3OVERVIEW* An Infectious Disease is a disease that is caused by the invasion of a host by agents whose activities harm the host’s tissues. * They cause disease (by impairing normal tissue function) and can be transmitted to other individuals (they are infectious)
4VocabularyPathogens – Microorganisms that are capable of causing disease.Infection – Results when a pathogen invades and begin growing within a host.Disease – results only if and when tissue function is impaired (i.e. burns, skin lesions)
5Infectious ProcessThe body has defense mechanisms to prevent infection and to prevent disease after infection occurs.In order to cause disease, pathogens must be able to enter the host body, adhere to specific host cells, invade and colonize host tissues, and inflict damage on those tissues.
6Infectious Process Cont. Entrances to the host: mouth, eyes, genital openings, or wounds.Growth of pathogens or the production of toxins/enzymes cause disease.Some normal flora prevent disease.
7Latent PeriodA "latent period" is the lag time between exposure to a disease-causing agent and the onset of the disease the agent causes.For instance, the latent period between exposure to HIV infection and the onset of AIDS may be many years.Example: Magic Johnson
9BACTERIASmall unicellular microorganism that multiplies by cell division.Found as bacillus (rod shaped), coccus (spherical), or spirillum (spiral)Anthrax, Cholera, Legionellosis, Lyme Disease, Salmonellas, Strep, TB, Typhoid, Yersinia pestis (plague)Treatable with antibiotics
10Bacteria Cont. Staphylococcus aureus (Staph) Favorite hangout: skin and noseLikes: getting inside the body where it can cause a minor infection like a boil, or serious, sometimes fatal infections such as blood infections or pneumonia.Dislikes: many antibiotics
11Bacteria Cont. AEROBES • Reproduces only in the presence of oxygen ANAEROBESReproduce only in the absence of oxygenFacultative anaerobic bacteria:can produce in either environment
17VirusesApart from the host cell, have no metabolism and cannot reproduce or survive unless they take over a living cell
18Retroviruses – a classification of viruses HIVCertain types of CARetroviruses are viruses whose genome consists of RNA not DNA.
19Think about IT• In February 1997 it was reported that pig cells contain a retrovirus capable of infecting human cells. This is troublesome because of the efforts that are being made to transplant pig tissue into humans (e.g., fetal pig cells into the brains of patients with Parkinson's disease/ hearts etc).
20Virus Examples Chicken pox Cold sores Genital herpes Shingles • Many viruses are preventable via vaccinations• Can be treated with Antiviral drugs• ANTIBIOTICS do not workChicken poxCold soresGenital herpesShinglesSmall poxAIDSInfluenzaRabies-direct contactWest Nile VirusEbola →Hantavirus
27Yeast or candida are opportunists Yeast infections are the most common opportunistic infectionAntibiotics reduce normal flora and allow yeast to grow making the pt susceptible to an opportunistic infection
28PROTOZOAAcquired through contaminated food or water, or bite of an arthropod (mosquito)More common in wet climates like the tropicsAmoebic dysenteryMalaria- re-emerging d/t drug resistance and fear of vaccinationTreatable with antibiotics
29HELMINTHS (WORMS) ewwww! Simple, invertibrate animals, some infectious parasitesIn intestine, blood, body tissueMedications to force evacuation or death of worms
30Trichinella spiralis (roundworm) Swimmer’s itch in USSchistosoma (flatworm)Symptoms include abdominal pain and diarrheaTrichinella spiralis (roundworm)Ingested in undercooked pork from infected pigs.Symptoms include vomiting, diarrhea, and abdominal painSEE NEXT SLIDE FOR PICTURE!!!
31FilariasisFilariasis- worm infestation in lymphatic system that prevents normal draining of lymphatic fluids. Causes SEVERE swelling.
32PRIONS (pree-ons) • Extremely small particles that consist only of protein.• Resistant to heat andDisinfectants• No known treatmentsCreutzfeldt-Jakob disease“mad cow disease”in cattle