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What are examples of RNA viruses?
- -Coxsackievirus and echoviruses
- -Respiratory syncytial virus
What is poliovirus?
- -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
What is important about a naked virus?
-It is highly transmissible
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
What is the treatment of polio?
-No treatment except for physical therapy to recover function
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
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
What are symptoms of post polio syndrome?
- -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
What is the iron lung?
- -Used to treatment breathing problems in those with polio or pps.
- -60 people still use the iron lung
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
What are the symptoms of the common cold?
-Cough, inflammation of nasal cavity, sore throat, headache, and no fever usually.
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
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
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
What are viruses that are members of enteroviruses?
-Coxsackieviruses, polioviruses, echoviruses, and hepatitis A virus
What is the echovirus?
- -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
What is the coxsackievirus?
- -two types: A (23 serotypes) and B (6 serotypes)
- -Both effect the heart
- -Named after a town in NY
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
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.
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.
What is the treatment of coxsackievirus infections?
- -Treat the symptoms
- -No drugs for treatments or vaccines
- -Provide supportive care and bed rest
What is the influenza virus?
- -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
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
What are symptoms of influenza?
-fever, cough, headache, muscular aches and sore throat, and retro-orbital pain (looking up hurts more)
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
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)
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
What is an antigenic variation?
-the flu virus changes its H and N antigens
What kind of change can influenza B go through?
-Minor antigenic change only
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
What happens with an antigenic drift?
- -Minor change
- -Mutation in HA
- -Occurs in influenza A and B viruses: resulting the local epidemic of flu
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
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
What is influenza A?
- -Severe illness
- -Animal Reservoir
- -Spread in human: pandemic
- -Shift and drift change
What is influenza B?
- -Less severe than A
- -No animal reservoir
- -Drift change
What is influenza C?
- -Not very severe
- -No animal reservoir
- -sporadic in humans
- -Drift change
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
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
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
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
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
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
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
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
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
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)
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
What is measles?
- -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
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
What is important in the diagnosis of measles?
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
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
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
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
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
What is the treatment of rubella?
- -No treatment
- -In infection occurs during the first trimester, therapeutic abortion is recommended
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
What is rabies virus?
- -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
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
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
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
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.
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
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
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
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
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
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
What is the prevention of rotavirus?
- -2006 vaccine: Rotateq (Merck): live attenuated pentavalent oral vaccine.
- -Has 5 different viruses in it
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
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
Which RNA viruses are enveloped? and what do they share?
- -Respiratory syncytial virus (RSV)
- These are all spread in closer contact- example droplets
What are the RNA viruses are naked?
- -Coxsackievirus and echoviruses
- All spread by fecal oral route
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
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
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
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
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)
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
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
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
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
- -Thrush is a problem, yeast infection of gum. If get more than twice test for HIV
What area of the world is HIV the highest?
-Sub saharan africa
What are the top two areas that HIV is seen?
-Africa and asia
What race is most effective by HIV?
- - Black
- -Then white then hispanic
Which gender is most effected by HIV?
- -Women: heterosexual higher
- -Men: homosexual men are higher
- -Women high chance of STDs b/c of anatomy
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
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
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
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.