Persistence: how infections linger in the body
Miscellaneous / / May 16, 2021
Herpes, measles and coronavirus viruses can lurk in the brain and eyes. Or testicles - if you're a man.
What is persistence
PersistencePersistence (from the Latin verb persisto - "to remain", "to remain constantly") is the ability of some infections for years and even decades to linger in the body, despite taking medications and other therapy.
Scientists call the presence of such persistent pathogens persistentPersistant Viral Infections infections.
Often a virus or microbe capable of persistence does not manifest itself at all for a long time. That is, it seems to a person that the disease has receded. But there is a pathogen in the body and at any moment it can remind of its existence with a new outbreak of the disease.
Where does persistence come from
Scientists are only studying this issue so far. It is assumed that some bacteriaPersistent bacterial infections and persister cells and virusesAnatomy of Viral Persistence there are some adaptive mechanisms that allow them to quickly adapt to the effects of drugs, as well as hide from immune system.
Professor of medical sciences, infectious disease specialist William Petrie, in a column for The Conversation, saidDoes coronavirus linger in the body? What we know about how viruses in general hang on in the brain and testicles about one such mechanism, which is used, in particular, by viruses.
William Petrie
Infectionist
There are several places in the body that are poorly accessible for the immune system. These include the central nervous system, eyes, testes in men. It is very difficult to eradicate an infection that has settled there, the immune system simply cannot get it.
Such places are called by infectious disease specialistsPeripheral tolerance induction: lessons from immune privileged sites and tissues. "Immunologically privileged regions".
Although at first glance the existence of such sites seems illogical, in fact it is evolutionarily justified. Immune-protected places help us survive. Indeed, if during an infection, the immune system actively attacks, for example, the brain, causing a powerful inflammatory reaction in it, this can lead to serious physiological disorders and even death. Therefore, the body protects the organ in advance from potentially destructive immune defenses.
However, this is just one of the mechanisms that provide viruses and microbes with the opportunity for persistence. There are others. So, the same William Petrie mentionsDoes coronavirus linger in the body? What we know about how viruses in general hang on in the brain and testiclesthat some viruses may have a latent phase of development. This means that at some period of its existence the virus "sleeps": it does not infect cells, does not multiply. But then it goes into the active phase (reactivated) and begins to vigorously reproduce. This can happen months, years, or even decades after the virus has entered the body.
What viruses and bacteria are capable of persistence
The most famous example of persistence is chickenpox. After the temperature drops and the rash disappears, it seems as if the immune system has completely dealt with the infection. But this is not the case.
The causative agent of chickenpox, the varicella-zoster virus, remains in the nerve cells. Decades later, it can be reactivatedHerpes Simplex Virus Establishment, Maintenance, and Reactivation: In Vitro Modeling of Latency and cause herpes zoster (lichen) Is a painful disease in which some nerve endings become inflamed. All this is accompanied by a rash similar to chickenpox. In addition to pain, shingles often leads to serious complications.Shingles (Herpes Zoster): prolonged neuralgia, eye damage, paralysis of the cranial and peripheral nerves, inflammation of internal organs - from pneumonia and hepatitis to meningoencephalitis.
Another prime example is the measles virusPersistant Viral Infections. In some people, despite recovery and developed immunity, the virus remains in the cells of the brain. And after 5-15 years it can be reactivated, causing subacute sclerosing panencephalitis. This dangerous disease leads to a sharp deterioration in the mental state, involuntary twitching, muscle stiffness and even coma.
The Epstein-Barr virus also has the ability to persist (it causes mononucleosis), hepatitis virusesPersistent Hepatitis C Virus Infection In Vitro: Coevolution of Virus andHost B, C, D, some retroviruses (for example, HIV) and not only.
Scientists do not excludePersistent SARS ‑ 2 infections contribute to long COVID ‑ 19that the SARS ‑ CoV ‑ 2 coronavirus, which causes COVID ‑ 19, also has the ability to persist.
Perhaps the very fact that the coronavirus is permanently fixed in the cells of the nervous system and other organs becomes one of the reasons longcovid - protractedPost Covid Conditions the consequences of infection. Some reinfection cases are also possibleCOVID ‑ 19 reinfection: prolonged shedding or true reinfection?are explained by the reactivation of the virus.
When it comes to bacterial infectionsPersistent bacterial infections, antibiotic tolerance, and the oxidative stress response, then, for example, tuberculosis, salmonella gastroenteritis, bronchitis, prostatitis, inflammatory diseases of the pelvic organs can turn into a stable form.
Why persistence is dangerous
The main risk has already been voiced above. An infection lurking in the body at any time - for example, under the influence of stress, a harsh diet, or other conditions - can be reactivated. And cause an acute illness, sometimes much more serious than when you first met the virus. But this danger is not the only one.
William Petrie
Infectionist.
Being infected with a virus that can cause persistent infection means becoming infected for the rest of your life.
A person in whose body a persistent virus or microbe has settled remains a carrier of the disease. And it can transmit the infection to other people without even realizing it.
Is it possible to get rid of persistence
In theory, yes. So, for some persistent viral infections, drugs have been developed that do not givePersistant Viral Infections persistent virus to get out of the "dormant" (latent) state or multiply. Some lucky ones are lucky, and they get rid of the infection forever.
An encouraging example is chronic hepatitis C. Several years ago, it was considered incurable, that is, it was impossible to cope with the pathogen lurking in the body. But since 2013, pharmaceutical companies have begun to produce drugs, thanks to which they can say goodbye to chronic hepatitis C at leastOral Direct ‑ Acting Agent Therapy for Hepatitis C Virus Infection 90 people out of every 100 infected.
But science has not yet been able to defeat chronic hepatitis BHepatitis B. Medicines help only temporarily suppress the activity of the virus, but not get rid of it at all.
There are serious difficulties in the fight against persistent bacterial infections. Many of them do not respond to antibiotics and do not respond to treatment.Persistent bacterial infections and persister cells.
In general, the best way not to suffer from persistence is to try not to pick up a virus or bacteria capable of it. Therefore, it is important to timely vaccinate against vaccine-controlled infections. And follow the key rules of preventionHow to Prevent Infections infectious diseases.
- Wash your hands regularly. This is especially important after returning from crowded places, going to the toilet, and before preparing food.
- Do not share dishes, cups, personal hygiene items with other people.
- Try not to drink raw water from open sources.
- Wash fruits and vegetables thoroughly before eating.
- Avoid raw or undercooked meats.
- Use condoms during sex.
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