Zoonosis r Refers to an infectious disease transferred between vertebrate animals and humans. r More common than may be publicly perceived r Individuals having the greatest level of animal exposure are at greatest risk for contracting a zoonotic infection r Another important source of zoonotic infection--disease transmission from domesticated pets to their owners and other contacts. r A final source of zoonotic infection—results from enroachment of humans on virgin environmentsFransicella tularensis Disease-Tularemia • Caused by contact with wild animals or domestic animals that had contact with wild animals dog after they have • 5-30% fatal if untreated Pathogenesis • Facultative intracellular parasites • Overall pattern is typhoid-like, i.e. affecting the reticulo-endothelial system producing high fever and septicemia • Main defense is cellular mediated • A potential germ-warfare agent Brucella abortus Disease – Brucellosis • Found primarily in cattle (abortions) • Humans acquire through occupational exposure•Perry, et al., Microbial Life, Sinaeur, Sanderland, MA, 2002, p. 698Bauman, R.W.., Microbiology, Pearson, New York, 2004, p. 695Black, J., Microbiology, 6th ed., Wiley, 2005, p. 695Bordatella pertussis Highlights Distinctive Properties ü Gram negative coccobacillus ü Nutritionally fastidious Disease--Whooping Cough Spread by aerosol droplets, or direct contact Epidemiology ü Once common and dangerous, has now decreased. ü Some countries still high ü Incidence increases when immunization decrease. ü Primarily a childhood diseaseSymptoms: The two most troubling symptoms are: 1 - Heavy mucoid secretions 2 - Dry cough which becomes paroxysmal The sharp intake of breath between the paroxysm of cough represents the person struggling for air and results in a whoop sound. The cough can become so severe that it can cause convulsions and cyanosis convulsion, sudden, violent, involuntary contraction of the muscles of the body, often accompanied by loss of consciousness. Cyanosis is a bluish discoloration of the skin or mucous membranes caused by lack of oxygen in the blood. Paroxysmal- spasmodic, brief automatic jerkingPathogenesis q Bacteria colonize the respiratory mucosa q Grow on ciliated epithelial cells; toxins kill cells q Bacteria stimulate inflammatory response q Also systemic effects caused by toxinsBauman, R.W.., Microbiology, Pearson, New York, 2004, p. 586Major concerns with this disease? • Highly communicable among susceptible infants less than one year old • Over 70% of fatal cases in children under 1 yr old. • Life threatening in infants with underlying cardiac/pulmonary disease. • Can cause neurological damage.Prevention The development of a vaccine made the disease uncommon in developed countries. But is still a major killer (hundreds of thousands) worldwide The original vaccine (cellular) had some undesirable side effects of vaccine which have been mostly eliminated with the new acellular versionBacteria in the Gastrointestinal Tract 1- Over_________ species of bacteria in the GI tract. 2- About ____ bacteria compared to _____cells in the body 3- __________% of indigenous flora of the large intestines are anaerobic. 4- ____________the most extensively studied organisms in the large intestines. 5- About _____% of the indigenous GI flora has not been cultured in the laboratory.Streptococci Lactobacilli Facultative Enterics / Related Anaerobes BacteroidesCharacteristics of Selected GI tract OrgansStomach Small Intestines Large Intestines High acid Constant Motion Undigested food residue High turnover of cells Bile Large numbers of bacteria Constant cleansing IgA Inhospitable Turnover of cells Relatively sterile Normal Flora Few bacteriaSalmonella Clinical Syndromes 1. Focal infection of Vascular Endothelium 2. Infections of Particular Organ Systems 3. Typhoid Fever—Salmonella typhi Source of symptoms- 4. Gastroenteritis--S.enterica -- food poisoning; Symptoms--Nausea, vomiting, myalgia, headache, diarrhea (might continue 2-7 days) Source of contamination--animal reservoir maintained by animal to animal spread and the use of Salmonella contaminated animals feedsShigella Representative Species Shigella flexneri— Shigella sonnei--causes shigellosis; Shigella dysenteriae <10-1000 bacteria can cause infection Transmission - Pathogenesis Fundamental event is invasion of the human colon; triggers inflammation response with ulceration of the mucosa and abscess formation leading to a bloody diarrhea Some strains produce a toxin (Shiga toxin) which contributes to the severity of the disease.Tortora, G., B.R. Funke and C.L. Case, Microbiology, 6th ed., Benjamin Cummings, Menlo Park, Ca, 1998, ISBN 0-8053-8535-5Tortora, G., B.R. Funke and C.L. Case, Microbiology, 6th ed., Benjamin Cummings, Menlo Park, Ca, 1998, ISBN 0-8053-8535-5Source: Schaecter, M., Mechanisms of Microbial Disease, 1999.Bauman, R.W.., Microbiology, Pearson, New York, 2004, p. 617Bauman, R.W.., Microbiology, Pearson, New York, 2004, p. 618Schaecter, M., et al. Mechanism of Microbial Disease, 3rd ed., Lippincott, Williams and Wilkins, New York, 1999. Page 219SyphilisSymptoms of Lyme Disease Primary Skin Rash (1/3 never develop) Flu-like symptoms Migratory joint pains Intermediate and Late Stages Confused with: Multiple Sclerosis Brain Tumor Stroke Mental Depression Alcoholism Personality Changes Alzheimers Disease Memory Loss ConcentrationChlamydiae Properties • Obligate Intracellular Parasite • Among smallest bacteria • Unabale to synthesize amino acids • No detectable murein • Unique developmental cycle EB--infective; dormant RB--10-100X larger; noninfectious; replicates Diseases 1.Chlamydia psittaci Infections--psittacosis contracted through inhalation of respiratory secretions or dust form drops of infected birds, especially parrots.1.Acute infection of lower respiratory tract. Occasionally become systemic--->myocarditis; encephalitis; hepatitis 2.Chlamydia trachomatis • Eye Infections-- Inclusion concunctivitis, acute infection; no permanent damage Trachoma--a chronic conjunctivitis; afflicts several hundred million worldwide. Has blinded millions particularly in Africa; control by improved sanitation and hygiene • Genital Infections--venereal disease caused by C. trachomatis is the number one STD. Clinical spectrum