7.3.11: General Categories of Viral Infections
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- Ying Liu
- City College of San Francisco
Describe and give an example of an acute viral infection, a late complication following an acute infection, a latent viral infection, a chronic viral infection, and a slow viral infection.
Most viruses that infect humans, such as those that cause routine respiratory infections (e.g., cold viruses, influenza viruses) and gastrointestinal infections (e.g., Rotaviruses, Noroviruses), cause acute infections. Acute infections are of relatively short duration with rapid recovery.
In persistent infections, the viruses are continually present in the body. Some persistent infections are late complications following an acute infection and include subacute sclerosing panencephalitis (SSPE) that can follow an acute measles infection and progressive encephalitis that can follow rubella. Other persistent infections are known as latent viral infection. In a latent viral infection the virus remains in equilibrium with the host for long periods of time before symptoms again appear, but the actual viruses cannot be detected until reactivation of the disease occurs. Examples include infections caused by HSV-1 (fever blisters), HSV-2 (genital herpes), and VZV (chickenpox-shingles). In the case of chronic virus infections, the virus can be demonstrated in the body at all times and the disease may be present or absent for an extended period of time. Examples include hepatitis B (caused by HBV) and hepatitis C (caused by HCV). Slow infections are ones in which the infectious agents gradually increase in number over a very long period of time during which no significant symptoms are seen. Examples include AIDS (caused by HIV-1 and HIV-2) and certain lentiviruses that cause tumors in animals. Although not viruses, prions also cause slow infections.
Summary
- Acute infections are of relatively short duration with rapid recovery.
- Persistent infections are where the viruses are continually present in the body.
- In a latent viral infection the virus remains in equilibrium with the host for long periods of time before symptoms again appear, but the actual viruses cannot be detected until reactivation of the disease occurs.
- In a chronic virus infection, the virus can be demonstrated in the body at all times and the disease may be present or absent for an extended period of time.
- Slow infections are ones in which the infectious agents gradually increase in number over a very long period of time during which no significant symptoms are seen.