CDC
Brucella The Brucella ts of s cles four of which cause human brucellosis Af 鲁菌病: Brucella melitensis羊布鲁菌, Brucella suis猪布鲁菌, Brucella abortus 牛布鲁菌, and Brucella canis犬布鲁菌 Are all intracellular organisms .B neotomae.B ovis
Brucella • The genus Brucella consists of six species, four of which cause human brucellosis 布 鲁菌病： Brucella melitensis 羊布鲁菌, Brucella suis 猪布鲁菌, Brucella abortus 牛布鲁菌, and Brucella canis 犬布鲁菌 • Are all intracellular organisms • B. neotomae; B. ovis
Brucella are small(0.40.8 X05-1.5 u m), non-motile. non-capasulate, gram negative coccobacilli The organism is aerobic, and their nutritional requirements are complex. All strains grow best in a medium enrich with animal serum and glucose 5-10% carbon dioxide
• Brucella are small (0.4～0.8 ×0.5～1.5μm), non-motile, non-capasulate, gramnegative coccobacilli. • The organism is aerobic, and their nutritional requirements are complex. • All strains grow best in a medium enrich with animal serum and glucose • 5-10% carbon dioxide
Antigenic Structure and classification Two main antigen: A and m The three main brucella differ from one another in the amount or the two main antigen they have In common B abortus A M=20: 1 B melitenSis.A M=1: 20 B suis: A: M=2: 1
Antigenic Structure and classification • Two main antigen: A and M • The three main Brucella differ from one another in the amount or the two main antigen they have in common : B.abortus : A:M=20:1 B.melitensis: A:M=1:20 B.suis: A:M=2:1
B. abortus Bacteria is excreted in genital secretions (including semen), milk, colostrum Survival time Cheese at 40C: 180 days ! Water at 25C: 50 days Meat and salted meat: 65 days Manure at 120C: 250 days !! Widespread: Cattle, Bison, Elk, Deer,Moose,Horse Sheep, Goat, Swine, Donkey, Dogs, Birds, Hares, Fox, Rats mice. Camels and Human
B. abortus • Bacteria is excreted in genital secretions (including semen), milk, colostrum. • Survival time: Cheese at 4oC: 180 days !!! Water at 25oC: 50 days Meat and salted meat: 65 days Manure at 12oC: 250 days !!!! • Widespread: Cattle, Bison, Elk, Deer, Moose, Horse, Sheep, Goat, Swine, Donkey, Dogs, Birds, Hares, Fox, Rats, mice, Camels and Human
B abortus B abortus Bacteria is excreted in genital secretions (including semen), milk, colostrum Survival time Sources of human Infection Cheese at 4.C: 180 days Raw milk and products /Direct contact Water at 25C: 50 days Portal of entry: oral mucosa, nasopharynx and conjunctivae, genital then X in regional lymph Meat and salted meat: 65 days node and spread to RES (nodes of udder, uterus Manure at 12 C: 250 days ! erythritol.). Placentitis with endometritis. Fetus Widespread: Cattle,Bison,Elk, Deer, Moose,Horse die with edema /congestion of lung dissimenated Sheep, Goat, Swine, Donkey, Dogs, Birds, Hares, Fox, Rats hemorrhages of epicardium and splenic capsule mice. Camels and Human Bacteria in lung and digestive tract of the fetus B. suis B. melitensis wild pigs, Rats, Swine. Abortion, metritis, burst ulitis (Lumbar and sacral), Goat(1886), Sheep, arthritis. orchitis Cow(1905 in paralysis. Malta), Swine Brucella canis Hares. camel Buffalo. Impala Brucella canis was first described as a cause of abortion in beagles in the USa It was subsequently shown to infect dogs in many other countries, irrespective of breed An occasional cause of brucellosis in humans
B. abortus • Sources of Human Infection: Raw milk and products /Direct contact • Portal of entry: oral mucosa, nasopharynx and conjunctivae, genital then X in regional lymph node and spread to RES (nodes of udder, uterus, erythritol...). Placentitis with endometritis. Fetus die with edema /congestion of lung, dissimenated hemorrhages of epicardium and splenic capsule. Bacteria in lung and digestive tract of the fetus. B. abortus • Bacteria is excreted in genital secretions (including semen), milk, colostrum. • Survival time: Cheese at 4oC: 180 days !!! Water at 25oC: 50 days Meat and salted meat: 65 days Manure at 12oC: 250 days !!!! • Widespread: Cattle, Bison, Elk, Deer, Moose, Horse, Sheep, Goat, Swine, Donkey, Dogs, Birds, Hares, Fox, Rats, mice, Camels and Human. B. melitensis • Goat (1886), Sheep, Cow (1905 in Malta), Swine, Hares, Camels, Buffalo, Impala. B. suis • Wild pigs, Rats, Swine. • Abortion,metritis, bursitis, spondylitis (Lumbar and sacral), arthritis, orchitis, paralysis. Brucella canis • Brucella canis was first described as a cause of abortion in beagles in the USA • It was subsequently shown to infect dogs in many other countries, irrespective of breed • An occasional cause of brucellosis in humans
Spread of Brucella in the body BruceNa-infected phagocytic cell Bone marrow mph node Spleen
Spread of Brucella in the body
Incubation period Acute or subacute disease follows an incubation period which can vary from 1 week to 6 or more months In most patients for whom the time of exposure can be identified, the incubation period is between 2 and 6 weeks The length of the incubation period may be influenced by many factors virulence of the infecting strain size of the inoculum route of infection resistance of the host
Incubation period • Acute or subacute disease follows an incubation period which can vary from 1 week to 6 or more months. • In most patients for whom the time of exposure can be identified, the incubation period is between 2 and 6 weeks • The length of the incubation period may be influenced by many factors – virulence of the infecting strain – size of the inoculum – route of infection – resistance of the host
Portals of entry Oral entry- most common route Ingestion of contaminated animal products (often raw milk or its derivatives) contact with contaminated fingers A aerosols Inhalation of bacteria Contamination of the conjunctivae Percutaneous infection through skin abrasions or by accidental inoculation
Portals of entry • Oral entry - most common route – Ingestion of contaminated animal products (often raw milk or its derivatives) – contact with contaminated fingers • Aerosols – Inhalation of bacteria – Contamination of the conjunctivae • Percutaneous infection through skin abrasions or by accidental inoculation
Clinical manifestations The presentation of brucellosis is characteristically variable The onset may be insidious or abrupt Influenza-like with fever reaching 38 to 400C Limb and back pains are unusually severe, night sweating and fatigue are marked Anorexia, weakness, severe fatigue and loss of weight, depression Headache The leukocyte count tends to be normal or reduced with a relative lymphocytosis Relative leukopenia On physical examination, splenomegaly may be the only finding
Clinical Manifestations • The presentation of brucellosis is characteristically variable • The onset may be insidious or abrupt • Influenza-like with fever reaching 38 to 40oC – Limb and back pains are unusually severe, night sweating and fatigue are marked. – Anorexia, weakness, severe fatigue and loss of weight, depression – Headache • The leukocyte count tends to be normal or reduced, with a relative lymphocytosis – Relative leukopenia • On physical examination, splenomegaly may be the only finding