week 9

• Virus


  Latin word "virus" means "poison or venom"
• Virus


  • Obligatory intracellular parasites
  • Does not have the capacity to create their own food
  • Can't make energy or proteins / independent to hosts
  • Undergo mutation
  • Destroyed by UV rays
  • Viral genes carried provide a record of viral evolution

  
• Characteristics of virus


  • Contain only either DNA or RNA
  • Contain a protein coat that covers the nucleic acid (which is sometimes surrounded by envelope of lipids, proteins, and carbohydrates)
  • Multiply inside living cells by utilizing the cell's synthesis mechanism
  • Cause the formation of specialized structures capable of transferring viral nucleic acid to other cells
  • Host range are all living things like invertebrates, vertebrates, plants, protists, fungi, and bacteria
  • Extremely small in size (20 nm (tiniest), 100 nm (influenza))

  
• Non-living


  • Lack cellular structures
  • Do not respire
  • Do not move/grow
  • No metabolic activity
• Classification of virus

  • Classified by their nucleic acid and by differences in the structures of their coats
  • The genome of a virus can be single or double stranded

  
• Capsid


  • Protein shell that encloses and protecting the viral genome
  • Come in different shapes: icosahedral, prolate/complex, helical

  
• Capsomeres


  Protein subunits that composes the capsid
• Helical shape


  • Made up of a single type of capsomere that is stacked around a central axis to produce a helical structure with a central cavity or hollow tube
• Icosahedral shape


  • Made up of identical subunits that form equilateral triangles that are then stacked symmetrically
• Prolate/Complex shape


  • An icosahedron extended along one axis, which is a common arrangement of bacteriophages
• Envelope


  Extra layer outside, also known as membrane, may help viruses avoid the host immune system
• Non-envelope

  HAV, PHARVO
• Complex viruses


  • Contain capsids that are neither entirely helical nor purely icosahedral
  • May include additional structures like protein tails or a complex outer wall

  
• Exanthem


  Defined as any eruptive cutaneous rash accompanied by fever and other systemic symptoms, caused by a drug reaction, a disease, or both, most children's exanthems are viral infections
• Skin viral infections - Infections Associated with Maculopapular Exanthem


  • Measles or hard measles (Rubeola)
  • German Measles (Rubella)
  • Roseola Infantum (Exanthem Subitum or Sixth Disease)
  • Erythema Infectiosum
• Measles or hard measles (Rubeola)


  • Tigdas, fever, conjunctivitis, cough, light sensitivity, Koplik spots (buccal/white) in the mouth and a red blotchy skin rash, highly contagious child exanthem, rash from head to toe, rubeola virus an RNA virus in the family Paramyxoviridae
• German Measles (Rubella)


  • Mild, febrile viral disease, fine, pinkish flat rash appears, spread through respiratory tract, rubella virus is the pathogen, headache, red patches of soft pallet, rashes from face to body, malaki kulani
• Roseola Infantum (Exanthem Subitum or Sixth Disease)


  • Caused by Human Herpes virus 6, manifests are sudden onset of high-grade fever followed by a generalized rash that lasts for two days, affects 6-36 months old of child, abrupt high fever, rashes from proximal to distal part of the body
• Erythema Infectiosum


  • Common childhood infection causing a slapped cheek appearance and a rash, also known as fifth disease, caused by human parvovirus B19
• Skin viral infections - Infection Associated with Vesicular Exanthem


  • Chickenpox
  • Herpes Zoster (Shingles)
• Chickenpox


  • Bulutong, caused by varicella-zoster virus (VZV), known as varicella is an acute, generalized viral infection, with fever and a skin rash, mild, self-limiting, can be severely damaging to a fetus, serious complications include pneumonia, rash starts from the chest and face before turning into blisters
• Herpes Zoster (Shingles)


  • Caused by herpes zoster virus, reactivation of the varicella virus, result of immunosuppression, involves inflammation of sensory ganglia of cutaneous sensory nerves, producing fluid-filled blisters, and pain, paresthesia (numbness and tingling), rash will look blotchy before it blisters and oozes one side of the body
• Treatment of Shingles


  1. Vaccination (pre-exposure)

  2. Antiviral (to limit the spread) - Acyclovir

  3. V216 as post exposure (prophylaxis)

  4. Isolation
• Smallpox


  • Caused by 2 strains variola virus - Variola major, Variola minor (1% fatality rate), fever, malaise, headache, severe backache, distinct skin rash, prostration (person is so tired or weak that he/she is unable to do anything)
• Warts


  • Common warts (verrucae vulgaris), venereal warts, and plantar warts are among the many types of skin and mucous membrane lesions, most are harmless but some can become cancer, caused by at least 70 types of human papillomaviruses (HPV), classified in the genus papillomaviruses within the family papovaviridae, painless papule or nodule with papillary projections or rough surface (skin warts (common, plantar, and flat warts), genital and anogenital warts)
• Herpes Simplex Virus


  • Causes infection of the skin and mucous membranes, capable of latency and recurrent infections, watery blisters on the skin or mucous membranes of the mouth, lips, nose, or genital results
• Hand and Foot Mouth Disease (HFMD)


  • Mild, contagious viral infection common in young children, caused by coxsackievirus A16; belongs to the family of enterovirus, coxsackievirus A6 can also cause HFMD and the symptoms may be severe, incubation period is around 3 to 5 days, symptoms include fever, body aches, sores in the mouth and a rash on the hands and feet, spreads from person to person by direct contact with nasal discharge, saliva, and fluid from the rash of an infected person, symptomatic treatment is given to provide relief from fever, aches, and pains, infectious period remains while there is fluid in the blisters
• Oral region viral infections

  • Cold sores (Fever blisters, Herpes Labialis)
• Cold sores (Fever blisters, Herpes Labialis)


  • Superficial clear vesicles on an erythematous (reddened base), may appear on the face or lips, group together in patches, caused by HSV 1, HSV2 (genital)
• Types of skin lesions

  • Macule – flat and red (mapula)
  • Papule – elevated (pataas)
  • Vesicle – small fluid fill blisters
  • Ulcer - hukay
  • Nodule – may laman
  • Pustule – has pus (nana)
  • Plaque - hard
  • Fissure – hiwa or bitak-bitak
• Eye viral infections

  • Adenoviral conjunctivitis – caused by adenovirus "pink eye", self limiting
  • Keratoconjunctivitis - inflammation or infection involving both the conjunctiva and cornea
  • Hemorrhagic conjunctivitis - with sudden onset, with redness, swelling, and pain in one or both eyes, small, discrete subconjunctival hemorrhages may enlarge to form confluent subconjunctival hemorrhages, there is a bleeding inside