Brucellosis Quiz

Brucellosis Overview

• Brucellosis is a zoonotic bacterial disease, primarily an infection of animals transmissible to humans.
• Caused by small, gram-negative, rod-shaped, non-motile, non-spore-forming, intracellular coccobacilli of the genus Brucella.
• Various Brucella species primarily infect domestic livestock.
• Examples of infected livestock: cattle (B. abortus), sheep and goats (B. melitensis), pigs (B. suis), and dogs (B. canis).
• Other names for brucellosis include undulant fever, Malta fever, and Mediterranean fever.
• Brucellosis is a global issue, traditionally associated with farm workers, veterinarians, and those involved in handling meat or dairy products.

Objectives

• Epidemiology and transmission of brucellosis.
• Preventive measures, epidemic control, and international efforts to control brucellosis.

Identification

• Brucella species are prevalent in domestic animals.
• The infection can be transmitted to humans.
• The type of animal impacted determines the pathogenicity level:
• B. melitensis (sheep): highest pathogenicity
• B. suis (pigs): high pathogenicity
• B. abortus (cattle): moderate pathogenicity
• B. canis (dogs): moderate pathogenicity

Pathogenicity

• Brucella melitensis has the highest pathogenicity.

Spread of Brucellosis

• Transmission is linked to the infected animal.

Geographical Distribution

• Worldwide distribution.
• Higher incidence in specific regions (Mediterranean countries, Africa, Middle East, parts of Asia, and Central/South America and Mexico)
• Cases can occur in people returning from endemic regions.
• Often under-diagnosed.
• Relatively rare in many European countries, North America, and Australia.

Age-Related Demographics

• High incidence in mid-20s males, particularly in the Mediterranean region.
• Data reveals a pattern of high incidence between ages 13-40 years, followed by those younger than 13 years and slightly lower numbers aged 40-60, with even fewer above 60 years of age. This is mostly from cases of Brucella melitensis.
• Individuals in the 13-40 age range appear more susceptible to illness from B. melitensis.

Sex-Related Demographics

• Higher incidence in males than females worldwide.
• This is potentially due to occupation-related exposure to animals.

Clinical Manifestation

• Common symptoms include fever, night sweats, malaise, anorexia, fatigue, weight loss, and depression.
• Bone and joint involvement are frequent complications.
• Possible complications include sacroiliitis, spondylitis, peripheral arthritis, osteomyelitis, bursitis, and tenosynovitis.
• Genito-urinary involvement (orchitis, epididymitis) occurs in 2-20% of cases.
• Neuro-brucellosis is rarer but can be severe.
• Relapse is possible.

Key Points on the Disease in Humans

• Usually presents as an acute febrile illness.
• Primarily caused by B. melitensis.
• All age groups affected.
• Complications can affect any organ system.
• May persist as relapse, chronic localized infection, or delayed convalescence.

Mode of Transmission

• Contact with infected animal fluids (blood, urine, vaginal discharges, aborted fetuses, placentas).
• Ingestion of raw milk, dairy products, or undercooked meat from infected animals.
• Airborne transmission in laboratory or slaughterhouse settings.
• Accidental inoculation of animal vaccines.
• Possible rare person-to-person or sexual transmission.
• Transmission from mother to infant via breastfeeding or ingestion of raw milk.

Key Points on the Epidemiology of Brucellosis in Humans

• Cattle, sheep, goats, and pigs are the primary animal reservoirs.
• Transmission often occurs via occupational or environmental contact with infected animals or products.
• Foodborne transmission (e.g., raw milk, cheese) is a significant risk factor.
• Brucellosis can be a travel-associated illness.
• Blood or organ/tissue transfer is a possible mode of infection, but not common.
• Person-to-person transmission is rare.

Reservoir

• Cattle, swine, goats, and sheep are main reservoirs.
• Dogs can be a reservoir for B. canis.

Incubation Period

• Variable, typically 1-3 weeks, but can extend to 6 months or more.

Period of Communicability

• Rare person-to-person transmission; risk for medical personnel in areas with limited resources.

Susceptibility

• Severity and duration of illness vary.
• Duration of acquired immunity uncertain.

Diagnosis

• Isolation of the infectious agent from blood, bone marrow, or other tissues.
• PCR
• Serological tests, such as Rose Bengal, seroagglutination, or ELISA (95% accurate).

Key Points on the Diagnosis of Brucellosis in Humans

• Culture often negative, especially with long-standing disease.
• Serology is the most useful diagnostic tool.
• Different serological tests (RBT, tube agglutination, ELISA) can be used.
• Key to differentiate active vs. past infection using IgM & IgG analysis.

Case Scenario

• 81-year-old man presented with flu-like symptoms, back pain, and arthralgia.
• High CRP, low Hb, mild liver enzyme elevation, and positive blood culture for Brucella melitensis.
• Confirmed brucellosis diagnosis.

Methods of Control - Preventive Measures

1. Public awareness, especially for tourists, about the risk of consuming unpasteurized milk products.
2. Education for farmers, workers in slaughterhouses, and butcher shops about disease prevention and safe practices when handling animals and products.
3. Education for hunters handling feral animals to use appropriate protective clothing.

Methods of Control - Other Preventive Measures

4. Testing and culling/isolation of infected animals.
5. Pasteurization of milk and dairy products; avoidance of raw products.
6. Proper handling and disposal of aborted animals or contaminated products (like placentas); proper disinfection.

Methods of Control - Patient, Contacts, and Environment

1. Reporting to local health authorities.
2. Isolation precautions if sores/draining lesions are present.
3. Disinfection of purulent discharges.
4. Tracing contacts and infection sources (e.g., animals, milk products).

Methods of Control - Treatment

• Recommended treatment (for adults and children >8 years): a. Doxycycline 100mg PO twice daily plus Rifampin 600-900 mg/day PO for 6 weeks. b. Doxycycline 100mg PO twice daily for 6 weeks and Streptomycin 1g IM for 2-3 weeks. (considered more effective against relapse)
• Ciprofloxacin-based regimens have shown equal treatment efficacy as Doxycycline regimens.

Key Points on Prevention of Brucellosis in Humans

• Occupational and food hygiene are central to prevention.
• Vaccination not routinely recommended.
• Heat-treated milk and dairy products are safer.
• Avoid raw milk and products from potentially infected animals.
• Cooked meat is safer.

Key Points on Prevention, Control, and Eradication of Animal Brucellosis

• Careful herd management and hygiene are critical.
• Vaccination (especially B. abortus 19 and RB 51) is often helpful but is not always sufficient by itself; appropriate use is very important.
• Effective control requires collaboration between communities.
• Prevention & control must be planned, coordinated, and resourced.
• Education & information campaigns.
• Eradication programs must include testing, culling, and controlling animal movement.

Epidemic and International Measures

• Identify sources of infection (e.g., raw milk, infected animals).
• Stop production/distribution of contaminated products (unless pasteurization is done)
• International control of animal trade and transport.

KEY POINTS ON SURVEILLANCE BRUCELLOSIS IN HUMANS AND ANIMALS

• Continued surveillance is key to monitoring the presence/absence of brucellosis and controlling outbreaks.
• Case definitions, reporting systems, data analysis, and disseminating information for action are essential components.
• Design the surveillance program based on the existing control strategies.
• Human cases can indicate potential animal infections.

Summary

• Brucellosis is a reportable disease globally.
• Similar to flu-like symptoms (fever, weakness, malaise, weight loss).
• Rare person-to-person transmission
• Caused by Brucella species (mainly cattle, swine, goats, sheep, and dogs).

Test your knowledge on Brucellosis, a significant zoonotic disease. This quiz covers various aspects including pathogenicity, transmission modes, endemic regions, and affected demographics. Perfect for students and professionals in veterinary medicine and infectious diseases.