week #9: viral infections of humans

viral tropism explains why viruses:

• infect particular cells and tissues

• requirements: access, entry, replication

access

virus must reach tissue

entry

compatible cell receptors help virus attach and enter

replication

cell must support viral replication

how viruses cause disease:

immune defenses against viruses:

active and passive protection

patterns of viral infection consist of:

• acute infection that resolves

• chronic infection

• latency and reactivation

acute infection that resolves: what happens + ex

• immune defenses eliminates virus

• ex: hepatitis A

chronic infection: what happens + ex

• virus persists w/ ongoing or intermittent replication

• ex: chronic hepatitis C

latency and reactivation: what happens + ex

• viral genome remains in cells. virus production can restart

• ex: varicella-zoster virus - chickenpox followed by shingles

viral infections in nursing care

viral infections by body site & system

measles (rubeola)

• pathogen: measles virus (enveloped RNA virus)

• reservoir: humans

• transmission: airbone - virus can remain the air for up to 2 hrs after person leaves

• mechanism: respiratory entry → viral replication → spread through lymphatic tissues and blood → systemic infection

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

measles (rubeola) nursing assessment

measles (rubeola): precautions

• begin standard + airborne precautions immediately when suspected

• airborne infection isolation room; staff wear a fit-tested N95 or higher

• mask the patient when appropriate and tolerated

measles (rubeola): notify

promptly notify clinical team, infection prevention, and public health

measles (rubeola): support & treat

• support hydration, nutrition, and comfort

• give prescribed antipyretics, oxygen PRN, and vitamin A for children

• reassess and escalate deterioration

measles (rubeola): prevent

• review immunity and vaccination needs

• arrange prompt postexposure prophylaxis (PEP) for eligible susceptible contacts: MMR within 72 hours or immunoglobulin within 6 days

• teach patients to call ahead before seeking care

rubella

• pathogen: rubella virus (enveloped RNA virus)

• resevoir: humans

• transmission: respiratory droplets and transmissions across the placenta

• mechanism: respiratory entry → replication in nasopharynx and lymph nodes → bloodstream spread → systemic infection

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

rubella nursing assessment

rubella: precautions

• begin standard + droplet precautions when rubella is suspected

• continue through 7 days after rash onset

rubella: notify

promptly notify clinical team, infection prevention, and public health

rubella: protect pregnancy

• arrange prompt obstetric evaluation for exposure or suspected infection during pregnancy

• identify potentially exposed pregnant contacts

rubella: support & reassess

• provide fluids and prescribed fever/pain relief

• reassess symptoms and intake

rubella: prevent

• review rubella immunity and MMR eligibility

• MMR is contraindicated during pregnancy

• arrange postpartum vaccination and for those without evidence of immunity

chicken and shingles

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

• reservoir: humans

• transmission: contact w/ blister fluids or inhalation of infectious virus particles

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

• infectious period:

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

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

chickenpox and shingles nursing assessment

chickenpox and shingles: precautions

• chickenpox/widespread shingles: standard + airbone + contact until lesions crust

• localized shingles, immunocompetent: standard, cover lesions until crusted

chickenpox and shingles: treat

• shingles: give prescribed antivirals promptly

• chickenpox: antivirals for selected high-risk or severe cases

chickenpox and shingles: support & reassess

• relieve pain/itching, support hydration and skin care, and reassess

• avoid aspirin in children w/ chickenpox: reye syndrome risk

chickenpox and shingles: escalate

• eye symptoms, respiratory distress, new neurologic changes, widespread shingles

• suspected bacterial skin infection

chickenpox and shingles: prevent

• review vaccination and exposed contacts’ immunity

• arrange prompt postexposure reassessment

mpox

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

• reservoir/source: natural reservoir is uncertain. infected people + animals can transmit virua

• transmission: close physical contact, including sexual content; contaminated materials and exposure

• mechanism: entry through skin/mucosa → replication → lesions and sometimes systemic illness

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

mpox nursing assessment

mpox skin lesions

mpox: precautions

• single-person room; standard precautions plus gown, gloves, eye protection and N95 or higher respirator

• continue isolation until all lesions have healed, scabs have fallen off, and new skin has formed

mpox: notify

promptly notify the clinical team, infection prevention, and public health

mpox: support & treat

• provide fluids, pain relief, and skin care

• seek specialist advice for severe or higher-risk illness

mpox: prevent

• avoid close physical contact and sharing person items

• assess vaccine eligibility and arrange prompt postexposure evaluation

seasonal influenza

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

• reservoir: humans

• transmission: respiratory droplets and smaller particles

• mechanism: respiratory entry → replication in respiratory epithelial cells → cell injury and inflammation

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

seasonal influenza nursing assessment

seasonal influenza: precautions

• standard + droplet precautions

• staff wear a medical mask on room entry

• mask the patient during transportation, if tolerated

seasonal influenza: support & reassess

• support hydration, nutrition, and comfort

• give oxygen PRN

• reassess breathing, oxygenation, and mental status

seasonal influenza: treat

• give prescribed antivirals promptly without waiting for test results

• best within 48 hours, but still indicated later for hospitalized, high-risk, or severe/progressive cases

seasonal influenza: prevent

• review annual influenza vaccination for everyone aged >= 6 months

• teach respiratory hygiene, hand hygiene, and when to seek care

avian influenza (H5N1)

• pathogen: avian influenza A (H5N1), an enveloped RNA virus

• reservoir: wild birds; infected poultry and other animals, including dairy cattle, can exposure humans

• transmission: animal exposure can introduce virus through the eyes, mouth, or inhalation

• mechanism: entry through eyes or respiratory tract → infection and inflammation → conjunctivitis or respiratory illness; severe disease may develop

• infectious period: not reliably established for human cases

avian influenza (H5N1) nursing assessment

avian influenza A (H5N1): precautions

• standard + contact + airborne precautions

• N95 or higher respirator, eye protection, and an airbone infection isolation room

avian influenza A (H5N1): notify

promptly notify clinical team, infection prevention, and public health

avian influenza A (H5N1): support & treat

• give prescribed oseltamivir promptly, even after 48 hrs - do not wait for results

• support oxygenetation + hydration

• reassess breathing + mental status

avian influenza A (H5N1): prevent

• teach animal-exposure precautions and appropriate PPE

• monitor exposed ppl for 10 days after last exposure

covid-19

• pathogen: SARCS-CoV-2 (an enveloped RNA coronavirus)

• reservoir: humans

• transmission: inhalation of infectious respiratory particles

• mechanism: viral replication causes respiratory cell injury + inflammation. severe lung involvement can impair gas exchange and cause hypoxemia

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

covid-19 nursing assessment

covid 19: precautions

• standard precautions plus N95 or higher respiratory, eye protection, and gloves

• single-person room: airborne infection isolation room for aerosol-generating procedures

covid 19: support & reassess

• support hydration, nutrition, and comfort, give oxygen PRN

• reassess breathing, oxygenation, and mental status

covid-19: treat

• promptly assess eligible high-risk patients for antiviral treatment

• check medication interactions + kidney/liver function

covid-19: prevent

• review current covid-19 vaccination eligibility

• teach source ctrl, ventilation, and when to seek urgent care

respiratory syncytial virus (RSV) infection

• pathogen: respiratory syncytial virus (enveloped RNA virus)

• reservoir: humans

• transmission: respiratory droplets, direct contact, and contaminated hands or surfaces

• mechanism: airway infection → inflammation, in infants: swelling, mucus, and cell debris can obstruct small airways

• infectious period: usually contagious 3-8 days, may begin 1-2 days before symptoms

RSV infection nursing assessment

RSV infection: precautions

• standard + contact for infants, young children, and immunocompromised adults for duration of illness

RSV infection: support, treat, and reassess

• provide fluids and oxygen PRN

• gentle nasal suction when secretions impair feeding or breathing

• reassess breathing, oxygenation, and mental status

• antivirals not routinely used

RSV infection: prevent

• infant protection: maternal RSV vaccination or long-acting RSV antibody for infant

• eligible adult: RSV vaccination

infectious mononucleosis

• pathogen: most often epstein-barr virus (EBV), enveloped DNA virus

• reservoir: humans

• transmission: mainly saliva (ex: kissing, sharing drinks/utensils)

• mechanism: orpharyngeal entry → infection of B lymphocytes → immune activation and lymphoid tissue enlargement. EBV remains latent after infection + can reactivate

• infectious period: may spread before symptoms; salivary shedding can persist for months and recur intermittently

infectious mononucleosis nursing assessment

infectious mononucleosis: precautions

• standard precautions

• select PPE for anticipated contact w/ saliva or other body fluids

infectious mononucleosis: support & treat

• encourage fluids, rest, and prescribed pain/fever relief

• reassess swallowing and hydration

• antivirals are not routinely indicated

infectious mononucleosis: protect the spleen

avoid contact sports, heavy lifting, and strenuous activity until cleared by clinician

infectious mononucleosis: prevent

• avoid kissing and sharing drinks, utensils or toothbrushes during illness

• no licensed EBV vaccine is available

mumps

• pathogen: mumps virus, an enveloped RNA virus

• reservoir: humans

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

• mechanism: replication in upper respiratory tract + nearby lymph nodes → bloodstream spread → inflammation of salivary glands + sometimes other organs

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

mumps nursing assessment

mumps parotid gland swelling

mumps: precautions

• begin standard + droplet precautions when suspected - continue through 5 days after gland swelling begins

• staff wear medical mask on entry. mask patient during transport

mumps: notify

notify clinical team, infection prevention, and public health

mumps: support & treat

• provide fluids, soft foods, and prescribed pain/fever relief

• use warm or cool compresses for comfort

• reassess intake and response

mumps: prevent

• review MMR documentation and vaccination eligibility

• public health may recommend a third MMR dose for designated groups during outbreak

viral gastroenteritis

• pathogens: norovirus and rotavirus (both nonenveloped RNA viruses

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

• mechanism: intestinal infection disrupts absorption and secretion. vomiting and diarrhea cause fluid and electrolyte losses

• infectious period: transmission is greatest during illness and early recovery. viral shedding can continue after symptoms resolve

viral gastroenteritis nursing assessment

viral gastroenteritis: precautions

• norovirus and rotavirus: standard + contact precautions

• norovirus: continue for at least 48 hrs after symptoms resolve

• rotavirus: continue throughout illness

viral gastroenteritis: support and treat

• give oral rehydration solution in small, frequent amounts when tolerated

• give prescribed IV fluids for severe dehydration or unsuccessful oral rehydration

viral gastroenteritis: reassess

monitor intake/output, perfusion, mental status, and response to fluids

viral gastroenteritis: prevent

• use soap-and-water handwashing and environmental disinfection

• report suspected outbreaks

• review infant rotavirus vaccination

viral hepatitis viruses

• HAV

• HBV

• HCV

• HDV

• HEV

viral hepatitis, HAV: main transmission + course & prevention

• fecal-oral route, including contaminated food/water, and close contact

• acute infection only, vaccine avail

viral hepatitis, HBV: main transmission + course & prevention

• blood, sexual contact and perinatal exposure

• acute or chronic infection, vax avail

viral hepatitis, HCV: main transmission + course & prevention

• mainly blood exposure

• often chronic, curable w/ treatment but no vax

viral hepatitis, HDV: main transmission + course & prevention

• blood and other infectious body fluids

• requires HBV, can cause more severe liver disease, preventing HBV infection

viral hepatitis, HEV: main transmission + course & prevention

• contaminated water or undercooked infected meat

• usually acute, greater risk of severe disease during pregnancy

  • may become chronic w/ immunosuppression

viral hepatitis

viral hepatitis: precautions

• standard precautions and safe sharp handling

• add contact precautions for incontinent patients w/ HAV or HEV

viral hepatitis: support

• support hydration and nutrition, advise avoiding alcohol

• review medications and supplements for potential liver injury

viral hepatitis: treat

• HAV and most acute HEV: supportive care

• chronic HBV: antiviral suppression when indicated

• HCV: curative antiviral treatment

• HDV or complicated HEV: specialist management

viral hepatitis: reassess

• monitor symptoms, mental status, bleeding, and ordered liver tests

• support treatment adherence and follow-up

viral hepatitis: prevent

• review HAV/HBV vaccination

• arrange prompt assessment of exposed contacts for indicated postexposure prophylaxis

genital herpes

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

• reservoir: humans

• transmission: direct skin or mucosal contact during sexual activity, including oral-genital contact. transmission to newborn can occur during birth

• mechanism: local infection → lifelong latency in sensory nerve ganglia → possible reactivation

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

genital herpes nursing assessment

genital herpes: precautions

• standard precautions for recurrent localized disease

• add contact precautions for severe primary or disseminated mucocutaneous disease until lesions are dry and crusted

genital herpes: treat

• give prescribed antivirals promptly for all first clinical episodes

• suppressive therapy reduces recurrences and can reduce HSV-2 transmission

genital herpes: support & reassess

• provide pain relief, reassess urination, hydration, and lesion healing

• coordinate care w/ obstetric team during pregnancy

genital herpes: prevent

• avoid sexual contact during lesions or prodromal symptoms

• condoms reduce risk but do not eliminate transmission

• support partner communication