Lecture 351. Describe the difference between reservoirs and carriers a. Reservoirs- Are places or populations that contain infectious agents capable of infecting susceptible individuals i. For many infectious diseases, living organisms are the only reservoirs. Diseases that primarily infect animals but can also infect humans are zoonoses (or zoonotic diseases) b. Carriers- are infected individuals with mild or no symptoms that are capable of infecting other susceptible individuals 2. How do vehicle control, vector control, reservoir control, and quarantine help prevent outbreaksa. Vehicle control- Eliminates many common source diseasesi. Sewage and wastewater treatment and treatment of distributed water b. Reservoir control- Eliminating (rare) or vaccination of reservoir populationsi. Immunization of domestic animal populations against rabies ii. Elimination of domestic rats to reduce plague c. Vector Control- Reducing contact of vectors with susceptible populationsi. Mosquito spraying/nets to reduce the number of malaria, yellow fever, west nile virus casesii. Control of ticks (Rocky Mountain Spotted fever, Lyme disease) or fleas (plague)d. Quarantine- The isolation of possible disease carriers until a disease free state can be assuredi. All mammals entering rabies-free Australia must be quarantined to make sure they do not have rabies 3. How can travel restrictions prevent outbreaks a. Then the disease stays in one area and does not spread to another area4. Define emerging infectious diseases a. Newly appearing diseases in populations, reappearing after manyyears of absence b. Many emerging pathogens are transmitted by or originate from: animals, food, water, vectors, healthcare settings5. Comprehend the reasons why emerging infectious diseases are becoming more common a. Ecological changes/economic development- agriculture, dams, deforestationb. Human demographics- Population growth, migration; wars; I.V. drug usec. Increased international traveld. Technology and industry- Centralized processing of food supplies,overuse of antibioticse. Microbial adaptation- ability to undergo genetic changes andacquire genesf. Shortcomings of public health measure- cutbacks in mosquito abatement and pollution control, ineffective AIDS treatment in undeveloped regions.6. What causes smallpox and how was it eradicated from the human populationa. Variola major virus; transmitted by aerosol or direct contacti. After infection development of skin rash which progresses to formation ofpustulesii. Septic shock and toxemia (toxic substances in the blood) can result in fatality rates of up to 30%iii. Eradicated in the world1. Factos that aided eradication- Only human reservoir, no asymptomatic carriers, short period of infectivity, effective vaccine7. What pathogen causes AIDS and why are more humans able to live with this disease a. Caused by human immunodeficiency virus (HIV) that has tropism for specific human cell typesb. Acquired Immunodeficiency Syndrome (AIDS)i. Programs of public education and access to drug therapies has decreased HIV prevalence in developed regionsii. HIV is a retrovirus (RNA genome copied to DNA by reverse transcriptase) 8. Why did AIDS incidence begin decreasing in the mid 1990’s a. Public awareness drugs9. Define nosocomial infections; know important facts about the three examples discussed in class a. Occur in individuals as a result of visiting some type of healthcare settingb. A problem in acute care hospitals, 5-10% of all U.S. hospital patients acquire nosocomial infectionsc. Transmission by:i. Contact- Human to human by healthcare workers and patients, invasive procedures ii. Airborne- Exposed tissues resulting from burns, abrasions, trauma, surgical proceduresiii. Device associated- Resulting form use of medical devices such as ventilation10. Know why Clostridium difficile is a problem in healthcare settings and what organ it infects; what are the symptoms a. A spore forming gram positive anaerobic rodb. Symptoms include watery diarrhea, fever, abdominal pain, c. Mostly occurs in patients undergoing antibiotic therapyd. Occurs in the intestines 11. What are CRE bacteria and what mechanisms do they use for antibiotic resistance to carbapenemsa. CRE bacteria- organisms usually fall into two bacteria:i. E.coli ii. Klebsiella pneumoniab. The mechanisms of resistance usually are one of several types ofenzymes in these bacteria that inactivate antibiotics c. CREs occur in hospitals and long term care facilitiesd. Many CREs are resistant to nearly all antibioticsi. Morality rates for these strains can be up to 50%12. Know what MRSA means, how it is commonly transmitted, where on the body it is normally found, and what type of infections does it usually cause a. MARSA-named because of resistance to the B-lactam methicillin is also resistant to many other antibiotics b. Causes over 80,000 server invasive infections and 11,000 deathsper year and an unknown number of less severe infectionsc. A leading cause of healthcare associated infectionsd. S. aureus us a normal skin inhabitant, but some forms can be pathogenice. Infections often start on skin or wounds but can progress to bloodstream or other sites f. Transmission form direct skin to skin contactg. 2% of people are carriers of MRSA in their upper respiratory
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