Viral Respiratory Pathogens Flashcards

Question

Coronavirus Transmission

Answer 1

* Aerosols of respiratory secretions * Direct transmission via fomites * Fecal-oral transmission rare

Answer 2

* **Accounts for 10-30% of all colds** * Usually in URT * LRT disease used to be uncommon * **Fewer infections in children than rhinoviruses** * **Young children most likely infected** * Most people infected w/ 1+ common coronaviruses in lifetime * **Winter and spring seasonality**

Answer 3

* **Common cold sx** * Rhinorrhea * Coughing * Sore throat * Headache * Fever * **Can sometimes cause LRTI ⇒ bronchitis or PNA** * People w/ cardiopulmonary disease * Immunocompromised * Infants * Elderly * **Gastroenteritis in infants**

Answer 4

* Diagnosis * Clinical suspicion for common human coronavirus * Serology for complicated/novel cases * **MERS, SARS, COVID-19** * Treatment * Symptomatic * No abx * Prevention * Currently no vaccine * Wash hands * Avoid touching face * Avoid close contact with sick people

Answer 5

**Severe Acute Respiratory Syndrome** * Caused by **SARS-CoV-1** * **Mortality 3-6%** * 45-63% in persons \> 60 y/o * **Severe viral PNA** * Associated Coronavirus SARS-HCoV * **Incubation ⇒ 2-7 days** * **Greatest transmission around 10th day** * When person is sickest ⇒ easy to isolate * Began with bats ⇒ Civet cats ⇒ humans

Answer 6

* High fever (usu. \> 100.4 F) * Headache * Mild respiratory sx * Myalgia * Fatigue * Diarrhea ⇒ 10-20% * Non-productive cough ⇒ day 2-7 * Chills * Dizziness * Many pts develop PNA

Answer 7

* PCR of two sites or two different times * ELISA test for Ab

Answer 8

**Middle East Respiratory Syndrome** * Caused by **MERS-CoV** * Distinct from other coronavirus * Most similar to those found in bats * Also found in camels * **Transmission mode unclear** * Few primary cases with direct camel contact

Answer 9

* **Range of presentations** * 62% severe respiratory illness * 5% mild sx * 21% asymptomatic * Data from early cases * High mortality * LRTI, fever * Data from more recent cases * Lower mortality * Higher proportion w/ URTI * **No vaccine, no specific treatment**

Answer 10

* Fever \> 38°C or 100.4°F * Cough * SOB * Malaise * Vomiting * Diarrhea * PNA

Answer 11

* **65% male** * **Age ranges 9 m/o to 94 y/o** * Median 49 y/o * Mean 56 y/o * **Infectious period unclear** * Not believed to be contagious before sx onset * **~75% identified as "secondary"** * Mostly healthcare workers ⇒ 19% * Many with little or no sx * Many clusters * **No sustained person-to-person transmission**

Answer 12

**Coronavirus disease 2019** * Caused by **SARS-CoV2** * **Incubation ⇒ 2-14 days** * Median 4-5 days * ↑ Risk of severe illness in specific populations * Cardiopulmonary disease, DM, immunodeficiency

Answer 13

* **Transmits easier from person-to-person** * **Droplet** * **Aerosol** * **Contact/fomites** * ? Fecal-oral route * **Transmits easily when sx early or pt asymptomatic**

Answer 14

* Most common sx * **Fever** * **Cough** * **SOB** * Other sx * Sore throat * Runny or stuffy nose * Body aches * Headache * Chills * Fatigue * Nausea and diarrhea * **Loss of taste and smell** * Myocarditis demonstrated in asymptomatic pts * Elderly w/ higher rates of severe illness * Children and younger adults w/ less severe illness and less death * ? Effect on pregnant women and fetus

Answer 15

* PCR from anterior nasal swab * ELISA test for Ab

Answer 16

* Family ⇒ Adenoviridae * **Large, non-enveloped, icosadeltahedron virions** * **Linear dsDNA ass. w/ ⊕-charged protein core** * **~50 Ag distinct serotypes in 6 subgenera ⇒ A-F** * Adenovirus types 1-7 most common

Answer 17

* **Capsid made of 240 capsomeres** * Consists of hexons and pentons * **Fiber proteins project from capsid** * Contains viral attachment proteins * Can act as hemagglutinin * Determine target cell specificity * Pentons and fibers also carry type-specific Ag

Answer 18

* **Incubation ⇒ 5-10 days** * **Sx duration ⇒ 1-2 weeks** * **Viral shedding ⇒ several months up to years** * _Infections are very common and mostly asymptomatic_ * Most ppl infected with at least one type by age 15 * Affects respiratory, GI, and eyes * Oncogenic potential in animals

Answer 19

* Methods: * **Respiratory droplets** * **Fecal-oral contact** * **Fingers** * **Fomites** (including towels and medical instruments) * **Poorly chlorinated swimming pools** * Resistant to: * **Drying** * **Detergents** * **GI tract secretions** (acid, protease, bile) * **Mild chlorine treatment** * **Close interactions promotes viral spread** * Classrooms, military barracks * **Asymptomatic infections also faciliate spread**

Answer 20

* Initial site of replication likely oropharynx or eye * Local infection ⇒ ± viremia ⇒ ± systemic spread to visceral organs * Destruction of infected cells & immune response ⇒ host injury * Transmitted via lungs, OP, and stool

Answer 21

* Infects children \> adults * _Clinical syndromes typically involve respiratory tract, GI tract, or eyes_ * **Respiratory tract infections** * **PNA** * **Conjunctivitis** * **Hemorrhagic cystitis** * **Gastroenteritis** * Affects respiratory and GI tract equally * Sx vary depending on strain * Most recover but mortality possible * **Reactivation has been documented** * Can persist in host lymphoid tissue for years * Occurs in immunocompromised ppts

Answer 22

**"Swimming pool conjunctivitis"** * **Mild follicular conjunctivitis** * Mucosa of palpebral conjunctiva becomes nodular * Caused by adenoviruses d/t chlorine resistance * **Transmission in contaminated swimming pools** * Risk factors ⇒ irritation of eye by FB, dust, or debris

Answer 23

* **Immunoassays** * Fluorescent Ab * Enzyme-linked immunosorbent assays * **PCR** * Detect & type virus in clinical samples * **Serological assays** * CFA, HI, EIA * Neutralization techniques * Rarely used

Answer 24

* Treatment * **No specific antiviral therapy** * Given supportive care * Prevention * **Vaccine against ARDS** * **Consists of live adenovirus 4, 7, and 21** * Enterically coated capsules * Given to new recruits in the military

Answer 25

* Family ⇒ Paramyxoviridae * Closely related to Mumps virus * **Enveloped ⊖-sense ssRNA virus** * Pleomorphic morphology * Replicates in cytoplasm * **5 serotypes** ⇒ 1, 2, 3, 4a, and 4b * Distinguished by Ag, cytopathic effect, and pathogenesis

Answer 26

* **Linear nucleocapsid** * Envelop contains * **Hemagglutinin/neuraminidase** * **Fusion F protein**

Answer 27

* **Incubation ⇒ 3-6 days** * **Sx duration ⇒ 7-10 days** * **Viral shedding ⇒ 1 week** * **Replication limited to respiratory epithelial cells** * Serious problem in infants and small children * Infection becomes milder as child ages

Answer 28

* **Direct person-to-person contact** * **Large droplet aerosols** * Infectious for \> 1 hour

Answer 29

* **Croup (laryngotracheobronchitis)** * _Most common manifestation_ * Caused mostly by HPIV-1 and sometimes -2 * Other viruses may cause croup e.g. flu and RSV * **Bronchiolitis** ⇒ mostly HPIV-3 * **PNA** ⇒ mostly HPIV-3 * Flu-like tracheobronchitis * Coryza-like illnesses

Answer 30

* Viruses multiply throughout tracheobronchial tree * Induces production of mucus * **Vocal cords of larynx become grossly swollen** * Obstructs inflow of air ⇒ **inspiratory stridor**

Answer 31

**Parainfluenza more genetically stable than influenza virus:** Very little mutation Minimal antigenic drift No antigenic shift

Answer 32

* **Only transient immunity to infection** * **Maternal Ab not protective for infants** * Secretory IgA protects against reinfection ⇒ short-lived * F protein Ab's * Neutralize infectivity * Prevent cell-to-cell spread * HN protein Ab's * Only neutralize infectivity

Answer 33

* Diagnosis * **Rapid test** by Ag detection from nasopharyngeal aspirates and throat washings * **Viral isolation** * **Serology** * Retrospective dx * CFT most widely used * Treatment * **No specific antivrals** * Severe croup hospitalized and placed in oxygen tents * **No vaccine available**

Answer 34

* Family ⇒ Orthomyxoviridae * **Enveloped virus** * Spikes extend from envelope ⇒ major Ag * **Segmented ⊖-sense ssRNA** * 3 types ⇒ Influenza A, B, C

Answer 35

**Spikes extend from envelope.** Act as major antigens. _Type A & B_ ⇒ hemagglutinin & neuraminidase _Type C_ ⇒ hemagglutinin only * **Hemagglutinin** * Bind to cellular receptors containing sialic acid * **Neuraminidase** * Important in release of virus from infected cells

Answer 36

**Segmented ⊖sense ssRNA** * _Flu A & B_ * 8 viral RNA segments * Codes for 10 proteins * _Flu C_ * 7 viral RNA segments * Codes for 8 proteins * Total genome ~ 12-15K nucleotides * First 12-13 nucleotides conserved among all RNA segments

Answer 37

* Flu A ⇒ antigenic shift and drift * Flu B ⇒ antigenic drift only * Flu C ⇒ relatively stable

Answer 38

* **Type** ⇒ A, B, or C * **Based on ribonucleoprotein (NP)** * **Strain** (Serotypes or Subtypes) * **Based on hemagglutinin (H) and neuraminidase (N)** * Immunologically distinct hemagglutinin subtypes ⇒ 16H, 9N * Common infections in humans ⇒ H1, H2, H3; N1, N2 * "Emerging" ⇒ H5 and H6

Answer 39

Designated by: 1. **Type** 2. **Geographic origin** 3. **Strain number** 4. **Year of isolation** 5. **Description of hemagglutinin and neuraminidase** Type/Geo/Strain no./Year/H,N Ex. A/Hong Kong/03/68/(H3N2) Ex. A/New Jersey/9/1976/(H1N1) Ex. A/swine/Iowa/15/30(H1N1)

Answer 40

* Upper and/or lower respiratory tract * Primarily in cilicated epithelial cells * **Incubation ⇒ 18-96 hours (~ 2 days)** * **Duration of disease ⇒ 2-5 days** * **Highly contagious** ⇒ begins 1 day prior to onset of infection, lasts 4-5 days * Infections ⇒ sporadic, local outbreak, widespread epidemics * Usually causes a mild febrile illness * Epidemics * **Northern hemisphere ⇒ winter months** * **Southern hemisphere ⇒ May-Sept**

Answer 41

* **Aerosol** ⇒ coughing or sneezing * 100k - 1 mil virons per droplet * **Shedding** * Touching an infected person or an item contaminated with the virus then touching your eyes, nose, or mouth * **Able to infect others 1 day before sx appear and up to 7 days after**

Answer 42

Presentations can vary * Fever * Headache * Extreme tiredness * Dry cough * Sore throat * Runny or stuffy nose * Muscle aches * GI sx ⇒ N/V/D * More common in kids \> adults

Answer 43

* PNA ⇒ viral and bacterial * Croup * Asthma * Bronchitis * Myocarditis and pericarditis * Death

Answer 44

* _Inoculation_ via **respiratory aerosols or fomites** * _Few respiratory epithelial cells infected if:_ * **Avoid removal by cough reflex** * **Escape neutralization by sIgA** * **Avoid inactivation by nonspecific inhibitors in mucous secretions** * _Replication and spread to adjacent cells_ * **Viral NA protein** ⇒ ↓ viscosity of mucus ⇒ uncovers cellular surface receptors ⇒ **promote spread of virus-containing fluid to LRT**

Answer 45

* **IFN-𝛾** ⇒ limits spread of disease * **Cytotoxic T-cells** ⇒ limit shed of virus by killing infected cells * **Ab** ⇒ induced and limits subsequent infections

Answer 46

* **0.5-1 mil deaths/yr worldwide** * 36k in US * 200k hospitalizations in US * 5-20% infected in US * _3 pandemics of 20^thcentury_ * **1918 Spanish flu** * H1N1 strain * Killed up to 100 million * **1957 Asian flu** * H2N2 strain * Killed 70k in US * Killed \> 1 mil worldwide * **1968 Hong Kong flu** * H3N2 strain * Killed 34k in US * Billion $ economic cost associated

Answer 47

* **Rapid Diagnosis** * NP, throat, or nasal swabs * Ag detection ⇒ IFA or EIA * RNA detection ⇒ RT-PCR * Best sensitivity and specificity * Expensive and technically demanding * **Virus isolation** * **Serology** * Retrospective dx * CFT most widely used * HAI and EIA may be used for type-specific dx

Answer 48

* **_M2 ion channel blockers_** * ***Amantidine & Rimantadine*** * ⊗ M2 ⇒ ⊗ H⁺ ion flow ⇒ ⊗ viral replication * Drop in pH needed for viral uncoating * Adverse neurological and GI effects * Rapid emergence of resistant strains * 2011 -- no longer recommended by CDC to treat or prevent Flu A * **_Neuraminidase inhibitors_** * ***Zanamivir (Relenza)*** & ***Oseltamivir (Tamiflu)*** & **_Peramivir (Rapivab)_** * ⊗ Release of virions from infected cells * Virions aggregate @ cell surface * ⊗ Spread of infection * No or minor AEs * Broadly active against all Flu A and Flu B

Answer 49

* **Trivalent vaccine** ⇒ 2 Flu A & 1 Flu B * **Quadvalent vaccine** ⇒ 2 Flu A & 2 Flu B * IM or SubQ injection * **Grown in eggs** * Newer vaccines grown in cell culture * **Must be updated yearly through prediction based on WHO surveillance** * _Success of vaccine based on:_ * Ag matching of prediction strain & circulating strain * Age of recipient * Previous vaccinations and flu exposure

Answer 50

* **Inactivated killed virus vaccine** * Whole virus * Subvirion * Surface Ag preparations * Given IM \> intradermal * Approved for \> 6 m/o * Healthy or w/ chronic medical conditions

Answer 51

* **Live attenuated viruses** * Strains are cold adapted, temperature sensitive, weakened * **Induce secretory and systemic immune response** * Mimic natural infection * **Contains genes encoding HA & NA of WT virus & 6 remaining internal segments** * **Approved for healthy people age 2-49** * No pregnant women * Intranasal administration * 78-100% effective * No severe side effects

Answer 52

**Occur when new avian flu strains gain ability to infect people and easily spread from person-to-person.** _Can occur in two ways:_ 1. **Reassortment** * Exchange of seasonal and avian influenza genes in person or pig infected with both strains 2. **Mutation** * Avian strain becomes more transmissible through adaptive mutation of the virus during human avian influenza infection

Answer 53

* **Point mutations accumulate** ⇒ ∆ AA in protein * **Immune system selects for advantagous ∆** * Does not cause variation * **Need ≥ 2 mutations** before new epidemiologically significant strain emerges

Answer 54

* **Drastic ∆ in HA or NA too big to be caused by mutation** * **Occurs by reassortment** * **Genetic segments from 2 different flu viruses infecting the same cell swap genetic segments** * Suspect migratory birds infecting domestic birds * Pig then infected by both * Exchange occurs w/ new avian strain but can still work in the pig * **Only in Flu A**

Answer 55

* Family ⇒ Paramyxovirus * Genus ⇒ Pneumovirus * **Enveloped but no HA or NA** * **Non-segmented ⊖-sense ssRNA virus** * **Subgroups A and B** by monoclonal sera * Both circulate * Causes sizable epidemic each year

Answer 56

**Envelop contains G protein and F protein.** * **G protein** * Attachment protein * Receptor binding ⇒ unknown target * Group determinant * **F protein** * Fusion protein * Promotes virus-cell and cell-cell fusion * Candidate vaccine target * Target for palivizumab (Synagis) * Preventative mAb

Answer 57

* **Incubation ⇒ 4-6 days** * **Duration ⇒ 2-8 days, up to 3 weeks** * **Shedding ⇒ 3-8 days** * Infants & immunocompromised can shed for _up to 4 wks_ * **Most common cause of severe LRT infections in infants** * 50-90% of Bronchiolitis * 5-40% of Bronchopneumonia * **Causes 10% of Croup** * Sx mild in older children and adults

Answer 58

* **Aerosol** ⇒ sneezing * **Direct transmisson** ⇒ fomites, contagious secretions * **Highly infectious and ubiquitious** * ~100% of children infected by 2 y/o

Answer 59

_Primary sx (mild to severe):_ * **URI** ⇒ rhinorrhea, ST, minimal cough, low grade fever * **Bronchitis** ⇒ cough * **Bronchiolitis** ⇒ wheezing, SOB * **PNA** ⇒ severe SOB, tachypnea, hypoxemia _High risk groups for complications:_ * Premature infants * Cardiopulmonary disease * Immunocompromised

Answer 60

* **Infants w/ congenital heart disease** * Worse if hospitalized within first few days of life * **Infants w/ underlying pulmonary disease** * Esp. bronchopulmonary dysplasia * Can develop prolonged infections w/ RSV * **Immunocompromised infants** * May develop LRT disease at any age

Answer 61

* **Highly infectious, transmits via respiratory secretions** * 1° multiplication in epithelial cells of URT ⇒ mild illness * In ~50% of children \< 8 m/o, goes to LRT ⇒ bronchitis, PNA, croup * ? Contribution to SIDS and asthma * **Extensive direct virus-induced damage** * Primarily epithelial cells of LRT * **Intense inflammatory response** * _Skewed T_h2-like response_ * Induces only partially effective immunity * Hallmark of RSV infection is _bronchiolitis_

Answer 62

1. **Detection of Ag** * Rapid dx via RSV Ag from NP aspirates * Important b/c of available therapy 2. **Virus isolation** * Readily isolated from NP aspirates * Takes several days 3. **Serology** * Retrospective dx * CFT most widely used

Answer 63

1. **Symptomatic** 2. **Aerosolized ribavarin** * Used for infants w/ severe infection * Used for those at risk of severe disease * ? Utility

Answer 64

* **Passive immunization** ⇒ Palivizumab (Synagis) * Expensive * **Live attenuated vaccine** * Under development * Deaths associated w/ inactivated vaccine in 1960's

Answer 65

_Immunoprophylaxis for high risk infants \< 24 m/o_ Both shown to ↓ hospitalization for any respiratory cause by 50%. * **RSV-IGIV** * Pooled polyclonal hyperimmune globulin from selected donors * **Palivizumab** * Humanized murine mAb directed against F protein * Given IM

Answer 66

"Mumps" * **Paramyxovirus genus** * **Rubulavirus family** * Pleomorphic, **enveloped** virus w/ **helical nucleocapsid** * **⊖-sense ss-RNA** * Only one mumps serotype * Humans are the only natural host

Answer 67

_Two glycoprotein spikes:_ 1. **HN** * Has both hemagglutinin & neuraminidase activity 2. **Fusion protein** * Enables virus to form multinucleated giant cells by fusing infected cells together

Answer 68

* Highly contagious, infectious childhood disease * Can occur any time w/ ↑ incidence during **late winter to early spring** * **Incubation ⇒ 16-18 days** * Can arise 12-25 days after exposure * Infectious period ⇒ **3 days before - 4 days after active parotitis** * **Prodromal period** ⇒ can last 3-5 days * **Moderate fever, malaise, pain on chewing or swallowing esp. w/ acidic liquids** * After prodrome, clinical path depends on organ affected * **Parotitis** ⇒ most common * Caused by direct viral infection of the ductal epithelium * See localized gland inflammation & swelling in front of the ear * Other sites * CNS * Eyes * Pancreas * Kidneys * Testes * Ovaries * Joints

Answer 69

_Airborne virus_ * **Tiny respiratory droplets w/ coughing or sneezing** * **Direct contact w/ saliva** * Can occur several days before onset of swelling to 9 days after * After entry, travels to back of throat, nose, and cervical lymph glands

Answer 70

* Sore throat * Fever * Tiredness * Muscle and body aches * Loss of appetite * Chills * Pain w/ chewing or swallowing * Salivary gland swelling

Answer 71

* **Causes inflammation of salivary glands** * Parotid glands most common * Symptomatic in 20-30% of persons * Adults more severely affected vs children * **Lifelong immunity s/p clinical or subclinical infection** * Second infections have been documented

Answer 72

* Aseptic meningitis * Encephalitis * Orchitis after puberty, usually unilateral * Pancreatitis * Oophoritis * Thyroiditis

Answer 73

* **Clinical diagnosis** * Symptoms * Current medical conditions * Current medications * Family hx of medical conditions * Physical exam helps * **Serology** for Ab * **Throat culture** for virus * **Lumbar puncture** to ID virus in CSF

Answer 74

* **No effective antivirals for established infection** * **Supportive treatment** * Antipyretics and analgesics * Vit A recommended for children w/ measles but does not help with mump

Answer 75

* **MMR ⇒ live, attenuated mumps vaccine** * Greatly ↓ incidence * Children ≥ 1 y/o get 2 doses * Between 15-18 m/o * Between 4-6 y/o

Viral Respiratory Pathogens Flashcards

(100 cards)