Virus is one of the most popular words in the last year and a half. We all know that we need to protect ourselves from it, and we also remember that there are many other microorganisms around - for example, bacteria. By the way, how are they different from viruses? What do antibiotics actually help with, and why should you be vaccinated against the flu every fall? Are viruses and bacteria the only representatives of the microcosm? Is it possible to create a universal medicine to get rid of dangerous microorganisms once and for all? To answer these questions and know how to protect yourself from them, you need to understand what these invisible creatures are. In this article we will find out what microorganisms, viruses and bacteria are, and why universal weapons will never appear from them.
- Viruses, microbes, bacteria - what are they? Viruses
- Bacteria
- Microbes
Viruses, microbes, bacteria - what are they?
Viruses
Strictly speaking, viruses are not exactly creatures: scientists call them non-cellular life forms or even organisms on the border of life. This is because viruses1 do not have an important property of living things - a cellular structure, which is found in all animals, plants, fungi and bacteria. They do not have their own metabolism, so they cannot live on their own. To exist, they always need another organism; in fact, viruses are intracellular parasites.
The sizes of viruses range from 20 to 350 nm (a nanometer is one millionth of a millimeter). The smallest are parvoviruses, which cause diseases in animals: only 18 nm in diameter. Larger influenza viruses: 80–120 nm. And the causative agents of smallpox and trachoma are absolutely “giants”: they reach 300 nm, and they can even be viewed with a regular light microscope (and to see smaller viruses, you need an electronic one).
Although viral diseases have haunted people at all times, viruses themselves were discovered only recently by historical standards: their existence was confirmed in 1892 by Russian microbiologist Dmitry Ivanovsky. As a student, he studied plant diseases and became interested in the nature of tobacco mosaic disease. After several years of experiments, Ivanovsky was able to see clusters of the causative agent of this disease in a light microscope, after which he spoke about his research in an article. And the first causative agent of a human viral disease, yellow fever, was discovered only in 1901. And only in 1937 was it possible to develop a vaccine against it, but this disease has been killing people for several centuries! Since their discovery, viruses have been actively studied, but most of them are still not even systematized. But new viruses appear regularly! Moreover, there is not even a single hypothesis about how viruses originated that all virologists would agree with. Some consider them to be descendants of pre-cellular life forms, others - “escaped” genetic structures that have won a little independence from cells. But the number of all viruses on the planet has already been calculated: 10 to the 39th power is more than stars in the Universe. Before obtaining such a number, scientists found out that more than 800 million viruses accumulate every day in a square meter of the lower layer of the earth’s atmosphere.
Viruses are designed very succinctly - because of this, scientists once considered them to be inert crystals. These “crystals” look different in appearance - they can be spherical, spiral-shaped, oblong. But, in essence, any viruses are just a shell containing genetic material in the form of DNA or RNA molecules. This “or” is an important difference between a virus and us living beings: our cells always contain both: DNA and RNA. But what we have in common with the virus is the desire to multiply our genetic material. To do this, viruses must enter a living cell. It happens that the viral genome simply integrates into the host DNA, and years may pass before the virus “wake up.” And if the virus enters the germ cells and integrates into the chromosomes, then it will be transmitted to the descendants of the host. The human genome contains a lot of such inclusions (approximately 8%) obtained millions of years ago during evolution. Some of them are gradually destroyed, while others have proven useful to us and are involved in physiological processes. For example, in 2021, scientists found3 that a gene of viral origin plays a critical role in the formation of our long-term memory.
But what if the virus doesn’t want to hide, but craves activity? Then its genetic material actually takes over command in a living cell: it forces it to multiply its copies, which penetrate into more and more new tissues and organs. And during this “stamping”, a process occurs due to which viruses acquired the reputation of insidious killers. New viruses are not produced as 100% copies; some come out with an “error,” i.e., a slightly altered genome. These are viral mutations that help the microorganism survive, despite the efforts of the body, which is actively fighting the infection. Due to mutations, viruses can look different and deceive the immune system - it has to re-acquaint itself with it and develop a fight strategy. This trick is actively used by influenza viruses, which mutate continuously and come to us every year in the form of new strains. But the most successful situation for a virus is to be in the same cell with its “colleagues” of another species: for example, when human, bird and monkey viruses meet. Then they can exchange entire pieces of the genome, and the result will be a fundamentally new strain, a powerful and dangerous mutant that even interspecies barriers will not stop - it can first infect an animal and then a person. Such viral experiments tend to happen in hot, overpopulated countries where sanitation is poor and people are more likely to come into contact with wild and farm animals. That's why we hear so often that a new infection has broken out in Southeast Asia.
Bacteria
Unlike viruses, bacteria are the most living organisms, although they are also very small (up to 10 microns long, that is, one hundredth of a meter). They are single-celled, but this one cell can have different shapes: bacteria can be round, in the form of rods, stars or cubes, there are even corrugated and C-shaped ones. Bacteria are more complex in structure than viruses - they have a cell wall, intracellular structures, organelles, and flagella for movement. They live and reproduce independently (using simple division).
Bacteria are one of the first inhabitants of the Earth, and they are also the most ubiquitous - they are found even in places where no one can survive at all. Bacteria are not afraid of either cold or acidic springs, where the water temperature is almost 100° C. They live in the Dead Sea, in the lower layer of the stratosphere, in the Mariana Trench, and even in radioactive waste. Scientists have described approximately 10 thousand species of bacteria, but in reality there are many more. The first to see bacteria was the Dutch scientist Antonie van Leeuwenhoek in 1676. He wanted to find out why hot pepper irritates the tongue, and decided to study the pepper tincture under a microscope. Imagine the naturalist’s surprise when he saw moving creatures in a tiny drop! Leeuwenhoek called them “animakuli” and began looking everywhere: in rainwater, on clothes, in scrapings from his own teeth. He spoke about his observations in a letter to the Royal Society of London for the Advancement of Knowledge of Nature. But real interest in Leeuwenhoek’s discovery arose much later, closer to the middle of the 19th century, when the cell theory began to develop.
Microbes
When you tell your child that there are a lot of germs around, you are not wrong. Microbes, or microorganisms, is the collective name for all living things that are smaller than 0.1 mm and cannot be seen with the naked eye. These include protozoa (microscopic single-celled animals), bacteria and tiny fungi, as well as viruses (not all scientists agree with this, since viruses are still not living organisms). The term “microbe” combines the Greek μικρό (small) and βίος - life. Most microbes consist of a single cell, but some are multicellular.
Furuncle
It is also an inflammation of the hair follicle and surrounding tissues. The difference with follicular inflammation is that during the formation of a boil, death and destruction of the tissue around the follicle occurs. A tumor is formed containing dead tissue, which either spontaneously or as a result of intervention is separated, leaving a skin defect.
Furuncle
The damage takes several days to form and is often painful. The skin is initially bright red and swollen, and after a few days a pimple forms on its surface. After healing, a scar may remain.
What is more dangerous - viruses or bacteria?
But it is impossible to answer this question: viruses and bacteria can be both dangerous and harmless, depending on the situation. Most people calmly tolerate seasonal flu - an annual viral disease, but at the beginning of the twentieth century, the Spanish flu claimed, according to various estimates, 3-5% of the world's population. Terrible epidemics of the past - plague, cholera, smallpox - were caused by bacteria, but we easily come into contact with millions of other bacteria every day. By the beginning of July 2021, the new coronavirus infection had already affected more than 182 million people worldwide, while practice shows that, although initially highly pathogenic, new viruses become less dangerous over time. As you can see, the danger that viruses or bacteria pose depends on their “species” characteristics. As for resisting viruses and bacteria, there are difficulties in both cases.
If the virus has already entered the cell, it cannot be killed - you can only wait for the body to cope with it. Therefore, the best way to fight infection is to prevent it from happening. This is why vaccination exists: during vaccination, the immune system becomes familiar with the virus and develops a control strategy in advance. It was with the help of vaccines that people defeated viral diseases from which there was once no salvation. If today we suddenly begin to refuse vaccinations en masse, we risk going back to the past - almost forgotten diseases will begin to affect us again: smallpox, measles, tetanus, etc. However, in the case of frequently mutating viruses, vaccinations do not always help. A vaccine may be effective against one strain, but useless against another, new one. That is why scientists turned their attention to the capabilities of immunity. Its main weapon in the fight against viruses is interferon proteins, which the body produces in response to invasion. They have a nonspecific effect, that is, they act on a wide range of viruses. Interferons were created in the process of evolution, currently being an integral part of antiviral immunity. However, interferon may not be enough; this happens for various reasons: childhood and old age, the presence of concomitant diseases, pregnancy and others. It is in such cases that experts may recommend interferon-based drugs, such as Viferon.
People also learned to fight dangerous bacteria long ago - with the help of antibiotics (note: they do not affect viruses, since they were developed for a completely different form of life!). But there is another problem: bacteria develop resistance to them over time. And the more often we use them, the more bacteria there are that are not at all sensitive to them. For example, today bacteria are already indifferent to penicillin, with which the history of antibiotics once began. And 80 years have passed since its first use. New antibiotics are also being developed, but this is a very long and expensive process, so existing drugs are often modified.
Folliculitis and fever
As the name suggests, it is an inflammation of the hair follicle. This condition manifests itself in the appearance of a single vesicle or numerous vesicles filled with purulent contents, sometimes riddled with hair in the center. Changes may appear on the face, trunk or limbs. Sometimes they are associated with depilatory procedures or shaving.
Folliculitis
The chronic form of folliculitis occurs more often in men on the face, especially on the chin, and less often on the scalp. This form is characterized by a duration of several months and the appearance of inflammatory tumors in the skin.
Treatment of acute inflammation of hair follicles with low intensity consists of skin disinfection and the use of topical medications containing an antibiotic. However, treatment for folliculitis is often difficult and lengthy.
What diseases are caused by viruses?
Among all the viruses studied (and this is about 6000), a very small part is pathogenic. Human viral diseases - influenza, measles, smallpox, polio, mumps, rubella, herpes, infectious mononucleosis, hepatitis, encephalitis, AIDS, etc. In animals - foot and mouth disease, plague, rabies. Plants have various mosaic diseases and jaundice. Basically, viruses do not cause harm or benefit. Among them, the most important for us are viruses that only infect bacteria: they are called bacteriophages, that is, “bacteria eaters.” They are used in agriculture to protect animals and plants from bacterial diseases. There is also an assumption that viruses help ruminants convert cellulose into sugars, which then become milk or participate in weight gain. Another merit of phages is the regulation of the number of bacteria in the ocean. The microorganisms that live there produce almost half of the earth's oxygen. If one type of bacteria suddenly begins to multiply uncontrollably, the entire food chain will be disrupted, and many species simply will not survive. Some viruses have become important components of symbiotic systems—natural “partnerships” in which organisms of different species help each other. For example, grass grows on hot soil near geysers in Yellowstone National Park (USA), which survives in extreme conditions only thanks to a fungus infected with a certain virus. And there are viruses that slow down the development of dangerous diseases in humans: for example, people infected with hepatitis G have a milder course of another infection - Ebola fever, also a viral disease. And viruses can also be used against bacterial infections: this was practiced in the USSR back in the 1920s. Today, bacteriophages are even “trained” to destroy cancer - this is called oncolytic viral therapy. As you can see, killing viruses outright is a bad idea given the benefits they bring. In addition, this is impossible even theoretically: in order to develop a universal viral poison, we must first study absolutely all viruses. In the short term this is impossible.
Furunculosis
Most often, the development of one boil occurs quickly, and healing occurs within a few days. However, it should be remembered that in the case of boils in the facial area, especially around the orbit, nose, upper lip and auricles, due to the specific vascularization of these areas and the close proximity of important structures of the central nervous system within the skull, serious complications can occur.
Furunculosis is a condition in which many abscesses occur. Numerous changes tend to coalesce and form larger tumors. These symptoms often occur in malnourished people with underlying medical conditions such as cancer or diabetes.
Treatment of boils should be carried out by a dermatologist. For a single boil, topical antiseptics and astringents are usually sufficient. Multiple boils or clustered boils should be treated with systemic antibiotics. Fusion of purulent tumors requires surgical intervention.
What diseases are caused by bacteria?
Like viruses, bacteria5 can be harmless to living organisms or pathogenic. Such parasitic bacteria enter the body and begin to feed on it, actively multiply, damaging cells and poisoning them with the products of their vital activity. This is how the disease begins. In humans, bacteria cause tuberculosis, whooping cough, meningitis, plague, typhoid, tetanus, cholera, diphtheria, furunculosis, streptococcal tonsillitis. In animals - brucellosis, anthrax. In plants, such an infection causes rot, burns, spots, and wilting. But there are still much more beneficial bacteria. For example, millions of bacteria inhabit our intestines, skin, even respiratory tract. They are called microbiota, and its balance is very important for maintaining health: it creates conditions in which harmful microorganisms cannot live. You know for sure two groups of such bacteria: bifidobacteria and lactobacilli, which live in the intestines.
Classification of bacterial diseases
Despite the huge variety of species, all bacteria can be divided into three groups:
1. Non-pathogenic - do not cause disease.
2. Opportunistic pathogens - constantly present in the human body without harming his health, but under certain conditions (decreased immunity, hypothermia, and so on) can cause the development of diseases. The most well-known opportunistic bacteria are streptococci, staphylococci, and Escherichia coli.
3. Pathogenic. Always cause the development of diseases.
Based on the location of the pathogen, the following human bacterial diseases are distinguished:
- respiratory;
- bacterial diseases of the external integument;
- blood;
- intestinal bacterial diseases.
Infectious impetigo and hepatitis
This is an acute bacterial skin disease that often affects children. As a result of the growth of bacteria, blisters filled with serous or purulent contents form on the skin. After a few days, the blisters burst, forming crusts with a characteristic honey-yellow color.
Infectious impetigo
The changes usually occur around the mouth and nose, but can occur anywhere. If the infection covers the deeper layers of the skin, small ulcers occur. Skin changes are not accompanied by general symptoms. Impetigo is highly contagious, so the epidemic can affect kindergartens and boarding schools.
The disease always requires medical consultation. Treatment with topical disinfectants and antibiotics is most often effective and sufficient.
Brief conclusions
- The most common oral diseases are tooth decay, gum disease, infectious diseases and oral cancer.
- Caries and gum disease are highly treatable in the early stages.
- The causes of infectious diseases of the oral cavity vary - from viruses to poor diet and uncontrolled use of medications.
- For prevention, it is important to review “life hygiene” and regularly visit the dentist.
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Rosacea
This is an acute inflammation of the skin and deeper tissues.
The disease can occur at any age. Skin lesions are most often localized on the face and lower extremities. The inflammatory focus of the skin is bright red, swollen, clearly demarcated from the environment, the skin is smooth and shiny. The disease is characterized by a sudden onset. Skin changes are accompanied by fever, chills and cold-like symptoms.
Rosacea
This disease can cause serious systemic disorders and should always be treated by a doctor. Without treatment, rosacea can lead to the spread of purulent infection into surrounding tissues, introducing bacteria into the bloodstream and thus causing sepsis.
The main therapeutic method for rosacea is the use of antibiotics in general. Compresses with astringents can be used locally.
