Brucella spp.
• Gram negative, coccobacilli bacteria
• Facultative, intracellular organism
• Environmental persistence– Temperature, pH, humidity
– Frozen and aborted materials
• Multiple species
Species Biovar/Serovar
Natural Host Human Pathogen
B. abortus 1-6, 9 cattle yes
B.melitensis 1-3 goats, sheep yes
B. suis 1, 3 swine yes
2 hares yes
4 reindeer, caribou yes
5 rodents yes
B. canis none dogs, other canids yes
B. ovis none sheep no
B. neotomae none Desert wood rat no
B. maris (?) marine mammals ?
The Many Names of Brucellosis
Human Disease
• Malta Fever
• Undulant Fever
• Mediterranean Fever
• Rock Fever of Gibraltar
• Gastric Fever
Animal Disease
• Bang’s Disease
• Enzootic Abortion
• Epizootic Abortion
• Slinking of Calves
• Ram Epididymitis
• Contagious Abortion
History of Malta Fever
• 450 BC: Described by Hippocrates
• 1905: Introduction into the U.S.
• 1914: B. suis Indiana, United States
• 1953: B. ovis New Zealand, Australia
• 1966: B. canis in dogs, caribou, and reindeer
History
• Alice Evans, American bacteriologist– Credited with linking the organisms– Similar morphology and pathology between:• Bang’s Bacterium abortus • Bruce’s Micrococcus melitensis
• Nomenclature today credited to Sir David Bruce– Brucella abortus and Brucella melitensis
Transmission to Humans• Conjunctiva or broken skin contacting infected
tissues– Blood, urine, vaginal discharges, aborted fetuses,
placentas
• Ingestion – Raw milk & unpasteurized dairy products– Rarely through undercooked meat
• Incubation varies – 5-21 days to three months
Who is at Risk?
• Occupational Disease– Cattle ranchers/dairy farmers
– Veterinarians
– Abattoir workers
–Meat inspectors
– Lab workers
• Hunters
• Travelers
• Consumers of unpasteurized dairy products
B. melitensis
• Latin America, Middle East, Mediterranean, eastern Europe, Asia, and parts of Africa
• Accounts for most human cases– In the Mediterranean and Middle East• Up to 78 cases/100,000 people/year• Arabic Peninsula 20% seroprevalence
• Recent emergence in cattle on Middle Eastern intensive dairy farms
B. abortus
• Worldwide
• Some countries have eradicated it
• Notifiable diseasein many countries– Poor surveillance and reporting
due to lack of recognition
– Fever of Unknown Origin (FUO)
Human Disease
• Can affect any organ or organ system
• All patients have a cyclical fever
• Variability in clinical signs– Headache, weakness,
arthralgia, depression, weight loss, fatigue, liver dysfunction
Human Disease
• 20-60% of cases– Osteoarticular complications• Arthritis, spondylitis, osteomyelitis
• Hepatomegaly may occur
• Gastrointestinal complications
• 2-20% of cases– Genitourinary involvement• Orchitis and epididymitis most common
Human Disease
• Neurological– Depression, mental fatigue
• Cardiovascular– Endocarditis resulting in death
• Chronic brucellosis is hard to define– Length, type and response to treatment variable
– Localized infection
• Blood donations of infected persons should not be accepted
Human Disease• Congenitally infected infants– Low birth weight
– Failure to thrive
– Jaundice
– Hepatomegaly
– Splenomegaly
– Respiratory difficulty
– General signs of sepsis (fever, vomiting)
– Asymptomatic
Diagnosis in Humans
• Isolation of organism– Blood, bone marrow, other tissues
• Serum agglutination test– Four-fold or greater rise in titer
– Samples 2 weeks apart
• Immunofluorescence– Organism in clinical specimens
• PCR
Treatment of Choice
• Combination therapy has the best efficacy– Doxycycline for six weeks in combination with
streptomycin for 2-3 weeks or rifampin for 6 weeks
• CNS cases treat 6-9 months– Same for endocarditis cases plus surgical
replacement of valves
Yersinia pestis• Yersinia originally classified in Pasteurellaceae
family– Based on DNA similarities with E. coli, Y. pestis is
now part of Enterobacteriaceae family
• 11 named species in genus 3 are human pathogens– Y. pestis, Y. pseudotuberculosis, Y. enterocolitica– Y. pestis and Y. pseudotuberculosis rarely infect
humans– Y. enterocolitica is the cause of 1 – 3% of diarrhea
cases caused by bacteria
Yersinia pestis
• Gram-negative bacteria
• Can grow with or without oxygen
• Most commonly found in rats but also found in:–Mice, squirrels, fleas, cats, dogs, lice, prairie dogs,
wood rats, chipmunks
Types of Plague• Bubonic Plague– Most common– Infection of the lymph system (attacks immune
system)• Pneumonic Plague– Most serious type of plague– Infection of the lungs leading to pneumonia– Primary and Secondary
• Septicemic Plague – Bacteria reproduces in the blood– Can be contracted like bubonic plague but is most
often seen as a complication of untreated bubonic or pneumonic plague
• Symptoms– Bubonic
• Fever, headache, chills, weakness, swollen and tender lymph glands
– Pneumonic• Fever, headache, weakness,
rapid onset of pneumonia (usually accompanied by: shortness of breath, chest pain, cough, bloody or watery sputum)
– Septicemic• Fever, chills, weakness,
abdominal pain, shock, bleeding underneath skin or other organs
• Diagnosis and Treatment– Most cases of plague are
diagnosed initially from presented symptoms, especially Bubonic plague. If plague is suspected, blood work is completed to determine how far the plague has progressed and to determine antibiotic resistances.
– Since no major antibiotic resistances have developed, plague is usually treated with Streptomycin. Other antibiotics that can be used are: tetracyclines, fluoroquinolones and other aminoglycosides.
– Antibiotics are administered to the patient as well as to those who are believed to have been exposed.
Transmission
• Bubonic and Septicemic can not be transferred human to human. They can only be contracted if bitten by an infected rodent or flea.
• Pneumonic can be transferred through exposure to infected particles. This usually occurs when in close contact with someone who is infected and is exposed to sputum that is coughed up.
History
• There have been three major pandemics of the plague.– Mid 6th century, mid 14th century, early 20th century
• The most well known plague pandemic was in the mid 14th century in Europe known as the Black Death– The plague came from Asia and spread through Europe in
two years.
– In the two years, it killed more than half of the population.
– People didn’t understand how the plague worked which allowed it to spread .
– Benefits.
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Sedlec Ossuary in Kutna Hora
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