dr. wael h. mansy , md assistant professor college of pharmacy king saud university
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Infectious Diseases. Dr. Wael H. Mansy , MD Assistant Professor College of Pharmacy King Saud University. Infectious Diseases. Study Objectives : to know. What is an infectious disease?? What is an infection?? Causes of re-emerging of the problem of the infectious diseases - PowerPoint PPT PresentationTRANSCRIPT
Dr. Wael H. Mansy, MDAssistant Professor
College of Pharmacy King Saud University
Infectious Diseases
Infectious Diseases
Study Objectives: to know 1. What is an infectious disease??2. What is an infection??3. Causes of re-emerging of the problem of the infectious diseases4. Microbiological Classification of Infectious Diseases.5. Means of Transmission of Infectious Diseases.6. The action of pathogen in infectious process (pathogenicity)7. What is infectivity ,virulence, Immunogenicity and incubation period .8. Manifestations of infectious process (Infection spectrum).9. The immune reaction of host in infectious process.10. Common symptoms and signs.
Infectious disease is:① A group of common diseases
② Caused by different pathogens
③ Possessing infectivity.
④ To form epidemic.
⑤ Infectious disease is a threat to the health of people.
What is an infectious diseases??
Infectious Diseases
A case is a risk factor …Infection in one person can be transmitted to others
What is an infectious disease??
Infectious Diseases
Definition of infection① Complex process of interaction between pathogen
and human body
② Infection is composed of three factors: pathogen, host and environment
③ There are commensalisms and opportunistic infection
What is an infection??
Infectious Diseases
Causes of re-emerging of the problem of the infectious diseases:
Infectious Diseases
1. Loss of Antibiotic Effectiveness.
2. Increased Population Density: Transmission from person to person is more likely.
3. Travel: Travelers may bring back pathogens.
4. Global Warming: May affect rainfall or other factors that currently affect diseases
or their carriers.
5. Biological Warfare or Terrorist Attacks: There have recently been a number of
threats of such attacks involving anthrax.
6. New Routes of transmission: Organ Transplants.
7. Complacency and Ignorance: Many, possibly most, people do not wash their hands
after using the toilet.
Bacterial Gram-negativeGram-positive
Viral DNA virusRNA virusEnveloped vs non-enveloped
Fungal DisseminatedLocalized
Parasitic ProtozoaHelminths
Microbiological Classification of Infectious Diseases
Contact Requires direct or indirect contact (fomite, blood, or body fluid)
Food or WaterIngestion of contaminated food or water
Airborne Inhalation of contaminated air
Vector-borne Dependent on biology of vector as well as infectivity of organism
Perinatal
Sexual
Similar to contact infection, however, the contact may occur in utero or during delivery. transmission by sexual intercourse.
Means of Transmission of Infectious Diseases
Factors Influencing Disease Transmission
• Weather• Housing• Geography• Occupational setting• Air quality• Food
EnvironmentAgent
Host• Age• Sex• Genotype• Behaviour• Nutritional status•Health status
• Infectivity• Pathogenicity• Virulence• Immunogenicity• Antigenic stability• Survival
The pathogenicity of pathogen is related to :
1. Invasiveness
2. virulent
3. Number of pathogen
4. Mutation (variability)
Pathogenicity What does pathogenicity mean???
It means the ability of a microbiological agent to induce disease
Infectious DiseasesFactors Influencing Disease Transmission( Agent)
Infectivity: Ability of agent to cause infectionNumber of infectious particles requiredIn person-to-person transmission, secondary attack rate is a measure of
infectivity
Infectious Diseases
Virulence :Severity of the disease after infection occurs.
Measured by case fatality rate or proportion of clinical cases that develop severe
disease.
Factors Influencing Disease Transmission( Agent)
Immunogenicity Ability of an organism to produce an immune response that provides protection
against reinfection with the same or similar agent
Can be life long or for limited periods
Important information for development of vaccines
Infectious DiseasesFactors Influencing Disease Transmission( Agent)
Infection and ImmunityManifestations of infectious process (Infection spectrum):1) Clearance of pathogen (no infection)2) Covert infection (subclinical infection)3) Overt infection (Clinical infection or apparent infection)4) Carrier states
Health carrier after covert infection. Convalescent carrier after overt infection. Incubatory carrier before onset of disease.
According to carrier time : #acute (transient) carrier #chronic carrier5) Latent infection.
Infectious Diseases
Direct tissue invasion: like smallpox
Production of a toxin: anthrax produce toxins that invade and
destroy tissue
Immunologic enhancement or allergic reaction
Persistent or latent infection
Enhancement of host susceptibility to drugs
Immune suppression
Pathogenetic Mechanisms:
Infectious Diseases
Cases Index – the first case identified Primary – the case that brings the infection into a population Secondary – infected by a primary case Tertiary – infected by a secondary case
Transmission
Infectious Diseases
P
S
S
T
Susceptible
Immune
Sub-clinical
Clinical
ST
Incubation period
Time between exposure and onset of symptoms or signs of infection.
Each disease has typical incubation period but varies widely.
Requires replication of the organism to some threshold level for producing
symptoms
Infectious Diseases
Tuberculosis Scarlet Fever tetanus Gonorrhea Diptheria Streptococcal Infections Pneumonia (can also be viral or fungal) Pertussis Bubonic Plague There are many others.
Bacterial Diseases
*Common Cold
*Influenza
*AIDS/HIV
*Herpes (Simplex and Zoster)
*Hepatitis A,B,C, D, E, F and G.
*Measles, Mumps and Rubella.
*Poliomyelitis.
*Infectious mononucleosis.
Viral Diseases
*Organisms, but without chlorophyll
*Generally life off of dead organisms or dead material within a living organism.
*Some are single cell organisms (yeast)
*Some are multi-cell organisms (mushrooms)
*Many are extremely valuable:
-yeasts give us bread and alcohol
-mushrooms.
*Can cause disease by releasing enzymes that damage cells or by producing toxins. Some mushrooms produce VERY deadly toxins.
Fungi
Fungal Diseases-Candidiasis.-Athlete’s foot - Tinea pedis-Jock itch - Tinea cruris-Nail fungus - Tineu unguis-Ringworm-Histoplasmosis-Over-the-counter medications are usually effective for mild
infections, except of the nails.-Systemic treatments can be prescribed for serious infections,
including the nails, and for histoplasmosis.
Fever: Three stages : effervescence fastigium deffervescence Five kinds of fever: *Sustained fever.
*Remittent fever: one that shows significant variations in 24 hours but without return to normal temperature. ,
*Intermittent fever: an attack of malaria or other fever, with recurring fever episodes separated by times of normal temperature ,
*Relapsing fever: alternating periods of fever and apyrexia, each lasting from five to seven days.
*Saddle type fever.
*Irregular fever.
Common symptoms and signs
Infectious Diseases
Mechanism of Fever
• Temperature is ultimately regulated in the hypothalamus. A
trigger of the fever, called a pyrogen, causes a release of
prostaglandin E2 (PGE2). PGE2 then in turn acts on the
hypothalamus, which generates a systemic response back to
the rest of the body, causing heat-creating effects to match a
new temperature level.
• A pyrogen is a substance that induces fever. These can be either internal (endogenous) or external (exogenous) to the body.
• The bacterial substance lipopolysaccharide (LPS), present in the cell wall of some bacteria, is an example of an exogenous pyrogen.
• Cytokines (especially interleukin 1) are a part of the innate immune system, are produced by phagocytic cells, and cause the increase in the thermoregulatory set-point in the hypothalamus. Other examples of endogenous pyrogens are interleukin 6 (IL-6), and tumor necrosis factor-alpha.
Mechanism of Fever
Rash eruption Date of eruption 1st: chickenpox 2nd: scarlet fever 3rd: smallpox 4th: measles 5th: typhus 6th: typhoid fever Location of eruption Form of rash Exanthema : *maculo-papular rash: A maculopapular rash is a flat, red area on the
skin that is covered with small confluent bumps e.g. measles.*Petechia: *Vesiculo-pustular rash *Urtecaria. Enanthema
Common symptoms and signsInfectious Diseases
Toxemic symptoms Mononuclear phagocyte system reactions Hepato- splenomegaly Lymph nodes enlargement Clinical types
acute, sub acute, mild, common, severe, fulminant, typical, atypical, abortive, ambulatory
Infectious DiseasesCommon symptoms and signs