Brucellosis PDF

Brucellosis ILOs At the end of this session, the student will be able to: § Recognize brucellosis as a common occupational zoonotic illness. § Demonstrate knowledge of the causative agent, and mode of transmission § Understand the pathogenesis of acute and chronic brucello...

Brucellosis ILOs At the end of this session, the student will be able to: § Recognize brucellosis as a common occupational zoonotic illness. § Demonstrate knowledge of the causative agent, and mode of transmission § Understand the pathogenesis of acute and chronic brucellosis. § Recognize brucellosis as a possible diagnosis of fever, joint and back pain. § Recognize brucellosis as a cause of PUO in endemic areas. § Understand the possibility of progressing to a chronic nature if not properly treated. § Recognize complications of brucellosis § Collaborative clinical presentation and laboratory testing in reaching a diagnosis. § Discuss treatment regimens for the disease. Introduction ´ It is also called undulant fever, Malta fever or Mediterranean fever. ´ Until the early 20th century, the disease was endemic in Malta to the point of it being referred to as "Maltese fever". Since 2005, due to a strict regimen of certification of milk animals and widespread use of pasteurization, the illness has been eradicated from Malta. Brucellosis is a zoonotic disease due to most often one of three species: 1. Brucella abortus 2. Brucella melitensis 3. Brucella suis Aerobic G-ve bacilli or coco-bacilli. They are non-motile and non-sporing. They are intracellular pathogens.  Antigens and cross reaction: They are two lipopolysaccharides surface antigens in agglutination reaction. M and A antigens. M predominates in Br.melitensis, A predominates in abortus and suis Epidemiology ´ Infected animals are the reservoirs from which human are infected. ´ Br abortus ( bovines are reservoirs), Br melitenesis ( goats, camels and sheep), Br suis( pigs). Mode of transmission: Ingestion of contaminated unpasteurized milk. Soft cheeses and milk products from unpasteurized milk also transmit the infection. This is because the shorter time for preparation does not allow PH to fall sufficiently to kill organisms. Brucella are acid sensitive. Milk is neutralizing gastric acid, allowing organisms to survive transient through the stomach, duodenum where they enter the mucosa. (persons are high risk those taking antacicds, H2 antagonists). Contacts with infected animals or animal products (placenta, membranes, carces, milk). Brucella can enter through abrasions, cuts in hand. Aerosols of infected fluids are also source of infection and entry of organisms can take place through nasopharynx or contact with conjunctiva. Workers in microbiology labs who handle infected specimens are at high risk. Blood transfusion Bone marrow and kidney transplants Congenital infection is reported as in infection through human breast milk. Inhalation of contaminated dust in hot dry countries may be a source of infection as brucella is capable of surviving in environments for longer periods. Pathogenesis: Once brucella crossed epithelial cells, the organisms are phagocytosed by neutrophils and macrophages which then pass to local LNs. Organisms are then retained in this site but replicate intracellularly and bacteria from lysed cells can infect other cells or disseminate.  Pathology: Granuloma formation: liver and spleen are more involved. Necrosis with pus formation Micro abscess formation. lymph glands and spine are more usual sites. Clinical manifestations: 1. IP: 2-4 weeks 2. Acute illness The onset of the disease is either sudden or insidious. Manifestations include swinging temperature (39oC to 41oC) with chills and rigors, excessive sweating, headache, anorexia, lethargy and prostration, often musculoskeletal pain and arthralgia and constipation. On examination: the spleen is slightly enlarged and tender (20%); lymphadenopathy especially in children (10%); tender spines. Relapse occurs most often in the first 2 months after treatment. Joint and bone involvement: § Arthritis is common, severe and disabling, common with Br. Melitenesis. § Large joints are commonly affected (lumber spine, sacroiliac joint, hips and knees). § Vertebral infection can produce abscess which may protrude laterally, anteriorly. § Posterior abscess can compress spinal cord or cauda equine. § Psoas abscess occasionally § Septic arthritis with organisms isolated from joint fluid. Localized infections: § Epididymo-orchitis is present in 5-9% of cases. § pyelonephritis and glomerulonephritis § pulmonary involvement § endocarditis, pericarditis § neurologic involvement: papilledema, cranial cerebritis, meningoencephalitis, parkinsonian syndrome, spinal cord compression, cauda equine syndrome, acute poliomyelitis, monoradiculopathy, polyradiculopathy § lymphadenopathy and abdominal lymphoid hyperplasia § skin rash § ocular involvement § brucellosis in pregnancy can result in abortion especially in 1st trimester. 3. Chronic brucellosis: ´ 77% have symptoms for 2ms. ´ 13% have symptoms lasting 2-12 ms. ´ 10% have symptoms for a year. ´ Intermittent fever and splenomegaly may be found. ´ Manifested by recurrent bouts of headache, malaise, musculoskeletal pain, extreme fatigue and depression. It may remain undiagnosed for many years. Diagnosis of Brucellosis: Laboratory findings 1. Normal or slightly reduced Hb level. 2. Leucopenia below 4000 and lymphocytosis in 50% of cases. 3. Reduced platelets count in 10% of cases and DIC has been seen. 4. Moderate elevation of transaminases and alkaline phosphatase. Culture: Blood culture. Clot culture is frequently positive. Bone marrow culture give 90% +ve results. Any pus should be cultured. Serology: Serum agglutination test: A titer of 1/160 is suggestive. It remains positive for longer periods. The main agglutinating Ab is IgM. ELISA PCR Negative agglutination can occur even when the organisms can be cultured. This is the Prozone phenomenon. A titre of 1/160 is associated with infection and below this titre does not exclude infection. § This test can extended by 2- mercaptoethanol test which inactivates IgM. § If the initial high +ve titer is reduced to a low level after adding 2-me: this suggests that IgM is the major Ab, and the infection is recent. § If the titer is not affected by the addition of 2-me: this suggests that IgG Ab is present, and the infection is long standing.  Predominantly labile 2-me test indicates low chance of relapse after treatment. IgG disappear after 30ms after treatment. Differential Diagnosis: Cerebral malaria Relapsing fever Cerebral tumor Infectious mononucleosis Typhoid fever Rheumatic fever Pulmonary tuberculosis Infective endocarditis Treatment of brucellosis: Streptomycin: 1gm IM daily for 14-21 days together Doxycycline 200mg/daily for 6-8 weeks. Longer duration of treatment needed when there is evidence of joint, neurologic lesions and endocarditis. Doxycycline: 200mg daily for 6 weeks plus Rifampicin 600mg daily for 6 weeks. However the above combination can’t be given to children under 8 years and in pregnant so, cotrimoxazole and Rifampicin is appropriate. Quinolones: are thought to be active.