Of Infectious Disease: Gu Junsheng

INTRODUCTION OF INFECTIOUS DISEASE The First Teaching Hospital of Zhengzhou University, Department of Infectious Disease

Gu Junsheng 1

SUMMARIZATIONS A new subject: Infectious Disease-- one of the most important clinical courses.

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SUMMARIZATIONS • In the past… • Nowadays: • HIV/AIDS • Bacillus anthracis/`Anthrax • Prion/v CJD (New Variant Creutzfeldt-Jackob Disease) • SARS • Bird flu • In the future 3

SUMMARIZATIONS Our topics of this term: Measles Epidemic Encephalitis B Viral Hepatitis AIDS SARS Epidemic Hemorrhagic Fever 4

SUMMARIZATIONS Our topics of this term:

Cholera (By Sun Changyu) Epidemic Cerebrospinal Meningitis Typhoid Fever (By Yu Zujiang) Bacillary Dysentery Bacteremia and Septicemia FUO 5

Definitions • Infectious Disease: • Caused by virus, bacteria, chlamydia, rickettsia, prion, fungus, spirochete, protozoa, helminth etc.

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Definitions • Infectious Disease • Communicable disease • Noncommunicable disease

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Definitions • Communicable Disease: • Caused by upper microorganisms • And be communicable

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INFECTION AND IMMUNITY Definitions: Infection: Interaction between pathogen and the host (results in different consequence) Opportunistic infection: During evolutionary process of microorganisms balance commensalism imbalance opportunistic infection 9

Pathogenecity of Pathogen • Pathogenecity: • Invasiveness: adherence • Virulence: exotoxin, endotoxin & other virulence factor • Quantity: • Variability:

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Immune Response of the Host During the Infection Process • Nonspecific immunity • Specific immunity:

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Immune Response of the Host During the Infection Process • Nonspecific immunity: skin

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Natural barrier: Phagocytosis Humoral factors

mucosa BBB

`complement lysozyme cytokines

interleukin TNF

interferon-γ 12

Immune Response of the Host During the Infection Process • Specific immunity: • Cell-Mediated Immunity • intracellular autoeciousness • T-cell • regulates humoral immunity • 13

Immune Response of the Host During the Infection Process • Specific immunity: • Humoral Immunity • B-cell plasma cell immunoglobulin: IgA IgD IgE IgG IgM

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Infection Process (Infection spectrum) • • • • •

Clearance of pathogen Covert infection /subclinical infection Overt infection /clinical infection Carrier state Latent infection

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Infection Process (Infection spectrum) • Clearance of pathogen: • Cleared by: • 1.nonspecific immunity • 2.specific immunity(prior, foregoing) • vaccination • Immunoglobulin active immunity • passive immunity 16

Infection Process (Infection spectrum) • Covert infection /subclinical infection: • 1. Very light damage • 2. Asymptomatic • 3. Only induces specific immune response and can be tested by immunological tests 17

Infection Process (Infection spectrum) • Overt infection /clinical infection: • 1.Symptomatic (the damage is severe) • 2.Result in: • clearance of pathogen always with a stable post-infection immunity or • chronic carrier state • latent infection 18

Infection Process (Infection spectrum) • Carrier state: • Common character: • 1. Asymptomatic • 2. Carrying & discharging pathogen

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Infection Process (Infection spectrum) • Latent infection: • The pathogen and the host cant not beat each other. • Latent infection can become overt infection when stress comes or immunity is inhibited. • Asymptomatic • No pathogen discharged • eg.vericella-zoster virus (chichenpox in children & herps zoster in adults) 20

Infection Process • The most common type: • The most typical type:

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Infection Process • Questions: difference between each type? • The difference between type 1 (clearance of pathogen) and type 2 (covert infection/subclinical infection) ? • The difference between carrier state and latent infection ? 22

Basic Conditions of the Process of Communicable Disease Sources of infection: patients covert infection ones carriers infected animals

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Basic Conditions of the Process of Communicable Disease Routes of transmission: respiratory tract digestive tract contact blood sex `arthropod 24

Basic Conditions of the Process of Communicable Disease Routes of transmission: horizontal transmission vertical transmission congenital transmission

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Basic Conditions of the Process of Communicable Disease Susceptible persons: different susceptibility of different groups

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Basic Character of Communicable Disease • • • •

Pathogen Infectivity Epidemiologic feature Post-infection immunity

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Basic Character of Communicable Disease • Pathogen:

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virus, bacteria, chlamydia, rickettsia, prion, fungus, spirochete, protozoa, helminth, etc.

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Basic Character of Communicable Disease • Infectivity • Communicable

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Basic Character of Communicable Disease • Epidemiologic feature : • sporadic occurrence: normal • epidemic: with a higher morbidity than that in normal time • pandemic:in a large area • epidemic outbreak:in a short time 30

Basic Character of Communicable Disease • Post-infection immunity: • IgM • IgG

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Clinical Features • Phases of the course: • Incubation period • Prodromal period • Period of apparent manifestation • Convalescent period

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Clinical Features • Phases of the course: • Incubation period: • asymptomatic

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Clinical Features • Phases of the course: • Prodromal period: • nonspecific clinical manifestations such as: headache, fever, fatigue, inappetent, etc.

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Clinical Features • Phases of the course: • Period of apparent manifestation: • specific rashes, hepatomegaly, splenomegaly, jaundice etc.

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Clinical Features • Phases of the course: • Convalescent period:

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Clinical Features • Other features: • recrudescence • relapse

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Common Symptoms & Signs • Pyrexia: • effervescence • fastigium • defervescence

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Common Symptoms & Signs • Eruption • Following rashes can be seen in eruptive infectious disease. • 1. maculopapule

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Common Symptoms & Signs • Eruption • Following rashes can be seen in eruptive infectious disease. • 2. petechia

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Common Symptoms & Signs • Eruption • Following rashes can be seen in eruptive infectious disease. • 3.`vesicle

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Common Symptoms & Signs • Eruption • Following rashes can be seen in eruptive infectious disease. • 4. urticaria

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Common Symptoms & Signs • Toxemic symptoms: Discomfort, fatigue, inappetent, headache, etc caused by metabolite and toxins of the pathogen.

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Common Symptoms & Signs • Reaction of the Monocyte-Macrophage system: hepatomegaly splenomegaly lymphadenectasis

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DIAGNOSIS • Diagnosis of communicable disease should be depended on information from: • 1. Epidemiology • 2. History of disease: symptoms & signs • 3. Laboratory tests

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TREATMENT • • • • •

General treatment: Supportive treatment: Etiologic treatment: Symptomatic treatment: Rehabilitative therapy:

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PREVENTION • Management of the source of infection: • I. plague, cholera, SARS, AIDS • II. viral hepatitis, measles, epidemic hemorrhagic fever, epidemic cerebrospinal meningitis, typhoid fever, bacillary dysentery

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III. mumps, influenza.etc

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PREVENTION • Cut off the transmitting route:

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PREVENTION • Protection of the susceptible persons:

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