Control of aerosol transmitted diseases

Dr. Ashish V. JawarkarDr. Ashish V. Jawarkar

Infection Control ofInfection Control ofAerosol Transmissible Aerosol Transmissible

DiseasesDiseases


The Chain Model of The Chain Model of Communicable DiseasesCommunicable Diseases



Infectious agent Infectious agent

Reservoirs and/or sourcesReservoirs and/or sources– humanhuman– animalanimal– EnvironmentEnvironment

Portal(s) of exit:Portal(s) of exit:– Respiratory tractRespiratory tract– GI tractGI tract– Genital/urinary tractGenital/urinary tract– Breaks in skinBreaks in skin



Modes of transmissionModes of transmission– Direct contactDirect contact– Indirect contactIndirect contact

Portals of entryPortals of entry

Susceptible hostsSusceptible hosts


Modes of Transmission Modes of Transmission

Direct TransmissionDirect Transmission– Direct ContactDirect Contact– Droplet Droplet

Indirect TransmissionIndirect Transmission– Vector-borneVector-borne

Vertical transmission (mother to Vertical transmission (mother to infant)infant)


Infectious AerosolsInfectious Aerosols

Department of Medical Microbiology,Edinburgh University


Transmission of Infections by Transmission of Infections by Respiratory AerosolsRespiratory Aerosols

• DropletsDroplets: land directly on mucosal lining of nose, : land directly on mucosal lining of nose, mouth, eyes of nearby persons or can be inhaled.mouth, eyes of nearby persons or can be inhaled.

Highest exposures within 3-6 feet.Highest exposures within 3-6 feet.

• AirborneAirborne: aerosols become smaller by evaporation; : aerosols become smaller by evaporation; small aerosols (≤ 10 microns) remain suspended for small aerosols (≤ 10 microns) remain suspended for longer periods, if inhaled travel deep into the lungs. longer periods, if inhaled travel deep into the lungs.

• ContactContact: Aerosols/ secretions contaminate nearby : Aerosols/ secretions contaminate nearby surface. Touch surfaces surface. Touch surfaces can infect self or others.can infect self or others.

Relative contribution of three routes varies with agent.Relative contribution of three routes varies with agent.


Modes of Transmission viaModes of Transmission viaInfectious Respiratory SecretionsInfectious Respiratory Secretions

Droplet: Droplet: meningococcal meningitis, rubella, meningococcal meningitis, rubella, pertussis, common cold, SARS, influenza*pertussis, common cold, SARS, influenza*

Airborne: Airborne: tuberculosis, measles, varicella, tuberculosis, measles, varicella, smallpox, SARS, avian influenzasmallpox, SARS, avian influenza

Indirect contact: (fomite) Indirect contact: (fomite) RSV, SARSRSV, SARS

*Influenza traditionally droplet, increasing evidence *Influenza traditionally droplet, increasing evidence for airborne componentfor airborne component


Infection Control in aInfection Control in aHealth Care SettingHealth Care Setting


Infection Control in a Health Care Infection Control in a Health Care SettingSetting

Basic principlesBasic principles

Standard precautionsStandard precautions

Transmission-based precautionsTransmission-based precautions

Seasonal influenza in health care settingsSeasonal influenza in health care settings

Vaccination of HCWsVaccination of HCWs

TB screening of HCWsTB screening of HCWs

Proper donning and doffingProper donning and doffing

Choose your PPEChoose your PPE


Basic Principles Basic Principles All body fluids are potentially infectious (except All body fluids are potentially infectious (except

sweat) sweat) – blood and blood-tinged fluids including open-blood and blood-tinged fluids including open-

woundswounds– stool, urine, vomit, respiratory secretions, stool, urine, vomit, respiratory secretions,

saliva, semen, vaginal secretions, breast milk, saliva, semen, vaginal secretions, breast milk, other body fluids such as pericardial and other body fluids such as pericardial and synovial fluidssynovial fluids

Minimize exposure to potentially infectious body Minimize exposure to potentially infectious body fluidsfluids

Infection control measures designed to “break the Infection control measures designed to “break the chain” of transmissionchain” of transmission


Standard Precautions in Health Standard Precautions in Health Care SettingsCare Settings

1.1. Appropriate hand hygieneAppropriate hand hygiene2.2. Barrier protective equipment:Barrier protective equipment:

– if splash, splatter, or sprays can be if splash, splatter, or sprays can be reasonably anticipatedreasonably anticipated

– choose appropriate PPE as needed: choose appropriate PPE as needed: gloves, gown, mask, eye protection gloves, gown, mask, eye protection (face shield, goggles)(face shield, goggles)

3.3. Proper use and handling of Proper use and handling of patient care equipmentpatient care equipment


Standard Precautions in Health Standard Precautions in Health Care SettingsCare Settings

4.4. Proper environmental cleaning and Proper environmental cleaning and disinfectiondisinfection

5.5. Proper Handling of LinenProper Handling of Linen6.6. Adherence to Bloodborne Pathogens Adherence to Bloodborne Pathogens

StandardsStandards7.7. Proper patient placement Proper patient placement 8.8. Respiratory Hygiene/Cough EtiquetteRespiratory Hygiene/Cough Etiquette9.9. Safe injection practicesSafe injection practices


Expanded Isolation Precautions:Expanded Isolation Precautions:Transmission-based Standards Transmission-based Standards

When standard precautions are When standard precautions are not enoughnot enough

Additional measures based on Additional measures based on mode of transmissionmode of transmission Contact Precautions Contact Precautions Droplet PrecautionsDroplet Precautions Airborne PrecautionsAirborne Precautions


Transmission-Based Precautions: Transmission-Based Precautions: Contact PrecautionsContact Precautions

For known or suspected infections For known or suspected infections that represent an increased risk of that represent an increased risk of spread by direct or indirect spread by direct or indirect contact with the patient or the contact with the patient or the patient’s environmentpatient’s environment


Transmission-Based Precautions: Transmission-Based Precautions: Contact Precautions Contact Precautions

Personal Protective Equipment Personal Protective Equipment Gown & Gloves for all patient interactionsGown & Gloves for all patient interactions Don PPE on entry, discard before exiting Don PPE on entry, discard before exiting

room.room. (in addition to Standard (in addition to Standard Precautions)Precautions)

Examples: MRSA, Examples: MRSA, C difficileC difficile, Norovirus, other , Norovirus, other GI pathogens, RSV, antibiotic-resistant GI pathogens, RSV, antibiotic-resistant

pathogenspathogens


Transmission-Based Precautions: Transmission-Based Precautions: Droplet PrecautionsDroplet Precautions

Single room preferred, no special ventilationSingle room preferred, no special ventilation Patient: Mask if transport necessary. Instruct Patient: Mask if transport necessary. Instruct

on respiratory hygiene/cough etiquetteon respiratory hygiene/cough etiquette HCWs wear surgical or procedure mask within HCWs wear surgical or procedure mask within

6 feet of patient. Eye protection if splash, spray 6 feet of patient. Eye protection if splash, spray

anticipated anticipated

(in addition to Standard Precautions)


Transmission-Based Precautions: Transmission-Based Precautions: Airborne Precautions Airborne Precautions

Airborne Infection Isolation Room (AIIR) if availableAirborne Infection Isolation Room (AIIR) if available

Patient: Mask if transport necessary (as tolerated). Patient: Mask if transport necessary (as tolerated).

Health care workers (HCWs):Health care workers (HCWs):

N95 respirator N95 respirator priorprior to entry into room, discarded to entry into room, discarded afterafter exit. exit. Higher level respirators for aerosol-gen procedure. Careful Higher level respirators for aerosol-gen procedure. Careful

attention to proper putting on & taking off (don/doff) attention to proper putting on & taking off (don/doff)

respirator, including seal check.respirator, including seal check. Hand hygiene Hand hygiene before & afterbefore & after don/doff.don/doff. Alert others if need to transferAlert others if need to transfer

(in addition to Standard Precautions)


Seasonal Influenza in Healthcare Seasonal Influenza in Healthcare Settings: Isolation PrecautionsSettings: Isolation Precautions

For aerosol-generating procedures: For aerosol-generating procedures: N95 respirator N95 respirator + standard + standard precautions (gown, gloves, goggles precautions (gown, gloves, goggles for spray/splash)for spray/splash)


Vaccination of HCWs Vaccination of HCWs

Protect patients, protect yourself and other HCWsProtect patients, protect yourself and other HCWs CDC recommends CDC recommends

– Measles, mumps, rubella (MMR): vaccinate unless Measles, mumps, rubella (MMR): vaccinate unless documentation of immunity or previous documentation of immunity or previous vaccinationvaccination

– Varicella (chicken pox): vaccinate unless Varicella (chicken pox): vaccinate unless documentation of immunity or previous documentation of immunity or previous vaccinationvaccination

– TdapTdap

– Yearly influenza vaccinationYearly influenza vaccination

– Hepatitis B: vaccinate unless documentation of Hepatitis B: vaccinate unless documentation of previous vaccinationprevious vaccination


Tuberculosis ScreeningTuberculosis Screeningfor Health Care Workersfor Health Care Workers

TB screening at hire and then TB screening at hire and then annually for all licensed healthcare annually for all licensed healthcare facilities (e.g., acute care hospitals, facilities (e.g., acute care hospitals, skilled nursing facilities, primary skilled nursing facilities, primary care clinics)care clinics)


Sequence for Donning PPESequence for Donning PPE

1.1. GownGown

2.2. Mask or RespiratorMask or Respirator

www.cdc.gov/ncidod/dhqp/ppe.html


Sequence for Donning PPESequence for Donning PPE

3.3. Goggles/Face ShieldGoggles/Face Shield

4.4. GlovesGloves



Sequence for Removal of PPESequence for Removal of PPE

1.1. GlovesGloves




2.2. Goggles/Face ShieldGoggles/Face Shield




3.3. GownGown




4.4. Mask or RespiratorMask or Respirator



What Type of PPE Would You What Type of PPE Would You Wear?Wear?

Giving a bed bath?Giving a bed bath?– Generally noneGenerally none

Suctioning oral secretions?Suctioning oral secretions?– Gloves and mask/goggles or a face Gloves and mask/goggles or a face

shield – sometimes gownshield – sometimes gown




Transporting a patient in a wheel Transporting a patient in a wheel chair?chair?– Generally none requiredGenerally none required

Responding to an emergency where Responding to an emergency where blood is spurting?blood is spurting?– Gloves, fluid-resistant gown, Gloves, fluid-resistant gown,

mask/goggles mask/goggles




Taking vital signsTaking vital signs– Generally noneGenerally none

Drawing blood from a vein?Drawing blood from a vein?– Gloves Gloves




Cleaning an incontinent patient with Cleaning an incontinent patient with diarrhea?diarrhea?– Gown, glovesGown, gloves

Taking vitals on a patient with Taking vitals on a patient with suspect TB?suspect TB?– N95 respiratorN95 respirator



Controlling the Spread of Controlling the Spread of Aerosol Transmissible Aerosol Transmissible

Diseases in Health Care Diseases in Health Care SettingsSettings

Breaking the ChainBreaking the Chain


Aerosol Transmissible Diseases in Aerosol Transmissible Diseases in Health Care and Public Safety SettingsHealth Care and Public Safety Settings

DropletDroplet– Meningococcal Meningococcal

meningitismeningitis– PertussisPertussis– MumpsMumps– Rubella (German Rubella (German

measles)measles)– Strep pharyngitisStrep pharyngitis– InfluenzaInfluenza

AirborneAirborne– TuberculosisTuberculosis– Varicella Varicella

(chickenpox)(chickenpox)– MeaslesMeasles– SARSSARS– Avian influenzaAvian influenza– SmallpoxSmallpox– InfluenzaInfluenza


Hierarchy of Infection Prevention and Hierarchy of Infection Prevention and Control MeasuresControl Measures

PPE

Engineering Controls

Protects only the wearer

Elimination of Potential Exposures

Administrative Controls

Protects most

people


Hierarchy of Control TechnologiesHierarchy of Control Technologies

• Goal is to reduce exposures to a hazardGoal is to reduce exposures to a hazard

Order in which these elements are Order in which these elements are selected to control exposure is selected to control exposure is importantimportant

– Elimination of Potential ExposuresElimination of Potential Exposures– Engineering controlsEngineering controls– Administrative and work practice controlsAdministrative and work practice controls– Personal protective equipment/apparelPersonal protective equipment/apparel


Elimination of Potential Elimination of Potential ExposuresExposures

• Example: patients with mild influenza Example: patients with mild influenza like illness stay homelike illness stay home


Engineering ControlsEngineering Controls

Physically separates the employee Physically separates the employee from the hazardfrom the hazard

Does not require employee Does not require employee compliance to be effectivecompliance to be effective

Examples:Examples:– physical barriers at triagephysical barriers at triage– airborne infection isolation room for airborne infection isolation room for

patients with known or suspect airborne patients with known or suspect airborne infectious diseasesinfectious diseases


Administrative Controls/ Administrative Controls/ Workplace PracticesWorkplace Practices

Policies, procedures, and programs that minimize Policies, procedures, and programs that minimize intensity or duration of exposureintensity or duration of exposure– Examples: Examples:

signs on door of an airborne isolation roomsigns on door of an airborne isolation roomtriage, mask symptomatic patienttriage, mask symptomatic patientprovide tissues/ masks/hand sanitizer to provide tissues/ masks/hand sanitizer to

publicpublic Standard procedures/ behaviors in caring for Standard procedures/ behaviors in caring for

patients e.g. hand hygiene, HCW vaccinationpatients e.g. hand hygiene, HCW vaccination Only as good as enforcementOnly as good as enforcement


Personal Protective EquipmentPersonal Protective Equipment

Lowest level of hierarchy - requires Lowest level of hierarchy - requires employee compliance for efficacyemployee compliance for efficacy

Means higher elements of hierarchy Means higher elements of hierarchy fail to adequately protect employeefail to adequately protect employee

May involve use of gowns, gloves, May involve use of gowns, gloves, eye/splash protection or respiratorseye/splash protection or respirators

Last line of defenseLast line of defense


Face Masks vs. N95 RespiratorsFace Masks vs. N95 Respirators Loose fitting, not designed to Loose fitting, not designed to

filter out small aerosols filter out small aerosols Place on coughing patient Place on coughing patient

(source control)(source control) HCW should wear mask toHCW should wear mask to

– protect patient during protect patient during certain procedures (e.g., certain procedures (e.g., surgery, LP) surgery, LP)

– protect HCWprotect HCW droplet precautionsdroplet precautions Mask + goggles for Mask + goggles for

anticipated anticipated spray/splash spray/splash

Tight fitting respirator, Tight fitting respirator, designed to filter the airdesigned to filter the air

Protects the wearerProtects the wearer

HCW should wear when HCW should wear when concerned about concerned about transmission by airborne transmission by airborne routeroute


Aerosol-Generating ProceduresAerosol-Generating Procedures

Sputum induction, bronchoscopy, Sputum induction, bronchoscopy, elective intubation and extubation, elective intubation and extubation, autopsiesautopsies

CPR emergent intubation, open CPR emergent intubation, open suctioning of airwayssuctioning of airways


Aerosol Transmissible DiseasesAerosol Transmissible DiseasesBreaking the ChainBreaking the Chain

Source controlSource control– stay home, isolate or separate mask stay home, isolate or separate mask

patientpatient Respiratory hygiene, cough etiquetteRespiratory hygiene, cough etiquette Hand hygieneHand hygiene HCW protectionHCW protection

• VaccinateVaccinate• Droplet – MaskDroplet – Mask• Airborne- N95 respiratorAirborne- N95 respirator


Questions?Questions?

Control of aerosol transmitted diseases

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