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PRINCIPLES OF DISEASE AND EPIDEMIOLOGY.

PRINCIPLES OF DISEASE AND EPIDEMIOLOGY. By Dr. Ijeoma Otigbuo. Alias Dr. E.J. PATHOLOGY, INFECTION, AND DISEASE. Pathology. Etiology. Pathogenesis. Infection. Disease. Relationship Of Microorganisms To Healthy Human Body. Normal Microbiota. Normal Flora. Transient Microbiota.

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PRINCIPLES OF DISEASE AND EPIDEMIOLOGY.

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  1. PRINCIPLES OF DISEASE AND EPIDEMIOLOGY. By Dr. Ijeoma Otigbuo. Alias Dr. E.J.

  2. PATHOLOGY, INFECTION, AND DISEASE. • Pathology. • Etiology. • Pathogenesis. • Infection. • Disease.

  3. Relationship Of Microorganisms To Healthy Human Body. • Normal Microbiota. • Normal Flora. • Transient Microbiota.

  4. RELATIONSHIPS B/W NORM MICROBIOTA AND HOST. • Microbial Antagonism. • Symbiosis: Commesalism, Mutualism, Parasitism.

  5. OPPORTUNISTIC MICROORGANISMS. • Opportunistic Pathogens. • E. coli. • Pneumocystis carinii. • Streptococcus pneumoniae. • Cooperation Among Microorganisms.

  6. THE ETIOLOGY OF INFECTIOUS DISEASES. • Koch’s Postulates: • The same pathogen must be present in every case of the disease • The pathogen must be isolated from the diseased host and grown in pure culture • The pathogen from the pure culture must cause the disease when it is inoculated into a healthy susceptible lab.animal

  7. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism. • Exceptions to Koch’s postulates: Treponema pallidum, Mycobacterium leprae, Mycobacterium tuberculosis.

  8. CLASSIFYING INFECTIOUS DISEASES. • Symptoms. • Signs. • Syndrome. • Communicable disease. • Contagious disease. • Noncommunicable disease

  9. THE OCCURRENCE OF DISEASE. • Incidence. • Prevalence. • Sporadic disease. • Endemic disease. • Pandemic disease.

  10. THE SEVERITY OR DURATION OF DISEASE. • Acute disease. • Chronic disease. • Subacute disease. • Latent disease. • Herd Immunity.

  11. THE EXTENT OF HOST INVOLVEMENT. • Local infection. • Systemic(generalized) infection. • Focal infection. • Bacteremia. • Septicemia. • Toxemia.

  12. Viremia. • Primary infection. • Secondary infection. • Subclinical(inapparent) infection.

  13. PATTERNS OF DISEASE. • A definite sequence of events usually occurs during infection and disease. • There must be a reservoir of infection as a source of pathogens for an infectious disease to occur. • Pathogen must be transmitted to a susceptible host by direct contact, by indirect contact, or by vectors.

  14. Transmission is followed by invasion, in which the microorganism injures the host through a process called pathogenesis. • The extent of injury depends on the degree to which host cells are damaged, either directly or by toxins. • Occurrence of disease ultimately depends on the resistance of the host to the activities of the pathogen.

  15. PREDISPOSING FACTORS. • Gender. • Genetic background. • Climat and weather. • Inadequate nutrition.Fatigue. • Age. • Environment. • Habits.

  16. Lifestyle. • Occupation. • Prexisting illness. • Chemotherapy. • Emotional disturbances.

  17. THE DEVOLOPMENT OF DISEASE. • The Incubation Period. • The Prodromal Period. • The Period of Illness. • The Period of Decline. • The Period of Convalascence.

  18. THE SPREAD OF INFECTION. • Reservoirs of Infection: • Human ( Carriers ) • Animal (Zoonoses ) • Nonliving

  19. THE TRANSMISSION OF DISEASE. • SEE NEXT SLIDE FOR TYPES OF TRANSMISSION.

  20. CONTACT TRANSMISSION. • Direct contact: Shaking hands. • Indirect contact: Formites. • Droplet: Air.

  21. VEHICLE TRANSMISSION. • Waterborne: Cholera. • Foodborne: Clostridium. • Airborne: Histoplasmosis.

  22. VECTORS. • Mechanical. • Biological.

  23. PORTALS OF ENTRY. • Portals of exit: Respiratory and Gastrointestinal tracts, Urogenital tract.

  24. NOSOCOMIAL(HOSPITAL-ACQUIRED) INFECTIONS. • Results from the Interaction of Several Factors: • Microbes in the hospital environment • The compromized (or weakened) status of the host, and • The chain of transmission in the hospital.

  25. Microorganisms in the hospital. • The Compromised host. • The Chain of Transmission. • The Control of Nosocomial Infections.

  26. THE CONTROL OF NOSOCOMIAL INFECTIONS. • Aseptic Techniques. • Education. • Hand washing. • Disinfection. • Infection Control Committee.

  27. EMERGING INFECTIOUS DISEASES. • Factors that that contribute to the emergence of new infectious diseases include: • A new serovar such as Vibrio cholera. • Global warming. • Known diseases. • Previously unrecognized infections may appear.

  28. Animal control measures may affect the incidence of a disease. • Failures in public health measures may be a contributing factor to the emergence of previously controlled infections.

  29. CDC, NIH, AND WHO PRIORITIES. • To detect , promptly investigate, and monitor emerging infectious pathogens, the disease they cause, and factors that influence their emergence. • To expand basic and applied research on ecological and environmental factors, microbial changes and adaptations, and host interactions that influence EIDs.

  30. To enhance the communication of public health information and the prompt implementation of prvention strategies regarding EIDs. • To establish plans to monitor and control EIDs worldwide.

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