3. Species Biovar/Ser
ovar
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 ?
4. 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
5. 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
6. 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
7. 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
8. Who is at Risk?
• Occupational Disease
– Cattle ranchers/dairy farmers
– Veterinarians
– Abattoir workers
– Meat inspectors
– Lab workers
• Hunters
• Travelers
• Consumers of unpasteurized dairy products
9. 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
10. B. abortus
• Worldwide
• Some countries have
eradicated it
• Notifiable disease
in many countries
– Poor surveillance and reporting
due to lack of recognition
– Fever of Unknown Origin (FUO)
12. 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
13. 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
14. 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
15. Human Disease
• Congenitally infected infants
– Low birth weight
– Failure to thrive
– Jaundice
– Hepatomegaly
– Splenomegaly
– Respiratory difficulty
– General signs of sepsis (fever, vomiting)
– Asymptomatic
16. 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
17. 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
19. 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
20. 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
21. 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
22. • 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.
24. 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.
26. 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.
28. Incidence
• Considered a re-emerging disease.
– Incidence is on the rise: 2,000 to 3,000 cases a
year worldwide.
http://www.cdc.gov/ncidod/dvbid/plague/world98.htm
