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