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Infectious Diseases

Infectious Diseases. Pathogens: Microorganisms that are capable of causing disease Infection: Results when a pathogen invades and begins growing within the host Disease: Results only if and when normal tissue function is impaired

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Infectious Diseases

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  1. Infectious Diseases

  2. Pathogens: Microorganisms that are capable of causing disease • Infection: Results when a pathogen invades and begins growing within the host • Disease: Results only if and when normal tissue function is impaired • The body has defense mechanisms to prevent infection (i.e. burns, skin lesions)

  3. In order to cause disease, pathogens must be able to enter, adhere, invade, colonize, and inflict damage • Entrance to the host typically occurs through natural orifices such as the mouth, eyes, genital openings, or through wounds that breach the skin barrier to pathogens • Growth of pathogens or the production of toxins/enzymes cause disease • Some normal flora prevent diseases

  4. Infectious Disease – a disease caused by the invasion of a host by pathogens causing impaired tissue function and can be transmitted to other individuals Five major types of infectious agents (microbes): bacteria, viruses, fungi, protozoa, and helminthes: • Bacteria: They contain no organized internal membranous structures. Most reproduce by growing and dividing into two cells in a process known as binary fission.

  5. Types of Bacteria: • Salmonella typhi: a gram-negative organism that causes typhoid fever. • Yersinia pestis- Causes plague The reservoir is rodents. *** • Staphylococcus aureus- causes skin, respiratory and wound infections.

  6. Salmonella Typhi

  7. Yersinia Pestis

  8. Staphylococcus aureus

  9. Viruses: Infect all organisms from plants and animals to fungi and bacteria. They are not organisms themselves because apart from a host cell, they have no metabolism and cannot reproduce.***

  10. You Tube • http://www.freetech4teachers.com/2013/10/a-fun-video-about-cold-prevention.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+freetech4teachers%2FcGEY+%28Free+Technology+for+Teachers%29#.UmkMKj_aJ-V

  11. Types of viruses: • Herpes viruses: cause chicken pox, cold sores, and painful genital lesions, and the pox virus that causes smallpox. • Rhinoviruses: cause most common colds.

  12. Smallpox

  13. Viruses (continued) • Myxoviruses and paramyxoviruses: cause influenza, measles, and mumps. • Rotaviruses: cause gastroenteritis. • Retroviruses: cause AIDS and several types of cancer.

  14. Measles, Mumps, Influenza

  15. Fungi: Reproduce primarily by forming spores. Types of diseases caused by fungi: • Ringworm • Histoplasmosis (a mild to severe lung infection transmitted by bat or bird droppings) • Candida genus: opportunistic pathogens*** that may cause diseases such as vaginal yeast infections and thrush.

  16. Fungi: Ringworm, Histoplasmosis, Candida genus

  17. Protozoa: Do not have cell walls and are capable of a variety of rapid and flexible movements. • Can be acquired by contaminated food or water or by the bite of an infected arthropod such as a mosquito.

  18. Helminths: Simple, invertebrate animals, some of which are infectious parasites. Difficult to treat because the drugs that kill helminthes are frequently very toxic to human cells. Diseases caused by helminths: • TrichinellaSpiralis: occurs when improperly cooked pork from infected pigs is ingested. • Symptoms include vomiting and diarrhea and fever*** • Respiratory paralysis can occur in fatal cases of trichinellaspiralis***

  19. Helminths

  20. TrichinellaSpriralis

  21. Prions: Infectious particles that consist of only protein. • Diseases caused by Prions: • Creutzfeldt-Jakob disease (in humans)*** • Bovine spongiform encephalopathy (mad cow disease)

  22. Prions

  23. Epidemiology- the study of the occurrence of disease in populations. • Disease reservoirs- The reservoir for a disease where the infectious agent survives (example: rodents, soil • Modes of transmission: Infectious agents may be transmitted through either direct or indirect contact.

  24. Host defenses against infectious diseases: • Nonspecific mechanisms-the body’s primary defense against disease – these include anatomical barriers to invading pathogens, physiological deterrents to pathogens, and presence of normal flora. (skin, low pH and high salinity)

  25. Specific mechanisms of host resistance- our immune system • Immunity – when a host encounters an antigen that triggers a specific immune response for the second time and the body responds quickly and produces antibodies • Vaccination- produces immunity

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