Transmission of Streptococcal Pharyngitis (Strep Throat)
Strep throat is primarily transmitted through respiratory droplets when an infected person coughs or sneezes, or through direct contact with infected persons or contaminated objects.
Primary Transmission Routes
Respiratory droplets are the main transmission route when an infected person coughs or sneezes, releasing fine infective droplets containing Streptococcus pyogenes (Group A Streptococcus) that can be inhaled by others 1, 2
Direct contact with infected individuals, particularly through close personal contact, is a significant transmission pathway 1
Fomite transmission can occur through contact with contaminated objects such as utensils, towels, keyboards, toys, and telephones 1
Droplet spread has been documented at close distances (within 30 cm) during conversation with symptomatic individuals 2
Environmental Factors
Streptococcus pyogenes can survive on various surfaces and foods, enabling indirect transmission 3
The bacteria can remain viable on food contact surfaces such as plastic and ceramic plates, plastic cups, and stainless steel utensils for at least 2 hours at room temperature 3
Communal facilities such as baths, bidets, and showers have been implicated in transmission during outbreaks, particularly in healthcare settings 1
Environmental contamination can occur when infected individuals move around, as demonstrated in healthcare outbreak investigations 1
High-Risk Settings
Close-contact environments such as schools, day care centers, and domiciliary institutions are particularly prone to outbreaks of Group A streptococcal infections 1
Healthcare settings present specific risks, with documented transmission from healthcare workers to patients through direct contact or airborne dispersal 1
Organized sports environments can facilitate transmission through shared equipment, close contact, and communal facilities 1
Household Transmission
Approximately 25% of individuals within the household of an infected person may harbor Group A streptococci in their upper respiratory tracts 1
Asymptomatic carriers (particularly children) can be sources of transmission, with carriage rates of up to 20% in school-aged children during winter and spring in temperate climates 1, 4
Prevention Strategies
Good personal hygiene practices, including proper hand washing, are essential in preventing transmission 1
Avoiding sharing of drinking vessels, mouth guards, towels, and personal protective equipment can reduce transmission risk 1
Regular cleaning and decontamination of communal facilities and equipment is important, particularly in healthcare and sports settings 1
Proper management of infected individuals, including appropriate antibiotic treatment, helps reduce the period of communicability 1
Important Considerations
Asymptomatic carriers have a low risk of transmitting the organism to close contacts compared to symptomatic individuals 1, 4
The risk of transmission from environmental sources appears to be lower than from direct person-to-person contact, based on limited experimental evidence 2
While household contacts have increased risk of harboring the bacteria, routine screening and treatment of asymptomatic household contacts is generally not recommended unless there are specific risk factors 1