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Minimum Infective Dose of the Major Human Respiratory and Enteric Viruses Transmitted Through Food and the
Saber Yezli1, Jonathan A Otter2
1Bioquell UK Ltd, 52 Royce Close, West Portway, Andover, Hampshire, SP10 3TS, UK. saber.yezli@bioquell.com.
Abstract:
Viruses are a significant cause of morbidity and mortality around the world. Determining the minimum dose of virus particles that can initiate infection, termed the minimum infective dose (MID), is important for the development of risk assessment models in the fields of food and water treatment and the implementation of appropriate infection control strategies in healthcare settings. Both respiratory and enteric viruses can be shed at high titers from infected individuals even when the infection is asymptomatic. Presence of pre-existing antibodies has been shown to affect the infectious dose and to be protective against reinfection for many, but not all viruses. Most respiratory viruses appear to be as infective in humans as in tissue culture. Doses of <1 TCID50 of influenza virus, rhinovirus, and adenovirus were reported to infect 50% of the tested population. Similarly, low doses of the enteric viruses, norovirus, rotavirus, echovirus, poliovirus, and hepatitis A virus, caused infection in at least some of the volunteers tested. A number of factors may influence viruses' infectivity in experimentally infected human volunteers. These include host and pathogen factors as well as the experimental methodology. As a result, the reported infective doses of human viruses have to be interpreted with caution.
Insights
Determining the minimum infective dose (MID) of viruses is crucial for public health. Even low virus doses can cause infection, highlighting the need for careful interpretation of experimental data.
Area of Science:
- Virology
- Infectious Diseases
- Public Health
Background:
- Viruses cause significant global morbidity and mortality.
- Understanding the minimum infective dose (MID) is vital for risk assessment and infection control.
- Asymptomatic shedding of respiratory and enteric viruses occurs at high titers.
Purpose of the Study:
- To review the factors influencing viral infectivity and the minimum infective dose (MID) in humans.
- To highlight the importance of MID in food/water safety and healthcare infection control.
- To discuss the interpretation of experimental data on viral infectivity.
Main Methods:
- Review of existing literature on human viral infection studies.
- Analysis of reported minimum infective doses (MID) for various respiratory and enteric viruses.
- Consideration of host, pathogen, and experimental factors affecting infectivity.
Main Results:
- Low doses (e.g., <1 TCID50) of influenza, rhinovirus, adenovirus, norovirus, rotavirus, echovirus, poliovirus, and hepatitis A virus can cause infection in humans.
- Pre-existing antibodies can influence infectivity and protection against reinfection.
- Respiratory viruses generally show similar infectivity in humans and tissue culture.
Conclusions:
- The minimum infective dose (MID) for many human viruses is low, posing a risk even at sub-clinical levels.
- Factors such as host immunity, viral characteristics, and experimental methods influence reported MIDs.
- Reported viral infective doses require cautious interpretation due to variability in influencing factors.
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