Brucellosis: Infectious Diseases PDF

# Fifth year Pure Science ## Infectious Diseases: Brucellosis ### Synonyms: * **In animal:** * Contagious abortion * Bang's disease * **In human:** * Mediterranean fever * Undulant fever * Malta fever ### Brucellosis: * Primarily a disease affecting animals and can be transm...

# Fifth year Pure Science ## Infectious Diseases: Brucellosis ### Synonyms: * **In animal:** * Contagious abortion * Bang's disease * **In human:** * Mediterranean fever * Undulant fever * Malta fever ### Brucellosis: * Primarily a disease affecting animals and can be transmitted to humans. * A major health and economic problem in many parts of the world. * Sir David Bruce isolated the Malta in 1886, causative agent from a soldier. * Discovery of the disease was through soldiers who had a shipment of infected sheep. They drank the sheep's milk and developed symptoms of undulant fever, profuse sweating, and foul-smelling sweat. * Remains the commonest zoonotic disease worldwide. ### Definition: * A highly contagious bacterial disease affecting all warm-blooded animals. * Characterized by: * Rare in young animals, but if they contract it the disease tends to be mild and the animal clears the infection. * A small percentage (5%) of infected young animals may develop symptoms as they age. * Inflammation of the genital organ and fetal membranes. * Abortion in late stage of gestation (storm of abortion). * Retained placenta & Infertility. ### Persistent Lifelong Infection: * Animal becomes a carrier due to facultative intracellular M.O, shedding in reproductive and mammary secretions (milk). * This is not a problem for calves as they are usually not susceptible; however, human infection can occur. ### Etiology: * Small, G-ve, cocco-bacillus and non-motile. * Facultative intracellular organisms, making diagnosis, control and treatment difficult. * **Multiplication in uterus:** * Brucella becomes latent infection (no pathway), waiting until pregnancy. * Erythritol, a CHO produced by the fetus and fetal membranes stimulates multiplication, leading to abortion in late pregnancy. * The animal becomes a carrier (no further abortion, but still shedding M.O in its secretions and excretion). ### Antigenic Structure: * **B. abortus & B. melitensis:** * **Difference in ratio between A and M Antigens:**    * **Protein A** found in B. abortus > B. melitensis.    * **Protein M** found in B. melitensis > B. abortus. ### Brucella is Excreted In: * Genital secretions (including semen) * Milk * Colostrum ### Survival Time: * Cheese at 4°C for 180 days * Water at 25°C for 50 days * Meat and salted meat for 65 days * Manure at 12°C for 250 days ### Types & Susceptible Hosts: | Species | Subtypes | Natural Host | Infect Human | |:---|:---|:---|:---| | B. abortus | 1 to 9 | Cattle, Horse/Camel/Human (nonspecific) | Yes | | B. melitensis | 1 to 3 | Sheep & goats | Yes | | B. suis | 1 & 3, 2, 4, 5 | Swine, Hares, Reindeer, Rodents | Rarely | | B. canis | none | Dogs and other canids | Rarely | | B. ovis | none | Sheep | No | | B. neotomae | none | Desert wood rat | No | * B. abortus & B. melitensis found in Egypt. * B. melitensis subtype 3 more common. ### Susceptible Hosts: * All warm-blooded animals, especially sexually mature animals. * **Cattle & buffalo:** B. abortus (mainly) & B. melitensis * **Sheep & goats:** B. melitensis (mainly) & B. abortus & B. ovis in sheep * **Camel:** B. abortus & B. melitensis * **Equine:** B. abortus & B. melitensis * **Pig:** B. suis ### Sources of Infection: * **In animal:** * Aborted foeti * Placenta & Uterine discharges after abortion or normal parturition * Milk and colostrum * Contaminated pasture, bedding, food and water * Semen (not a major source) * **In human:** * B. melitensis, B. abortus, B. suis & B. canis ### Transmission: * **Ingestion:** * **Direct Contact** by conjunctiva or broken (or even contact) skin in contact with infected tissues, vaginal discharges, aborted fetuses & placenta. * **Ingestion** raw milk & unpasteurized dairy products & rarely undercooked meat (like fresh cheese). * **Inhalation** of infectious aerosols pens, stables, slaughter houses, laboratory transmission. * **Inoculation with animal live vaccines:** * B. abortus strain 19, RB51 & B. melitensis Rev-1. * **No evidence of person to person transmission.** ### Pathogenesis in Animals: * **Latent infection** at the start of the disease. * **Carrier** by the end of the disease. **Pathway:** * **Brucella → Lymph nodes → Blood → bacteremia** (not associated with fever). * **Septicemia** (fever) in some cases in sheep & goat. **Localization:** * **Male:** * **Testis & epididymis:** Orchitis & epididymitis. * **Joints:** Hygromas (inflammation of joints) * **Non-pregnant females:** * Udder & supramammary LN (become latent infection). * No multiplication wait till Erythritol secreted as Erythritol sugar secreted after 5th month of pregnancy. ### Clinical Signs: **Pregnant Female:** * **Gravid uterus:** Placentitis, necrosis, abortion (storm of abortion) & retained placenta. * **Abortion only for one time.** * **Spleen, Udder & Lymph nodes.** **Carrier:** * **Shedding of brucella is intermittent not continuous.** * **Diagnosis by serology in the early stage (bacteremia) (humoral immunity).** * **Diagnosis by cell mediated immunity (Brucellin test) in the late stage (facultative intracellular).** * **Storm of abortion** indicates an acute stage. **Chronic Infection:** * **Localization to reproductive organs.** * **No fever as it cause bacteremia only.** **Brucellosis in Cattle:** * **Third trimester abortions (storm of abortion) with retained placenta.** * Once a cow has aborted, subsequent gestations are normal. * **Birth of dead or weak calves** (die after birth). * **Small percentage (5%) have residual sterility.** * **Shed in large numbers in milk and reproductive tissues for life (carrier).** * **Aborted Fetus:** * Swollen due to excessive fluid in abdominal cavity. * **Umbilical cord:** thickened & swollen. * **Necrotic foci on liver of fetus.** * **Placenta:** swollen, necrosis & leathery appearance. **Conditions for Storm of Abortion:** * **Infection by specific etiology:** * The infection in the cattle herd must be caused by B. abortus, and not B. melitensis. * **1st time for infection (non-immune herd).** * **Pregnant animals at the same stage of pregnancy.** **Brucellosis in Bull:** * **Orchitis & epididymitis.** * **Seminal vesiculitis.** * **Arthritis & bursitis** (Hygroma) in joint → lameness. * **Insidious (unnoticed in action) form of brucella:** * No clinical signs but can cause something very bad at the end (secretly harmful). ### Brucella Melitensis: * **Most common species in the world:** Latin America, Middle East, Mediterranean, Eastern Europe, Asia & parts of Africa (Goats & camels → reservoir. * **Recent emergence in cattle:** Middle Eastern & intensive dairy farms. ### Brucellosis in Horses (B. abortus most common): * **Fistulous Withers or Poll Evil:** * Formation of inflammation of the supraspinous bursa. * Exudative process fills with clear viscous liquid. * Eventually rupture. ### Brucellosis in Sheep & Goat: * **Late-term abortions & Retained placenta.** * **Birth of dead or weak lambs/kids.** * **Goats:** Skeletal lesions articular & periarticular. * **Male:** Epididymitis - Orchitis - Fertility problems. * **Some fever** (due to septicemia). ### Brucellosis in Human: * **Undulant fever characteristic:** Intermittent or irregular fever with variable duration. * **Profuse bad odor sweating.** * **Headache, weakness, athralgia (pain joint), depression, weight loss & fatigue.** * **Liver dysfunction, CNS or heart disease** if not treated → more difficult outcome. ### Differential Diagnosis: * Diseases cause abortion in last trimester: * **Bacterial:** Leptospirosis, Listeriosis, Salmonellosis (sheep), Campylobacterosis & Chlamydiosis * **Viral:** RVF, IBR, BVD, BT & Akabane * **Parasitic:** Toxoplasmosis, Trichomoniasis * **Fungal:** Aspergillosis ### Treatment: * **Non in animals** (as Zoonotic Carriers). ### Treatment in Man: * **Doxycycline + Rifampin** (drug of choice). * **Tetracycline + Rifampin** * **Tetracycline + Streptomycin** * **Co-trimoxazole + Rifampin** * **Cephalosporines + Rifampin** ### Control: * **Brucella is difficult to control due to:** * **Latent infection:** sero-negative (false -ve). * **Vaccinated animals:** sero-positive (false +ve). * **Large No. of domestic & wild infected (Wide host).** * **Carrier animals & Latent infection** (facultative intracellular). * **Rodents, dogs which are the source of infection.** * **Up till now no specific serological test for detection.** * **Survival time & resistant for environment.** * **Role of dogs and rats in spreading of infection.** **1. Test & Slaughter:** * Regular testing every 1-3 month (MRT → Rose Bengal or ΒΑΡΑ → CFT). * **Positive in 3 tests:** slaughter * **Negative:** retested till get 3 successive negative test → retained. **2. Prevent Spread of Infection:** * **Notification (zoonotic).** * **Boiling milk at 70-75° C for 15-30 sec. can kill the M. O.** * **Quarantine:** * Isolation of infected animals & prevent movement. * Hygienic disposal of aborted fetus & fetal membrane. * Cleaning & disinfection. * Avoiding feeding of calves on infected milk from infected dams. * **Control of rodents, cats and dogs.** * **Newly introduced animals should be Br. free.** **3. Vaccination:** **Live Vaccine:** * **Strain 19 (calf hood vaccine).** * Live smooth strain B. abortus. * 5 ml S/C in 4-8 month age. * Give protection for 5 seasons (once in life). * **RB51 vaccine** * Live rough strain B. abortus. * 2 ml S/C for calves and adult. * Give protection for 2 years. * **Rev 1 vaccine** * Live strain B. melitensis. * For sheep & goat. * 1 ml S/C 3-6 month age once a life. **Live vaccine not used in pregnant.** **Killed Vaccine:** * **45/20 Abortex** * Killed rough strain B. abortus. * **Used in Anamnestic test** * 3 ml S/C or I/M * 2 doses, 1 month interval. * 4-8 month age & give protection for 1 year. * **H38 Aborlane Vaccine** * Killed strain B. melitensis. * For sheep & goat. **NB** * Carrier diseases → Brucella & FMD. * Zoonotic diseases difficult in T.T.T → Brucella & T.B * Diseases difficult in T.T.T → Bovine Leukosis.