MICRO CH 25
what drug came out by the FDA in 2012, that was specific for pre-exposure prophalyxis for those at risk of HIV?
Truvada ( a single daily pill)
how to treat RSV
most only need supportive care for the sickest pts (immunocompromised or organ transplant pts)- antiviral drug ribivarin
what are some of the most VIRULENT complications of HIV/AIDS?
mostly neurological -lesions on the brain, meninges, spinal column, and peripheral nerves
what kind of capsid does poliomyelitis have? whats it resistant to?
naked capsid that confers with its resistance to acid, bile, and detergents *survives the gastric environment so easily transmitted in body*
does permanent sterility occur with mumps
no, tenderness for a long time after infection but permanent sterility is rare
togaviruses.. what is an example?
nonsegmented, single stranded RNA viruses with a loose envelope rubella is an example of a togavirus
what is the best known calcivirus?
norovirus also known as Norwalj agent -believed to be 90% of all viral gastroenteritis
once the virus enters the cell, what are the tx strategies done to prevent replication?
nucleoside revers transcriptase inhibitors (NRTIs)
who is at risk for contracting the flu
occupational contact with chickens, other poultry, and swine = high risk rates of infection highest in children (30%) and lowest in adults (6%)
how is Hep A spread?
oral-fecal rote -usually due to poor hygiene and lack of public health measures
how is norwalk transmitted?
oro-fecally in schools, reatsurants, cruise ships, and nursing home s/s= nausea, vomiting, cramps, diarrhea, and chills, recovery is rapid and complete
structural components of retroviruses
outermost compartment is a lipid envelope with transmembrane glycoprotein spikes and knobs that mediate viral adsorption and fusion to the host cell
what are the 3 paramyoviruses and how are they transmitted?
paramyxovirus, morbillivirus, and pneumonvirus-- all readily transmitted through respiratory droplets
pts with weakened host defenses are predisposed to secondary bacterial infections like
pneumonia caused by streptococcus pneumoniae or staphylococcus aureus
an acute enteroviral infection of the spinal cord that can cause neuromuscular paralysis
poliomyelitis
coronaviruses
relatively large RNA viruses with distinctive, widely spaced spikes on their envelopes
how do you treat measles
relies on reducing fever, suppressing cough, and replacing lost fluid therapy includes abx for bacterial complications and doses of vitamin A for children
HIV is a
retrovirus
what is the preferred diagnostic technique for RSV
reverse transcriptase-polymerase chain reaction (RT-PCR), which detects viral RNA
early in the infection
seems to be little virus in the pt with low probability of transmission BUT within a week, transmissibility is very high after 3 weeks, viral levels decrease significantly and symptoms subside
diagnosis of ebola and marburg depends on
serological testing for antibodies to the virus or PCR to amplify the genetic material of the virus
spasms of the neck and pharyngeal muscles leads to
severe pain upon swallowing attempts to swallow or even the sight of liquids brings on hydrophobia (fear of water)
Zika is transmitted by mosquitoes and
sexual contact
how is HIV transmitted
sexual contact and transfer of blood or blood products babies can be infected before or during birth and through breast-feeding
what is the latex agglutination card
simple, miniaturized test that provides rapid method for IgM assay
what is the most important bunyavirus? what are the symptoms
sin nombra hantavirus symptoms- high fever, lung edema, and pulmonary failure
what is rabies? who is the primary reservoir? how is it spread?
slow, progressive zoonotic disease characterized by a fatal meningoencephalitis primary reservoir is wild animals spread through bites, scratches, and inhalation of droplets
what is an orthomyxovirus
spherical particles with an average diameter of 80-120 nm
what is parainfluenza? who is susceptible?
widespread flu, usually more benign- spread by respiratory droplets and respiratory secretions that are inhaled or inoculated into mucus membranes newborns lacking passive antibodies are particularly susceptible, most infections are in kids under 6
how are children treated for rotavirus? what is vaccine?
with fluids and electrolytes vaccines= RotaTeq and Rotarix based on various live attenuated viruses
is there an arbovirus vaccine
yes! a live attenuated yellow fever vaccine give lif long immunity- required for travelers to the tropics dengue fever vaccine- live virus reduces chance of getting dengue fever by 60% but only for people 9-45
is measles bad? how is it transmitted?
yes! kills babies and young children, and very contagious spread by respiratory aerosols very important to vaccinate
Symptoms of yellow fever virus
starts acutely with fever, HA, and muscle pain some pts progress to oral hemorrhage, nosebleed, vomiting, jaundice, liver and kidney damage with significant mortality rates
what is the most serious complication of measles?
subacute sclerosing panencephalitis (SSPE)- a progressive neurological degeneration of the cerebral cortex, white matter, and brainstem
how to treat arbovirus
support measures to control fever, convulsions, dehydration, shock, and edema
how to treat for ebola and marburg virus
supportive care
how long does the virus survive? what is transmission greatly facilitated by?
survives 24 hours on nonliving surfaces transmission greatly facilitated by crowding and poor ventilation in living quarters in the late fall and winter (tropics occurs all year, not seasonal)
patho of RSV
the 1st symtpoms of primary infection are fever that lasts for 3 days, rhinitis, phayngitis, and otitis infection of the respiratory tree and lung parenchyma give rise to symptoms of croup with bouts of coughing, wheezing, dyspnea, and rales
what happens to babies when their mom has been infected by zika virus
the autoimmune disease- Guillain-Barre syndrome and birth defects (microcephaly)
what is antigenetic drift
the constant change of glycoproteins through mutation- the antigens gradually change their amino acid composition, resulting in decreased ability of host memory cells to recognize them
What is one of the HTLV-I genetic targets?
the gene and receptor for interleukin-2 a potent stimulator of T cells
what is the key to virus behavior and pathology
the glycoprotein spikes- *hemagglutinin (H) and neuraminidase (N)*
where are the primary portals of entry for RSV? where does it replicate?
the nose and the eye and the nasopharynx is the main site of RSV replication
where does mumps normally target
the parotid salivary glands but its not limited to this area
what happens in the dumb phase of rabies
the pt is paralyzed, disoriented, and stuporous
what is antigenetic shift
the substitution of one of the genes or strands from an influenza strand originating from a different animal host ex- a strand of influenza A can infect both humans and swine, and a different strand of influenza A can infect birds and swine
As the antibody levels rise in HIV what happens to the virus levels?
they decrease and this results in latency (an symptomatic period)
what is a retrovirus
they reverse the order of usual transcription contain reverse transcriptase (RT) that catalyzes the replication of double stranded DNA from a single stranded RNA
how is hep c transmitted
through blood contact like blood transfusions or needle sharing by IV drug users unlike HBV, sexual contact not a major mode of transportation
how is rubella transmitted
through contact with respiratory secretions shed through the prodromal phase until about a week after the rash appears close contact is required for the spread
what diseases do prions cause?
transmissible spongiform encephalopathies (TSEs), neurodegenerative disease with LONG incubation period but rapid progressions
how is arenavirus transmitted
transmitted to humans through aerosols and direct contact with the animal or its excretions
who is at special risk of arboviruses
travelers and military personnel bc they dont have immunity like the natives young children and elderly are most sensitive to injury by arbovirus
what is breakbone fever
a form of dengue hemorrhagic fever that can be lethal- severe pain in muscles and joints
how do you detect flu antigens
a rapid serological test can detect them in under 30 minutes but it has low specificity (false negatives) assays that detect and amplify the RNA of the virus is the gold standard and can be done in less than 2 hours
tx of hep A? prevention?
tx= no specify tx could do immune serum globulin early in disease prev= 2 inactivated viral vaccines are approved (HAVRIX AND VAQTA) and given in 2 doses between 6 months and 18 months of age
whats one way to prevent AIDS?
abstinence -but can also use condoms and don't share needles
are Leukemias acquired or inherited?
acquired
after being ingested polioviruses go where?
adsorb receptors of mucosal cells in the oropharynx and intestine>>> then multiply in the mucosal epithelia and lymphoid tissue
what is tx of polio?
alleviating pain and suffering
influenza is
an acute, highly contagious respiratory illness affecting people at all ages and marked by seasonal regularity and pandemics at irregular intervals
because the vaccine is live, it can cause
an atypical infection with rash and fever as a general rule, anyone who has had measles is protected against infection
what does neuraminidase do
an enzyme that breaks down the respiratory mucus, keeps viruses from sticking together, and assists in budding from the host cell
calciviruses are what?
an ill defined group of enteric viruses found in humans and mammals
how early should you start flu treatment
as early as possible, even before lab confirmation
what are the advantages of latex aggulintation?
available within minutes instead of days -most kits require a small sample of blood or saliva
why is hemagglutinin the most important virulence factor
bc its needed to bind to the respiratory mucosal receptors and induce viral entry
A person is diagnose with HIV infection by?
being testes positive on a series of tests for the human immunodeficiency virus *DIAGNOSIS IS NOT THE SAME AS HAVING AIDS*
once the CD4 cell level fall below ________ what appears?
below 200 symptoms of AIDS appear
what drugs block the receptors on CD4 cells that prevent the binding of HIV?
binding inhibitors
what are the chief vectors of arboviruses
blood sucking arthropods like mosquitoes, ticks, fleas, and gnats
SPPE spreads
unchecked though the brain by cell fusion, gradually destroys neurons and accessory cells and breaks down myelin leads to profound intellectual and neurological impairment and invariably leads to coma and death in a matter of months to years
Reoviruses are what kind of virus?
unsusual double stranded RNA genome and both and inner and outer capsid
yellow fever and dengue fever viruses cause
capillary fragility and disrupt the blood clotting systems, leading to localized bleeding, fever, and shock
what often develops in neonates that develop rubella within the first trimester
cataracts
dengue fever
caused by flavivirus and also carried by Aedes mosquitoes
what is rotavirus?
causes significant diarrhea in newborn huamns -trasmitted fecally contaminated food, water and fomites
how is Hep A dx?
certain liver enzymes and leuokopenia and detected by anti-HAV IgM antibodies produced early in the infection
what is the most common tick borne viral fever in the US
colorado tick fever (CTF) restricted to distribution in the rocky mountains
in both phases, if untreated it leads to
coma phase, resulting in death from cardiac arrest or respiratory arrest
how is rubella diagnosed
confirmatory methods of choice- serological testing and virus isolation IgM can determine recent infection
what are arenaviruses
consistent with a rodent host and continuously shed by the rodent during its lifetime
infection of ebola and marburg virus occur through
contact with wild animals or the fluids of infected people-- causes hemorrhagic fever and is lethal in 90% of cases depending on the medical care available
what are some complications of Leukemia?
cuteanous T cell lymphoma or lymphadenopathy and dissemination of tumors to the lung, spleen, and liver
when are humans a maintenance reservoir
dengue fever and yellow fever
diagnosis of SARS relies on? treatment?
detection of antibodies against the virus or amplification of viral RNA using PCR no specific treatment besides supportive care
most cases of arbovirus diagnosis are based off of
detection of arboviral RNA in the blood or serological detection of antibodies against specific viral proteins
whats the most effective drug strategy in the battle against HIV?
development of antiretroviral therapy (ART) -use of multiple drugs to block the replication cycle of the HIV virus at several points
rhabdovirus (rabies)
distinctive, bullet like appearance, round on one end and flat on the other helical nucleocapsid and spikes that protrude through the envelope
what are the problems with the rubella vaccine
doesnt always give long lasting immunity live virus so sexually active women must use contraception for 4weeks after getting vaccine bc virus is teratogenic
what are the symptoms of postnatal rubella
early symptoms- malaise, mild fever, sore throat, and LAD rash of pink macules and papules appears on the face first then progresses down the trunk and towards the extremities, advancing and resolving in about 3 days
St. Louise Encephalitis (SLE)
eastern and central US
all leukemias first manifest with what conditions?
easy bruising, bleeding, paleness, fatigue
fruit bats are the reservoir for
ebola and marburg virus
eastern equine encephalitis (EEE)
endemic along the the eastern coast of north america and canada high periods of rain in late summer increase chance of outbreak disease usually appears first in caged birds and horses
examples of when humans are a dead end, accidental host
equine encephalitis and colorado tick fever
the primary effects of HIV are
extreme leukopenia with lowered levels of lymphocytes in particular
what are some initial symptoms of AIDS?
fatigue, diarrhea, weight loss, and neurological changes -BUT most patients first notice this phase of infection because most patients have one or more opourtunistic infections
symptoms of SARS
fever above 38 (100.4) progresses to body aches and overall feeling of fatigue and malaise
chikungunya virus
first seen in the Caribbean, seen in US in those who have recently traveled DO become symptomatic- fever, HA, muscle and joint pain, N/V, occasionally rash symptoms stop in 7-10 days
how are picornaviruses named? examples?
for their small (pico) size and their RNA core ex: Enterovirus and Rhinovirus and Cardiovirus
what is tx of rhinovirus?
force fluids and relieve symptoms with various cold remedies and cough syrups
what other special feature do paramyxoviruses have
fusion (F) spikes that initiate attatchment the cell-to-cell fusions
what are 3 groups of rhinovirus? what are they associated with?
groups= A B C associated with common cold
what is a serious complication of flu vaccines
guillain-barre syndrome, a neurological condition- appears to be an autoimmunity induced by viral proteins and marked by varying degrees of demyelination of the peripheral nervous system, leading to weakness and sensory loss
coxsackies can cause a peculiar pattern of lesions on hands, feet and oral mucosa called?
hand foot mouth disease
what is an example of a flavivirus
hep C
what is the current vaccine of choice for rabies
human diploid cell vaccine (HDCV)- potent inactivated vaccine cultured in human embryonic fibroblasts routine in postexposure- IM or intradermal injection
who is the exclusive natural hosts of mumps? how is it transmitted?
humans are the exclusive natural host communicated primarily through salivary and respiratory secretions- high rates in crowded populations or communities with low levels of immunity
incidence of polio is more pronounced when? how is spread?
in summer and fall transmitted: through food, water, hands, and objects contaminated with feces and mechanical vectors
patho of postnatal rubella
incubation of 2-3 weeks, virus multiplies in the respiratory epithelium, infiltrates local lymphoid tissue, and enters the blood stream
patho of mumps
incubation of 2-3 weeks- nasal discharge, muscle pain, and malaise followed by inflammation of salivary glands--> gopher like cheeks on 1 or both sides virus can multiple in other organs esp testes, ovaries, thyroid, pancreas, meninges, heart, and kidney
with congenital rubella- infection during the first trimester is most likely to
induce miscarriage or multiple permanent defects in the newborn like ocular lesions, deafness, and mental/physical retardation
patho of rabies
infection begins when infected animal saliva enters puncture wound- remains in trauma site for up to a week, where it multiples gradually enters nerve endings, and advances toward the ganglia, spinal cord, and brain viral multiplication in the brain followed by migration to diverse sites like the eyes, heart, skin and oral cavity
how do people acquire the rhinovirus?
infection from contaminates hands and fomites, and to a LESSER EXTENT droplet nuclei
in 20-30% of young adult males with mumps
infection loacalizes to epididymis and testis, usually on one side only causes orchitis and epididymitis which can be painful but no permanent damage occurs
patho of the flu
influenza virus binds primarily to ciliated cells of the respiratory mucosa, infection causes rapid destruction of these cells which releases a load of viruses this eliminates the respiratory epithelium and gets rid of protective ciliary clearance and leads to severe inflammation illness aggravated by fever, HA, myalgia, pharyngeal pain, SOB, and coughing normal ciliated epithelium restored in about a week
how is poliovirus dx?
usually by inoculating cell cultures of stool or throat washing in the early part of the disease
infection and symptoms of ebola and marburg virus
initial incubation period of 5-10 days, flu-like symptoms- HA, fever, chills, myalgia a week later- maculopapular rash, nausea, vomiting, and pain in the throat, chest, and abdomen progresses to uncontrolled bleeding, shock, delirium, and eventually multiorgan failure
what is the criteria indicative of rabies
intracellular inclusions (negri bodies) in nervous tissues, isolation of rabies virus from saliva or brain tissue, and demonstration of rabies virus antigens in specimens of the brain, serum, CSF, or cornea using immunfluorescent methods
once HIV is inside a target cell
its reverse transcriptase converts RNA into DNA
adult rubella often accompanied by
joint inflammation and pain rather than rash
who is particularly susceptible to RSV
kids 6 months or younger-- actually the most prevalent cause of respiratory infection in this age group
how does croup manifest
labored and noisy breathing accompanied by a horse cough that is most common in infants and children
prions lack? prior are restsnat to?
lack genetic material and highly resistant to chemicals, radiation, and heat
what are the 2 drugs that offer a cure for Hep C
ledipasvir and sofobuvir inhibit two proteins crucial to the replication of Hep C RNA genome given as 1 pill- harvoni- a 12 week course has a 93-99% cure rate
enteroviral infections are other subclinical or all into what category?
"undifferentiated febrile illness" characterized by fever, myalgia, and malaise
how long does the latency period last? what happens to the number of T lymphocytes?
-varies from 2 to 15 years -the number of T cells in blood steadily decreases
how long is the incubation period of rabies
1-2 months, shorter if on the face, scalp or neck bc that is closer to the brain
what are some important complications of enteroviruses?
1. common cold syndrome 2. Pleurodynia (acute disease characterized by a sharp sudden intercostal or abdominal pain accompanied by fever and sore throat) 3. eruptive skin rashes that resemble rubella rash
what are the most common viruses that are similar to the polio virus but cause SHORT TERM mild infection?
1. coxsackies viruses A and B 2. echoviruses *incidence of infection is higher from spring to early summer in temperate climates*
what are the kinds of polio vaccines
1. inactivated poli vaccine (IPV) known as Salk vaccine 2. oral poli vaccine (OPV) known as the Sabin vaccine
people are diagnosed with AIDS if they follow what criteria?
1. positive for virus 2. if they fulfill one of the additional criteria: -CD4 count fewer than 200 -CD4 cells account for less than 14% of all lymphocytes -they experience one or more of a CDC provided list of AIDS defining illnesses
what sets rhinovirus and picornavirus apart?
1. rhino are sensitive to acidic environments 2. optimum temp of multiplication is not normal body temp but 33 degrees C, ave temp in the human NOSE
How is yellow fever transmitted?
2 patterns: urban cycle between humans and mosquito Aedes aegypti, which reproduces in standing water in cities sylvan cycle- maintained in forest monkeys and mosquitoes
what is incubation period of Hep A?
2 to 6 weeks -shed in feces, and enter blood and is carried to liver s/s= vague like flu symptoms, loss of appetite, dirahhera, fever, etc
what is the capsid of rhinovirus like?
2 types: protuberances (knobs) which are antigentically diverse and indentations (pockets) which exist in only 2 forms
what is mainstay prevention of polio?
vaccination as early in life as possible, usually 4 doses starting at about 2 months of age
to rule out a false negative result for HIV due to the window period, when should they be tested a second time?
3 to 6 months later
what are the primary treatments for the flu
4 prescription drugs: zanamivir (relenza), oseltamivir (tamiflu), peramivir (rapivab)-- target neuraminidase to block viral budding and release 4. balozivir marboxil (xofluva)- blocks initiation of viral RNA synthesis, preventing replication
symptoms of west nile virus
80% are asymptomatic 1/5 have fever, HA, body aches, joint pains, vomiting, diarrhea, or rash- recovery complete but fatigue and weakness can last months >1% get neurological illness like encephalitis or meningitis (10% with neurological infection die)
what influenza virus causes the most cases of infection
A
invasion of the motor neurons causes what?
various degrees of flackd paralysis over a period of a few hours to several days -paralysis of the legs, abdomen, back, intercostal, diaphragm, pectoral girdle, etc
the polio virus is neurotropic.. what does that mean?
virus infiltrates the motor neurons of the anterior horn of the spinal cord, though it can attack spinal ganglia, cranial nerves, and motor nuclei
patho of measles
virus invades the mucosal lining of the respiratory tract during an incubation period of 2 weeks initial symptoms are sore, throat, dry cough, HA, conjunctivitis, lymphadenitis, and fever in short time- *kopliks spots* - unusual oral lesions appear as a preclude to *exanthem* that erupts on the head and then moves to trunk and extremities until entire body is covered
T helper cells are responsible for regulating what
B cell antibody production and macrophage stimulation ex: as number of T helper cells declines so does the efficiency of the macrophage response and the ability to produce antibodies
is hep B or hep C more likely to become chronic?
C!!! without treatment, 75-85% will remain infected for life
how is a majority of influenza spread
virus-laden aerosols and droplets constitutes the major route of influenza infection, but fomites can play a secondary role
what can decrease the risk of infection by 90%
wash the wound scrupulously with soap and water, followed by debridement and application of a povidine-iodine antiseptic like betadine
what are some other signs and symptoms, patients may experience?
wasting of body mass, weight loss, diarrhea, and poor nutrient absorption, fatigue, sore throat, fever, and night sweats -even a rash and lymphadenopathy appear
what is the most prevalent arbovirus in the US
west nile virus
what is the confirmatory tests of HIV?
western blot
enterovirus severity usually depends on what?
what organs are affected
when is the infection cycle of rabies complete
when the virus replicates in the salivary glands and is shed into the saliva
what is the human TSE called?
Creutfeldtz Jackob disease (CJD) and fatal insomnia
how is mumps diagnosed
Direct fluorescent antibody (DFA) or ELISA method bc swelling isnt always present during incubation period
what is the initial screening tests of HIV?
ELISA and new latex agglutination and rapid antibody tests
what has the highest fatality rate for all encephalitis
Eastern equine encephalitis
what are the most common retroviruses
HIV and T-cell lymphotrophic viruses 1 and 2 (HTVL-1 and HTVL-2)
patho of HIV
HIV enters a mucous membrane or skin and is phagocytosed by a dendritic cell in the dendritic cell, the virus grows and is shed from the cell without killing it new viruses taken up and amplified by macrophages in the skin, lymph, and bone marrow, and blood infects CD4 lymphocytes, monocytes, dendritic cells, and macrophages
what is one enterovirus that affects the digestive tract alone?
Hep A
general name for at least 4 different malignant disease of WBCs forming elements originating in the bone marrow
Leukemias
what are the prodromal symptoms or rabies? what happens in the furious phase
N/V/HA, fatigue- prodromal furious- 1 acute signs of neurological involvement are agitation, disorientation, seizures, and twitching- throughout this phase pts are fully alert and coherent
is hep A oncogenic?
NO so does NOT predispose liver cancer
does influenza affect your GI tract
NO!!
lacrosse encephalitis virus (LACV)
midwest and Appalachian mountains most show no symptoms- disease often occurs in those 16 or younger
reovirus example?
Rotavirus and reovirus
what virus is associated with the adult T cell leukemia?
T cell lymphotropic virus ( HTLV-I)
how is west nile virus spread
mosquitoes become infected when they feed on birds infected with the virus, then they bite and transmit the virus to humans
