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 ie burns skin lesions ID: 780274
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Slide1
Infectious Diseases
Slide2Pathogens: 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)
Slide3In 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
Slide4Infectious 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.
Slide5Types 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.
Slide6Salmonella
Typhi
Slide7Yersinia
Pestis
Slide8Staphylococcus
aureus
Slide9Viruses: 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.***
Slide10You Tube
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Slide11Types 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.
Slide12Smallpox
Slide13Viruses (continued)
Myxoviruses and paramyxoviruses: cause influenza, measles, and mumps.
Rotaviruses: cause gastroenteritis.
Retroviruses: cause AIDS and several types of cancer.
Slide14Measles, Mumps, Influenza
Slide15Fungi: 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.
Slide16Fungi: Ringworm,
Histoplasmosis
, Candida genus
Slide17Protozoa: 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.
Slide18Helminths
: 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
:
Trichinella
Spiralis
: 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
trichinella
spiralis
***
Slide19Helminths
Slide20Trichinella
Spriralis
Slide21Prions: Infectious particles that consist of only protein.
Diseases caused by Prions:
Creutzfeldt-Jakob disease (in humans)***
Bovine spongiform encephalopathy (mad cow disease)
Slide22Prions
Slide23Epidemiology- 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.
Slide24Host 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)
Slide25Specific 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