Disease Transmission

Office of Epidemiology and Prevention ServicesDIVISION OF INFECTIOUS DISEASE EPIDEMIOLOGYwww.dide.wv.gov

Disease Transmission


Objectives

• Review disease transmission• Discuss standard precautions• Describe and demonstrate transmission-

based precautions


Modes of Disease Transmission

• Direct contact • Indirect contact• Droplet • Airborne


Direct Contact Transmission

• Microbes directly transferred from an infected person to another person

• Examples– Contact with blood or other body fluids– Ungloved contact with a scabies-infested

patient– Ungloved contact with wounds or mucous

membranes


Indirect Contact Transmission

• Microbes transferred through contaminated intermediate object

• Examples– Healthcare personnel not performing

adequate hand hygiene between patients– Sharing medical equipment without

cleaning or disinfection between patients– Defective medical equipment allowing for

inadequate disinfection or sterilization


Droplet Transmission

• Respiratory droplets carrying infectious pathogens– Generated during coughing, sneezing,

talking, or certain medical procedures (e.g. suctioning)

– Droplets traditionally defined as > 5 µm– Typically refers to distances within 3 feet

of infected patient


Airborne Transmission

• Dissemination of droplet nuclei containing infectious agents– Dispersed over long distances– Face-to-face contact not required– Special ventilation systems are required to

prevent airborne transmission


Standard Precautions (1)

• Group of infection prevention practices that apply to ALL patients

• Based on principle that the following can contain transmissible infectious agents:– Blood and body fluids– Secretions – Excretions (except sweat)– Non-intact skin–Mucous membranes



• Applied during patient care based on nature of healthcare worker-patient interaction

• Dependent on anticipated blood, body fluid, or pathogen exposure

• Intended to protect both healthcare worker and patient



• Education and training are critical and include the following elements:– Hand hygiene– Respiratory hygiene/cough etiquette– Personal protective equipment (PPE)– Safe injection practices– Environmental considerations


Transmission-Based Precautions

• Used when route of transmission is not completely interrupted using standard precautions alone

• Always used in addition to standard precautions

• Categories of precautions– Contact – Droplet – Airborne


Contact Precaution Basics

• Intended to prevent spread of infectious agents transmitted by direct or indirect contact

• Applied when excessive wound drainage, fecal incontinence, or other body discharges increase the potential for environmental contamination


Contact Precautions

• Single-patient rooms are preferred • For multi-patient rooms, > 3 feet separation

is recommended between beds• Healthcare personnel should wear gown and

gloves for ALL patient interactions• PPE donned upon entry and discarded

before exiting room


Droplet Precaution Basics

• Intended to prevent spread of infectious agents transmitted by respiratory secretions or mucous membrane contact

• Droplets do not travel far and do not require special ventilation systems


Droplet Precautions

• Single-patient rooms are preferred • For multi-patient rooms, > 3 feet separation

between beds and drawing the curtain is recommended

• Healthcare personnel should wear mask upon entering room

• Patients should wear mask (if tolerated) when transferred out of room– Follow respiratory hygiene/cough etiquette


Airborne Precaution Basics

• Prevent transmission of infectious agents that remain infectious in air over long distances

• An airborne infection isolation room (AIIR) for placement of patient– Single-patient room– Special ventilation system

• Healthcare personnel should don a fit-tested N95 mask before entry


Airborne Precautions

• Until AIIR can be instituted, the following should reduce likelihood of airborne transmission–Mask patient– Place patient in private room– Provide N95 or higher level respirator for

staff


Reference:

Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings 2007 (CDC)

http://www.cdc.gov/hicpac/pdf/isolation/Isolation2007.pdf


Example:

Key to abbreviations: see page 94


Group Exercise (1)

• Use Appendix A for guidance• Each group has been assigned a disease • Please complete the table affiliated with your

disease• Type of precautions• Type of PPE• Room placement• Discontinuation of precautions


Group Exercise (2)

• Use completed table to set up patient’s room• Demonstrate how to set up PPE / hand

hygiene • Classroom discussion


NorovirusPrecautions

Personal protective equipmentRoom placement

Discontinuation of precautions


NorovirusPrecautions Standard precautions; Contact

precautions for institutional outbreaksPersonal protective equipment

Contact precautions: gowns, gloves (masks)

Room placement

“cohort to separate airspaces and toilet facilities may help interrupt transmission during outbreaks”



InfluenzaPrecautions




InfluenzaPrecautions droplet

Personal protective equipment

don mask upon entering room … patient to wear mask (if tolerated) when out of room

Room placement

Private or cohort with spatial separation of >=3 feet.


5 days; duration of illness for immunocompromised patients


Clostridium difficile (C. diff)Precautions




Clostridium difficile (C. diff)Precautions contact


wear gown and gloves for ALL patient interactions; don PPE upon entry and discard before exiting room

Room placement

Private or cohort


Duration of illness


Streptococcus pneumoniae (single patient)

Precautions




Streptococcus pneumoniae (single patient)

Precautions standard


Only for anticipated contact with secretions or excretions or blood or body fluids …

Room placement

Private room and cohorting are not necessary


Standard precautions are NEVER discontinued


Streptococcus pneumoniae (outbreak)

Precautions




Streptococcus pneumoniae (outbreak)

Precautions droplet


don mask upon entering room … patient to wear mask (if tolerated) when out of room

Room placement

Private or cohort


(while there is transmission in the facility)


Pulmonary TuberculosisPrecautions




Pulmonary TuberculosisPrecautions Airborne


Fit-tested N95 mask

Room placement

Negative pressure room


When patient is on effective therapy, is clinically improving and has 3 consecutive negative smears for TB


ScabiesPrecautions




ScabiesPrecautions Contact precautions


Gloves and gown.

Room placement

Private or cohort


24 hours after completion of effective therapy


RSV(Respiratory Syncytial Virus)

Precautions




RSV(Respiratory Syncytial Virus)

Precautions Infants, children and immunocompromised adults: contact precautions


For contact precautions, don gowns and gloves before entry; discard before leaving and practice hand hygiene

Room placement

Private or cohort


Duration of illness

Disease Transmission

Documents

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