Brucellosis.pptx

Contain notes on brucellosis

1. Brucellosis Dr Okanga

2. Introduction Brucellosis is a systemic infection caused by intracellular bacteria of the genus Brucella transmitted from animals to humans (zoonosis). 4 species commonly cause disease in humans; B. melitensis (goats, sheep and camels), B. abortus (cattle), B. suis (pigs) and B. canis (dogs). Freezing dairy products or meat does not destroy the organisms but they are killed by pasteurization and boiling. The organisms are shed in animal urine, stool and products of conception, and remain viable in soil for 40 days or more.

3. Epidemiology The global incidence of human brucellosis is difficult to determine. B. melitensis is the most common cause of brucellosis in the world. Worldwide, the incidence of human and animal brucellosis is increasing because of: Expansion of animal industries with a lack of scientific and modern methods of animal husbandry. Traditional eating habits, standards of personal and environmental hygiene, methods of processing milk and its products, and the Rapid movement of animals, both locally and internationally

4. Mode of Transmission Ingestion of untreated dairy products, raw meat, liver or bone marrow is a common route of infection through the GI tract. Inhalation of the organisms is the most frequent route as an occupational hazard among herdsmen, dairy-farm workers, workers in meat-processing factories and laboratory workers. Penetration by pieces of bone or intact or abraded skin is a route of infection among slaughter house workers.

5. Pathogenesis Shortly after the entry of bacteria through the mucosa, polymorphonuclear leukocytes and activated macrophages migrate to the site of access. Lipopolysaccharides on the surface of Brucella are recognized by these cells, which deliver signals to activate macrophages and facilitate phagocytosis of bacteria. Brucellae multiply in the endoplasmic reticulum of macrophages without affecting host cell integrity. The organisms are then released by induced cell necrosis and lysis.

6. Pathogenesis After entry to the human body and being taken by local tissue lymphocytes, Brucellae are later transferred through lymphatics to regional lymph nodes, then via the bloodstream to all organs of the body, particularly the reticuloendothelial system. The localization process of the organisms in body organs may be associated with inflammatory cellular infiltrates with or without granulomatous formation, caseation, necrosis or even abscess formation.

7. Clinical Features Incubation period of brucellosis is about 1–3 weeks but may extend up to several months. Brucellosis presents as a febrile illness, with or without localization to particular body organs. Common symptoms include – Fever, Chills, Sweating, Body aches, Lack of energy, Joint pain, Back pain, Headaches, Loss of appetite, Weight loss, Constipation. Abdominal pain and Diarrhoea . Signs - Ill-looking, Pallor, Lymphadenopathy, Splenomegaly, Hepatomegaly, Arthritis, Spinal tenderness, Epididymo -orchitis, Skin rash, Jaundice, heart murmurs and CNS abnormalities.

8. Localizations Can present as septic monoathritis , spondylitis and osteomyelitis. Most commonly affected joints include hip, knee, sternoclavicular, sacroiliac, shoulder and sternum. Cardiovascular localization may result in endocarditis, myocarditis, pericarditis, aortic root abscess, myotic aneurysms, thrombophlebitis and pulmonary embolism. Hilar and paratracheal lymphadenopathy; pneumonia. Mesenteric lymphadenopathy with abscess formation, cholecystitis, peritonitis, pancreatitis and ulcerative colitis.

9. Localizations… Unilateral or bilateral epididymo-orchitis. Dysmenorrhoea , amenorrhoea , tubo -ovarian abscesses, chronic salpingitis, and cervicitis. CNS - meningoencephalitis, multiple cerebral or cerebellar abscesses, ruptured mycotic aneurysm, cranial nerve lesions, transient ischaemic attacks, hemiplegia, myelitis and, Guillain–Barré syndrome. Brucella in pregnancy - normal delivery of healthy infants, abortion, intrauterine fetal death, premature delivery, or retention of the placenta, as well as transmission to infants through breast milk

10. Diagnosis Culture of the organism from the blood, body fluids or tissues. Positive blood culture yield ranges between 40% and 70%. Detection of antibodies against Brucella - Due to the similarity of the O. polysaccharide of Brucella to that of various other Gram-negative bacteria (e.g. Francisella tularensis , E. coli, Salmonella Urbana, Yersinia enterocolitica, Vibrio cholerae, Stenotrophomonas maltophilia ) the appearance of cross-reactions of class M immunoglobulins may occur .

11. Treatment A combination of doxycycline plus streptomycin (DS) or of doxycycline plus rifampicin (DR), As both streptomycin and rifampicin are active against Mycobacterium tuberculosis, tuberculosis must be excluded as the cause of the patient’s illness before these agents are used. Doxycycline is given in an oral dose of 100 mg 12-hourly for 6 weeks. Streptomycin is administered intramuscularly, in a single daily dose of 15 mg/kg for 2–3 weeks. Rifampicin is used in a single oral daily dose of 600–900 mg for 6 weeks. Other regimens – Doxycycline 60 days and Gentamycin or netilmicin 2wks, Cotrimoxazole 960mg od plus Doxycycline or Rifampicin for 2 to 3 months.

12. Treatment … Patients with localizations such as spondylitis, endocarditis, neurobrucellosis and abscess formations in body organs may require hospitalization for possible surgery and triple antibiotics (doxycycline, aminoglycoside and rifampicin) should be used for a longer period of up to 6 months.

13. Prognosis and Prevention The mortality of the disease is 2%. The most frequent cause of death is endocarditis. Prevention of human brucellosis can be achieved by eradication of the disease in animals by vaccination and other veterinary control methods such as testing herds/flocks and slaughtering animals when infection is present – Requires prolonged commitment and financial support. Boiling milk before consumption or before using it to produce other dairy products is protective against transmission via ingestion, Patients who have had brucellosis should probably be excluded indefinitely from donating blood or organs

14. Prevention … Education of the community to desist from eating raw meat, liver or bone marrow - difficult to implement. Currently, no effective vaccine is available for humans

15. Summary Brucellosis is a zoonosis. Elimination of human disease depends on the prevention and control of animal infections. In endemic settings, brucellosis typically affects rural pastoralist communities with inadequate access to healthcare and preventive education. The commonest clinical features is fever, accompanied by musculoskeletal problems in almost half of patients. Most important differential diagnosis is tuberculosis, especially in localized infections. The diagnosis should be confirmed by prolonged cultures (when available) of blood or other sterile fluids, e.g. joint aspirates or by serological tests. Treatment regimens should include at least two antimicrobial agents for 6 weeks minimum, in order to prevent relapse. Aminoglycoside-containing regimens are superior.

16. Shigellosis (Bacillary Dysentery) Caused by four species, Shigella dysenteriae , Sh. flexneri , Sh. boydii and Sh. sonnei , Shigella species are members of the Enterobacteriaceae and are aerobic, Gram-negative, non-motile bacilli.

17. Epidemiology Man is the only natural host for infection by Shigella spp. Infection is by ingestion, the infective dose being as low as 10–100 bacteria for Sh. dysenteriae . Incubation period is 1–5 days. Shigellosis occurs as an endemic disease in conditions of crowding, poor sanitation and inadequate water supply and is primarily a disease of poor disadvantaged communities in the tropics. Routes of infection include direct person-to-person transmission (from cases or asymptomatic excreters)

18. Pathogenesis Shigella dysentery is characterized by invasion of the colonic mucosa, local spread of the infecting organism and death of intestinal epithelial cells. Some patients develop extraintestinal complications; seizures, hyponatraemia and hypoglycaemia , septicaemia , Reiter syndrome, encephalopathy and the haemolytic – uraemic syndrome.

19. Clinical Features May vary from relatively mild watery diarrhoea to severe dysentery with intestinal and extraintestinal complications. In severe cases, the onset is abrupt, with tenesmus, fever and frequent passage of bloody, mucoid stools. Diarrhoea is often accompanied by fever, headache and malaise. Intestinal complications include toxic megacolon, perforation and a protein-losing enteropathy.

20. Clinical algorithm in the differential diagnosis of diarrhoea .

21. Diagnosis In many parts of the tropical world, the diagnosis and subsequent management of Shigella infections occur in the absence of laboratory facilities. Typical feature - acute diarrhea with visible blood in the stools. Culture.

22. Treatment Requires appropriate rehydration and electrolyte therapy, antimicrobial treatment and the management of complications. Antiobitic of choice – Ciprofloxacin, levofloxacin

23. Prevention and Control Shigellosis is primarily a disease of crowded and usually poor communities, living in an environment characterized by inadequate sanitation and often polluted water. The incidence of shigellosis will be reduced only by improved public health, the alleviation of poverty and improvement in hygiene particularly through the provision of soap for hand washing.