Today we’ll be discussing persistent vs latent infections – how they compare, whether or not each type is permanent, and the symptoms and effects of each.
What is a persistent infection?
Persistent viral infections are those that are not eliminated from the host’s body even after symptoms of primary infection (if any) have disappeared. Viral genetic material will remain linked to certain cells.
What is considered a latent infection?
A latent viral infection occurs when viral genetic material lies dormant or inactive in the body’s cells, causing no symptoms. Latent infections typically remain undetected by the body’s immune system and can be difficult to target with medicine. Many viruses will undergo periods of latency followed by intermittent persistent infection.
Persistent vs latent infections: the differences
Building upon the definitions given above, several distinctions exist between latent and persistent infections.
First of all, it’s important to clarify that persistent viral infections are not always separate from latent ones. Many viral infections that are deemed persistent (see examples below) also include a stage of latency.
At the latent stage, the virus cannot be detected outside of the cell. Thus, latency is when the virus is asymptomatic, as the virus is not actively attacking at that time and cannot be detected by the immune system. During latent infection, the virus lies dormant in the body, so symptoms rarely present.
On the other hand, a persistent infection will likely cause symptoms as the virus is rapidly multiplying outside of the cell and becoming more aggressive. Unlike at the latent stage, a persistent virus remains infectious during this process. The virus is active at this stage, as opposed to dormant.
A chronic persistent infection will eventually be eliminated from the host, while a latent infection is lifelong. Persistent infections occur when the host’s immune system cannot fight off the initial bout of infection (or symptoms) and return to a state of viral dormancy; thus, infection continues. Therefore, persistent infections can spread into other areas of the body – impacting the central nervous system, for example.
Persistent infection examples
- Epstein-Barr Virus
- Human Immunodeficiency Virus (HIV-1)
- Varicella-Zoster Virus (Chickenpox)
- Measles Virus
- Human Cytomegalovirus
Persistent infection symptoms
Persistent infection symptoms depend on the organism that causes them. They can be caused by bacteria as well as viruses. Bacterial infections can usually be treated with medication such as antibiotics, but viral infections cannot be eradicated with antibiotics.
It’s therefore important to recognize the symptoms of a persistent viral infection. For example, Epstein-Barr virus – one of the most common viruses in humans worldwide – causes mononucleosis (‘the kissing disease’) when it becomes active (after its initial latent stage).
The symptoms of mononucleosis include:
- Swollen lymph nodes
- Fatigue
- Fever
- Headache
Many persistent viral infections will cause similar symptoms, as well as rashes, aches and pains, nausea, stomach upset, and loss of appetite or weight loss. Any unexplained symptoms like these should be discussed with a medical professional, who can recommend the best course of action.
Some persistent infections can spread throughout the body when untreated. As the immune system grows weaker, the infection can more easily spread while the body’s main defenses are down. For example, following an episode of mononucleosis, Epstein-Barr virus may spread into other organs, such as the liver or the kidneys, and cause further infection. In serious cases, EBV can increase the host’s risk of developing EBV-linked cancer. (This happens in very rare cases, and it is not possible to predict in advance who this will happen to.)
One of the best ways to prevent viral infection from spreading or getting worse is to maintain a healthy lifestyle and take care of the body’s immune system. This may include steps such as getting enough sleep, avoiding alcohol, quitting cigarettes, and eating a healthy and varied diet.
Featured image by Andrea De Santis on Unsplash: Persistent vs latent infections: here’s everything you need to know.
Latent infection examples:
- Hepatitis B
- Chronic Congenital Rubella
- CMV
- Adenovirus
Are latent infections permanent?
Are latent infections curable or permanent? This depends on the infection. Latent viral infections cannot usually be cured, as the viral cells will stay within the host for their lifetime. Viral infections don’t cause symptoms at the latent stage and the host may not even be aware that they are infected.
While the virus itself cannot be eliminated from the body’s cells, symptoms (which present during cycles of persistent infection) can be treated using pain relief or other suitable methods recommended by a medical professional. So while viral infections may not be curable, symptoms of an infection can be managed.
Featured image by Towfiqu barbhuiya on Unsplash
