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Brucella

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)

Brucellosis in U.S.: 1975-2006

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 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.

http://rarediseases.about.com/od/infectiousdiseases/ig/Pictures-of-Bubonic-Plague/hand-gangrene.htm

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.

http://www.unbc.ca/nlui/wildlife_diseases_bc/plague_cycles.gif

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.

http://neatorama.cachefly.net/images/2005-12/sedlec-ossuary.jpg

Sedlec Ossuary in Kutna Hora

http://www.earth-photography.com/photos/Countries/CzechRepublic/Czech_KutnaHora_Ossuary1.jpg

http://z.about.com/d/goeasteurope/1/0/o/5/-/-/SedlicOssuary11.JPG

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


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