Microbiology

• Viruses can infect only the cells bearing appropriate surface receptors
• Viruses cannot replicate on their own
• Viruses escape from cells by either lysis or budding
• Efficiency


  How much of the virus were you exposed to?
• Transmissions


  • How healthy are you?
  • At what stage of infection was the original host?
  • How infective is the virus?
• Route of Transmission


  • Contact Transmission (Direct and Indirect)
  • Airborne Transmission
  • Vector Borne Transmission
• Route of Transmission


  • Fecal Route
  • Airborne Transmission
• Viral Infection of the Skin

  • Disease
  • Pathogen
  • Pathognomonic Sign
  • Mode of Transmission
• Chickenpox and Shingles


  • Varicella-zoster virus (VZV)
  • vesicular rash
  • Direct Contact, Droplet Spread, and Airborne Spread
• German measles (rubella)


  • Rubella virus
  • rash, tender lymph nodes, fever
  • Droplet Spread and Direct Contact
• Hand, foot, and mouth disease (HFMD)


  • Coxsackie A16 & Enterovirus 71
  • sores/ulcers in the mouth, non itchy rash
  • Droplet Spread
• Measles


  • Measles virus (rubeola virus)
  • koplik spots (irregularly shaped, bright red spots)
  • Droplet Spread and Direct Contact
• Smallpox


  • Variola virus
  • centrifugal pattern of skin lesions
  • Droplet Spread
• Warts


  • Human papillomaviruses
  • koilocytic cells
  • Direct Contact
• Koplik spots


  Irregularly shaped, bright red spots associated with measles
• Hepatitis Viruses


  • DNA: Hepatitis B
  • RNA: Hepatitis A, C, D, E
• Sexually transmitted viral diseases include...
• Viral Infection of the Eyes

  • Disease
  • Pathogen
  • Pathognomonic Signs
• Conjunctivitis, Keratitis, Keratoconjunctivitis


  • Adenoviruses
  • Conjunctivitis: Redness of the conjunctiva, itching, tearing, discharge (may be clear, mucoid, or purulent), photophobia

  Keratitis: Eye pain, redness, blurred vision, tearing, sensitivity to light, discharge, sensation of foreign body in the eye

  Keratoconjunctivitis: Similar to conjunctivitis with additional corneal involvement (e.g., corneal opacity, blurred vision, pain)
• Hemorrhagic conjunctivitis


  • Adenoviruses & enteroviruses
  • Redness, swelling, and pain
• Uveitis and retinitis


  • Cytomegalovirus (retinitis) & Toxoplasma gondii (Uveitis)
  • Eye pain, redness, blurred vision, decreased visual acuity
• Appropriate Therapy


  Conjunctivitis: Contact Precautions; Supportive care (cool compresses, artificial tears) - resolves on its own

  Hemorrhagic conjunctivitis: Contact Precautions; Supportive care (artificial tears, lubricants, cold compresses) - resolves on its own

  Uveitis and retinitis: Steroid eye drops or injections to reduce inflammation; Antiviral medications (viral)
• Viral Infection of the Ears

  • Disease
  • Pathogen
  • Pathognomonic Signs
• Otitis Externa


  • Escerichia coli, P. aeruginosa, Proteus vulgaris, and Staphylococcus aureus
  • Ear pain, irritation, and ear discharge

  
• Otitis Media (middle ear infection)

  • Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis
  • Ear pain, reduced hearing, fever

  
• Appropriate Therapy


  Otitis Externa: Topical antibiotics & pain relief

  Otitis Media (middle ear infection): Watchful waiting for most, pain relief, decongestants (if needed), antibiotics for severe cases
• Viral Infection of the Respiratory System

  • Disease
  • Pathogen
  • Pathognomonic Signs
  • Mode of Transmission
  • Appropriate Therapy
• Common Cold (Acute Viral Rhinitis and Acute Coryza)

  • Rhinoviruses
  • coryza(profuse discharge from nostrils)
  • Direct contact transmission & Airborne transmission
  • Drink plenty of fluids, get plenty of rest. Droplet precautions
• Influenza


  • Influenza virus types A,B and C
  • Fever, chills, headache, aches, and pains throughout the body, sore throat, cough, nasal drainage
  • Transmission via airborne spread and direct contact
  • Droplet Precautions; Antiviral medications (e.g., oseltamivir, zanamivir); Rest, fluids, and over-the-counter pain relievers (like acetaminophen or ibuprofen) can help manage symptoms
• Hantavirus Pulmonary Syndrome (HPS)


  • Hantavirus
  • Fever, myalgias (muscular pain),GI complaints, Cough, difficulty breathing, hypotension
  • Inhalation of aerosolized rodent feces, urine and saliva
  • Standard Precautions; Supportive care (oxygen therapy, intravenous fluids, medications); In severe cases: respiratory support (ventilator) or extracorporeal membrane oxygenation (ECMO)
• Avian influenza(bird flu)


  • Avian influenza virus type A
  • fever, cough, sore throat, muscle aches
  • Bird to human via contact infected poultry or contaminated surfaces from infected birds
  • Droplet Precautions; Antiviral medications (e.g., oseltamivir, zanamivir) to reduce symptoms and illness duration
• Middle East Respiratory Syndrome(MERS)

  • Coronavirus
  • High fever, chills, headache,general feeling of discomfort,body aches,diarrhea
  • Respiratory droplets, touching mouth, nose, eyes
  • Standard, Contact and Airborne Precaution; Supportive care (fluids, pain relief, oxygen therapy) is the mainstay of treatment
• Acute, Febrile,viral respiratory disease


  • parainfluenza viruses, Human Metapneumovirus, adenovirus, rhinoviruses, coronaviruses, coxsackieviruses, echoviruses
  • Chills, headache, aching,malaise, anorexia
  • Direct oral contact or by droplets; Via handkerchiefs, eating utensils
  • Standard Precautions for adults and Contact Precautions for children; Supportive care (rest, fluids, pain relievers like acetaminophen or ibuprofen) * Antiviral medications may be helpful depending on the specific virus causing the illness
• Viral Infection of the Oral Region

  • Disease
  • Pathogen
  • Pathognomonic Signs
  • Mode of Transmission
  • Appropriate Therapy
• Cold Sores (Fever Blisters and Herpes Labialis)


  • HSV Type 1 & 2
  • Superficial clear vesicles on an erythemathous (reddened) base
  • Contact Transmission
  • Antiviral creams
• Viral Gastrointestinal Tract Infection

  • Disease
  • Pathogen
  • Pathognomonic Signs
  • Mode of Transmission
  • Appropriate Therapy
• Viral Gastroenteritis (Viral Enteritis and Viral Diarrhea)


  • adenoviruses, astroviruses, caliciviruses, noroviruses, and rotaviruses
  • watery diarrhea, nausea or vomiting
  • Fecal oral route
  • oral rehydration drinks
• Types of Hepatitis


  • Disease
  • Pathogen
  • Pathognomonic Signs
  • Mode of Transmission
• Viral Hepatitis A


  • Hepatitis A virus (HAV) RNA
  • Fever, malaise, loss of appetite, diarrhoea, nausea, abdominal discomfort, dark-coloured urine and jaundice (a yellowing of the eyes and skin)
  • Through ingestion of contaminated food and water or through direct contact with an infectious person
• Viral Hepatitis B


  • hepatitis B virus (HBV) DNA
  • Abdominal pain, Dark urine, Fever, Joint pain, Loss of appetite, Nausea and vomiting, Weakness and fatigue
  • When blood, semen, or another body fluid from a person infected with HBV enters the body of someone who is not infected