Immunity and Immunity and InfectionInfection

Chapter 17Chapter 17

Immunity and infection 2

The Chain of InfectionThe Chain of Infection• Links in the ChainLinks in the Chain

– Transmitted through a chain (six links)Transmitted through a chain (six links)• Pathogen Pathogen - - disease causing microorganismdisease causing microorganism• Reservoir - natural environment of the pathogen: Person, Reservoir - natural environment of the pathogen: Person,

animal, or environmental componentanimal, or environmental component• Portal of ExitPortal of Exit• Means of transmissionMeans of transmission

– Direct transmissionDirect transmission– Indirect transmissionIndirect transmission

• Vectors – carrier of the pathogenVectors – carrier of the pathogen from one host to anotherfrom one host to another

• Portal of entryPortal of entry– Penetration of the skinPenetration of the skin– Inhalation through mouth or noseInhalation through mouth or nose– IngestionIngestion

• New hostNew host– Breaking the ChainBreaking the Chain

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Body’s Defense SystemBody’s Defense System

• Physical and Chemical barriersPhysical and Chemical barriers– Skin, mucous membranes, respiratory tractSkin, mucous membranes, respiratory tract

• The Immune SystemThe Immune System– Immunological DefendersImmunological Defenders

• NeutrophilsNeutrophils• Macrophages – “big eaters”Macrophages – “big eaters”• Natural killer cellsNatural killer cells• Dendritic cells – eat pathogens and activate lymphocytesDendritic cells – eat pathogens and activate lymphocytes• LymphocytesLymphocytes

– T-cellsT-cells• Helper, Killer, and SuppressorHelper, Killer, and Suppressor

– B-cellsB-cells• AntibodiesAntibodies

– Memory T and B cellsMemory T and B cells

Identify Body DefensesIdentify Body Defenses

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The Inflammatory The Inflammatory ResponseResponse

• Histamine.Histamine.• Dilation of blood vessels, heat, redness, and swelling.Dilation of blood vessels, heat, redness, and swelling.

• The immune responseThe immune response– Phase 1 – Dendritic cells are drawn to the sitePhase 1 – Dendritic cells are drawn to the site– Phase 2 – Helper T cells multiplyPhase 2 – Helper T cells multiply

• Production of Killer T and B cellsProduction of Killer T and B cells• Cytokines – chemical messengersCytokines – chemical messengers

– Phase 3 – Killer T cells strikePhase 3 – Killer T cells strike• Cell-mediated immuneCell-mediated immune• Antibody-mediated immune responseAntibody-mediated immune response

– Phase 4 – Last Phase – Phase 4 – Last Phase – • Suppressor T-cellsSuppressor T-cells• Slow down activitySlow down activity

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ImmunityImmunity

• An infected person will never get the An infected person will never get the same illness again.same illness again.

• Lymphocytes create amplification of the Lymphocytes create amplification of the immune response are reserved by immune response are reserved by memory T and B cellsmemory T and B cells

• Symptoms and contagionSymptoms and contagion– Incubation – viruses are multiplying in the Incubation – viruses are multiplying in the

body or when bacteria are actively multiplyingbody or when bacteria are actively multiplying• Will not feel symptoms until the second or third Will not feel symptoms until the second or third

phase of the immune response cyclephase of the immune response cycle– Prodromal period – the infected host has Prodromal period – the infected host has

acquired immunityacquired immunity

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ImmunizationImmunization

• The process of ‘priming’ the body to remember an The process of ‘priming’ the body to remember an encounter with a specific antigen.encounter with a specific antigen.

• Types of vaccinesTypes of vaccines– VACCINE- VACCINE- Introduction of a killed or weakened Introduction of a killed or weakened

pathogen to stimulate the body to produce antibodies.pathogen to stimulate the body to produce antibodies.

– ACTIVE IMMUNITY ACTIVE IMMUNITY - - person produces his or her person produces his or her own antibodies to the microorganismown antibodies to the microorganism..

– PASSIVE IMMUNITYPASSIVE IMMUNITY- - Injection of antibodies Injection of antibodies produced by other human beings or animals.produced by other human beings or animals.

– ACQUIRED IMMUNITY-ACQUIRED IMMUNITY-The ability of a The ability of a memory lymphocytes to remember a previous infection. memory lymphocytes to remember a previous infection. (chicken pox).(chicken pox).

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Immunization IssuesImmunization Issues

• Vaccine shortages in the U.S.Vaccine shortages in the U.S.• Vaccine safetyVaccine safety

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Allergy: The Body’s Allergy: The Body’s Defense System Gone Defense System Gone

HaywireHaywire• The Body’s Defense System Gone The Body’s Defense System Gone

HaywireHaywire– AllergiesAllergies– AllergensAllergens

• Pollen, Animal Dander, Dust mites and Pollen, Animal Dander, Dust mites and cockroaches, Molds, Food, Insectscockroaches, Molds, Food, Insects

– The Allergic responseThe Allergic response• Immunoglobulin (IgE)Immunoglobulin (IgE)• AnaphylaxisAnaphylaxis

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Dealing With AllergiesDealing With Allergies• AvoidanceAvoidance• MedicationMedication• Immunotherapy “allergy shotsImmunotherapy “allergy shots

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Pathogens and DiseasePathogens and Disease

• Bacterium – Bacterium – Microscopic single celled organismMicroscopic single celled organism– PneumoniaPneumonia– MeningitisMeningitis– Strep Throat and other streptococcal infectionsStrep Throat and other streptococcal infections– Toxic shock and other staphylococcal Toxic shock and other staphylococcal – TuberculosisTuberculosis– Tickborne infectionsTickborne infections– UlcersUlcers– Other Bacterial infectionsOther Bacterial infections

• TetanusTetanus• PertussisPertussis• Urinary tract infectionsUrinary tract infections

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Antibiotic TreatmentAntibiotic Treatment

• Actions of AntibioticsActions of Antibiotics• Antibiotic resistanceAntibiotic resistance• Proper antibiotics usageProper antibiotics usage

– Don’t take an antibiotic every time you Don’t take an antibiotic every time you are sickare sick

– Use antibiotics as directedUse antibiotics as directed– Never take an antibiotic without an Never take an antibiotic without an

prescriptionprescription

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Type of PathogensType of Pathogens• Viruses – (parasites – take what they need)Viruses – (parasites – take what they need)• Most common contagious diseaseMost common contagious disease

– Common ColdCommon Cold– InfluenzaInfluenza– Measles, Mumps and RubellaMeasles, Mumps and Rubella– Chickenpox, Cold Sores, and other herpes-virus infectionsChickenpox, Cold Sores, and other herpes-virus infections

• Varicella-zoster virusVaricella-zoster virus• Herpes simplex virus (HSV) types 1 and 2Herpes simplex virus (HSV) types 1 and 2• Epstein-Barr virus (EBV)Epstein-Barr virus (EBV)

– Viral encephalitisViral encephalitis– Viral hepatitisViral hepatitis– PoliomyelitisPoliomyelitis– RabiesRabies– Human papillomavirus (HPV)Human papillomavirus (HPV)

• TreatmentTreatment

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Types of PathogensTypes of Pathogens

• Fungi – Fungi – – Primitive plant – Yeast infections, athletes foot, jock itch, and Primitive plant – Yeast infections, athletes foot, jock itch, and

ringwormringworm– Candida albicansCandida albicans

• Protozoan – Protozoan – – Microscopic single-celled animal – Malaria, African sleeping Microscopic single-celled animal – Malaria, African sleeping

sickness, Giardiasis, Tricomonias, Trypanosomiasis, and Amoebic sickness, Giardiasis, Tricomonias, Trypanosomiasis, and Amoebic dysentary.dysentary.

• Parasitic wormParasitic worm – –– Largest organism that can enter the body – Tapeworm, Hookworm, Largest organism that can enter the body – Tapeworm, Hookworm,

and Pinworm.and Pinworm.• PrionsPrions – –

– Fetal degeneration disorders of the CNS, linked to “proteinaceous Fetal degeneration disorders of the CNS, linked to “proteinaceous infectious particles.infectious particles.

– Lack DNA and RNALack DNA and RNA– Transmissible spongiform encephalopathies (TSEs)Transmissible spongiform encephalopathies (TSEs)

• Spongelike holes in the brainSpongelike holes in the brain• Creutzfeldt-Jakob disease – HumanCreutzfeldt-Jakob disease – Human

– Bovine spongiform encephalopathy (BSE) or mad cow diseaseBovine spongiform encephalopathy (BSE) or mad cow disease

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Emerging Infectious Emerging Infectious DiseasesDiseases

• Selected Infections of concernSelected Infections of concern– West Nile virusWest Nile virus– Severe acute respiratory syndrome (SARS)Severe acute respiratory syndrome (SARS)– RotavirusRotavirus– Escherichia coli 0157:H7Escherichia coli 0157:H7– HantavirusHantavirus– EbolaEbola

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Factors Contributing to Factors Contributing to Emerging InfectionsEmerging Infections

• Drug ResistanceDrug Resistance• PovertyPoverty• Breakdown of public health measuresBreakdown of public health measures• Environmental changesEnvironmental changes• Travel and CommerceTravel and Commerce• Mass food production and distributionMass food production and distribution• Human behaviorsHuman behaviors• BioterrorismBioterrorism

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Other Immune Other Immune Disorders: Cancer and Disorders: Cancer and Autoimmune DiseasesAutoimmune Diseases

• If the immune system breaks downIf the immune system breaks down• Getting olderGetting older• HIV infectionHIV infection• ChemotherapyChemotherapy

• Autoimmune diseasesAutoimmune diseases– Rheumatoid arthritisRheumatoid arthritis– Systemic lupus erythmatosusSystemic lupus erythmatosus

Support Your Immune Support Your Immune SystemSystem

How to support your immune systemHow to support your immune systemGeneral guidelinesGeneral guidelines

• Balanced dietBalanced diet• Enough sleepEnough sleep• ExerciseExercise• Don’t smokeDon’t smoke• Moderation of Moderation of

alcoholalcohol• Wash your handsWash your hands• Avoid contact with Avoid contact with

contagious peoplecontagious people

• Plenty of clean Plenty of clean waterwater

• Avoid contact with Avoid contact with verminvermin

• Practice safe sexPractice safe sex• Do not use Do not use

Injectable drugsInjectable drugs• VaccinationsVaccinations• Controlling StressControlling Stress

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