week 9: viral infections of humans -

what is viral tropism?

the ability of a virus to infect and replicate within a particular kind of cell or tissue

what are direct viral effects on cells, once a virus infects a host?

• disrupted protein production

• damage to cell structures

• —> cell dysfunction or death

what are examples of some protective and some potentially harmful effects of the host immune response?

• protective

  • interferons slow viral replication

  • antibodies block entry

• harmful

  • inflammatory mediations cause fluid leakage and tissue injury

  • killing infected cells adds to cell loss

what is active protection?

• our own adaptive response that takes time

• memory can form

what is passive protection?

• from received antibodies

• rapid, temporary

• no memory

what is naturally acquired active immunity?

a virus leads to an individuals own adaptive response & subsequent memory

what is medically provided active immunity?

from vaccination —> own adaptive response

what is naturally acquired passive immunity?

materal antibodies given to the placenta

what is medically provided passive immunity?

• from antibodies given to a recipient

  • in pt with rabies exposure they’re given rabies IGs

what is the pattern of an acute virus, what happens to the virus, and what is an example?

• Quickly resolves

• immune defenses eliminate the virus

• Hep A

what is the pattern of a chronic infection, what happens to the virus, and what is an example?

• lasts for a long time

• virus persists with ongoing or intermittent replication

• Chronic Hep C

what is the pattern of latency and reactivation, what happens to the virus, and what is an example?

• viral genome remains in cells

• virus production can restart

• varicella zoster: chickenpox followed by shingles

what is the pathogen, reservoir, transmission, mechanism, and infectious period of measles (rubeola)?

• pathogen: measles virus (enveloped RNA virus)

• reservoir: humans

• transmission: airborne (can stay in air for 2 hours after sick individual leaves)

• mechanism: respiratory entry —> viral replication —> spread through lymphatic tissue & blood —> systemic infection

• infectious period: 4 days before through 4 days after rash onset

manifestations of measles/rubeola

• maculopapular rash from face —> trunk —> limbs

  • flat, raised lesions

• conjuctivitis

• koplik spots (small white spots inside cheeks, before rash onset)

complications of measles/rubeola

• altered alertness & behavior

• seizures

  • encephalitis

• rate, work of breathing, SpO2

  • pneumonia

• assess urine I/O and hydration level

  • dehydration

what precautions are used for measles/rubeola?

• standard + airborne

• AIIR room

• N95 mask

how to treat & prevent measles/rubeola

• treat

  • hydration & nutrition

  • antipyretics, oxygen PRN, vitamin A administration

• prevent

  • vaccinate

  • postexposure prophylaxis for those exposed within 3 days

what is the pathogen, reservoir, transmission, mechanism, and infectious period of measles (rubeola)?

• pathogen: rubella virus (enveloped RNA virus)

• reservoir: humans

• transmission: respiratory droplets & across placenta

• mechanism: respiratory entry —> replication in nasopharynx & lymph nodes —> bloodstream spread —> systemic infection

• infectious period: 7 days before through 7 days after rash onset

manifestations of rubella

• lymph node enlargement

• maculopapular rash

• mild fever

• joint pain

complications of rubella

• fetal risk in first trimester!!

  • fetal loss or congenital rubella syndrome (hearing loss, cataracts, heart defects)

• confusion/seizures

• unusual bruising/bleeding

  • encephalitis

  • thrombocytopenia (low platelets)

testing for rubella

throat/nasopharyngeal swab for RT-PCR = serum rubella lgM

testing for measles

throat/nasopharyngeal swab for RT-PCR

what precautions for rubella

• standard + droplet for 7 days post onset

what to do if pregnant pt has rubella

• arrange obstetric eval for exposure

• ID pregnant exposed contacts

treating & preventing rubella

• fluids & fever/pain relief

• rubella & MMR vax (except if pregnant)

• postpartum vax

what is the pathogen, reservoir, transmission, mechanism, and infectious period of chickenpox & shingles?

• pathogen: varicella-zoster virus (VZV) (enveloped DNA virus)

• reservoir: humans

• transmission: contact w/ blister fluid, inhalation

• mechanism: primary VZV infection —> chickenpox —> latency in sensory nerve ganglia —> possible later reactivation —> shingles

• infectious period:

  • chicken pox: 1-2 days before rash onset until all lesions crust

  • shingles: from blister appearance to all lesions are dry and crusted

manifestations of chickenpox

• generalized, itchy blisters

• lesions at different stages

manifestations of shingles

• pain/tingling before rash

• grouped vesicles in one or adjacent dermatomes

• unilateral and doesn/t cross midline

manifestations of chickenpox/shingles

• persistent pain after healing

• pneumonia, encephalitis, cerebellar involvement (unsteady walking)

• postherapeutic neuralgia

• facial weakness (shingles)

testing for chickenpox/shingles

• lesion PCR testing

• collecting vesicle fluid

precautions for chickenpox/shingles

standard + airborne + contact

how to treat and prevent chickenpox/shingles

• treat

  • chickenpox

    • antivirals for select high-risk pts

  • shingles

    • antivirals promptly

  • relieve pain/itching, avoid aspirin in children with chickenpox

• prevent

  • vax & postexposure assessment

what is the pathogen, reservoir, transmission, mechanism, and infectious period of Mpox?

• pathogen: monkeypox virus (MPXV), enveloped DNA virus

• reservoir: uncertain, infected people & animals can transmit

• transmission: physical contact, sexual contact, contaminated materials, animal exposure

• mechanism: skin entry —> replication —> lesions, sometimes systemic illness

• infectious period: may begin before symptoms & continues until all lesions heal, scabs separate, and healthy skin forms

manifestations of Mpox

• firm, deep, painful lesions w/ central indentation

• few or widespread

• fever, enlarged lymph nodes

complications of Mpox

• eye infection and vision loss

• secondary bacterial infection

• dehydration, proctitis rectal inflammation)

testing for Mpox

swab lesions for PCR

precautions for Mpox

• single-person room

• standard + gown, gloves, eye protection, N95

• continue isolation until lesions have healed & new skin formed

treating & preventing Mpox

• treat

  • provide fluids & pain relief

• prevent

  • avoid close contact & sharing personal items

  • vax

what is the pathogen, reservoir, transmission, mechanism, and infectious period of seasonal influenza?

• pathogen: influenza A & B viruses (enveloped RNA)

• reservoir: humans

• transmission: resp droplets

• mechanism: resp entry —> replication in resp epithelium —> cell injury & inflammation

• infectious period: 1 day before through 5-7 days after symptom onset

manifestations of seasonal influenza

• fever, chills

• headache

• cough

• sore throat

complications of seasonal influenza

• pneumonia, resp failure, worsening heart/lung disease

testing for seasonal influenza

respiratory nucleic acid amplification test (NAAT)

precautions for seasonal influenza

• standard + droplet precautions

• medical mask

• mask patient during transport

treat & prevent for seasonal influenza

• antivirals promptly, without waiting for test results

  • best within 48 hours

• annual vax

what is the pathogen, reservoir, transmission, mechanism, and infectious period of COVID-19?

• pathogen: SARS-CoV-2 (enveloped coronavirus)

• reservoir: humans

• transmission: inhalation of respiratory particles

• mechanism: viral rep —> resp cell injury —> inflammation

• infectious period: 1-2 days before through 8-10 days after symptom onset

manifestations of of COVID-19

• fever/chills

• cough

• vomitting

• muschle aches

• diarrhea

complications of COVID-19

• dehydration

• delirium

• pnemonia

• hypoxemia

• resp failure

• blood clots or shock

precautions for COVID-19

• standard = N95, eye protection, gown, gloves

• single-person room

• AIIR room

treat & prevent for COVID-19

• antiviral treatment

• vax

what is the pathogen, reservoir, transmission, mechanism, and infectious period of respiratory syncytial virus (RSV) infection?

• pathogen: respiratory syncytial virus (enveloped RNA virus)

• reservoir: humans

• transmission: resp droplets, direct contact, contaminated hands/surfaces

• mechanism: airway infection —> inflammation

• infectious period: contagious for 3-8 days, may begin 1-2 days prior to symptoms

manifestations of respiratory syncytial virus (RSV)

• runny nose

• cough

• wheeze

• less active infants

• absent fever

complications for respiratory syncytial virus (RSV)

• dehydration

• bronchiolitis

• pneumonia w/ hypoxemia

• worsening asthma and COPD

precautions for RSV

contact

treat & prevent RSV

• nasal suction

• not antivirals!

• infant protection

  • maternal RSV vax or long acting RSV antibody

what is the pathogen, reservoir, transmission, mechanism, and infectious period of infectious mononucleosis?

• pathogen: Epstein-Barr virus (EBV), enveloped DNA

• reservoir: humans

• transmission: mainly saliva (kissing, sharing drinks)

• mechanism: oropharyngeal entry —> B lymphocyte infection —> immune activation & lymphoid tissue enlargement

• infectious period: may spread before symptoms

manifestations of infectious mononucleosis

• enlarged tonsls

• swollen lypmh nodes at back of neck (posterior cervical)

• rash

  • amoxicillin or ampicillin use, can trigger rash during mononucleosis

complications of infectious mononucleosis

• airway obstruction from tonsillar swelling

• dehydration

• hepatitis

• splenic rupture

treat & prevent of infectious mononucleosis

• assess swallowing and hydration

• no antivirals

• avoid kissing and sharing drinks during illness

• no EBV vax avail

precautions for infectious mononucleosis

• standard

• select PPE for saliva or fluids

what is the pathogen, reservoir, transmission, mechanism, and infectious period of mumps?

• pathogen: mumps, enveloped RNA

• reservoir: humans

• transmission: resp droplets and direct contact w/ infected saliva

• mechanism: replication in upper resp tract and nearby lymph nodes —> bloodstream spread —> inflammation of salivary glands and some organs

• infectious period: 2 days before through 5 days after salivary gland swelling begins

manifestations for mumps

• swollen lymph nodes at the back of neck

• marked fatique

• enlarged tonsils, fever, sore throat

• assess rash & recent use of amoxicillin or ampicillin

complication for mumps

• airway obstruction from tonsillar swelling

• dehydration

• hepatitis or splenic rupture

what is the pathogen, reservoir, transmission, mechanism, and infectious period of gastroenteritis?

• pathogen: norovirus & rotavirus (non-enveloped RNA)

• transmission: fecal-oral spread via contaminated hands, food, water, or surfaces

• mechanism: intestinal infection —> messed up absorption, fluid loss

• infectious period: transmission is greatest during illness 7 early recovery, but viral shedding can continue

precautions for mumps

droplet

treat & prevent for mumps

• fluids, soft foods

• MMR and vax

manifestations of gastroenteritis

• watery diarrhea

• vomiting

• abdominal cramps

complications of gastroenteritis

• acute kidney injury from reduced kidney perfusion

• dehydration

• hypervolemia

• hypovolemic shock

• electrolyte imbalance

precautions for gastroenteritis

contact precautions

• norovirus: at least 48 hrs after symptoms resolve

• rotavirus: continue throughout illness

treat & prevent gastroenteritis

• oral rehydration

• IV fluids

• soap-and-water handwashing

what is the main transmission form and course/prevention for HAV?

• fecal-oral route

• acute infection

• vaccine

what is the main transmission form and course/prevention for HBV?

• blood, sexual contact

• acute/chronic infection

• vaccine

what is the main transmission form and course/prevention for HCV?

• blood

• chronic

• curable with treatment

• no vax

what is the main transmission form and course/prevention for HDV?

• blood and other infectious body fluids

• requires HBV

  • can cause more severe liver disease

• prevented by preventing HBV (vax)

what is the main transmission form and course/prevention for HEV?

• contaminated water or undercooked infected meat

• acute

• greater risk of severe disease during pregnancy

• can become chronic when immunocompromised

manifests of viral hepatitis

• jaudice

• itching

• dark urine

• pale stool

• - cannot identify the virus -

complications of viral hepatitis

• dehydration

• hepatic encephalopathy (altered mental status)

• impaired clotting

• cirrhosis

  • healthy liver tissue —> becomes scarred

• liver cancer

precautions for viral hepatitis

• standard precautions

• contact precautions for incontinent patients w/ HAV or HEV

treatment and prevention for viral hepatitis

• treat

  • HAV, HEV: support

  • chronic HBV: antiviral suppression

  • HCV: curative antivirals

  • HDV, complicated HEV: specialist

what is HAV’s main transmission, is it chronic, and is there a vaccine?

• fecal-oral

• no

• yes

what is HBVs main transmission, is it chronic, and is there a vaccine?

• blood, sex

• yes

• yes

what is HCV main transmission, is it chronic, and is there a vaccine?

• blood

• yes

• no

what is the pathogen, reservoir, transmission, mechanism, and infectious period of genital herpes?

• pathogen: HSV-1 or HSV-2, enveloped DNA

• reservoir: humans

• transmission: direst skin or mucosal contact during sex

• mechanism: local infection —> lifelong latency in sensory nerve ganglia

• infectious period: viral shedding can occur with or without visible lesions

manifestations for genital herpes

• lesions

• genital ulcers

• tingling or burning before lesions

complications for genital herpes

• urinary retention

• dehydration

• meningitis

• neonatal HSV infection

precautions for genital herpes

contact

treat/prevent for genital herpes

• avoid sexual contact during lesions

• condoms reduce risk but don’t elim transmission

what is the pathogen, reservoir, transmission, mechanism, and infectious period of HPV?

• pathogen: HPV, nonenveloped

• reservoir: humans

• transmission: intimate skin-to-skin contact

• mechanism: undetectable through immune control

  • wart-causing types: HPV 6

  • persistent high-risk types: HPV 16/18 —> cancer

• infectious period: variable

manifestations of HPV

• genital warts

• itching

• discomfort

complications of HPV

• ulceration may need biopsy to exclude cancer

precautions for HPV

• standard

• contact PPE for lesions

treat/prevent HPV

• topical treatment

• HPV vax

what is the pathogen, reservoir, transmission, mechanism, and infectious period of HPV?

• pathogen: HIV-1, HIV-2, enveloped RNA

• reservoir: humans

• transmission: sex, shared needles, blood, pregnancy, breastfeeding

• mechanism: infects CD$ T cells —> persistent infection —> AIDS

• infectious period: nonspecific febrile illness, can be asymptomatic

what does antiretroviral therapy (ART) do?

suppresses HIV so it cannot be transmittable

manifestations of HIV

• fever, fatiguem enlarged lymph nodes, oral ulcers

• chronic can be asymptomatic

complications of HIV

• pneumonia

• CNS infection

• candidiasis

• GI infection

HIV precautions

standard

treat/prevent HIV

• use ART

• phrophylaxis

• prevent

  • PrEP

    • prevention

  • PEP

    • assesses exposure

what is the pathogen, reservoir, transmission, mechanism, and infectious period of dengue?

• pathogen: dengue viruses, enveloped RNA

• reservoir: humans

• transmission: bite from infected aedes mosquito (become infected from biting human with viremia)

• mechanism: viral rep —> viremia

• infectious period: 2 days before symptoms until 2 days after fever resolves

manifestations of dengue

• servere bleeding

• pain behind eyes

• rash

• gum/nose bleeding

complications of dengue

• dehydration

• plasma leakage

• shock or fluid accumulation

• severe organ involvement of brain, liver, heart