Common Viral Infections

Norwalk virus

34 diffferent genotypes major cause of diarrhea in adults: epidemic gastroenteritis Food handlers are largely responsible. responsible for 90% cold weather non-bacterial diarrhea incubation 24 hours. Illness is short-lived 12-60 hours as it causes a high frequency of vomiting and some watery diarrhea

coxsackievirus

50 serotypes "hand foot mouth disease" S/s: herpangina- herpes vesicles on soft palate herpangina acutte pericarditis myocarditis viral conjunctivitis DX: no labs TX: symptomatic

parainfluenza virus (CROUP)

75% of all croup MC airway obstruction in children 6 motnhs-6 years cause of hospitilizations in young children (RSV is number 1) SS: starts 1-3 days of low fever and coryza affects larynx and trachea. inflammation causes airway obstruction, barking cough, hoarse voice, inspiratory stridor, respiratory distress possibly DX: Xray neck: steeple sign TX: self limited, goof prognosis: Mist therapy (cool mist humidifier) Corticosteroids: (PO dexamethasone) Racemic Epinephrine: Controversial

poxviruses

9 different types (small pox was one) MC manifestation: Molluscum Contagiosum. does not change or go away. pearly, raised umbilicated skin nodule. Alllover body but not on palms and soles skin to skin contact TX:destruction with cryotherapy, curettage, Rx: cantharidin (naturally occuring, best for kids) cimetidine imiquimoid

Biggest concern of rubella

Congenital rubella syndrome: 80% chance to pass infection. Infant may be normal at birth but will develop problems later: early onset glaucoma and cataracts deafness mental retardation congenital heart detects organomegaly infant death due to heart and other orgams

Croup Vs Epiglottitis

Croup: gradial with URI symptoms. low grade fever. no dysphagia. barking cough. steeple sign AP view. Epiglottitis: sudden. high fever. severe dysohagia, hot potato voice. no cough. swelling of larynx with airway obstruction. "thumb print sign" on Xray showing a swollen epiglotittis on lateral neck view. Emergency- controlled intubatuon

Rubella

Droplet 2-3 incubation period, can be contagious before symptoms like viruses Symptoms are similar to other viral illness: tender suboccipotal lymphadenopathy may precede rash fine pink maculopapular rash Arthralgias Dx: Rubella IgM TX: Symptmmatic treatment

Influenza

Droplet acute febrile illness type A or type B virus Outbreaks in fall/winter months S/S: abrupt onset of high-grade fever with headaches, myalgies, anorexia, and malaise. Cough, sore throat, and runny nasal discharge status asthamatics may occur in asthmatic patients influenza pneumonia- common viral pneumonia. Secondary post flu bacterial (Staph) dx: rapid antigen test- nasal throar swap labs: reverse transcription PCR test are more accurate but not fast chest xray: patchy and peribronchial interstitial infiltrates TX: only reduce duration by 1 day oseltamivir (75 BID X 5D) zanamivir (2 puffs BID X5D) otherwise: supportive care such as tylenol, bed rest, and fluids

Mumps

Droplet exposure 14-21 day incubation period MC in teens/young adults parotif gland tenderness and enlargement (will be fine in 1 week) Overlying facial edema Can cause : Pancreatitis meningitis orchitis 25% swollen balls decreased testosterone sterility is rare Dx: Igm and physical and hsitory Tx: is symptomatic, scrotal support and ice. 1-2 weeks long. Prevent with vaccine

Herpes simplex 1 and 2

HSV 1 - common at the mouth HSV 2 more common in genital either can occur in either location "fluid filled vesicles with surrounding erythema" can cause: Gingivosomatitis Herpes LAbialis Genital Herpes Herpes keratitis-eye blindness Herpetic Whitlow- nail Bells Palsy viral pneumonia neontal genital abnormalities

herpesviruses

Herpes Simplex Virus (HSV) 1 and 2 Varicella Zoster Virus EBV Epstein Barr Cytomegalovirus human herpes virus 6- roseola latent phase-persisting in the rest of the hosts life reactivates in times of immunocompromise latent (Lysogenic cycle) phase can lead to neoplasms (EBV)

EBV- Epstein Barr Virus

Herpesvirus4- lysogenic viral infection 95% people worldwide show evidence of past infection Infectious Mono Symptoms: fever, sore throat, excessive fatigue, general malaise., myalgias, exudates Others: posterior lymphadenopathy, transient upper lid edema "hoagland sign",splenomegaly (50%), maculopapular rash, conjunctival hemmorhage confused for strep

DX and TX measles

Measles IgM Elisa Tx: supportve

polio vaccines

Oral polio vaccine- contains live virus Inactivated Polio vaccine - very effective and given to children in the US

prophylactic therapy, pre and post exposure:

Pre exposure: vaccine indicated for those at increased risk of rabies exposure post exposure prophylaxis: 100% successful human rabies immune globulin (HRIG) Rabies vaccine is also administered with HRIG observe a pet for 10 days.

measles (rubeola)

airborne reportable systemic viral infection babies get vaccine at age 1 and then 4-6 before kindergarten disneyland outbreak

DX/TX EBV

antiviral capsid Antigen- IgM and IgG- ot very specific but better than monospot Monospot- gets a lot of false positives and negs it is possible to have mono and strep. if any suspicion of strep, test for it Associated with cancers like hodgkins lymphoma Treatment is supportive: patients must avoid contacrt sports to avoid splenic ruptures. Significant fatigue can last for months.

Endocytosis

binds to host cell receptor and is internalized

fusion

binds to host membrane receptor and fuses to the membrane

Human Herpesvirus 6

cause of roseola most commin in children under 2 years of age causes high fever, febrile seizure, maculopapular rash on neck and extremiities, runny nose reactivation earlier in life is extremely rare although possible. Seems to cause mono-like syndrom TxL supportive self limited

adenovirus

common cold (URI) viral pharyngitis viral bronchiolitis / bronchitis Acute gastroenteriris Viral myocarditis (not common) TX:Self limited, TX supportive ribavirin:used in immunocompromised patients with severe illness

Cytomegalovirus

condenital, perinatally, or through close contact can lead to blindness in HIV populations and can reactivate over and over, gasteroenteriris and neurological conditions, Congenital infection: from unfected mom who may be asymptomatic at birth. may deevvelop sensorineural hearing loss or mental retardation Dx: IgM and IgG Tx of choice in Ganciclovir- CMV vaccine is currently in clinical trials

DX herpes TX herpes

direct flourescent antibody testing of scraped esions = Tzanck Smear fot multinucleated giant cells PO acyclovir, Famiciclovir valaciclovir . topical penciclovir disclosure to sexual partner is associated with 50% reduction in genital herpes acquisition

why are viruses hard to kill?

dont have a lot of real targets

Parvovirus B19

erythrovirus (5th disease) besy known for Erythema infectiosum (rash) S/S: fiery red slapped cheeck rash, perioral palor, maculopapular rash on trunk and limbs DX: clinic TX: supportive

Rotavirus

leading cause of dehydrating gastroenteriris in children worlwide 500K children die due to rotavirus yearly allroutes transmitted fecal oral contamination TX: self limited 1-4 days for prodrome fever followed by watery, non-bloody diarrhea- rehydration prevention: rotavirus vacine at 2,4,6

Major vaccine preventable

measles mumps rubella poliomyelitis

Hemorrhagic Fevers

most famous is Ebola Ebola=fruit bats organ failure, leukopenia, Hemorrhage. Blood dyscrasia and DIC

characteristics? 3 essential retroviral enzymes?

not living creatures energyless floating around the world until they come in contact with someone to infect gets into a cell and replicates itself= viral replication 3: protease reverse transcriptase integrase RNA must be retrotranscribed into DNA before it can be transcribed into mRNA DNA is then integrated into a host cells DNA

All viruses contain

nucleic acid- DNA or RNA Coat of proteins encasing their genetic material-capsid

Symptoms polio

only 5% get symptoms. 3 manifestations: 1)abortive poliomyelitis- minor illness with fever, headache, vomiting , diarrhea, sore throar (only suspect during an epidemic) 2)Non-paralytic poliomyelitis: can develop miningeal irritation with muscle spasms 3) paralytic poliomyelitis: flaccid paralysis- possibly even respirtory(iron lungs). Can occur anytime during an acute febrile infection. Mortality rate is 50% Long term motor defecit in other 50% (post-polio syndrome)

some viruses contain

outer lipid membrane- envelope

other important viruses

rabies adenovirus parvovirus b19 poxviruses coxsackivirus parainfluenza virus HIV

Poliomyletis (Polio)

reportable viral illness contracted through fecal oral route highly contagoius during first week. Dx: PCR stool or CSF-shows increased proteins and lymphocytes TX: bedrest seems to decrease rate of paralysis. Otherwise supportive

GI viruses

responsible for 30-40% infectious diarrhea in the US rotaviruses Norwalk viruses

measles rubeola s/s

symptoms: high fever, malaise, coryza (URi ), rash, Koplik Spots (small, irregular, red and white spots) rash begins 3-4 days after fever and coryza starts: Brick red maculopapular, starts inface and goes down and out on palms and soles. (Can be confused with roseola- fever and no vaccination) severe encephalitis: 3-7 days after rash in 1% Can produce severe respiratory illness and diarrhea Post viral bacterial infections are commin and can be severe

varicella zoster virus

varicella rash (chickenpox): pruritic. starts as papular changing to vesicular "dewdrops on a rose petal" and rupture with crusting. DX:dermatomal distributionYou can see lesions and vesicles and ruptured crusty vesicles, all different stages one one patient fever and malaise are worse in adults than kids. inhalation OR contact Post-herpetic neuralgia can occur in 2/3 of shingles patients tx: isolation, antohistamines, itching, possibly acyclovir (doesnt help much )

Rabies

viral encephalitis - secondary to an animal bite virus gains entry into salivary glands of the animal 5-7 days before their death from rabies transmitted to humans through saliva into your skin. travels up neurons to the brain and causes encephalitis with leukocyte infiltration: focal hemmorrhage and dymyelination throughout the CNS 100% fatal. (7 survived) After variable incubation, first symptoms include a prodrome possibly consisting of pain/paresthesias at the bite site, malaise, headaches, fever,anxiety, depression Later: hydrophobia, and aerophobia (pathoneumonic for rabies) Coma and death ensue

Dengue Fever

viral illness AEDES mosquito S/S: flu like symptoms +depression -Dengue Shock syndrome: hemmorhagic shock -Dengue Hepatitis -widespread maculopapular rash spares palms and soles Dx:IgM ELISA Tx: supportive: blood products, volume support

herpes zoster (shingles)

you would see it unilaterally because eruption of vesicles are in a dermatomal distribution. tingling with pain (prodrome). Evolves to pustules and crusting Tx: valacyclovir or Famciclovir within first 72 hours. Does not prevent postherpetic neuralgia Varicella Vaccine- safe and over 98% effective