1. Dr. Wael H. Mansy, MD Assistant Professor College of Pharmacy King Saud University 2009 Infectious Diseases

2. 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 diseases 4.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.

3. Infectious disease is :  A group of common diseases  Caused by different pathogens  Possessing infectivity.  To form epidemic.  Infectious disease is a threat to the health of people. What is an infectious diseases?? Infectious Diseases

4. A case is a risk factor …  Infection in one person can be transmitted to others What is an infectious disease?? Infectious Diseases

5. Definition of infection  Complex process of interaction between pathogen and human body  Infection is composed of three factors: pathogen, host and environment  There are commensalisms and opportunistic infection What is an infection?? Infectious Diseases

6. 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.

7. BacterialGram-negative Gram-positive ViralDNA virus RNA virus Enveloped vs non-enveloped FungalDisseminated Localized ParasiticProtozoa Helminths Microbiological Classification of Infectious Diseases

8. ContactRequires direct or indirect contact (fomite, blood, or body fluid) Food or Water Ingestion of contaminated food or water AirborneInhalation of contaminated air Vector-borneDependent 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

10. 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

11. 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 Diseases Factors Influencing Disease Transmission( Agent)

12. Infectivity:  Ability of agent to cause infection  Number of infectious particles required  In 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)

13. 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 Diseases Factors Influencing Disease Transmission( Agent)

14. Infectious Diseases The immune reaction of host in infectious process will be :

15. Barriers for Defense Against Infection: Infectious Diseases 1.Skin:  Prevents entry of infectious organisms, unless injured.  Severe burn patients who die are usually killed by infections. So much skin is damaged they are very vulnerable to infections. 2.Mucus membrane:  Mucous is usually rich in enzymes that will kill many pathogens 3.Cilia :  These are hair-like structures lining the respiratory tract. They work to sweep foreign particles out of the respiratory tract.  Damaged by smoking, leaving smokers more vulnerable to infections. 4.Coughing:  Helps remove foreign material from respiratory tract. 5.Personal Hygiene  Helps reduce the number of pathogenic organisms on the skin and other surfaces of the body.

16. Infection and Immunity Manifestations of infectious process (Infection spectrum): 1) 1) Clearance of pathogen (no infection) 2) 2) Covert infection (subclinical infection) 3) 3) Overt infection (Clinical infection or apparent infection) 4) 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 carrier 5) 5) Latent infection. Infectious Diseases

17.  like smallpox  Direct tissue invasion: like smallpox  produce toxins that invade and destroy tissue  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

19. P S S T Susceptible Immune Sub-clinical Clinical S T 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

20. 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

21.  Tuberculosis  Scarlet Fever  tetanus  Gonorrhea  Diptheria  Streptococcal Infections  Pneumonia (can also be viral or fungal)  Pertussis  Bubonic Plague  There are many others. Bacterial Diseases

22. *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

23. *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

24. 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.

25. Fever:  Three stages : effervescence fastigium fastigium deffervescence deffervescence   Five kinds of fever: *Sustained 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

26. 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. hypothalamusPGE2 hypothalamusPGE2

27.  A pyrogen is a substance that induces fever. These can be either internal (endogenous) or external (exogenous) to the body. internalendogenousexternalexogenousinternalendogenousexternalexogenous  The bacterial substance lipopolysaccharide (LPS), present in the cell wall of some bacteria, is an example of an exogenous pyrogen. lipopolysaccharide  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. Cytokinesinterleukin 1 innate immune systemphagocytic cellsinterleukin 6 tumor necrosis factor-alpha Cytokinesinterleukin 1 innate immune systemphagocytic cellsinterleukin 6 tumor necrosis factor-alpha Mechanism of Fever

28.  PGE2 acts on neurons in the preoptic area (POA) through the prostaglandin E receptor 3 (EP3). EP3-expressing neurons in the POA innervate the dorsomedial hypothalamus (DMH), the rostral raphe pallidus nucleus in the medulla oblongata (rRPa) and the paraventricular nucleus (PVN) of the hypothalamus. preoptic areaprostaglandin E receptor 3dorsomedial hypothalamusraphemedulla oblongata paraventricular nucleus hypothalamuspreoptic areaprostaglandin E receptor 3dorsomedial hypothalamusraphemedulla oblongata paraventricular nucleus hypothalamus Mechanism of Fever

29.  Fever signals sent to the DMH and rRPa lead to stimulation of the sympathetic output system, which evokes non- shivering thermogenesis to produce body heat and skin vasoconstriction to decrease heat loss from the body surface. sympathetic  It is presumed that the innervation from the POA to the PVN mediates the neuroendocrine effects of fever through the pathway involving pituitary gland and various endocrine organs pituitary glandendocrine organspituitary glandendocrine organs Mechanism of Fever

30. Rash eruption Date of eruption 1 st : chickenpox 2 nd : scarlet fever 3 rd : smallpox 4 th : measles 5 th : typhus 6 th : typhoid fever Location of eruption Form of rash Exanthema : A maculopapular rash is a flat, red area on the skin that is covered with small confluent bumps e.g. measles. *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 signs Infectious Diseases

31.   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 Diseases Common symptoms and signs