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

Abstract

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.

Does the Misuse of Oral Hygiene Facilitate the Spread of COVID-19 Among Cohabiting Individuals? A Cross-sectional Study

“…However, Schmalz et al, in an in vitro study, showed that the viral load of coronavirus and influenza virus is reduced by air-drying, especially following water rinsing. They concluded that toothbrushes per se play an insignificant role in the self-transmission of coronavirus and influenza virus (40).…”

Hygienic Practices and Level of Contamination in Toothbrushes at Mexican Homes in Guadalajara, Jalisco

“…Nevertheless, a risk associated with toothbrush contamination has been recorded since 1920, and in 1992, it was observed that contaminated brushes may cause bacteremia and septicemia. Also, this contamination can be linked to opportunistic microorganisms and even respiratory viruses such as SARS-CoV-2 or influenza, which may be lethal for humans [1][2][3].…”

“…Unfortunately, Alzheimer's disease and pneumonia development have been correlated with anaerobic bacteria, causing periodontal disease and modifying oral cavity bacteria. Even though toothbrushing favors the removal of these bacteria, humidity and food leftovers may remain in toothbrushes, turning into pathogen reservoirs that can become potential risks for oral diseases [2].…”