two to four weeks. This long and variable incubation period contributes to delayed diagnosis because patients frequently cannot identify a clear exposure event.
Brucellosis is distinguished by its characteristic undulating fever pattern , fever that rises and falls over days to weeks, giving the historical name “undulant fever” , and by its tendency to cause prolonged, relapsing illness if not adequately treated. Unlike malaria, typhoid, or dengue, which are typically measured in days to weeks, untreated or inadequately treated brucellosis can cause chronic illness lasting months to years.
Key Fact
Important
AT A GLANCE
Disease Summary
Symptoms
Common Symptoms
Brucellosis develops gradually and presents with non-specific symptoms that overlap significantly with malaria, typhoid, and other febrile illnesses.
Undulating Fever
Profuse Night Sweats
Muscle and Joint Pain
Fatigue and Malaise
Headache
Loss of Appetite and Weight Loss
Depression and Mood Changes
Danger Signs
Seek urgent medical attention immediately if any of the following symptoms develop. These may indicate serious complications of brucellosis.
Severe Back or Joint Pain
Severe Headache With Neck Stiffness
Chest Pain or Palpitations
Confusion or Altered Mental State
Diagnosis
Clinical Assessment
Physical Examination
Laboratory Confirmation
Laboratory Tests
Blood Culture
Blood culture is the reference standard for brucellosis diagnosis. Brucella species grow slowly and require prolonged incubation , typically one to three weeks , which is significantly longer than blood cultures for typhoid or other bacterial infections. The laboratory must be informed that brucellosis is suspected so that cultures are held for the appropriate duration. Blood culture sensitivity is approximately 50 to 70 percent in acute brucellosis. Sensitivity decreases with prior antibiotic use and in chronic brucellosis.
Rose Bengal Test
The Rose Bengal test is a rapid agglutination screening test for brucellosis. A positive result indicates the presence of antibodies against Brucella and should prompt confirmatory testing. It is inexpensive, rapid, and widely available, making it a useful first-line screening test in Ghana. A negative Rose Bengal test in a patient with low clinical suspicion essentially rules out brucellosis. However, a positive result requires confirmation with the Standard Agglutination Test (SAT) because false positives can occur.
Standard Agglutination Test (SAT)
The Standard Agglutination Test measures antibody titres against Brucella antigens. A titre of 1:160 or higher in the context of a compatible clinical presentation is diagnostic of brucellosis. The SAT is the most widely used confirmatory serological test for brucellosis. Serial titres taken two to four weeks apart showing a fourfold or greater rise in titre provide strong diagnostic evidence.
PCR (Polymerase Chain Reaction)
PCR can detect Brucella DNA directly in clinical specimens and is highly sensitive and specific. It is particularly useful in patients who have already received antibiotics (which reduces culture sensitivity) and in chronic brucellosis where serological results may be difficult to interpret. PCR is available in reference laboratories in Ghana but not in most primary health facilities.
Complete Blood Count (FBC)
The complete blood count in brucellosis may reveal low white blood cell count (leucopenia), low platelet count (thrombocytopenia), and anemia. These findings are non-specific but can support a diagnosis of brucellosis when interpreted in the appropriate clinical context.
Laboratory Note
The Rose Bengal test is the most practical first-line test for brucellosis in most Ghanaian health facilities. A positive Rose Bengal test should be followed by the Standard Agglutination Test for confirmation. Inform the laboratory that brucellosis is suspected when requesting blood culture so that the specimen is held long enough for Brucella to grow.
Treatment
Doxycycline Plus Rifampicin
The WHO-recommended first-line treatment for uncomplicated brucellosis is doxycycline 100mg twice daily combined with rifampicin 600 to 900mg once daily, both given for six weeks. Combination therapy is essential , single antibiotic treatment has unacceptably high relapse rates because Brucella bacteria survive inside human cells where some antibiotics cannot penetrate effectively. Both antibiotics must be taken simultaneously for the full six weeks.
Doxycycline Plus Streptomycin
An alternative regimen combining doxycycline with intramuscular streptomycin for the first two to three weeks, followed by completion of six weeks of doxycycline alone. This combination has lower relapse rates than doxycycline plus rifampicin in some studies and is preferred by some guidelines, particularly for more severe disease. However, streptomycin requires injections and may not be readily available in all settings.
Extended Treatment for Complicated Brucellosis
Brucellosis with complications , including vertebral osteomyelitis (spinal infection), endocarditis (heart valve infection), neurobrucellosis (brain involvement), or other focal organ infections , requires significantly prolonged treatment lasting three to six months or longer. The exact regimen depends on the site and severity of involvement and should be managed by a specialist.
Treatment Note
Six weeks of treatment is the minimum for uncomplicated brucellosis , not six days. This is the most important point for patients to understand. Stopping treatment early because symptoms improve is the primary cause of relapse. Relapsed brucellosis is more difficult to treat and may require even longer courses of antibiotics. Complete the full prescribed course regardless of how well you feel.
Prevention
Consume Only Pasteurized Dairy Products
Avoiding unpasteurized milk, cheese, butter, and other dairy products from cattle, goats, and sheep is the single most important prevention measure for brucellosis in the community. Pasteurization kills Brucella bacteria effectively. Boiling milk before consumption provides equivalent protection where pasteurized products are not available.
Use Protective Equipment During Animal Contact
Farmers, veterinarians, slaughterhouse workers, and others with direct animal contact should wear waterproof gloves, protective eyewear, and appropriate clothing when handling livestock, animal placentas, blood, or carcasses, particularly during calving, lambing, or slaughter.
Thorough Handwashing After Animal Contact
Washing hands thoroughly with soap and water after any contact with animals, animal products, or animal environments reduces the risk of transmission.
Vaccination of Livestock
Vaccination of cattle, goats, and sheep against brucellosis using approved veterinary vaccines reduces the animal reservoir and thereby reduces human exposure risk. This is a community and agricultural intervention rather than an individual one.
Prevention Note
In Ghana, where fresh unpasteurized dairy is widely consumed and livestock rearing is common, the most immediately actionable prevention measure for most people is boiling milk before consumption and avoiding fresh unpasteurized cheese. Healthcare workers and farmers who handle animals should use protective equipment consistently.
Risk Factors
Occupational Risk Factors
These occupations carry the highest documented brucellosis risk.
- Dairy farmers and agricultural workers handling cattle, goats, or sheep
- Veterinarians and veterinary assistants
- Slaughterhouse and abattoir workers
- Laboratory workers handling Brucella cultures
- Shepherds and pastoral communities with close livestock contact
Dietary Risk Factors
These dietary practices increase the risk of brucellosis transmission.
- Consuming raw or unpasteurized milk from cattle, goats, or sheep
- Consuming unpasteurized soft cheese or fresh cheese
- Consuming unpasteurized butter or cream
Individual Risk Factors
These personal factors increase the risk of severe or complicated brucellosis.
- Immunocompromised individuals including those living with HIV
- Pregnant women , brucellosis during pregnancy can cause miscarriage, premature delivery, and congenital brucellosis
- Males , brucellosis is more common in males, likely reflecting higher occupational exposure
- Age , children and older adults may be at higher risk of severe disease
- Delayed or incomplete treatment , the most important risk factor for chronic relapsing brucellosis
Risk Note
In Ghana, both occupational risk (livestock farming communities) and dietary risk (unpasteurized dairy consumption) are significant and common. The highest risk individuals are those who combine both , dairy farmers who also consume fresh milk and cheese from their own animals.
Complications
Osteoarticular Complications
Bone and joint complications are the most common complication of brucellosis, occurring in up to 40 percent of cases. Vertebral osteomyelitis (infection of the spine, particularly the lumbar vertebrae) is the most serious osteoarticular complication and can cause severe back pain, nerve compression, and spinal deformity if not treated promptly and adequately. Sacroiliitis (infection of the sacroiliac joint), septic arthritis of large joints, and bursitis also occur.
Endocarditis
Brucellosis endocarditis , infection of the heart valves , is uncommon but is the most life-threatening complication, responsible for most brucellosis deaths. It typically involves the aortic valve. Brucellosis endocarditis is notoriously difficult to treat and frequently requires both prolonged antibiotic therapy and surgical valve replacement. It should be suspected in any patient with brucellosis who develops new cardiac symptoms.
Neurobrucellosis
Nervous system involvement occurs in approximately 1 to 2 percent of brucellosis cases. Manifestations include meningitis, encephalitis, myelitis, radiculopathy (nerve root inflammation), and neuropsychiatric presentations. Neurobrucellosis requires prolonged treatment with antibiotics that penetrate the central nervous system.
Obstetric Complications
Brucellosis during pregnancy is associated with miscarriage (spontaneous abortion), premature delivery, and congenital brucellosis in the newborn. Pregnant women with brucellosis require specialist management because some first-line antibiotics (doxycycline) are contraindicated in pregnancy.
Chronic Brucellosis
Inadequately treated or relapsing brucellosis can become chronic, with symptoms persisting for more than twelve months. Chronic brucellosis is difficult to treat and can significantly impair quality of life through persistent fatigue, joint pain, and neuropsychiatric symptoms.
Complication Note
Most complications of brucellosis are preventable with early diagnosis and completion of the full treatment course. The most important contributor to complications is incomplete treatment. Completing the minimum six-week antibiotic course is the single most important factor in preventing chronic and complicated brucellosis.
When to Seek Medical Care
Prolonged Fever Lasting More Than Two Weeks
Fever lasting more than two weeks without a clear diagnosis , particularly in someone with animal contact or unpasteurized dairy consumption , should prompt evaluation for brucellosis. Most acute febrile illnesses including malaria and typhoid resolve or are diagnosed within two weeks; persistent unexplained fever beyond this point warrants broader investigation.
Fever With Joint or Back Pain
The combination of fever and joint pain , particularly affecting the spine, sacroiliac joints, or large joints , in someone with animal contact history should raise immediate suspicion for brucellosis. Seek medical evaluation and inform your healthcare provider about any animal contact or unpasteurized dairy consumption.
Fever Not Responding to Antimalarial or Antibiotic Treatment
If fever has been treated as malaria or typhoid but is not improving, brucellosis should be considered and tested for, particularly if there is a history of animal contact or unpasteurized dairy consumption.
New Cardiac Symptoms During Brucellosis
Any chest pain, palpitations, or irregular heartbeat developing in a patient known to have brucellosis requires urgent evaluation for endocarditis.
Neurological Symptoms During Brucellosis
Severe headache, neck stiffness, confusion, or any neurological symptom developing during a brucellosis illness requires urgent evaluation for neurobrucellosis.
Emergency Advice
Animal contact history and unpasteurized dairy consumption are the key clinical clues that point toward brucellosis. If you work with animals or regularly consume fresh milk or cheese from local farms and develop prolonged fever with joint pain, communicate this history clearly to your healthcare provider. This information directly guides which laboratory tests are ordered and which diagnosis is considered.
Prognosis
Excellent With Early Diagnosis and Complete Treatment
Most patients with uncomplicated brucellosis who receive early diagnosis and complete the full six-week antibiotic course recover completely without lasting complications. The relapse rate with appropriate treatment is approximately 5 to 10 percent.
Significantly Worse With Delayed Diagnosis or Incomplete Treatment
Delayed diagnosis allows the bacteria to seed multiple organ systems, increasing the risk of focal complications including vertebral osteomyelitis and endocarditis. Incomplete treatment , stopping antibiotics early because symptoms improve , is the primary cause of relapse and chronic brucellosis.
Chronic Brucellosis Carries Significant Morbidity
Chronic brucellosis, typically resulting from incomplete treatment, can cause persistent fatigue, joint pain, and neuropsychiatric symptoms lasting months to years. Some patients with chronic brucellosis experience significant long-term impairment of quality of life.
Prognosis Note
The prognosis of brucellosis is almost entirely determined by how early treatment begins and whether the full course is completed. Completing six weeks of combination antibiotic therapy is non-negotiable , it is the difference between cure and chronic relapsing disease.
Differential Diagnosis
Malaria
Both malaria and brucellosis present with fever, headache, and muscle pain, and both are common in Ghana. Key differences: malaria typically has a shorter and more acute course; brucellosis presents with prolonged undulating fever lasting weeks to months. Malaria does not typically cause prominent joint pain or spinal involvement; brucellosis does. A negative malaria test does not rule out brucellosis, and both can coexist. Animal contact history points toward brucellosis; mosquito exposure points toward malaria.
Typhoid Fever
Both brucellosis and typhoid present with prolonged fever, malaise, and constitutional symptoms. Typhoid develops with a step-ladder fever pattern over days; brucellosis has an undulating pattern over weeks to months. Typhoid is transmitted through contaminated food or water; brucellosis through animal contact or unpasteurized dairy. Typhoid treatment is shorter (7 to 14 days); brucellosis treatment requires six weeks minimum. Laboratory testing can distinguish them.
Leptospirosis
Both are zoonotic bacterial febrile illnesses with occupational risk. Leptospirosis is transmitted through water contaminated with animal urine; brucellosis through direct animal contact or unpasteurized dairy. Leptospirosis typically has a shorter acute course; brucellosis has a prolonged undulating course. Both can cause liver and kidney involvement in severe cases. Water exposure history points toward leptospirosis; animal contact or dairy history points toward brucellosis.
Tuberculous Arthritis or Vertebral Tuberculosis
Both brucellosis and tuberculosis can cause prolonged febrile illness with spinal or joint involvement. Tuberculosis spinal disease (Pott’s disease) can closely resemble brucellosis vertebral osteomyelitis radiologically and clinically. Both require prolonged antibiotic treatment. Microbiological testing and clinical context are needed to distinguish them.
Clinical Note
The most important distinguishing feature for brucellosis is the history of animal contact or unpasteurized dairy consumption combined with prolonged undulating fever and joint pain. This combination should prompt specific brucellosis testing regardless of what other diagnoses are being considered. Brucellosis, malaria, and typhoid can coexist in the same patient.
References
World Health Organization (WHO) , Brucellosis
World Health Organization comprehensive guidance on brucellosis epidemiology, transmission, diagnosis, treatment, and prevention. Updated February 2024.
Centers for Disease Control and Prevention (CDC) , Brucellosis
CDC clinical guidance on brucellosis diagnosis, treatment, and management including occupational risk and prevention. Updated April 2024.
StatPearls , Brucellosis (NBK470523)
Evidence-based clinical overview of brucellosis covering pathophysiology, clinical presentation, diagnosis, treatment, and complications. Updated March 2024.
Ghana Health Service , Zoonotic Disease Surveillance
Ghana Health Service data and public health guidance on brucellosis and other zoonotic diseases in Ghana.
MSD Manual Professional Edition , Brucellosis
Evidence-based clinical reference covering brucellosis diagnosis, treatment, complications, and management.
Frequently Asked Questions
Can I get brucellosis from drinking fresh milk bought at the market?
Yes. Fresh milk that has not been pasteurized or boiled can contain Brucella bacteria if it comes from an infected cow, goat, or sheep. This is one of the most common transmission routes for brucellosis in Ghana, where fresh unpasteurized milk and cheese from local farms are widely consumed.
Pasteurization kills Brucella bacteria effectively. If you are not certain that milk has been pasteurized, boiling it before drinking provides equivalent protection. This applies to all dairy products , milk, fresh cheese, and butter , made from unpasteurized milk.
Can brucellosis spread from person to person?
Direct person-to-person transmission of brucellosis is extremely rare in ordinary circumstances. You cannot catch brucellosis from being near someone who has it, sharing a room, or touching them. Brucellosis is essentially an animal-to-human disease , it requires contact with infected animals or their products.
There are theoretical transmission routes between people , sexual transmission has been documented rarely, and breastfeeding from an infected mother carries a small risk , but these are uncommon. Person-to-person transmission is not a significant public health concern for brucellosis in the way it is for malaria, typhoid, or tuberculosis.
Why does brucellosis treatment take six weeks? My malaria treatment was only three days.
This is one of the most important things to understand about brucellosis. The reason treatment takes so long is the biology of Brucella bacteria.
Brucella bacteria are intracellular pathogens , they invade and hide inside the body’s own cells, particularly white blood cells, where many antibiotics cannot penetrate effectively. This means that killing all the bacteria requires antibiotics that can get inside cells, combined for long enough to eradicate bacteria hiding in places that antibiotics reach slowly. Shorter courses leave behind bacteria that survive inside cells and cause relapse.
Most malaria treatments work against parasites in the bloodstream, which is much more accessible than the inside of immune cells. This is why malaria can be treated in three days while brucellosis requires six weeks minimum.
Stopping brucellosis treatment early , even after symptoms fully resolve , is the primary cause of relapse. Relapsed brucellosis is more difficult to treat and may require even longer courses.
I work on a farm with cattle. What should I do to avoid brucellosis?
Several practical measures significantly reduce the risk of brucellosis for farm workers:
Always wear waterproof gloves when handling animals during birth, miscarriage, or any procedure involving blood, urine, or reproductive secretions. Wear protective gloves when slaughtering or butchering animals. Wash hands thoroughly with soap and water after any animal contact. Avoid touching your face, eyes, or mouth with unwashed hands after working with animals.
Do not consume raw milk or unpasteurized dairy products from your own animals or from other farms. Boil milk before drinking.
If an animal on your farm miscarries or appears ill, seek veterinary advice promptly and handle the animal with extra protective measures, as brucellosis is a common cause of livestock abortion.
If you develop fever with joint pain after animal contact, seek medical care and inform your healthcare provider about your occupation and any specific animal contact events.
Can brucellosis come back after I have been treated?
Yes, brucellosis can relapse after treatment, typically within three to six months of completing antibiotics. Relapse occurs in approximately 5 to 10 percent of patients who complete the full six-week treatment course , and in significantly higher proportions of patients who stopped treatment early.
A relapse typically presents with the return of fever and other symptoms. It is treated with another full course of antibiotics, sometimes extended or using a different combination. The more times brucellosis relapses, the more difficult it becomes to cure.
Completing the full six-week course of antibiotics the first time, even after symptoms fully resolve, is the most important way to reduce your risk of relapse.