Viral load could be an important determinant for fomites based transmission of viral infections

BACKGROUND AND OBJECTIVE: Fomites are common sources of transmission of certain infections. Infectious pathogens, such as viruses known to cause respiratory tract infections, are common examples of being transmitted by fomites. However, the load of the particular pathogen on these inanimate surfaces is a crucial factor for the transmission. The current study aims at investigating the load of one such viral pathogen on the surfaces of commonly used materials. METHODS: Based on the cycle threshold (Ct) values in the diagnostic system using gene amplification for the considered viral pathogen, we categorized the positive samples for high (17 to < 24), moderate (24 to < 31), or mild (31 to < 38) viral load. Five randomly selected samples from each of these category were smeared on commonly used cardboard surface (absorbent surface) and stainless steel (non-absorbent surface). After an observation duration of 90 min, samples from the surfaces were analyzed again for gene amplification using RT-PCR. RESULTS: Viral load/titter positively correlated with the viral material on either of these investigated surfaces post-observation duration. Higher viral load (low Ct) samples exhibited higher probability of being detected on the surfaces than those samples with lower/moderate (high Ct) viral load. INTERPRETATION AND CONCLUSION: Common inanimate surfaces are potential source of the viral transmission, however the viral load on these surfaces are key determinant of such transmission.