Dirty Money
To control influenza outbreaks or a pandemic, it is important to identify and characterize the different vectors that could promote influenza virus transmission between people. The respiratory tract of influenza virus-infected individuals is the main reservoir for the chain of transmission in a community. Based on experiments with animal models and observational field studies, large respiratory droplets are considered to be the most frequent vectors sustaining influenza transmission. However, experimental studies with animals with no direct contact have demonstrated that aerosols also play a significant role. In humans, the hypothesis that there is an aerosol route of transmission is supported by indirect evidence in special circumstances, such as confinement for a prolonged period of time in an airplane in the presence of a patient infected with influenza virus. In addition, it has been documented that human influenza A viruses can survive for a prolonged period on different types of surfaces once they are present in the environment. Although controversial, the possibility that contaminated surfaces and fomites could act as vectors of transmission needs to be considered in the context of overall influenza pandemic preparedness.
For any environmental contamination to be relevant, the virus should not only remain infectious but also persist at a sufficient concentration to enable it to reach the respiratory tract via finger contamination. Rhinovirus is the most common respiratory virus known to be easily transmitted by this route. Whether influenza virus is also commonly transmitted by this route remains a subject of debate. However, given that the biological properties of a potential influenza virus pandemic strain have not been established, this route of transmission has to be considered. The severe acute respiratory syndrome coronavirus SARS highlighted the ability of respiratory viruses to act in unconventional ways since environmental contamination by stools played a significant role in some population clusters. All these questions should be considered not only from a scientific standpoint. We must also take into account and provide answers to the many possible questions raised by various communities and public health authorities.
The authors of a recent paper hypothesized that banknotes may be one of various possible influenza vectors and may offer opportunities for infection. In Switzerland, a small country with a population of approximately 7 million, it is estimated that 20 to 100 million banknotes are exchanged each day, and billions of individual notes are exchanged daily worldwide. So could influenza be transmitted by money?
Survival of influenza virus on banknotes. Appl Environ Microbiol 2008 74: 3002-7
Successful control of a viral disease requires knowledge of the different vectors that could promote its transmission among hosts. We assessed the survival of human influenza viruses on banknotes given that billions of these notes are exchanged daily worldwide. Banknotes were experimentally contaminated with representative influenza virus subtypes at various concentrations, and survival was tested after different time periods. Influenza A viruses tested by cell culture survived up to 3 days when they were inoculated at high concentrations. The same inoculum in the presence of respiratory mucus showed a striking increase in survival time (up to 17 days). Similarly, B/Hong Kong/335/2001 virus was still infectious after 1 day when it was mixed with respiratory mucus. When nasopharyngeal secretions of naturally infected children were used, influenza virus survived for at least 48 h in one-third of the cases. The unexpected stability of influenza virus in this nonbiological environment suggests that unusual environmental contamination should be considered in the setting of pandemic preparedness.
Related:
- Influenza virus transmission is dependent on humidity and temperature
- Global migration of influenza viruses
- UK national framework for responding to an influenza pandemic
- Negative sense RNA viruses
Tags: Biology, Environment, Health, Influenza, Medicine, Microbiology, Science, Virology
Computer keyboards, public telephones and mobile sets in addition, are similar offenders (fomites). Some banknotes also contain cocaine, as have been determined by tandem mass spectrometry.