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What are examples of RNA viruses?
- -Poliovirus
- -Rhinovirus
- -Coxsackievirus and echoviruses
- -Influenza
- -Respiratory syncytial virus
- -MMR
- -Rhabdovirus
- -Arbovirus
- -Rotavirus
- -Norovirus
- -HIV
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What is poliovirus?
- -Poliomyelitis
- -ss RNA, naked virus
- -three serotypes, human is the only host
- -Route: fecal- oral
- Alimentary canal to replication in GI tract to lymph to blood to CNS/muscles
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What is important about a naked virus?
-It is highly transmissible
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What are symptoms of polio?
- -Fever, malaise, sore throat, followed by muscle pain, stiffness, and paralysis 1-2 days later in 1% of cases
- -Clinical disease is paralysis
- -Spinal cord gets infected may lead to paralysis of legs and arms
- -Partial recovery is seen
- -If in lung, may require iron lung
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What is the treatment of polio?
-No treatment except for physical therapy to recover function
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What is the prevention of polio?
- 1. Salk vaccine: injected USA
- -Killed vaccine, all 3 serotypes
- -It protects from disease but does not prevent the spread
- -Need 3 shots 2-18 mo plus booster at 4-6 yrs
- 2. Sabin vaccine: oral vaccine, weaker
- -Live, attenuated vaccine, protects against all 3 serotypes
- -Protects from both disease and spread of disease
- -Usually life long immunity
- -There is one disadvantage: 1 serotype may revert to wild type virulent polio in 1 i in 1 million
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What is post-polio syndrome (PPS)?
- -Condition that affects polio survivors around 10-40 yrs after recovery
- -PPS is characterized by a further weakening of muscles that were previously affect by the polio infection
- -Some patients experience only minor symptoms, while others develop spinal muscular atrophy
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What are symptoms of post polio syndrome?
- -Fatigue
- -Slowly progressive muscle weakness and possibly muscular atrophy
- -Difficulty swallowing and breathing
- -Joint pain and increasing skeletal deformities
- -Gradual decline in the ability to carry out activities of daily living
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What is the iron lung?
- -Used to treatment breathing problems in those with polio or pps.
- -60 people still use the iron lung
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What is rhinoviruses?
- -ss RNA containing naked viruses that cause common cold
- -#1 causes of common cold
- -About 140 serotypes that cause 30-50%of upper respiratory tract infections
- -Usually 3/5 cases per person per year
- -Transmitted by personal contact (just about anyway)
- -incubation time 2-3 days
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What are the symptoms of the common cold?
-Cough, inflammation of nasal cavity, sore throat, headache, and no fever usually.
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What is the treatment of rhinoviruses?
-Just like any other common cold virus, there are no treatments that can kill a rhinovirus. Therefore, it involves relieving symptoms as the body fights the virus
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What is the prevention of rhinoviruses?
- -There is no vaccine because of the mildness of the disease large number of serotypes involved. You need 140 colds to get immunity
- -Reduce chance by: Washing hands regularly, keep hands away from nose, mouth, and eyes, limiting exposure to infected people, practicing healthy habits, using disinfectants
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What are enteroviruses?
-Family on non-enveloped small RNA viruses that live in the human digestive tract and the 2nd most common viral infectious agents in humans and transmitted by fecal-oral route
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What are viruses that are members of enteroviruses?
-Coxsackieviruses, polioviruses, echoviruses, and hepatitis A virus
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What is the echovirus?
- -Enteroviruses
- -31 serotypes
- -High infectious, target is children
- -Among the leading causes of acute febrile illness in infants and children
- -Most common cause of aseptic meningitis
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What is the coxsackievirus?
- -enterovirus
- -two types: A (23 serotypes) and B (6 serotypes)
- -Both effect the heart
- -Named after a town in NY
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What is Group A coxsackievirus?
- -Generally tend to infect the skin and mucous membranes
- 1. Herpangina: an acute febrile illness associated with small vesicular or ulcerative lesions on the posterior orophayngeal structures
- 2. Acute hemorrhagic conjunctivitis (AHC) conjunctival congestion, onset of edema
- 3. Hand-foot-and mouth (HFM): vesicular lesions in the mouth and can involve the HFM, buttocks and/or genitalia
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What is group B coxsackievirus?
- -Generally infects the heart, pleura
- 1. Pleurodynia: fever, intense abd and chest pains with headache. Chest pain is worsened by breathing or coughing like pleurisy. Illness lasts 4-7 days and is self limiting.
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What can both group A and B coxsackievirus cause?
- -Aseptic meningitis
- -Myocarditis, pericarditis (inflammation of heart): Most older children and adults usually recover, it can be fatal in neonates
- -the development of IDDM has recently been associated with enteroviral infection, group B.
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What is the treatment of coxsackievirus infections?
- -Treat the symptoms
- -No drugs for treatments or vaccines
- -Provide supportive care and bed rest
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What is the influenza virus?
- -Flu
- -Helical, ss RNA, 8 RNA segments, enveloped (but hardy virus, can be spread)
- -Serotype A: pandemics
- -Serotype B: Local epidemics
- -Serotype C: rarely causes diseases in man
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How is influenza transmitted?
- -URT by coughing and sneezing
- -Virus survives better in cold, dry air
- -Hence, so many cases in the winter time
- -Incubation period 1-2 days
- -More in winter
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What are symptoms of influenza?
-fever, cough, headache, muscular aches and sore throat, and retro-orbital pain (looking up hurts more)
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What is the structure of the influenza virus?
- - envelope contains 2 proteins (H and N)
- H (Hemagglutinin) Attaches to ciliated epithelial cells and kills them
- N (Neuraminidase) Destroys the mucous layer in the throat
- -Decreases PMN activity
- -Secondary bacterial infections common: strep pneumoniae and staph aureus
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Why is the influenza virus a worry for older adults?
-Elderly patients with decreased cardio-pulmonary function are especially susceptible to flu and post-flu pneumonia. It can be fatal (40,000 deaths per year in the US)
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How does the body protect against the flu?
-Antibod is important for future protection against infection and is specific for defined epitopes on HA and NA proteins. Therefore on you get the flu, you should have life-long immunity, but this does not always happen
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What is an antigenic variation?
-the flu virus changes its H and N antigens
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What kind of change can influenza B go through?
-Minor antigenic change only
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What kind of change can influenza A go through?
- -Minor change (drift): Point
- -Major change (Shift): panademic, antigenic changes to ensure the presence of immunologically naive, susceptible people
- -A can infect humans and animals
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What happens with an antigenic drift?
- -Minor change
- -Mutation in HA
- -Occurs in influenza A and B viruses: resulting the local epidemic of flu
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What happens in an antigenic shift?
- -Major changes
- -Reassortment of genomic fragments in A flu only with those in animals which results in major antigenic change in viral HA and NA resulting in pandemics of flu
- -Complete change
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How does an antigenic shift of flu happen?
Example: H3N2 to H5N1: Pigs were infected with a duck virus and another set of pigs with a human virus. At some point a pig underwent mixed infection with both viruses. The result virus created by reassortment of the viral gene segments that could be transmitted to and infect humans
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What is influenza A?
- -Severe illness
- -Animal Reservoir
- -Spread in human: pandemic
- -Shift and drift change
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What is influenza B?
- -Less severe than A
- -No animal reservoir
- -Epidemic
- -Drift change
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What is influenza C?
- -Not very severe
- -No animal reservoir
- -sporadic in humans
- -Drift change
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What are the flu pandemics from influenza A?
- 1918: HswN1: probable swine flu strain
- 1947: H1N1
- 1957: H2N2: asian flu strain
- 1968: H3N2, hong kong flu strain
- 1977: H1N1
- H5N1, bird flu, recently in china
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What is the treatment of the influenza virus?
- -Amantadine: inhibits uncoating of the virus
- -two new drugs approved in 1999 by the FDA: Relenza: nasally inhaled neuraminidase inhibitor (used for little kids) and tamiflu oral neuraminidase inhibitor
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What is the prevention of influenza virus?
- -killed vaccine is available about 70% effective. Immunity short lived about 1 year, but you should still use it
- -LAIV live, attenuated vaccine called FluMist: nasal spray for 2 mo-49yr old healthy individuals, approved in 2003. Used for children and high risk older individuals
- -Bird flu vaccine approved in 2007, 45% vaccine
- -Swine flue vaccines was FDA approved on sept 15, 2009
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What is guillain-barre syndrome?
- -Complications of the flu vaccine
- -Self-limiting paralysis that occurs within 8 weeks after vaccination in 10 in million people
- -Destroys the protective covering of the myelin sheath, disabling the nerves from transmitting signals to the muscles
- -5-10% have weakness which may last and about 5% die
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What is Reye's Syndrome?
- -Complication of the flu vaccine
- -Associated with aspirin consumption by children with viral diseases
- -Rare but deadly illness that can affect the liver and brain
- -Vomiting, lethargy, and delirium and if untreated coma and death in 40% of patients
- -Brain damage to survivors
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What is respiratory syncytial virus (RSV)?
- -Giant cell forming virus, ss RNA, enveloped virus
- -Three serotypes
- -Leading cause of bronchiolitis and pneumonia among infants and children under 1. Most children recover in 8-15 days
- -Kills 14,000/yr
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What are diseases caused by respiratory syncytial virus?
- 1. Coryza: common cold-sneezing, watery eyes
- 2. Croup: inflammation/ narrowing of larynx and trachea (laryngotracheitis). Mucous lining becomes inflamed. Coarse cough
- -although croup is mild, causes severe breathing problems that may need ER treatment.
- 3. Bronchitis and bronchiolitis 50% of infants
- 4. Pneumonia in about 25% of children
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What is the treatment of respiratory syncytial virus?
- -Virazole brand of ribavirin (aerosol) is effective in lessening the severity of the diseas
- -Immunity is type-specific but not for life
- -Re-infections are common but milder
- -Try putting child in hot bath
- -Hospital staff plays an important role in the transmission
- -Attenuated vaccines are currently being tested
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What is mumps?
- -ss RNA, enveloped virus
- -Only one serotype
- -Man is the only host
- -Goes to the URT then blood then to the salivary glands
- -Effects one side
- -Incubation time 2-3 weeks
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What are the symptoms of mumps?
- -Fever, headache, sore throat, loss of energy
- -swelling of salivary glands, chewing painful
- -benign disease, infants rarely affected because of the protective effect of maternal antibodies: Deafness, pancreatitis, diabetes, aseptic meningitis, encephalitis, orchitis (can lead to sterility)
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What is the prevention of mumps?
- -live, attenuated vaccine (MMR), 99% effective
- -Safest, only 31 states require proof before school
- -Not everyone immunized so cases increases
- -Immunity life-long, can only get once
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What is measles?
- -Rubeola
- -ss RNA enveloped virus
- -One serotype
- -Man only host
- -Transmitted by coughing
- -URT then into the blood and into the skin
- -Incubation time 7-10 days, 7 day measles
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What is the symptoms of measles (rubeola)
- -Fever, headahce, cough, runny nose, photophobia, conjunctivitis and rash
- -Rash on face then goes down the body and the extremities
- -A day or so before rash is visible, small red sports appear on the inside of the cheek. These are called Koplik's spots
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What is important in the diagnosis of measles?
-Koplik's spots
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What is the disease of measles (rubeola)?
- -Measles is one of the most communicable diseases in humans and in unimmunized populations almost every child will get measles early in life (6 mo-2 yrs)
- -Usually there is no scarring, complete recovery is normal, some complications
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What are complications of measles (rubeola)?
- -10% get secondary bacterial infections such as pneumonia
- -Encephalitis occurs in 1 of every 1000 cases, 20-40% die, 25% brain damage-can be serious problem
- -A rare sequela of measles infection (non-vaccine) is subacute sclerosing panencephalitis (SSPE) 100% DEATH
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What is the prevention of measles (rubeola)?
- -A live, attenuated vaccine is available
- -life long immunity
- -Should not be given to infants before their 1st bday
- -Pregnant women should not be vaccinated
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What is rubella virus?
- -ss RNA, enveloped virus
- -one serotype
- -man only host
- -URT to the blood to the skin, rash
- -3 day measles or german measles
- -Incubation is 7-14 days
- -Rash lasts 3 days, mild fever
- -Self limiting infection, arthritis seen in young women
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What is congenital rubella infection?
- -Infection of the fetus from infected pregnant mother because rubella virus can cross the placental barrier
- -Infection in 1st trimester: 30% of fetuses will be stillborn, aborted or deformed at birth
- -Infection in 2nd trimester: 15% deaths, survivors will have cataracts, glaucoma, heart defects, deafness, encephalitis, and underdeveloped organs or tissues
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What is the treatment of rubella?
- -No treatment
- -In infection occurs during the first trimester, therapeutic abortion is recommended
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What is the prevention of rubella?
- -Attenuated vaccine
- -Immunity life long
- -Pregnant women should never by vaccinated because vaccine can cross the placenta and lead to abnormalities. Women should wait 4 weeks after vaccine to get pregnant
- -Periodic outbreaks at hospital, so all hospital personnel who come in contact with pregnant women must be vaccinated
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What is rabies virus?
- -Rhabdovirus
- -ss RNA enveloped virus, bullet shaped
- -One serotype
- -Man accidental host
- -Virus affects warm blooded animal
- -Transmitted by bite of infected animal
- -Bite goes to muscles and CT to PNS then CNS (cell damage in the brain).
- -Affects more wild animals
- -Incubation period 2-16 weeks, but can last up to 2-3 yrs
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What are the symptoms of rabies?
- -Fever, headache, nausea, sneezing and watery eyes
- -Excitable, develop photophobia, difficulty in swallowing, drooling, fear of water
- -Seizures, delirium, lapse into coma and death
- -50% of those bitten by a rabid animal, get encephalitis of those who are symptomatic, 100% die
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How do you diagnosis rabies?
- -If a person is bitten, the animal is quarantined for 1-2 weeks to watch for symptoms of rabies. If symptoms develop its brain tissue is examined for the presence of negri bodies in the cytoplasm of nervous tissue.
- Negri bodies are seen in the purkinje cell of the human cerebellum
- -Immunofluorescence is used to look at the brain tissue of animal and human
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What is the treatment of rabies?
- -After exposure known post-exposure prophylaxis or PEP is successful in preventing the disease if administered promptly, within six days after infection and consists over 28 days
- 1. Wound care: soap and virus killing cleanser
- 2. One time injection of human rabies immune globulin (HRIG) one day-short term protection against rabies
- 3. active immunization with a vaccine HDCV human diploid cell vaccine-killed vaccine in tissue culture. Given on days 1, 3, 7, 14 and 28
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What is the prevention of rabies?
- -Vaccinate vets, park rangers, zoo animal handlers, boosters every 2 years
- -Vaccinate domestic animals and eliminate stray animals from the community
- -Wild-life rabies control is difficult
- -Vaccine laced wild animal cookies to fight rabies outbreak.
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What is arboviruses?
- -Arthropod-summer disease
- -ss RNA enveloped viruses
- -Man is accidental host, dead end
- -About 400 types of viruses known
- -Yellow fever eliminated except in some african countries
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What are 4 types of arboviruses?
- 1. West Nile Virus (WNV)-mosquito bites. Crows, robins are mina hosts
- 2. California encephalitis virus (CEV): reservoir in small mammals
- 3. St. Louis encephalitis virus (SLEV): reservoir in birds-someimes causes death in the elderly
- 4. Easter equine encephalitis virus (EEEV): Reservoir in birds, but from horses imported from east coast-65% die, mental sequelae common
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How is an arbovirus spread?
- -Arthropod (insect) borne viruses
- -arthropod bites animal then animal bites the human
- -Spread by mosquito bites
- -The virus grows in the salivary glands of the mosquitoes
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What is the prevention of arboviruses?
- -The most effective method of control is through reduction or elimination of mosquitoes-Kerosene sprays in the summer
- -No vaccine has yet proved effective
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What is a rotavirus?
- -ds RNA containing (11 segments), naked virus
- -Causes significant GI disease, diarrhea, infecting every child around the globe by age of 5.
- -In US and worldwide, leading cause of acute gastroenteritis. 50% infants infected
- -Incubation is 2 days
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What are the symptoms of rotavirus?
- -Fever, vomiting, and diarrhea
- -Recovery is normal, except in malnourished children-results in death because of dehydration and electrolyte imbalance
- -HIgh infant mortality in third world countries-formula milk
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What is the prevention of rotavirus?
- -2006 vaccine: Rotateq (Merck): live attenuated pentavalent oral vaccine.
- -Has 5 different viruses in it
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How is the rotavirus affecting the world?
- -2nd leading cause of death in developing countries
- -Most common cause of child diarrhea
- -600,000 children die
- -Heavily affects undeveloped countries
- -30-40 deaths from dehydration each year
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What is a norovirus?
- -ss RNA containing naked capsid virus
- -Causes approx. 90% epidemic non-bacterial outbreaks of gastroenteritis around the world
- -50% of all found borne outbreaks of gastroenteritis in the US
- -fecal oral route (Ships, hotels, restaurants)
- -Incubation 1-2 days
- -no vaccine
- -hand washing remains an effective method to reduce the spread
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Which RNA viruses are enveloped? and what do they share?
- -HIV
- -Flu
- -Respiratory syncytial virus (RSV)
- -Mumps
- -Measles
- -Rubella
- -Rhabdovirus
- -Arbovirus
- These are all spread in closer contact- example droplets
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What are the RNA viruses are naked?
- -Poliovirus
- -Rhinovirus
- -Coxsackievirus and echoviruses
- -Rotavirus
- -Norovirus
- All spread by fecal oral route
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What is HIV?
- -1985, first description of HIV infection, mononucleosis like, was published
- -ss RNA containing, enveloped virus
- -Two serotypes:
- 1. HIV 1 (Europe, Central Africa, and the Americans
- 2. HIV 2 (West Africa) and India
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How is the HIV infection spread?
- -Sexual intercourse, exposure to contaminated blood, or perinatal transmission (mother to baby)
- -Targets include: dendritic cells, APC, macrophages, CD4+ T cells
- -Transmitted via genital, anal, and oral sex
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How does the HIV spread through the body?
- -RNA (2 codes) that makes DNA uses the host DNA (macrophages/lymph nodes) also in resting (memory T)
- -Incubation period of 200 to 20 years
- -Virus binds to cells that have CD4 antigen (1st receptor)
- -Virus requires 2nd receptor: CXCR4 (Fusin) for T cell tropic or CCR5 for M cell tropic
- -HIV is captured by dendritic cells and delivered to the lymph node where the virus is transmitted to CD4 T cels, lymph node site of virus production
- -Must have receptors to bind
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What percent of the population is resistant to HIV?
-1% of caucasian population are naturally resistant to HIV infection because of mutation in CXCR4 gene
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What are the steps are HIV replication?
- 1. Binding and entry
- 2. Reverse transcription
- 3. Integration: Enzyme DNA to integrate into host cell
- 4. Transcription
- 5. Assembly
- 6. Release and protease (into the blood stream)
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What is the pathogenesis of HIV?
- -At time of initial infection with HIB, patients have a large # of susceptible CD4 t cells and no specific immune response
- -HIV destroy or disable t cells in an HIV infected individual by several mechanisms
- 1. Direct killing of CD4 cells by HIV gp120 Lysis
- 2. Syncytia formation b/w infected and unfected cells
- 3. Induction of apoptosis in infected cells: programmed cell death
- 4. Cytotoxic cell response to infected CD4 cells and kills them
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What is the typical course of an HIV infection?
- -Slow but progressive deterioration in the host immune system and most advanced stages is complicated by opportunistic infections, neurologic disorders, and some forms of cancer
- -Primary infection, HIV disseminates widely through the body. An immune response to HIV ensues with a detectable decrease in viral load. Clincial latency follows but CD4 t cells slowly continue to decrease until they fall to a critical level below which there is a risk of opportunistic infections
- -If person gets AIDs, it means death
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What are the six stages of HIV?
- 1. 6 mo-1yr: antibodies in blood, fever, headache, fatigue, t cell count normal (800 mm3)
- 2. 3- yrs, usually no symptoms but swollen lymph glands, viral replication, 3-100 billion a day, immune system can handle
- 3. 1-2 yrs, CMIR is severely impaired, T cell count drops (< 400)
- 4/5. 1-2 yrs, T cell count <200, opportunistic infections
- 6. 1-2 yrs after stage 5, total loss of T cells, weight loss, dementia, unable to walk/talk, waste away
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What are opportunistic infections of HIV?
- -60 different opportunistic infections
- -Pneumocystis carinii (fungus): 70% of AIDs patients die of this
- -Mycobacterium tuberculosis
- -yeast, bacterial and viral infections
- -Reactivation of latent herpes viruses
- -Kaposi's sarcoma- HHV 8
- -Encephalitis
- -Thrush is a problem, yeast infection of gum. If get more than twice test for HIV
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What area of the world is HIV the highest?
-Sub saharan africa
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What are the top two areas that HIV is seen?
-Africa and asia
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What race is most effective by HIV?
- - Black
- -Then white then hispanic
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Which gender is most effected by HIV?
- -Women: heterosexual higher
- -Men: homosexual men are higher
- -Women high chance of STDs b/c of anatomy
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How many cases of HIV infections are there a day?
- -16,000 (10/min)
- -more than 95% in developing countries
- -2000 are in children under 15 yrs of age
- -about 12,000 are persons aged 15 to 49 yrs of whom, almost 50% are women
- 50% are 15-24 years old
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What is the treatment of HIV?
- 1. Azido-dideoxythymidine (AZT): first drug treatment inhibits viral genomic replication, side effects virus resistance, toxicity(kids legs swell)
- 2. Protease inhibitors (PI's) inhibit maturation of viral particles. Examples are: Saqunavir, ritonavir, indinavir, and viracept
- HAART (Highly active antiretroviral therapy): A combo of AZT and Pi's
- -Works by suppressing the virus and decreasing rate of opportunistic infections
- -May cause unpleasant side effects in some patients
- -can still transmit HIV to others
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What is HIV prevention?
- -No vaccine
- -Avoid sex contact with those who have it
- -Use condoms
- -Avoid dirty needle sharing
- -screen blood and blood products for HIV before transfusion, avoid high risk blood donors
- -Abstinence best
- -Circumcision
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What is HIV prevention for healthcare personnel?
- -Should assume that the blood and other body fluids are infectious
- -Routinely use barriers
- -Wash hands!
- -Carefully handle and dispose sharp instruments during and after us
- -Report accidental exposure right away
- -Watch for mouth to mouth oral secretions.
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