Viral Pathogens Viruses effect all living organisms Viruses can be benign harmless Viruses can be extremely malignant serious No definitive treatment for any virus drugs just slow down the replication process and severity Vaccination is the most common and successful way to prevent viral disease o Small pox vaccination world wide o US childhood vaccinations Poliomyelitis Mumps Measles Rubella Viral Encephalitis US vector control to get rid of vectors like mosquitos which controls the rapid spread of disease Influenza An acute respiratory disease of warm blooded vertebrates Animals harbor the virus and persists in them but don t get influenza Wild birds are the reservoir but do not get the flu because avirulent in reservoir Hosts o Domesticated birds o Swine o Humans Seasonal epidemic outbreaks at certain times of year Enveloped RNA virus sense RNA in 8 segments Neuraminidase Envelope protein that helps virus penetrate mucus layer and get to the surface of host cell Hemagglutinin Used in adherence and penetration of host cell adsorbtion step Three major types A B C o A is the most serious and pathogenic type of influenza The flu is so dangerous because it can infect several species and change readily many different strains or type of virus Viruses change by o Antigenic Drift Mutations for viruses o Antigenic Shift Recombination of RNA from different types of the virus o New strains will always show up Epidemic Local outbreak Pandemic Larger epidemic spread throughout countries Influenza Type A Infection of the lower respiratory tract Lungs Sometimes upper respiratory Rapid onset unlike cold High fever 102 and above unlike cold Fatigue muscle aches congestion coughing More severe cold like symptoms Symptoms lasting 1 3 weeks Still kills many people mostly youth elderly people and people with lung problems immunocompromised Aerosol transmission inhaled Also direct contact for more virulent forms Crowded conditions cause rapid spread Most cases in winter and spring Fomites are sometimes involved Complications Transmission Treatment Antiviral drugs days Prevention all types of the flu Symptomatic Drugs to help remove congestion or lower fever and symptoms o Relenza Tamiflu o Limits symptoms and length of disease when taken within the first 3 New vaccines available each year because once vaccine will not protect from Cocktail vaccine protects against several types still not 100 effective Human Immunodeficiency Virus HIV Cause of acquired immunodeficiency syndrome Enveloped RNA virus If not treated AIDS will develop Retroviridae Retro Viruses o The most serious and dangerous viruses o Cause malignant disease o Causes different types of cancer and immunodeficiency diseases Reverse transcriptase o Converts viral RNA into DNA o Unique enzyme o Will not find in any other type of viruses HIV 1 randomly Main form of the virus that causes most cases Considered a New virus because it was not around and it just showed up Evolved from existing virus from mutations Virus evolved from apes and monkeys simian immunodeficiency virus then mutated to cause human disease Earliest Patients o Homosexual men o IV drug users o People receiving blood transfusions or organ donation Virus gets into the blood stream and spreads 35 million people infected worldwide 2 3 in Africa 5 million new cases a year 20 000 deaths per year in the USA 26 million deaths total worldwide since 1981 Transmission Spread through exchange of body fluids o Semen o Blood o Vaginal secretions o Breast milk Modes of Transmission o Sexual contact o IV drug sharing o Mother to infant through placenta during child birth and through breast milk o Blood transfusions and organ replacements Not spread through casual contact saliva or mosquitos Virus infects o Mainly T Helper lymphocytes o Lymphocytes o Macrophages o Dendritic cells T Helper cell count in blood is used to measure the progression of disease o Normal count is 800 1200 o AIDS patients less than 200 HIV adsorbtion to T Helper CD4 cells When patient is lacking too many T Helper cells o Immune system doesn t respond properly o Patients succumb to opportunistic pathogens o Then die from other disease Stages of Infection o Initial Infection Immune system is still functioning properly Develop antibodies against virus Flu like symptoms Lasts a couple weeks to a month o Latent Stage Becomes inactive when sitting in the nucleus Asymptomatic Do not exhibit symptoms of disease but are still capable of transmitting it Lasts 1 8 years then reactivated Reverse transcriptase Enzyme that converts RNA into double stranded DNA used for new viruses o HIV Disease with symptoms Weight loss Opportunistic Pathogens of AIDS o Protozoa Swollen lymph nodes Fever Blood abnormalities anemia leukopenia Some opportunistic infections that are recoverable rare types of pneumonia May develop a rare type of cancer called Kaposi s Sarcoma Severe opportunistic pathogens AIDS patients are infected with microbes that can not infect healthy people because of their weak immune system Die due to inability to fight off infections o AIDS Cryptosporidium Die from dehydration Toxoplasma Gets into the brain in AIDS patients and causes fatal brain infection o Fungi Candida Albicans Infection in mouth skin or vagina Ex thrush o Bacteria Pneumonxystis carinii Fatal pneumonia Mycobacterium avium Doesn t effect healthy humans Mycobacterium Tuberculosis Tuberculosis in healthy humans becomes fatal to AIDS patients o Viruses Cytomegalovirus Herpes Simplex All these infections are pretty much harmless or minor to healthy people but become much more severe or fatal for AIDS patients Prevention o Testing o Education o Developing vaccine Treatment o Treating opportunistic infections and disease o Passive immunizations immuneoglobin o Antiviral drugs Must be used together combination therapy Nitrogenous base analogs Protease inhibitors Hepatitis Viruses All causes inflammation of the liver Viruses not related to each other but all have liver inflammation in common Hepatitis B HBV Hepadnaviridae Hepatitis A HAV Picornaviridae an enterovirus that also infects intestinal o Jaundice The yellowing of tissue mostly whites of eyes and light Happens because blood is full of yellow pigmented chemicals and released throughout the body tract Hepatitis C HCV Togaviridae General Symptoms skin tones o Fatigue o Vomiting and diarrhea o Abdominal pain o Fever o Hepatomegaly Giant liver Hepatitis B Virus HBV Serum Hepatitis Enveloped DNA virus Double