Contamination of contact surfaces with SARS-CoV-2 has been reported as a potential route for the community transmission of COVID-19. This could be a major issue in developing countries where access to basic sanitation is poor leading to the sharing of toilet facilities. In this study, we present the first report of SARS-CoV-2 contamination on key contact surfaces in shared toilets, in the city of Durban, using droplet digital PCR and assessed the probabilistic risks of COVID-19 infections.
Approximately, 53-69% of the contact surfaces were contaminated, with SARS-CoV-2 viral loads per cm2 ranging from 25.9 to 132.69 gc/cm2. Toilet seats had the highest contamination per cm2. The results suggested that the leading cause of contamination in shared toilets could be the shedding of the viral particles in feces and contaminated hands. We observed a significant reduction in viral loads on the contaminated surfaces after cleaning, showing the potential of effective cleaning on the reduction of contamination of these surfaces. The probabilistic assessment showed a high potential for COVID-19 infections. Touching the internal latch of the toilet cubicle had the highest risk of infections (4.3x10-2(6.0x10-4)) when a person uses the toilet once in a day, increasing to 1.0x10-1(1.4x10-3) for three uses in a day. The risks estimated in this study were higher than any of the tolerable/acceptable risk figures proposed for COVID-19 from environmental exposure. This calls for the implementation of risk reduction measures, such as strict adherence to wearing face masks, regular washing of hands with soap, and effective and regular cleaning.