Microbe Human Interactions: The Host Parasite Relationship
In Chapter 13, we explore the complex interactions between microbes and humans, focusing on the transmission of infection and the development of disease. The human body is constantly exposed to
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About Microbe Human Interactions: The Host Parasite Relationship
PowerPoint presentation about 'Microbe Human Interactions: The Host Parasite Relationship'. This presentation describes the topic on In Chapter 13, we explore the complex interactions between microbes and humans, focusing on the transmission of infection and the development of disease. The human body is constantly exposed to. The key topics included in this slideshow are . Download this presentation absolutely free.
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Slide1Chapter 13 Chapter 13 Microbe-Human Interactions: Infection and Disease Microbe-Human Interactions: Infection and Disease
Slide2Contact-Infection-Disease: The Host-Parasite Relationship Contact-Infection-Disease: The Host-Parasite Relationship The human body is constantly in contact (contaminated) with microbes The human body is constantly in contact (contaminated) with microbes ► Some are pathogens that may cause an infection by circumventing the host defense system, entering normally sterile tissues, and multiplying there ► Some are pathogens that may cause an infection by circumventing the host defense system, entering normally sterile tissues, and multiplying there ► When infections lead to a disruption in tissues, infectious disease results ► When infections lead to a disruption in tissues, infectious disease results ► The outcome is highly variable, but most contacts do not result in infection, and most infections do not lead to disease ► The outcome is highly variable, but most contacts do not result in infection, and most infections do not lead to disease
Slide3Associations between microbes and humans Associations between microbes and humans
Slide4The Body as a Habitat The Body as a Habitat ► The resident flora or microflora is a huge and rich mixed population of microorganisms residing on body surfaces exposed to the environment, including the skin, mucous membranes, parts of the gastrointestinal tract, urinary tract, reproductive tract, and upper respiratory tract ► The resident flora or microflora is a huge and rich mixed population of microorganisms residing on body surfaces exposed to the environment, including the skin, mucous membranes, parts of the gastrointestinal tract, urinary tract, reproductive tract, and upper respiratory tract
Slide5The Body as a Habitat The Body as a Habitat ► Anatomical sites lying within the body cavity (organs) and fluids (blood, urine) in those sites do not harbor flora ► Anatomical sites lying within the body cavity (organs) and fluids (blood, urine) in those sites do not harbor flora ► Colonization: begins just prior to birth and continues over an individual’s life; variations occur in response to individual differences in age, diet, hygiene, and health ► Colonization: begins just prior to birth and continues over an individual’s life; variations occur in response to individual differences in age, diet, hygiene, and health
Slide6Normal Flora Normal Flora Bacteria may maintain a balance in the normal conditions Bacteria may maintain a balance in the normal conditions Studies with axenic animals (free of any normal flora) show that flora contribute to the development of the immune and gastrointestinal systems and also to some diseases (dental caries) Studies with axenic animals (free of any normal flora) show that flora contribute to the development of the immune and gastrointestinal systems and also to some diseases (dental caries) Normal flora are sometimes agents of infection Normal flora are sometimes agents of infection
Slide7Landscape of the skin Landscape of the skin ► Microbes live only in upper dead layers of epidermis glands, and follicles; dermis and layers below are sterile ► Microbes live only in upper dead layers of epidermis glands, and follicles; dermis and layers below are sterile
Slide8Distribution of flora in the gastrointestinal tract Distribution of flora in the gastrointestinal tract ► Oral cavity: colonize the epidermal layer of cheeks, gingiva, pharynx; surface of teeth; found in saliva in huge numbers ► Oral cavity: colonize the epidermal layer of cheeks, gingiva, pharynx; surface of teeth; found in saliva in huge numbers ► Large intestine and rectum have huge numbers of flora ► Large intestine and rectum have huge numbers of flora
Slide9Colonized regions of the respiratory tract Colonized regions of the respiratory tract ► The moist mucous blanket of the nasopharynx has a well-entrenched flora. ► The moist mucous blanket of the nasopharynx has a well-entrenched flora. ► Lower regions of bronchi, bronchioles, and lungs are free of resident microbes. ► Lower regions of bronchi, bronchioles, and lungs are free of resident microbes.
Slide10Flora of the reproductive tract Flora of the reproductive tract ► In females, the external genitalia, vaginal, and cervical surfaces have flora ► In females, the external genitalia, vaginal, and cervical surfaces have flora ► In females, the first portion of the urethral mucosa has flora. ► In females, the first portion of the urethral mucosa has flora. ► In males, the entire reproductive and urinary tract is sterile, except for a short portion of the anterior urethra ► In males, the entire reproductive and urinary tract is sterile, except for a short portion of the anterior urethra
Slide11Factors Affecting the Course of Infection and Disease Factors Affecting the Course of Infection and Disease
Slide12Pathogenicity and Virulence Pathogenicity and Virulence Pathogenicity is the property of microorganisms to cause infection and disease Pathogenicity is the property of microorganisms to cause infection and disease Virulence is the precise factors used by the microbe to invade and damage host tissues; it helps define the degree of pathogenicity Virulence is the precise factors used by the microbe to invade and damage host tissues; it helps define the degree of pathogenicity Pathogenicity varies with a microbe’s ability to invade or harm host tissues and with the condition of host defenses Pathogenicity varies with a microbe’s ability to invade or harm host tissues and with the condition of host defenses A true pathogen produces virulence factors that allow it to readily evade host defenses and to harm host tissues A true pathogen produces virulence factors that allow it to readily evade host defenses and to harm host tissues ► True pathogens can infect normal, healthy hosts with intact defenses ► True pathogens can infect normal, healthy hosts with intact defenses An opportunistic pathogen is not highly virulent but can cause disease in persons whose host defenses are compromised by predisposing conditions such as age, genetic defects, medical procedures, and underlying organic disease An opportunistic pathogen is not highly virulent but can cause disease in persons whose host defenses are compromised by predisposing conditions such as age, genetic defects, medical procedures, and underlying organic disease
Slide13Mechanisms of Infection and Disease Mechanisms of Infection and Disease ► The portal of entry is the route by which microbes enter the tissues, primarily via skin, alimentary tract, respiratory tract (pneumonia), urogenital tract (sexually transmitted diseases), or placenta ► The portal of entry is the route by which microbes enter the tissues, primarily via skin, alimentary tract, respiratory tract (pneumonia), urogenital tract (sexually transmitted diseases), or placenta
Slide14Transplacental infection of the fetus Transplacental infection of the fetus ► Microbes penetrate the maternal blood vessels and enter the blood pool of the placenta. ► Microbes penetrate the maternal blood vessels and enter the blood pool of the placenta. ► They then invade the fetal circulation by way of the umbilical vein ► They then invade the fetal circulation by way of the umbilical vein
Slide15Mechanisms of Infection and Disease Mechanisms of Infection and Disease Pathogens that come from outside the body are exogenous; those that originate from normal flora are endogenous Pathogens that come from outside the body are exogenous; those that originate from normal flora are endogenous The size of the infectious dose is of great importance The size of the infectious dose is of great importance
Slide16Mechanisms of Infection and Disease Mechanisms of Infection and Disease ► In the process of adhesion, a microbe attaches to the host cell by means of fimbriae, flagella, capsules, or receptors that position it for invasion ► In the process of adhesion, a microbe attaches to the host cell by means of fimbriae, flagella, capsules, or receptors that position it for invasion
Slide17Virulence Factors Virulence Factors ► Exoenzymes digest epithelial tissues, disrupt tissues, and permit invasion ► Exoenzymes digest epithelial tissues, disrupt tissues, and permit invasion
Slide18Virulence Factors Virulence Factors Toxigenicity is a microbe’s capacity to produce toxins at site of multiplication which affect cellular targets Toxigenicity is a microbe’s capacity to produce toxins at site of multiplication which affect cellular targets ► Toxinoses are diseases caused by toxins that damage structure or function of host cells ► Toxinoses are diseases caused by toxins that damage structure or function of host cells ► Toxemia refers to toxins absorbed into the blood ► Toxemia refers to toxins absorbed into the blood ► Intoxication means ingestion of toxins ► Intoxication means ingestion of toxins
Slide19Virulence Factors Virulence Factors ► An exotoxin is a protein secreted by living bacteria with powerful effects on a specific organ ► An exotoxin is a protein secreted by living bacteria with powerful effects on a specific organ ► Examples are hemolysins and tetanus and diphtheria toxins ► Examples are hemolysins and tetanus and diphtheria toxins ► An endotoxin is the lipopolysaccharide portion of a gram-negative cell wall released when a bacterial cell dies; causes generalized symptoms such as fever ► An endotoxin is the lipopolysaccharide portion of a gram-negative cell wall released when a bacterial cell dies; causes generalized symptoms such as fever
Slide20Virulence Factors Virulence Factors ► Antiphagocytic factors include leukocidins (white blood cell poisons) and capsules ► Antiphagocytic factors include leukocidins (white blood cell poisons) and capsules
Slide21Effects on Target Organ/Spread of Infection Effects on Target Organ/Spread of Infection ► Patterns of Infection: Stages in Infection/Disease ► Patterns of Infection: Stages in Infection/Disease Incubation period, the period from contact with infectious agent until appearance of first symptoms Incubation period, the period from contact with infectious agent until appearance of first symptoms Prodromium, a short period of initial, vague symptoms Prodromium, a short period of initial, vague symptoms Period of invasion, a variable period during which microbe multiplies in high numbers and causes severest symptoms Period of invasion, a variable period during which microbe multiplies in high numbers and causes severest symptoms Convalescent period, a period of recovery, with decline of symptoms Convalescent period, a period of recovery, with decline of symptoms
Slide22Types of Infectious/Diseases Types of Infectious/Diseases Localized infection, microbe remains in isolated site Localized infection, microbe remains in isolated site Systemic infection, microbe is spread through the tissues by circulation Systemic infection, microbe is spread through the tissues by circulation Focal infection, microbe spreads from local site to entire body (systemic) Focal infection, microbe spreads from local site to entire body (systemic) Mixed infection, several microbes cause one type of infection simultaneously Mixed infection, several microbes cause one type of infection simultaneously Primary infection, the initial infection in a series Primary infection, the initial infection in a series Secondary infection, a second infection that complicates a primary infection Secondary infection, a second infection that complicates a primary infection Septicemia and bacteremia refer to microbes in the blood Septicemia and bacteremia refer to microbes in the blood Acute infection appears suddenly, has a short course, and is relatively severe Acute infection appears suddenly, has a short course, and is relatively severe Chronic infection persists over a long period of time Chronic infection persists over a long period of time Subacute infection has a pattern between acute and chronic Subacute infection has a pattern between acute and chronic
Slide23Types of Infectious/Diseases Types of Infectious/Diseases
Slide24Signs and Symptoms: Manifestations of disease, indicators of pathogenic effects on target organs Signs and Symptoms: Manifestations of disease, indicators of pathogenic effects on target organs A sign is objective, measurable evidence noted by an observer A sign is objective, measurable evidence noted by an observer ► Examples include septicemia, change in number of white blood cells; skin lesions; inflammation; necrosis, lysis or death of tissues ► Examples include septicemia, change in number of white blood cells; skin lesions; inflammation; necrosis, lysis or death of tissues ► A symptom is a subjective effect of disease as sensed by patient ► A symptom is a subjective effect of disease as sensed by patient ► Examples are pain, fatigue, and nausea ► Examples are pain, fatigue, and nausea ► A syndrome is a disease that manifests as a predictable complex of symptoms; infections that do not show symptoms are called asymptomatic, subclinical, or inapparent ► A syndrome is a disease that manifests as a predictable complex of symptoms; infections that do not show symptoms are called asymptomatic, subclinical, or inapparent
Slide26Major portals of exit of infectious diseases Major portals of exit of infectious diseases ► Through the portal of exit, microbe is released with bodily secretions and discharges to have access to new host; portals include respiratory droplets from sneezing, coughing, saliva, skin, feces, urogenital tract (urine, mucus, semen) and blood ► Through the portal of exit, microbe is released with bodily secretions and discharges to have access to new host; portals include respiratory droplets from sneezing, coughing, saliva, skin, feces, urogenital tract (urine, mucus, semen) and blood ► A microbe may become dormant (latent) and cause recurrent infections ► A microbe may become dormant (latent) and cause recurrent infections ► Damaging effects that remain in organs and tissues after infection are sequelae ► Damaging effects that remain in organs and tissues after infection are sequelae
Slide27EpidemiologyEpidemiology Epidemiology is a science that determines the factors influencing causation, frequency, and distribution of disease in a community Epidemiology is a science that determines the factors influencing causation, frequency, and distribution of disease in a community ► Epidemiologists are involved in surveillance of reportable diseases in populations and consider measures to protect the public health ► Epidemiologists are involved in surveillance of reportable diseases in populations and consider measures to protect the public health ► They are concerned with disease statistics such as prevalence (the total number of cases), incidence (the number of new cases), morbidity (general health of the population), and mortality (death) ► They are concerned with disease statistics such as prevalence (the total number of cases), incidence (the number of new cases), morbidity (general health of the population), and mortality (death)
Slide28Graphical representation of epidemiological data Graphical representation of epidemiological data
Slide29Frequency of Disease Frequency of Disease ► Endemic, a disease constantly present in a certain geographic area ► Endemic, a disease constantly present in a certain geographic area ► Sporadic, a disease that occurs occasionally with no predictable patter ► Sporadic, a disease that occurs occasionally with no predictable patter ► Epidemic, sudden outbreak of disease in which numbers increase beyond expected trends ► Epidemic, sudden outbreak of disease in which numbers increase beyond expected trends ► Pandemic, worldwide epidemic ► Pandemic, worldwide epidemic
Slide30Origin of Pathogens Origin of Pathogens ► The reservoir is a place where the pathogen ultimately originates (its habitat) ► The reservoir is a place where the pathogen ultimately originates (its habitat) ► Source of infection refers to the immediate origin of an infectious agent ► Source of infection refers to the immediate origin of an infectious agent ► Carrier is an individual that inconspicuously shelters a pathogen and spreads it to others ► Carrier is an individual that inconspicuously shelters a pathogen and spreads it to others
Slide31Carriers in transmission of infectious agents Carriers in transmission of infectious agents Asymptomatic carrier is infected without symptoms Asymptomatic carrier is infected without symptoms Incubation carriers carry early in disease Incubation carriers carry early in disease Convalescent carriers carry in last phases of recovery Convalescent carriers carry in last phases of recovery Chronic carriers carry for long periods after recovery Chronic carriers carry for long periods after recovery Passive carriers are uninfected but convey infectious agents from infected persons to uninfected ones by hand and instrument contact Passive carriers are uninfected but convey infectious agents from infected persons to uninfected ones by hand and instrument contact
Slide32Vectors/ZoonosesVectors/Zoonoses ► A vector is an animal that transmits pathogens ► A vector is an animal that transmits pathogens ► A biological vector is an alternate animal host (mosquito, flea) that assists in completion of life cycle of microbe ► A biological vector is an alternate animal host (mosquito, flea) that assists in completion of life cycle of microbe ► A mechanical vector is an animal that does not host microbial life cycle, but is a short-term transmitter (housefly) ► A mechanical vector is an animal that does not host microbial life cycle, but is a short-term transmitter (housefly) ► A zoonosis is an infection for which animals are the natural reservoir and host that can be transmitted to humans ► A zoonosis is an infection for which animals are the natural reservoir and host that can be transmitted to humans
Slide34Acquisition of Infection Acquisition of Infection ► Communicable infectious disease occurs when pathogen is transmitted from host to host directly or indirectly; contagious diseases are readily transmissible through direct contact ► Communicable infectious disease occurs when pathogen is transmitted from host to host directly or indirectly; contagious diseases are readily transmissible through direct contact
Slide35Acquisition of Infection Acquisition of Infection ► Non-communicable diseases are not spread from host to host; acquired from one’s normal flora (pneumonia) or from a nonliving environmental reservoir (tetanus) ► Non-communicable diseases are not spread from host to host; acquired from one’s normal flora (pneumonia) or from a nonliving environmental reservoir (tetanus)
Slide36Acquisition of Infection Acquisition of Infection ► Direct transmission ► Direct transmission Infectious agent is spread through direct contact of portal of exit with portal of entry (STDs, herpes simplex) Infectious agent is spread through direct contact of portal of exit with portal of entry (STDs, herpes simplex) ► Indirect transmission ► Indirect transmission A material (vehicle) contaminated with pathogens serves as intermediate source of infections A material (vehicle) contaminated with pathogens serves as intermediate source of infections A fomite is an inanimate object contaminated with pathogens (public facilities, personal items) A fomite is an inanimate object contaminated with pathogens (public facilities, personal items) Food serves as a vehicle Food serves as a vehicle Droplet nuclei are airborne dried particles containing infectious agents, formed by sneezing and coughing Droplet nuclei are airborne dried particles containing infectious agents, formed by sneezing and coughing
Slide37Acquisition of Infection Acquisition of Infection ► Nosocomial infections are infectious diseases that originate in the hospital or clinical setting ► Nosocomial infections are infectious diseases that originate in the hospital or clinical setting They commonly occur among surgical and chronically ill patients They commonly occur among surgical and chronically ill patients Hospitals monitor various asepsis procedures to help reduce the number of infections Hospitals monitor various asepsis procedures to help reduce the number of infections Isolation of patients and other universal precaution are necessary controls Isolation of patients and other universal precaution are necessary controls
Slide38Koch’s Postulates Koch’s Postulates ► Koch’s postulates defines a series of criteria that must be followed to determine the etiologic (causative) agent of disease ► Koch’s postulates defines a series of criteria that must be followed to determine the etiologic (causative) agent of disease