The role of toothbrush in the transmission of corona- and influenza viruses - results of an in vitro study.

OBJECTIVES: The aim of this in vitro study was to investigate viruses' stabilities on manual toothbrushes using feline coronavirus (FeCoV) as representative of coronaviruses and an Avian influenza A virus H1N1 for influenza viruses.

MATERIAL AND METHODS: Two viruses, FeCoV (Strain Munich; titer 107.5 TCID50/ml) and H1N1 (RE 230/90; titer 106.5 TCID50/ml), were used in this study. Manual toothbrushes were disassembled into bristles, bristle fixation, and back of the toothbrush head, contaminated with the viruses and air-dried for 24 h. In a second experiment, whole toothbrush heads were contaminated, rinsed with water (5 ml for 15 s) and then air-dried.

RESULTS: For FeCoV, immediately after contamination, the following average titers were recovered: fixation: 106.41 , back of head: 106.81 and bristles: 106.63 TCID50 /ml. Following air-drying of 12 (fixation) and 24 h, titers of ≤ 102.5 , 103.75 , and 102.72 TCID50 /ml were found in the respective groups, with a detection limit of 102.5 TCID50 /ml. For H1N1, immediately after contamination, the following average titers could be recovered: fixation: 105.53 , back of head: 105.97 and bristles: 105.75 TCID50 /ml. Following air-drying of 8 (fixation) and 24 h, titers were ≤ 102.5 , 103.63 , and 103.53 TCID50 /ml in the respective group, again with 102.5 TCID50 /ml being the detection limit. In case of water rinse, no infectious virus could be recovered after 12 h.

CONCLUSION: Viral load of both viruses is reduced by air-drying, especially following water rinsing. Clinical relevance The toothbrush itself plays an insignificant role in the self-transmission of coronavirus and influenza virus.