Host-Parasite Interaction PDF

Host–Parasite Interaction Dr. Elena Enioutina Objectives List Koch’s postulates Define terms used to describe host-parasite interactions Describe microorganism capabilities that lead to disease Describe host barriers to infection Define host factors that lead to disease Discuss micr...

Host–Parasite Interaction Dr. Elena Enioutina Objectives List Koch’s postulates Define terms used to describe host-parasite interactions Describe microorganism capabilities that lead to disease Describe host barriers to infection Define host factors that lead to disease Discuss microbiome and its role in host defenses Summarize disease transmission  The Nobel Prize in Physiology/Medicine 1905 was awarded to Robert Koch "for his investigations and discoveries in relation to tuberculosis”. Koch also laid down the conditions, known as Koch’s postulates, which must be satisfied before it can be accepted that particular bacteria cause particular diseases https://www.nobelprize.org/prizes/medici ne/1905/summary/  Koch’s Postulates 1. The microorganism must be present in every case of the infectious disease. 2. The microorganism can be isolated in pure culture. 3. Inoculation of the pure culture into animals produces a similar disease. 4. The same species of microorganism must be recovered from the diseased animal. Define Host: an animal (human) or plant on or in which a parasite or commensal organism lives Parasite: an organism that lives in or on an organism of another species (its host) and benefits by deriving nutrients at the other's expense Define Pathogen: a microorganism capable of causing an infectious disease. Primary pathogen: microorganism that regularly causes infection and disease when it enters a healthy host. Opportunistic pathogen: microorganism that rarely causes disease in healthy humans but may in a host whose defense mechanisms have been compromised or weakened. Year Disease Causative Agent 1872 Anthrax Bacillus anthracis 1874 Leprosy Mycobacterium leprae 1879 Gonorrhea Neisseria gonorrhoeae 1882 Tuberculosis Mycobacterium tuberculosis 1883 Cholera Vibrio cholerae 1884 Diphtheria Corynebacterium diphtheriae 1884 Tetanus Clostridium tetani 1975 Lyme disease Borrelia burgdorferi 1976 Legionnaire’s disease Legionella pneumophila 1976 Ebola Ebola virus 1983 AIDS Lymphadenopathy-Associated Virus* 1989 stomach ulcers Helicobacter pylori 1993 Hemorrhagic Fever Hanta virus 1995 Cat Scratch Disease Bartonella henselae …also, Botulism, Brucellosis, Measles, Mumps, Whooping Cough Define Infection: invasion and multiplication of microorganisms in or on a host. A disease process may or may not be present. It may cause an immune response. Symptoms may be sub-clinical. Virulence: the degree of pathogenicity and extent to which a microorganism can cause damage to the infected host (variable due to individual host, infectious dose, and portal of entry) Carrier: an infectious host that, because of inherited genetic traits, either does not develop symptoms of disease or carries an organism in a latent state. (Symptoms may develop later, such as Herpes reactivation following stress). World Best Known Carrier Mary Mallon “Typhoid Mary” To establish an infectious disease, an organism must: Invade and proliferate Be capable of Reach the host and Overcome in the host tissues and resisting host find a protal of entry host defenses produce toxins or other defenses virulence factors Microbial factors leading to disease Evade immune response Antibiotic cleaving Ability to attach Can inhibit chemotaxis, phagocytosis Exotoxins Endotoxins Enterotoxin Clinical Microbiology Made Ridiculously Simple, by Mark Gladwin et al., MedMaster, Inc., 2019, pp. 11. Take to Exam Microbial factors leading to disease Tissue tropism Excrete enzymes Hyaluronidase splits hyaluronic acid, a component of connective tissue Collagenase Hemolysins lyse red blood cells Fibrinolysin, ketatinase, lecithinase, IgA proteases, etc. Slime layers / Biofilms Host defenses 15 Anatomic barriers: Skin: Sweat, lactic acid, free fatty acids Respiratory tract: Mucus and ciliated epithelium GI tract: Stomach acid, mucus, peristalsis, villi and microvilli Microbiome throughout the body https://www.123rf.com/  Host defenses  Innate defenses  Neutrophils and Macrophages  Lysozymes in saliva and tears  Complement and opsonins  Adaptive immune responses  Antibody  T cell mediated responses https://cellcartoons.net/phagocytosis/ Host factors leading to disease Behaviors Hematoproliferative disorders Occupation Burns Age/genetics/sex Steroid therapy Prior viral infections Prior course of antibiotics Splenectomy Immunosuppressive drugs Diabetes Take to Exam  Microbiome plays critical role in host defense against microbial infections Microbiome  Microbiome: A community of microorganisms living in a particular environment  The human microbiome is composed of bacteria, archaea, viruses and eukaryotic microbes that reside in and on our bodies.  Microbes impact our physiology:  metabolic functions,  protect against pathogens,  educate the immune system YOUR body is an Ecosystem! Missing Sea Otters New York Times January 5, 1999 OTTERS ORCAS Sea Urchins Sea Lions Clams (More food, easy to Mussels catch) Peaceful Co-Existence for Centuries! 90% Reduction in Sea Otter Population! Where’d they go? Whalers reduce whale population Proliferation of Plankton Proliferation of Pollock Competition by Pollock with nutritious, high-fat fish like Herring and Ocean Perch, reducing primary food for Sea Lions and Seals Commercial Fishing and global warming also contribute to decrease of Herring and Ocean Perch Decline in Sea Lions and Seals, reducing primary food for Orcas Orcas eat Otters Bacterial Microbiome Blum, Hubert E. "The human microbiome." Advances in medical sciences 62.2 (2017): 414-420. https://www.asm.org/image s/stories/documents/Colloqu iaDoc/Microbiome%20Infogra phic.pdf, accessed 6/14/17  Antibiotics and microbiome  Antibiotic administration can result in gut microbiota dysbiosis, i.e., disturbance in composition and function  Effects of Antibiotic-Induced Microbiota Alterations on:  Increased Susceptibility to Infections  Compromised Immune Homeostasis and Tolerance (Atopic, inflammatory and autoimmune diseases have been linked to gut microbiota dysbiosis) Francino MP. Antibiotics and the Human Gut Microbiome: Dysbioses and  Deregulated Metabolism (obesity has been Accumulation of Resistances. Front Microbiol. 2016;6:1543. Published 2016 Jan 12. doi:10.3389/fmicb.2015.01543 associated with phylum-level changes in the gut microbiota, reduced bacterial diversity) Infectious Disease Causation/Transmission Endogenous sources Breaks in natural barriers Change in host defense mechanisms Infectious Disease sources Exogenous source Inhalation Fomites Ingestion Animal contact, "zoonosis" Direct contact or Arthropod vector inoculation Congenital o Transplacental o Birth canal Routes of transmission Oral and mucous membrane: fecal-oral fomites Percutaneous: cuts and scratches Respiratory: needles, punctures droplets arthropods droplet nuclei Take to Exam  Reservoir  Human reservoirs (measles, mumps, streptococcal infection)  Animal reservoirs (brucellosis - cows and pigs, anthrax - sheep, plague – rodents)  Zoonosis is an infectious disease that is transmissible under natural conditions from vertebrate animals to humans  Environmental reservoirs (soil, water, plants) https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section10.ht ml Droplet spread Droplet nuclei Direct contact  80% of infectious diseases are transmitted by touch  The order for removing PPE  Gloves  Eye Protection  Apron or Gown  Surgical Mask Perform hand hygiene immediately on removal. All PPE should be removed before leaving the area and disposed of as healthcare waste. https://www.cdc.gov/ Thank you! Any questions, please email me.