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Natural Science
NATS 1670
Motti Anafi

FINAL EXAM REVIEW NATS 1670 August 11th, 2012 Chapter 13 Avian Influenza 1997 18 people in Hong Kong contracted avian influenza caused by H5N1 strain of influenza that spreads easily in chickens and other birds o Half caught disease from birds (scientists thought this was impossible) 60% mortality rate Hybrid of human and bird flu Mutate quickly, picking up genes from other flu viruses o Vaccine that may protect against H5N1 but as viruses mutate the vaccine is ineffective Chapter 18 Acquired Immunodeficiency Diseases Affect individuals who had a previously healthy immune system Causes As the immune system deteriorates with increasing age, older individuals has less effective immunity o Increased risk of viral diseases and cancers Stress can lead to increased quantities of glucocorticoids which are toxic to t cells, thus suppressing cell mediated immunity o Cold sores breaking out during exams Malnutrition and environmental toxins can also cause acquired immunodeficiency diseases by inhibiting the normal production of b and t cells AIDS Acquired immunodeficiency syndrome (1981) A syndrome is a group of signs, symptoms, and diseases associated with a common pathology o Epidemiologists define this syndrome as the presence of several opportunistic or rare infections associated with a severe decrease in the number of CD4 cells and a positive test showing the presence of human immunodeficiency virus (HIV) o Infections include Shingles, herpes (skin disease) Meningitis, toxoplasmosis, cytomegalovirus (nervous system disease) Tuberculosis, pneumonia, histoplasmosis, coccidioidomycosis (respiratory system) Chronic diarrhea, thrush, and oral hairy leukoplakia (digestive system) o Often results in dementia during final stages Type IV (delayed or cell-mediated) hypersensitivity Certain antigens contact the skin of sensitized individuals that provoke inflammation that beings to develop at the site after 12-24 hours Interactions among antigen, antigen-presenting cells, and t cells cause the cell-mediated hypersensitivity o Time delay reflects the time it takes for macrophages and t cells to migrate to and proliferate at the site of the antigen The Tuberculin Response Skin of an individual exposed to tuberculosis or tuberculosis vaccine reacts to an intravenous injection of tuberculin (a protein solution obtained from mycobacterium tuberculosismantoux test Tuberculin injected in infected person= red hard swelling, positive tuberculin test o Lesion is filled with lymphocytes and macrophages o Chapter 24 DNA viruses that cause human diseases are grouped into seven families based on several factors. o double stranded DNA (dsDNA) viruses Poxviridae, herpesviridae, papillomaviridae, polyomaviridae, and adenoviridae o Single stranded DNA (ssDNA) viruses Parvoviridae o Both dsDNA and ssDNA Hepadnaviridae Poxviridae 2 largest of viruses Large size allows them to be potential vectors for the introduction of genetic material in vaccinations and gene therapy Most animal poxviruses are species specific, unable to infect humans because they cannot attach to human cells All poxviruses produce lesions that progress through a series of stages 1. Macule 2. Papule 3. Vesicles 4. Pustules 5. Pocks Infection primarily through inhalation of viruses in droplets or dried crusts Small pox During middle ages 80% of European population contracted smallpox, later European colonists introduced smallpox to Native Americans, resulting in dead of 3.5 million people Jenner demonstrated immunization using the mild cowpox virus to protect against smallpox o Antigens of cowpox virus are chemically similar to those of smallpox. Exposure of cowpox results in immunological memory and subsequent resistance to both strains Variola major causes severe disease with mortality rate of 20% + Variola minor causes a less sever disease with a mortality rate of less than 1% Variola infects internal organs and produces fever, malaise, delirium, and prostration before moving via the bloodstream to the skin where they produce pox First human disease to be eradicated globally in nature (1980) Stocks maintained in US and Russia as research tools for investigations concerning virulence, protection against bioterrorism, recombinant DNA technology, etc. Herpesviridae Herpesvirus attaches to a host cells receptor and enters the cell through the fusion of its envelope with the cytoplasmic membrane The viral genome is replicated and assembled in the cells nucleus, the virion acquires its envelope from the nuclear membrane and exits the cell via exocytosis or lysis High infection rate Viruses often latent o May reactivate as a result of aging, chemotherapy, immunosuppression, or physical and emotional stress causing recurrence of the manifestations of diseases o Some insert into hosts chromosomes, causing genetic changes and potentially induce cancer o 3 types of Herpesvirus, herpes simplex, varicella zoster, and Epstien-barr o All types of viruses share similar capsids and genes, but are distinguished by genetic variations Infections of HHV-1 and HHV-2 Transmitted through close body contact Asymptomatic carriers shed HHV-2 genitally Enter the body through cracks or cuts in mucous membranes, viruses reproduce near infection site and produce inflammation and cell death HHV-1 (above the waist herpes) o Oral herpes First human Herpesvirus to be discovered Itchy skin lesions on the lips (cold sores/fever blisters) HHV-2 (Below the waist) o Usually associated with painful lesions on genitalia, typically virions are sexually transmitted o Oral sex is the result of HHV-2 present in the oral region and HHV-1 in the genital area Neonatal Herpes o HHV-2 usually the species involved o 30% mortality rate if infection is oral o 80% morality rate if central nervous system is infected o Infection at birth highly likely with contact with mothers lesions o Virus can cross placental barrier before birth HHV-3 infections Varicella-zoster virus (VZV) Also known as chickenpox, highly infectious disease in children Virus enters through respiratory tract or eyes, replicate in cells at the site of infection, then travel via the blood throughout the body, triggering fever, malaise, and skin lesions Rarely fatal Two weeks after infection skin lesions appear Viruses are shed through respiratory droplets and the fluid in lesions; dry crusts are not infective VZV can become latent within sensory nerves, and resurface as a rash in the form of shingles or herpes zoster HHV-4 infections Epstein-Barr Virus (EBV) o Transmission usually occurs via saliva therefore prevention is almost impossible o Causes Kissing disease o Viremia (viruses in the blood)
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