H A R T S H O R N E / VA N Z Y L
Table 1 : The infection chain pathway from pathogen to host and appropriate infection control strategies to mitigate or contain transmission of the coronavirus between health care workers and patients in the dental practice setting Infection chain pathway and definition Pathogen of sufficient virulence and adequate number (load) to cause disease
Reservoir or source (carrier) (A place that allows the pathogen to survive or multiply)
Portal of exit (Ways in which the virus leaves the reservoir)
Mode of transmission from source to host (Ways in which the virus spreads from reservoir to the susceptible host)
Portal of entry (Ways through which the pathogen can enter a susceptible host)
Susceptible host Is an individual who is not immune Susceptible individuals may have co-morbidities that affect their susceptibility to, and severity of COVID-19
Infection chain characteristics
Infection control strategy
• Contagion: Coronavirus (SARS-CoV-2) • Single stranded RNA • Enveloped – lipid bi-layer membrane • Diameter 60-140nm (0.06-0.14µm) • Spike protein 9-12nm - viral entry key • Very susceptible to standard disinfection methods • Very contagious
• Hand sanitizing – removes virus • Surface disinfection – Kills virus • Universal masking – evade virus • Social distancing – evade virus • Isolation • HEPA filters (virus scavenging) & UV light sterilization • HOCL fogging - airborne disinfection • Anti-viral drugs • Vaccine – antibody immune resistance
• Incubation (infectious period) 6.4 days • Human COVID-19 pre-symptomatic • Human COVID-19 asymptomatic • Respiratory tract (naso-pharynx and lungs • Oral cavity (Oral mucosal epithelial cells, salivary glands, tongue and periodontium) • Gastro-intestinal tract (intestinal epithelium) • Possible environmental reservoirs: Biofilm in waterlines and Ventilation systems
• Patient and staff screening for symptoms • Universal masking (evade) and hand sanitation (remove virus) • Maintain good hygiene and sanitation • Pre-procedural mouth rinse – kills virus and reduces viral load • Asepsis / sterilization • Waterline Disinfection • HEPA filters & UV sterilization
• Mouth (talking) aerosols • Mouth - Contaminated saliva (aerosols) • Mouth - Respiratory secretions (air droplets (coughing or talking) • Nose - Respiratory secretions (air droplets) -sneezing • Faecal
• Pre-procedural rinse & gargle • Rubber dam isolation • High volume evacuation • PPE (Masks and gloves) • Hand sanitation
• Direct contact (touch) with contagion (pathogen) in saliva or surfaces • Indirect contact with contaminated surface/objects (fomites) • Contact with conjunctiva, nasal or oral mucosa with contaminated droplets (coughing, sneezing and talking) • Inhalation of airborne microorganisms suspended in air • Aerosol generating procedures • Faecal-oral route • Superspreading events
• Hand sanitizing • Pre-procedural mouth rinse • Isolation – use of rubber dam • High volume evacuation • Appropriate PPE (Masks, Gloves, Gowns, Shields) • Appropriate surface disinfection • Ventilation, HEPA filters & UV sterilization • Prevent & control Superspreading events
• • • • • •
Deposition Attachment (ACE2 receptors) & Entry Replication and release Respiratory tract Nose (nasal mucosa) Mouth (oral mucosal)
• Preprocedural mouth rinse • Surgical masks (FFP2) or N95 respirators (FFP3) • Goggles and/or face shields • Appropriate disinfection
• • • • • • • • • •
Healthy individual Immune compromised individual Elderly Co-morbidities Smoking Patients receiving ACE2-increasing drugs Disease: COVID-19 Asymptomatic Pre-symptomatic Symptomatic
44 INTERNATIONAL DENTISTRY – AFRICAN EDITION VOL.11, NO. 1
• Pre-screening& risk identification • Isolation • Diagnostic testing • Universal masking • Hand sanitize • Preprocedural mouth rinse • Maintain good hygiene • Special precautions for individuals at high risk & co-morbidities • Enhance the immune system • Vitamin D supplementation • Healthy nutrition, reduce stress, adequate sleep • Eliminate smoking • Social distancing • Mucus modification • Anti-viral drugs • Designer antibodies & Vaccination
