human infectious

• Viruses


  Can't multiply outside a living host cell
• Growing Bacteriophages in the Laboratory

  Bacteriophages can be grown either in suspensions of bacteria in liquid media or in bacterial cultures on solid media
• Viral Identification


  Viruses can't be seen without the use of an electron microscope
• Oncogenes


  Cancer-causing alterations to cellular DNA that affect parts of the genome
• Oncogenic viruses


  Viruses capable of inducing tumors in animals
• DNA Oncogenic Viruses


  • Adenoviridae
  • Herpesviridae
  • Poxviridae
  • Papovaviridae
  • Hepadnaviridae
• Virtually all cervical and anal cancers are caused by human papillomavirus (HPV)
• Another DNA virus that causes cancer is hepatitis B virus (HBV)
• RNA Oncogenic Viruses


  • Retroviruses in the family Retroviridae
• Prions


  Infectious proteins that cause neurological diseases
• Viroids


  Acellular particles that are virus-like
• The first viroid discovered was found to cause potato tuber spindle disease, which causes slower sprouting and various deformities in potato plants
• Categories of human diseases

  • Degenerative diseases
  • Immune disorders
  • Infectious diseases
  • Metabolic disorders
  • Neoplasms (cancers and other types of tumors)
  • Nutritional disorder
  • Psychiatric disorder
• Microbial intoxications


  Follow ingestion of a toxin produced outside the body (in vitro) by a pathogen
• Infectious diseases (infections)


  Follow colonization of some body site by a pathogen
• Some infectious diseases affect more than one anatomic site
• Some pathogens move from one body site to another during the course of a disease
• Lecture outline


  • Infectious Diseases of the Skin
  • Infectious Diseases of the Ears
  • Infectious Diseases of the Eyes
  • Infectious Diseases of the Respiratory System
  • Infectious Diseases of the Oral Region
  • Infectious Diseases of the Gastrointestinal Tract
  • Infectious Diseases of the Genitourinary System
  • Infectious Diseases of the Circulatory System
  • Infectious Diseases of the Central Nervous System
  • Opportunistic Infections
  • Emerging and Reemerging Infectious Diseases
• Intact skin


  • Nonspecific host defense mechanism
  • Physical barrier
  • Body's first line of defense
  • Few pathogens can penetrate intact skin (low pH, presence of chemical substances (lysozyme and sebum), and indigenous microbiota)
• Epidermis


  The superficial portion of the skin

  
• Dermis


  The inner layer of skin, containing blood and lymphatic vessels, nerves, nerve endings, glands, and hair follicles

  
• Sebaceous gland


  Glands in the dermis that usually open into hair follicles and secrete an oily substance known as sebum
• Hair follicle


  The sac that contains a hair shafts
• Dermatitis


  Inflammation of the skin, an infection from Staphylococcus, Streptococcus, or other bacteria, as well as fungal infections (especially from Candida) and viral infections
• Folliculitis


  Inflammation of a hair follicle, commonly due to Staphylococcus aureus
• Sty (stye)


  Inflammation of a sebaceous gland that opens into a follicle of an eyelash, usually caused by Staphylococcal bacteria

  
• Furuncle


  A localized pyogenic (pus-producing) infection of the skin, usually resulting from folliculitis, also known as a boil
• Carbuncle


  A deep-seated pyogenic infection of the skin, usually arising from a coalescence of furuncles
• Macule


  A surface lesion that is neither raised nor depressed, such as the lesions of measles

  
• Papule


  A surface lesion that is firm and raised, such as the lesions of chickenpox

  
• Vesicle


  A blister or small fluid-filled sac, such as is seen in chickenpox and shingles
• Pustule


  A pus-filled surface lesion
• Pathways for pathogens to enter the ear

  • Through the eustachian (auditory) tube, from the throat, and nasopharynx
  • From external ear
  • Via the blood or lymph
• Otitis media


  1. Bacteria are trapped in the middle ear when a bacterial infection in the throat and nasopharynx causes the eustachian tube to close

  2. Anaerobic condition in middle ear

  3. Obligate and facultative anaerobe will proliferate

  4. Cause pressure on the tympanic membrane (eardrum)
• Swollen lymphoid (adenoid) tissues, viral infections, and allergies may also close the eustachian tube, especially in young children
• Otitis media


  Infection of the middle ear
• Otitis externa


  Infection of the outer ear canal
• Conjunctiva


  The thin, tough lining that covers the inner wall of the eyelid and the sclera (white of the eye)

  
• Cornea


  The domed covering over the iris and lens
• Conjunctivitis


  An infection or inflammation of the conjunctiva, with Staphylococcus species being the most common pathogens for bacterial conjunctivitis in adults, followed by Streptococcus pneumoniae and Haemophilus influenzae, while in children bacterial conjunctivitis is more common than the viral form