Chapter 15 Outline

Chapter 15 Outline - Chapter 15 Viral Infections of the...

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Chapter 15 Viral Infections of the Blood, Lymphatic, Gastrointestinal, and Nervous Systems Introduction 15.1 Viral Diseases of the Blood and the Lymphatic Systems The Human Immunodeficiency Virus (HIV) Is Responsible for HIV Disease and AIDS Acquired immunodeficiency syndrome (AIDS) first appeared in the U.S. in 1981 Luc Montagnier and Robert Gallo first isolated and cultured the human immunodeficiency virus type 1 and linked it to AIDS HIV is a member of the Retroviridae family HIV-2 is a second type of HIV, which develops more slowly than HIV-1 Its genome is packaged with reverse transcriptase Once the RNA is transcribed into double-stranded DNA, the DNA integrates into the host DNA as a provirus HIV normally infects the immune system cells, including T lymphocytes (CD4 + T cells) Incapacitation of T lymphocytes allows opportunistic pathogens to infect the body HIV also infects and paralyzes B lymphocytes Stage I can include a flu-like illness within a month or two of exposure Seroconversion means the immune system is activated against the virus, and antibodies can be detected in the blood In stage II, the individual usually remains free of major disease, even without treatment It can last 6-8 years, during which HIV levels in the blood slowly rise Stage III occurs when the immune system loses the fight against HIV Symptoms worsen and opportunistic infectious develop HIV is transmitted through blood and sexual contact Health care workers can be at risk through events such as needle sticks Infected mothers can transmit the virus to their fetus or to the baby during birth or breastfeeding Blood tests using ELISA are used to detect antibodies in the blood A test done during the first 3 months of infection may not be accurate; a later test is recommended Azidotheymidine (AZT) was the first drug used for treatment It interferes with reverse transcriptase activity HIV can become resistant to some antivirals, requiring a cocktail of drugs called highly active antiretroviral therapy (HAART) HAART reduces the risk of HIV transmission and can extend life of patients by about 8 years Prevention requires avoiding risky behaviors like sharing needles or unprotected sex A vaccine has not yet been developed HIV continually mutates and recombines, making vaccine development difficult A vaccine needs to activate T lymphocytes, which are the cells infected by the virus Two Herpesviruses Cause Blood Diseases Infectious mononucleosis is a blood disease, particularly affecting B lymphocytes in the lymph nodes and spleen It is spread by contact with saliva It is caused by the Epstein-Barr virus (EBV) Many children are infected and show no symptoms Adolescents or young adults who are infected may develop EBV disease (a precursor of mononucleosis) Complications include heart defects, facial paralysis, rupture of the spleen, and
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This note was uploaded on 04/17/2009 for the course MIC 201 taught by Professor Lacroix during the Spring '08 term at Rhode Island.

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Chapter 15 Outline - Chapter 15 Viral Infections of the...

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