Viruses and bacteria fall right out of the sky every day, study finds

A study published in the ISME Journal revealed that aerosol dispersal of soil and dust particles contribute to the long-term transport of bacteria and viruses. This could very well explain the number of cases of viruses with very similar genetic makeup despite being identified in distant environments, according to researchers.

• In the study, researchers noted that the downward flux of viruses in a day ranged from 0.26 × 10⁹ to greater than 7 × 10⁹ per square meter.
• In comparison, the deposition rates of bacteria were from 0.3 × 10⁷ to greater than 8 × 10⁷ per square meter per day.
• Head-to-head, the deposition rates of viruses were 9 to 461 times greater than those of bacteria.
• Atmospheric transport, particularly from marine sources, account for the high deposition levels in viruses.
• Researchers observed the rain events and dust intrusions from the Sahara created significantly higher deposition rates from bacteria. On the other hand, rainfall did nothing to influence the deposition of viruses.
• Virus deposition rates were linked to organic aerosols less than 0.7 micrometers (?m), while bacterial deposition rates were associated with aerosols greater than 0.7 ?m. These rates indicate that viruses can stay in the atmosphere longer, which allows them to be displaced further.

While researchers established that long-distance transport of virus and bacteria occurs, there are still certain areas that need closer examination – in particular, the mechanisms that impact deposition rates.

Journal Reference:

Reche I, D’Orta G, Mladenov N, Winget DM, Suttle CA. DEPOSITION RATES OF VIRUSES AND BACTERIA ABOVE THE ATMOSPHERIC BOUNDARY LAYER. ISME Journal. 2018. DOI: 10.1038/s41396-017-0042-4