How viruses cause disease?

  • Viruses gain access to the host through skin and mucous membranes, and via the respiratory, gastrointestinal, and genital tracts.
  • Their virulence or lack of it may be determined by very small mutations in the genome.
  • Viral infection of cells may result in lysis, fusion and syncytium formation, the appearance of inclusion bodies, or, in some instances, transformation to cells with characteristics of malignancy.
  • Infections caused by viruses are localized at or near the site of entry or generalized to involve one or more target organs.

How viruses cause disease

  • In generalized infections a common pattern of spread during the incubation period is site of entry? local lymph nodes? primary viraemia? liver, spleen, bone marrow? secondary viraemia? target organ.
  • In humans, viral infections follow various basic patterns: acute non-persistent, acute followed by persistent latent infection, and chronic with continued shedding of virus.
  • Very rarely, papovavirus, measles virus, and prions cause long-lasting, fatal disease of the CNS.
  • During the course of infection, viruses are shed from the primary site of multiplication, or—with the exception of the CNS—from target organs, and are then free to infect other susceptible hosts.
  • The Ro number is the average number of secondary cases generated by one primary case in a susceptible community; it may be useful in predicting the course of an epidemic.

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How viruses cause disease?

About Author

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Sagar Aryal

Sagar Aryal is a microbiologist and a scientific blogger. He is doing his Ph.D. at the Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal. He was awarded the DAAD Research Grant to conduct part of his Ph.D. research work for two years (2019-2021) at Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Saarbrucken, Germany. Sagar is interested in research on actinobacteria, myxobacteria, and natural products. He is the Research Head of the Department of Natural Products, Kathmandu Research Institute for Biological Sciences (KRIBS), Lalitpur, Nepal. Sagar has more than ten years of experience in blogging, content writing, and SEO. Sagar was awarded the SfAM Communications Award 2015: Professional Communicator Category from the Society for Applied Microbiology (Now: Applied Microbiology International), Cambridge, United Kingdom (UK). Sagar is also the ASM Young Ambassador to Nepal for the American Society for Microbiology since 2023 onwards.

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